**Meet the editor**

Dr Muhammad Salik Javaid has been working on research, development, execution, management and policy formulation assignments with Corps of Engineers within Pakistan and abroad for over three decades. He also worked as Chief Consulting Engineer and Director General Planning for the reconstruction and rehabilitation work after the 2005 earthquake in Pakistan. He is a

graduate of Georgia Tech, Atlanta, USA where he undertook his Masters and Doctoral studies in the fields of Dam Overtopping and Ocean Bed Hydrodynamics. Presently he is heading the Department of Civil Engineering at University of Lahore at Sihala Campus, Islamabad. He has also conducted courses on 'irrigation and drainage' and 'river engineering' for civil engineering students at various campuses.

Contents

**Preface IX**

Chapter 1 **Paleodrainage Systems 3**  Luis Américo Conti

Chapter 4 **Common Approximations**

Chapter 5 **Drainage of Bank Storage**

Mashael Al Saud

**Part 1 Sustainable Drainage Systems 1**

Chapter 2 **Sustainable Drainage Systems: An Integrated**

Chapter 3 **Sustainable Urban Drainage Systems 53**  Cristiano Poleto and Rutinéia Tassi

Marcelo Gomes Miguez, Aline Pires Veról and Paulo Roberto Ferreira Carneiro

**Part 2 Subsurface Drainage – Aquifer Management 71**

**to the Water Inflow into Tunnels 73**  Homayoon Katibeh and Ali Aalianvari

**in Shallow Unconfined Aquifers 87**

**Quality in Jeddah-Makkah Aquifer Zone, West Central Arabian Shield, Saudi Arabia 109**

**Part 3 Surface Drainage – Modern Trends and Research 135**

Chapter 7 **Use of Remote Sensing and GIS to Analyze Drainage System**

**in Flood Occurrence, Jeddah - Western Saudi Coast 137**

Chapter 6 **A Study of Subsurface Drainage and Water**

Mohammed Amin M. Sharaf

**Approach, Combining Hydraulic Engineering Design, Urban Land Control and River Revitalisation Aspects 17**

Djehiche Abdelkader, Gafsi Mustapha and Kotchev Konstantin

### Contents

#### **Preface XI**

	- **West Central Arabian Shield, Saudi Arabia 109**
		- Mohammed Amin M. Sharaf
	- **Part 3 Surface Drainage Modern Trends and Research 135**

### Preface

As soon as precipitated or glaciated water is brought through the irrigation system from the rivers to the farms and agricultural fields, the dynamic equilibrium between total water, its consumptive usage, groundwater recharge and discharge is disturbed. The deep percolation of seepage, from water applied to the lands for irrigation, forms a new increment in recharge which must be drained off efficiently. The concepts of irrigation and drainage have complimented each other since the inception of organized agriculture in human society, but drainage has always prevailed as more important of the two. Temporal and spatial variability, as well as uncertainties of water's availability as a natural resource, make the surface and subsurface drainage a permanent challenge for hydraulic engineers and hydrologists. In recent years considerable amount of research material has been published on hydrology, irrigation, and reservoir planning and management.

The subject of drainage, even though more important, has somehow not received due consideration by water experts.This book on drainage systems is a step towards meeting such shortfalls. As we explore the ideas and opinions of various contributing authors, gathered from a host of professional backgrounds, we are able to understand the drainage phenomenon in all its dimensions.

The objective of providing irrigation and drainage is to assist nature in maintaining moisture in the root-zone soil within the range required for maximum agricultural production. Hence, drainage systems may not be planned and designed merely on universal drainage criteria like frequency analysis of rainfall. Multivariate hydrological factors demand that drainage systems be designed on a complete description of statistical properties of flooding caused by a joint action of multiple factors. Ancient civilizations showed great care when constructing urban drainage systems, combining objectives of collecting rainwater, preventing flooding and conveying waste. A lot can be learnt from case histories and expertise from across the world.

The aim of this book, in the borrowed words of International Commission on Irrigation and Drainage, is 'to stimulate and promote the development and application of arts, sciences and techniques of engineering, agriculture, economics, ecological and social sciences in managing water for irrigation, drainage and flood management using research and development'.

#### X Preface

For ease of comprehension and coherence in understanding, the material presented in this book has been divided into three distinct knowledge areas consisting of ten chapters. First three chapters in Part-I deal with sustainable drainage systems. Chapters IV to VI in Part-II deal with subsurface drainage mainly focusing on aquifer management. The last four chapters forming Part-III deal with surface drainage, highlighting modern trends and research.

This book provides a broad understanding of the problems and the potential for improvement of drainage, and may be used by academics, researchers and field professionals. 'Drainage Systems' could not have been written without the hard work of many eminent drainage professionals, hydrologists, water resources engineers, scholars and scientists the world over.

The consistency and perseverance of Ms. Maja Jukic, Publishing Process Manager at InTech Open Access Publisher, are recognized for her constant reminders of the deadlines. The patience and support of my wife Sultana Salik and my children Humaira, Sumayyah and Hammaad during the period I was working on this book is heartily appreciated. I am also grateful to the National University of Sciences and Technology (NUST) and University of Lahore (UoL) for providing the academic forum to undertake this assignment.

Finally, the entire concept of InTech Open Access Publishing is lauded for its global outreach and universal benefit to the human race.

> **Dr. Muhammad Salik Javaid** National University of Sciences and Technology Pakistan

X Preface

highlighting modern trends and research.

scholars and scientists the world over.

to undertake this assignment.

outreach and universal benefit to the human race.

For ease of comprehension and coherence in understanding, the material presented in this book has been divided into three distinct knowledge areas consisting of ten chapters. First three chapters in Part-I deal with sustainable drainage systems. Chapters IV to VI in Part-II deal with subsurface drainage mainly focusing on aquifer management. The last four chapters forming Part-III deal with surface drainage,

This book provides a broad understanding of the problems and the potential for improvement of drainage, and may be used by academics, researchers and field professionals. 'Drainage Systems' could not have been written without the hard work of many eminent drainage professionals, hydrologists, water resources engineers,

The consistency and perseverance of Ms. Maja Jukic, Publishing Process Manager at InTech Open Access Publisher, are recognized for her constant reminders of the deadlines. The patience and support of my wife Sultana Salik and my children Humaira, Sumayyah and Hammaad during the period I was working on this book is heartily appreciated. I am also grateful to the National University of Sciences and Technology (NUST) and University of Lahore (UoL) for providing the academic forum

Finally, the entire concept of InTech Open Access Publishing is lauded for its global

**Dr. Muhammad Salik Javaid**

Pakistan

National University of Sciences and Technology

**Part 1**

**Sustainable Drainage Systems**

**Part 1**

**Sustainable Drainage Systems**

**1**

*Brasil*

**Paleodrainage Systems**

*Escola de Artes Ciências e Humanidades – Universidade de São Paulo*

*You can never step into the same river; for new waters are always flowing on to you.*

From a geomorphological perspective, river systems can be summarized as a hierarchy of water flux processes occurring in different spatial and temporal scales, organized in a specific geographic setting coupled with a climatic system in a condition of dynamic equilibrium. At the lower and detailed level there is localized turbulent water movement within a channel, which can be described by local flux equations. On a more generic level, other aspects and run off processes must be considered such as the sediment flow dynamic, the regional slope and the wider temporal scale variation (seasonal and multi annual). They can be modeled by open channel hydraulic methods. At a broader level of analysis, one can consider the basin scale associated with the geological conditioning and regional plus global

The concept of paleodrainage, as discussed in this chapter, states that large scale changes in fluvial features should be related to wider environmental processes that can alter the very nature of the basin system, thus*,* despite the breadth of the definitions of concepts such as "paleovalley" and "paleochannel" often attributed to local variations in the drainage system (i.e. seasonal flooding or small scale lateral migration), it is considered that only dynamic processes of effective geographical changes in drainage systems can be included in this

These processes do not necessarily occur as isolated events but rather as a set of environmental changes that include variation of sediment supply, topographic and geological settings, local and regional climate, vegetation coverage, etc. In this regional context, most studies involving paleodrainage are based on two types of analysis: The geomorphological approach based on the response of the landforms to the drainage processes (described in works like Al Sulaimi *et al.* 1997, Simpson, 2004 and Dollar, 2004) and Stratigraphic approaches based on the sedimentary records of the fluvial sequences related to conceptual frameworks such as Quaternary Time Stratigraphy (Wheeler, 1958)

and Fluvial Sequence Stratigraphy (Wilgus *et al.* 1988; Strong and Paola, 2008).

**1. Introduction**

climatological context in long-term processes.

range of definitions and related to most common causes: - Downstream drowning/exposure (base level variation) Luis Américo Conti

*Heraclitus of Ephesus*

## **Paleodrainage Systems**

Luis Américo Conti

*Escola de Artes Ciências e Humanidades – Universidade de São Paulo Brasil*

*You can never step into the same river; for new waters are always flowing on to you. Heraclitus of Ephesus*

### **1. Introduction**

From a geomorphological perspective, river systems can be summarized as a hierarchy of water flux processes occurring in different spatial and temporal scales, organized in a specific geographic setting coupled with a climatic system in a condition of dynamic equilibrium. At the lower and detailed level there is localized turbulent water movement within a channel, which can be described by local flux equations. On a more generic level, other aspects and run off processes must be considered such as the sediment flow dynamic, the regional slope and the wider temporal scale variation (seasonal and multi annual). They can be modeled by open channel hydraulic methods. At a broader level of analysis, one can consider the basin scale associated with the geological conditioning and regional plus global climatological context in long-term processes.

The concept of paleodrainage, as discussed in this chapter, states that large scale changes in fluvial features should be related to wider environmental processes that can alter the very nature of the basin system, thus*,* despite the breadth of the definitions of concepts such as "paleovalley" and "paleochannel" often attributed to local variations in the drainage system (i.e. seasonal flooding or small scale lateral migration), it is considered that only dynamic processes of effective geographical changes in drainage systems can be included in this range of definitions and related to most common causes:

These processes do not necessarily occur as isolated events but rather as a set of environmental changes that include variation of sediment supply, topographic and geological settings, local and regional climate, vegetation coverage, etc. In this regional context, most studies involving paleodrainage are based on two types of analysis: The geomorphological approach based on the response of the landforms to the drainage processes (described in works like Al Sulaimi *et al.* 1997, Simpson, 2004 and Dollar, 2004) and Stratigraphic approaches based on the sedimentary records of the fluvial sequences related to conceptual frameworks such as Quaternary Time Stratigraphy (Wheeler, 1958) and Fluvial Sequence Stratigraphy (Wilgus *et al.* 1988; Strong and Paola, 2008).

Paleodrainage Systems 5

controlled the paleo-Amazon River, which was connected to the Paleo-Orinoco until the mid Miocene period. The final breakthrough of the Amazon River towards its modern course occurred with the final uplift of the central Andean cordillera, related to the rise of the Purus

Tectonic processes have also controlled drainage evolution and basin infill trends in all active zones in the world. In the Himalayas, the Orogen began forming roughly 50 million years ago when India collided with the Asian continent producing complex relationships between regional metamorphism, anatexis, thrust faulting and normal faulting (Hodges, 2000). The establishment of the drainage systems and the evolutionary history of the fluvial network were controlled by this complex scenario characterized by both local and regional structures with multiple phases of deformation and shaped by active erosional dissection. Studies such as those done by Brookfield (1998), Zeitler *et al*, (2001), Najman *et al*. (2003), Clift and Blusztajn (2005), among others, affirmed that the transpressional tectonics across the Himalayan arc have produced large variations in fluvial morphodynamic processes in rivers such as the Indus, Kunar, Marsyangdi and Ganges. Most of these changes as

Fig. 1. Drainage distribution of Northern and Central areas of South America indicating the Amazon/Andes paleodrainage system (and flow direction) during Oligocene (modified

Furthermore, the climatic and erosional processes related to such uplifts, which have determined the resultant landscape structure, are as important as the direct upward topographic responses to tectonic forces. Finnegan *et al*. (2008) analyzing the balance between uplift of the Namche Barwa massif in Tibet related to the Yarlung Tsangpo–

after Potter, 1997 and Horn *et al.* 2010).

Arch (Gregory-Wodzicky, 2000; Figueredo *et al.*, 2009) (Figure 1).

described in Clift *et al.* (2006) can be related to capture/reversal processes.

Moreover, regardless of methodological differences, the analysis of ancient drainage patterns is almost always related to the tracking of large scale environmental conditions, especially those related to Quaternary glacial cycles and tectonic processes; however, it has also been seen as a means to provide a context for observed historical trends and to predict near future conditions in a changing climate as well as human intervention in land cover scenarios (Bloom & Tronqvst, 2000) and the understanding of the dynamic evolution of natural drainage systems can reveal important insights into the modeling, design and implementation of sustainable methodologies that integrate innovative water resource management and land use planning, which is the main focus of this book.

#### **2. Paleodrainage and environmental changes – why do rivers change?**

#### **2.1 Tectonic control and paleodrainage**

Tectonic conditioning of drainage changes have been widely described in the literature, and it is usually studied on the regional and continental scale. It can be considered the most dramatic effect not only for conditioning the pattern and texture of the drainage itself but also for determining the characteristics and amount of sediment that is transported to downstream depositional basins and where this sediment is delivered. Uplift, subsidence and faulting, all modify the overall shape of drainage systems, altering parameters such as slope, valley floor and channel gradient. The form and magnitude of these changes will depend on the amount of deformation and the capacity of the channels to adjust to the altered slope (Shumm, 1977; 1985), thus, in order to understand how tectonic evolution impacts drainage development, evolution and preservation, it is necessary to examine the coupling of externally (allogenic) and internally generated (autogenic) forces.

Examples of the characterization of how the tectonic events impacts drainage development especially associated with orogenic belts - are described in Burbank and Anderson (2001). A good example of such relationships between tectonic processes and drainage changes on a large scale is the case of rivers in Patagonia at the southern end of South America as described in Wilson 1991 and Tankard *et al.* 1995. The rifting process that separated South America and Africa first occurred at the southern part of the continent during the Middle Jurassic, and the development of broad uplifts, rifting and aulacogens were key factors in establishing the drainage patterns. The ancestral flow of the paleo Colorado and Negro rivers, for example, was associated with the Mesozoic paleosurfaces with sources east and north of the Neuquen basin directed to the Pacific Ocean. The Upper Cretaceous Andes arc uplift caused reversion of the slope direction to the southeast, yielding the rivers to flow to the Atlantic, skirting the north side of the Somuncura uplift (Potter, 1997).

The Andean uplift also has controlled the paleo-geographic settings of all drainage in the central and northern cordillera region modifying the position of rivers such as the Orinoco and Magdelena at northwestern part of South America. As described in Horn *et al.* 1995 and Diaz de Gamero, 1996, during the Middle Eocen, the Orinoco River had been flowing southnorth, draining the Central Cordillera of Colombia and the Guayana Highlands, with its mouth associated with the Lake Maracaibo and Caribbean Sea. After the Late Miocene period, the Andes attained their present configuration following the Eastern Cordillera uplift and the southwestern end of the Merida Andes deformation shifted the course of the river, deflecting it to a west-east direction. The eastern and central Cordillera uplift also

Moreover, regardless of methodological differences, the analysis of ancient drainage patterns is almost always related to the tracking of large scale environmental conditions, especially those related to Quaternary glacial cycles and tectonic processes; however, it has also been seen as a means to provide a context for observed historical trends and to predict near future conditions in a changing climate as well as human intervention in land cover scenarios (Bloom & Tronqvst, 2000) and the understanding of the dynamic evolution of natural drainage systems can reveal important insights into the modeling, design and implementation of sustainable methodologies that integrate innovative water resource

management and land use planning, which is the main focus of this book.

coupling of externally (allogenic) and internally generated (autogenic) forces.

the Atlantic, skirting the north side of the Somuncura uplift (Potter, 1997).

**2.1 Tectonic control and paleodrainage**

**2. Paleodrainage and environmental changes – why do rivers change?**

Tectonic conditioning of drainage changes have been widely described in the literature, and it is usually studied on the regional and continental scale. It can be considered the most dramatic effect not only for conditioning the pattern and texture of the drainage itself but also for determining the characteristics and amount of sediment that is transported to downstream depositional basins and where this sediment is delivered. Uplift, subsidence and faulting, all modify the overall shape of drainage systems, altering parameters such as slope, valley floor and channel gradient. The form and magnitude of these changes will depend on the amount of deformation and the capacity of the channels to adjust to the altered slope (Shumm, 1977; 1985), thus, in order to understand how tectonic evolution impacts drainage development, evolution and preservation, it is necessary to examine the

Examples of the characterization of how the tectonic events impacts drainage development especially associated with orogenic belts - are described in Burbank and Anderson (2001). A good example of such relationships between tectonic processes and drainage changes on a large scale is the case of rivers in Patagonia at the southern end of South America as described in Wilson 1991 and Tankard *et al.* 1995. The rifting process that separated South America and Africa first occurred at the southern part of the continent during the Middle Jurassic, and the development of broad uplifts, rifting and aulacogens were key factors in establishing the drainage patterns. The ancestral flow of the paleo Colorado and Negro rivers, for example, was associated with the Mesozoic paleosurfaces with sources east and north of the Neuquen basin directed to the Pacific Ocean. The Upper Cretaceous Andes arc uplift caused reversion of the slope direction to the southeast, yielding the rivers to flow to

The Andean uplift also has controlled the paleo-geographic settings of all drainage in the central and northern cordillera region modifying the position of rivers such as the Orinoco and Magdelena at northwestern part of South America. As described in Horn *et al.* 1995 and Diaz de Gamero, 1996, during the Middle Eocen, the Orinoco River had been flowing southnorth, draining the Central Cordillera of Colombia and the Guayana Highlands, with its mouth associated with the Lake Maracaibo and Caribbean Sea. After the Late Miocene period, the Andes attained their present configuration following the Eastern Cordillera uplift and the southwestern end of the Merida Andes deformation shifted the course of the river, deflecting it to a west-east direction. The eastern and central Cordillera uplift also controlled the paleo-Amazon River, which was connected to the Paleo-Orinoco until the mid Miocene period. The final breakthrough of the Amazon River towards its modern course occurred with the final uplift of the central Andean cordillera, related to the rise of the Purus Arch (Gregory-Wodzicky, 2000; Figueredo *et al.*, 2009) (Figure 1).

Tectonic processes have also controlled drainage evolution and basin infill trends in all active zones in the world. In the Himalayas, the Orogen began forming roughly 50 million years ago when India collided with the Asian continent producing complex relationships between regional metamorphism, anatexis, thrust faulting and normal faulting (Hodges, 2000). The establishment of the drainage systems and the evolutionary history of the fluvial network were controlled by this complex scenario characterized by both local and regional structures with multiple phases of deformation and shaped by active erosional dissection. Studies such as those done by Brookfield (1998), Zeitler *et al*, (2001), Najman *et al*. (2003), Clift and Blusztajn (2005), among others, affirmed that the transpressional tectonics across the Himalayan arc have produced large variations in fluvial morphodynamic processes in rivers such as the Indus, Kunar, Marsyangdi and Ganges. Most of these changes as described in Clift *et al.* (2006) can be related to capture/reversal processes.

Furthermore, the climatic and erosional processes related to such uplifts, which have determined the resultant landscape structure, are as important as the direct upward topographic responses to tectonic forces. Finnegan *et al*. (2008) analyzing the balance between uplift of the Namche Barwa massif in Tibet related to the Yarlung Tsangpo–

Paleodrainage Systems 7

Fig. 2. Drainage distribution of Southern Africa with the paleodrainage prior to the union of the middle and upper Zambezi in the early Pleistocene (modified after Thomas and Shaw,

localized events displacing and rearranging local streams. Oilier (1995), describes the relationship between directions of rivers in southeastern Australia (e.g. Hunter, Lachlan and Murrumbidgee) which reversed courses due to an Eocene/ early Oligocene Volcanism effect. On a more localized scale, Branca and Ferrara, 2001, mapped the ancient valley of the Alcantara and S. Paolo Rivers, below the northern flank of Mt Etna. The paleo-valley was filled by lava flow and volcano-sedimentary debris during several events starting from

The first empirical works relating environmental changes with variations in fluvial patterns always attempted to establish a direct correlation between climate changes and the settlement of morphosedimentary processes in drainage systems. Penk (1927) proposed links between incision and deposition patterns of fluvial canals in the Danube River region with glacial climatic cycles, which eventually became one of the main geo-indicators for the existence of glacial cycles. According to the authors, the sequence of terraces formed in fluvial plains would have resulted from alternating glacial (aggradation process) and interglacial (incision process) periods, forming the sequence of terraces that indicate specific environmental conditions. Davis, 1896, recognized the relationship between river

displacement and climatic changes studying the Moselle River (northern France).

1991 and Goudie, 2005).

170,000 years B.P. until 20,000 years B.P.

**2.2 Climatic and hydrologic changes**

Brahmaputra River system, concluded that the regional denudation driven by extreme efficient river incision, removes a large quantity of sediments yielding to a local relief producing erosional and thermo-mechanical coupling in an active orogen, thrusting Namche Barwa-Gyala Peri above the surrounding landscape in a process of "tectonic aneurysm" (Koons *et al.* 2002 and Simpson, 2004).

The tectonic dynamics can also affect large-scale drainage patterns through volcanism and distention processes in divergent plates. In the African continent there are at least two examples of rivers indicating complex histories involving shifts in the nature of their catchments and courses, associated with volcanism and rifting process. The Nile may be one of the most remarkable examples of drainage evolution in response to non-orogenic tectonic deformation. The Nile evolution model described by Sahin (1985), Foucault and Stanley (1989); Issawi and McCauley (1992) and Goudie (2004), details five phases since the late Eocene.

The first phase (called the "Gilf system" - Eocene) was marked by the presence of a set of parallel north flowing drainages occupying most of northeastern Africa and the present Nile Basin position fed by streams originating from eastern highlands (Red Sea area). The second Stage (Qena system - Miocene) was marked by intense tectonic activity followed by the reversion of the drainages taking up a southward position as well as establishing an immense river flowing south towards Aswan and the Sudan. The third stage (the Nile system – Late Miocene) was marked by a dramatic drop of the base level of the Mediterranean Sea (associated with the closure of the Straits of Gibraltar and the Messien Event – Gautier *et al.*, 1994) producing intense erosional activity forming gorges and canyons (designated as Eonile). As a result of such shifts, the Eonile took a northerly course. The fourth phase (Pliocene flooding), in the early Pliocene, the sea level rose at least 125 m so that an estuary or ria extended more than 900 km inland, reaching Aswan. After the Pleistocene, the Nile has been submitted to constant changes due to climate and hydrological regimes (detailed in Foucault and Stanley, 1985; Coutelier and Stanley, 1997).

The other example of a paleodrainage system controlled by distensive tectonics is the Zambezi River. The longitudinal profile of the Zambezi River forms two concave-upward sections, with their boundary at Victoria Falls, and there are studies suggesting that these sections were disconnected fluvial systems only joined together after the late Quaternary (Goudie, 2004; Nugent, 1990). The paleo-Zambezi was connected to both the Limpopo and Luangwa River system and took its present configuration, probably after the Pliocene with the uplift of the Makagdikgadi Basin along the "Kalahari Zimbabwe axis". The new position of the Middle Zambezi permitted the capturing of east and northeast tributaries such as the Kafue and Luangwa (Thomas and Shaw, 1991) (Figure 2).

The evolutionary history of the Congo River is also linked to the tectonic processes related to south-central Africa vertical crust movements. Stankiewicz & Dewit (2006) suggested that the Congo drained into the Indian Ocean until the uplift of East African Highlands in the Oligocene or Eocene (30– 40 Ma). The Congo then became a landlocked basin, until it was captured during the Miocene by a river system causing it to drain into the Atlantic.

Examples of drainage modifications in catchments affected by the formation and erosion of volcanoes can be found in several scales, from regional drainage system displacements associated with major volcanic structures (such as *Serra Geral*/Etendeka and Deccan) to

Brahmaputra River system, concluded that the regional denudation driven by extreme efficient river incision, removes a large quantity of sediments yielding to a local relief producing erosional and thermo-mechanical coupling in an active orogen, thrusting Namche Barwa-Gyala Peri above the surrounding landscape in a process of "tectonic

The tectonic dynamics can also affect large-scale drainage patterns through volcanism and distention processes in divergent plates. In the African continent there are at least two examples of rivers indicating complex histories involving shifts in the nature of their catchments and courses, associated with volcanism and rifting process. The Nile may be one of the most remarkable examples of drainage evolution in response to non-orogenic tectonic deformation. The Nile evolution model described by Sahin (1985), Foucault and Stanley (1989); Issawi and McCauley (1992) and Goudie (2004), details five phases since the late

The first phase (called the "Gilf system" - Eocene) was marked by the presence of a set of parallel north flowing drainages occupying most of northeastern Africa and the present Nile Basin position fed by streams originating from eastern highlands (Red Sea area). The second Stage (Qena system - Miocene) was marked by intense tectonic activity followed by the reversion of the drainages taking up a southward position as well as establishing an immense river flowing south towards Aswan and the Sudan. The third stage (the Nile system – Late Miocene) was marked by a dramatic drop of the base level of the Mediterranean Sea (associated with the closure of the Straits of Gibraltar and the Messien Event – Gautier *et al.*, 1994) producing intense erosional activity forming gorges and canyons (designated as Eonile). As a result of such shifts, the Eonile took a northerly course. The fourth phase (Pliocene flooding), in the early Pliocene, the sea level rose at least 125 m so that an estuary or ria extended more than 900 km inland, reaching Aswan. After the Pleistocene, the Nile has been submitted to constant changes due to climate and hydrological regimes (detailed in Foucault and Stanley, 1985; Coutelier and Stanley, 1997). The other example of a paleodrainage system controlled by distensive tectonics is the Zambezi River. The longitudinal profile of the Zambezi River forms two concave-upward sections, with their boundary at Victoria Falls, and there are studies suggesting that these sections were disconnected fluvial systems only joined together after the late Quaternary (Goudie, 2004; Nugent, 1990). The paleo-Zambezi was connected to both the Limpopo and Luangwa River system and took its present configuration, probably after the Pliocene with the uplift of the Makagdikgadi Basin along the "Kalahari Zimbabwe axis". The new position of the Middle Zambezi permitted the capturing of east and northeast tributaries such as the

The evolutionary history of the Congo River is also linked to the tectonic processes related to south-central Africa vertical crust movements. Stankiewicz & Dewit (2006) suggested that the Congo drained into the Indian Ocean until the uplift of East African Highlands in the Oligocene or Eocene (30– 40 Ma). The Congo then became a landlocked basin, until it was

Examples of drainage modifications in catchments affected by the formation and erosion of volcanoes can be found in several scales, from regional drainage system displacements associated with major volcanic structures (such as *Serra Geral*/Etendeka and Deccan) to

captured during the Miocene by a river system causing it to drain into the Atlantic.

aneurysm" (Koons *et al.* 2002 and Simpson, 2004).

Kafue and Luangwa (Thomas and Shaw, 1991) (Figure 2).

Eocene.

Fig. 2. Drainage distribution of Southern Africa with the paleodrainage prior to the union of the middle and upper Zambezi in the early Pleistocene (modified after Thomas and Shaw, 1991 and Goudie, 2005).

localized events displacing and rearranging local streams. Oilier (1995), describes the relationship between directions of rivers in southeastern Australia (e.g. Hunter, Lachlan and Murrumbidgee) which reversed courses due to an Eocene/ early Oligocene Volcanism effect. On a more localized scale, Branca and Ferrara, 2001, mapped the ancient valley of the Alcantara and S. Paolo Rivers, below the northern flank of Mt Etna. The paleo-valley was filled by lava flow and volcano-sedimentary debris during several events starting from 170,000 years B.P. until 20,000 years B.P.

#### **2.2 Climatic and hydrologic changes**

The first empirical works relating environmental changes with variations in fluvial patterns always attempted to establish a direct correlation between climate changes and the settlement of morphosedimentary processes in drainage systems. Penk (1927) proposed links between incision and deposition patterns of fluvial canals in the Danube River region with glacial climatic cycles, which eventually became one of the main geo-indicators for the existence of glacial cycles. According to the authors, the sequence of terraces formed in fluvial plains would have resulted from alternating glacial (aggradation process) and interglacial (incision process) periods, forming the sequence of terraces that indicate specific environmental conditions. Davis, 1896, recognized the relationship between river displacement and climatic changes studying the Moselle River (northern France).

Paleodrainage Systems 9

(Maizels, 1990; Langping *et al*. 2009) since the cause-effect relationships between long term rainfall and morphodynamic of paleodrainages are not always direct. In fact, recent studies have mapped near-surface paleochannels in Namibia (Lancaster *et al,* 2000; Lancaster, 2002) indicating that during the late Quaternary, there was no significant changes in precipitation in the desert itself, but there were considerable variations with more frequent and/or longer duration discharges in ephemeral rivers, suggesting an increase of precipitation only in the

It is not only deep variations in climatologic regimes, leading to desertification and drastic opposite states of wet and dry periods, that can be responsible for considerable changes within a drainage system. In some cases, smaller scale/higher frequency variations in factors such as sediment supply, vegetation coverage or catastrophic floods can provoke considerable displacements and shifts in the fluvial systems, with or without the presence of tectonic amplification. The concepts of "River Metamorphosis" (Schumm, 1967 and 1985), "Avulsion" and "Cutoff" (Allen, 1965) and "stream piracy" (Pederson, 2001) have been proposed to describe such processes of channel migration into the watershed and have been widely studied as they are often associated with changes in climatic conditions (e.g. Hocke

Knox, (2000) in an extensive study on the Mississippi and Colorado River Valley and tributaries, described how magnitude and recurrence of paleofloods are linked to major climatic events during the Holocene and suggests that, even relatively modest, changes in climate can cause important flood episodes, and these changes in morphodynamic processes have often occurred abruptly at various time scales from decadal to millennial and even longer. Similar results were described by Benito *et al.* (2003) for the Iberian Peninsula,

Despite that fluvial system adjustments to new climatic and hydrological regimes are able to produce major responses at upstream levels, the effects of base level control in downstream levels (in response to Glacio-eustatic fluctuations) effectively can produce clear paleodrainage records in continental margins and coastal plains, and the significance of these characteristics can be very elucidating for understanding geomorphic processes associated with sea level changes. The paleodrainage characteristics is one of the main geoindicators of continental margin evolution over the Glacial periods when most of the world´s shelves were exposed to sub aerial incision during relative sea level low-stands, and the cross-shelf valleys were directly connected to the continental slope and deep marine environments. From a sequence stratigraphy point of view (see Van Wagoner *et al*. 1990), an understanding of how, when, and where incised valleys are excavated in response to sea level variations remains a topic of considerable interest since the basal surface of paleovalley fills is commonly taken to define the sequence boundary, the most commonly used bounding surface for the identification of allostratigraphic units (Tronqvist *et al.* 2005).

Models developed by Koss *et al.* (1994), Ashley and Sheridan (1994), Meijer (2001); Gutierrez *et al*. (2003), Weber *et al*. (2004) and Hori *et al*. (2002) Strong and Paola (2006) suggest that, despite continental shelves, paleovalleys can be correlated with the paleo-hydrological regime in which the channel was formed; they also can be associated with submerging processes in the incised valleys during marine transgressions, reflecting the interaction between the autogenic and allogenic forcings. Still, the relative and absolute effect of these

1977; Werritty and Ferguson , 1980; Ashworth and Ferguson, 1986; Bridge, 2003).

St.Laurent *et al*. (2001) Canada, Sih et al. (1985) and China among others.

mechanisms remains unclear (Wellner and Bartek, 2003).

upper part of the basin.

Several models involving the relationship between drainage system patterns and climate change have been proposed throughout the 20th century incorporating concepts such as hydraulic geometry (e.g. Leopold and Maddock, 1956), fluvial facies and sequence stratigraphy (e.g. Wescot, 1993) along with dating techniques (e.g. Sanderson *et al*., 2003; Zhang *et al*., 2003, Wallbrink *et al.,* 2002). In recent decades, multidisciplinary studies have proposed a more holistic approach to integrate climate change and paleodrainage pattern response affected by multiple drivers of varying spatial and temporal dominance and complexity (Knox, 1993, Ely *et al.* 1993; Gibbard and Lewin, 2002; Andres *et al.* 2002; Goodbred, 2003, Vandenberghe, 2003).

The control of glacial cycles in a fluvial system occurs at two different levels: Upstream Controls associated with Continental Interiors and Downstream Control in continental margins. At the upstream level, the relationship between variation of climatic regime and fluvial morphodynamics is usually associated with hydrological changes, on a broader scale, as a regional manifestation of a global pattern of atmospheric circulation or internal dynamics, with feedback mechanisms, while in downstream systems, the base level variations (i.e. sea-level) are the underlying drivers of erosion and incision processes.

The variations of drainage patterns in upstream systems relate to climate changes, and their association with hydrologic processes has been the focus of investigations since the publication of the earliest works on fluvial geomorphology. Patterns of marginal terrace construction in glacial periods (in contrast to incision processes in interglacial periods driven by changes in hydrological and sedimentary processes) also can produce more dramatic landforms. The climatic conditions not only affect the hydrologic regime (i.e. the flow increase or decrease in stream discharge) but also act on factors such as the vegetation coverage, weathering processes (which determines the sediment supply to the system) and the role of the sediment transport agents.

The clearest examples of geographical changes in drainage landform patterns controlled by climatic agents are the drying and desertification processes, associated with an increasingly arid climate condition. Most of the world's deserts present clear signals of paleo drainage systems related to humid periods in the past. The Sahara paleo drainage, as an example, has been investigated by McCauley *et al.*, 1986; Pachur and Kroepelin, 1987, Burke *et al*. 1989; Robinson *et al*. 2006; Ghoneim and El-Baz, 2007 among others. Beneath the mobile Eolian sand sheet, sand covers several paleo basins and channels varying from a few to hundreds of meters in width. Most of these systems have been established during the Messinian salinity crisis period (late Miocene, 5–6Ma - previously discussed) when the incision activity reached its maximum, followed by recurring activity during wet periods in the Quaternary. Paiollou *et al.* 2009, using radar images and digital terrain modeling, mapped the Kufrah and Sirt basins (Southern Libya) and concluded that the ancient Kufrah/Wadi Sahabi Rivers would have been active during wet periods (until the Holocene) showing diverse depth levels of incised channels, moreover, during the Eemian interglacial maximum, 125 k.y. ago. The Kufrah River system would have been more than 1200 km-long, comparable in size to the Egyptian Nile.

Studies showing direct links between climatic data and geomorphological analysis of paleodrainage systems in semi arid as well as desert environments are relatively rare1

<sup>1</sup> Exceptions can be found in works related to karst systems (e.g. Frumkin *et al* 1998; Defni *et al* 2010).

Several models involving the relationship between drainage system patterns and climate change have been proposed throughout the 20th century incorporating concepts such as hydraulic geometry (e.g. Leopold and Maddock, 1956), fluvial facies and sequence stratigraphy (e.g. Wescot, 1993) along with dating techniques (e.g. Sanderson *et al*., 2003; Zhang *et al*., 2003, Wallbrink *et al.,* 2002). In recent decades, multidisciplinary studies have proposed a more holistic approach to integrate climate change and paleodrainage pattern response affected by multiple drivers of varying spatial and temporal dominance and complexity (Knox, 1993, Ely *et al.* 1993; Gibbard and Lewin, 2002; Andres *et al.* 2002;

The control of glacial cycles in a fluvial system occurs at two different levels: Upstream Controls associated with Continental Interiors and Downstream Control in continental margins. At the upstream level, the relationship between variation of climatic regime and fluvial morphodynamics is usually associated with hydrological changes, on a broader scale, as a regional manifestation of a global pattern of atmospheric circulation or internal dynamics, with feedback mechanisms, while in downstream systems, the base level

The variations of drainage patterns in upstream systems relate to climate changes, and their association with hydrologic processes has been the focus of investigations since the publication of the earliest works on fluvial geomorphology. Patterns of marginal terrace construction in glacial periods (in contrast to incision processes in interglacial periods driven by changes in hydrological and sedimentary processes) also can produce more dramatic landforms. The climatic conditions not only affect the hydrologic regime (i.e. the flow increase or decrease in stream discharge) but also act on factors such as the vegetation coverage, weathering processes (which determines the sediment supply to the system) and

The clearest examples of geographical changes in drainage landform patterns controlled by climatic agents are the drying and desertification processes, associated with an increasingly arid climate condition. Most of the world's deserts present clear signals of paleo drainage systems related to humid periods in the past. The Sahara paleo drainage, as an example, has been investigated by McCauley *et al.*, 1986; Pachur and Kroepelin, 1987, Burke *et al*. 1989; Robinson *et al*. 2006; Ghoneim and El-Baz, 2007 among others. Beneath the mobile Eolian sand sheet, sand covers several paleo basins and channels varying from a few to hundreds of meters in width. Most of these systems have been established during the Messinian salinity crisis period (late Miocene, 5–6Ma - previously discussed) when the incision activity reached its maximum, followed by recurring activity during wet periods in the Quaternary. Paiollou *et al.* 2009, using radar images and digital terrain modeling, mapped the Kufrah and Sirt basins (Southern Libya) and concluded that the ancient Kufrah/Wadi Sahabi Rivers would have been active during wet periods (until the Holocene) showing diverse depth levels of incised channels, moreover, during the Eemian interglacial maximum, 125 k.y. ago. The Kufrah River system would have been more than 1200 km-long, comparable in size to

Studies showing direct links between climatic data and geomorphological analysis of paleodrainage systems in semi arid as well as desert environments are relatively rare1

1 Exceptions can be found in works related to karst systems (e.g. Frumkin *et al* 1998; Defni *et al* 2010).

variations (i.e. sea-level) are the underlying drivers of erosion and incision processes.

Goodbred, 2003, Vandenberghe, 2003).

the role of the sediment transport agents.

the Egyptian Nile.

(Maizels, 1990; Langping *et al*. 2009) since the cause-effect relationships between long term rainfall and morphodynamic of paleodrainages are not always direct. In fact, recent studies have mapped near-surface paleochannels in Namibia (Lancaster *et al,* 2000; Lancaster, 2002) indicating that during the late Quaternary, there was no significant changes in precipitation in the desert itself, but there were considerable variations with more frequent and/or longer duration discharges in ephemeral rivers, suggesting an increase of precipitation only in the upper part of the basin.

It is not only deep variations in climatologic regimes, leading to desertification and drastic opposite states of wet and dry periods, that can be responsible for considerable changes within a drainage system. In some cases, smaller scale/higher frequency variations in factors such as sediment supply, vegetation coverage or catastrophic floods can provoke considerable displacements and shifts in the fluvial systems, with or without the presence of tectonic amplification. The concepts of "River Metamorphosis" (Schumm, 1967 and 1985), "Avulsion" and "Cutoff" (Allen, 1965) and "stream piracy" (Pederson, 2001) have been proposed to describe such processes of channel migration into the watershed and have been widely studied as they are often associated with changes in climatic conditions (e.g. Hocke 1977; Werritty and Ferguson , 1980; Ashworth and Ferguson, 1986; Bridge, 2003).

Knox, (2000) in an extensive study on the Mississippi and Colorado River Valley and tributaries, described how magnitude and recurrence of paleofloods are linked to major climatic events during the Holocene and suggests that, even relatively modest, changes in climate can cause important flood episodes, and these changes in morphodynamic processes have often occurred abruptly at various time scales from decadal to millennial and even longer. Similar results were described by Benito *et al.* (2003) for the Iberian Peninsula, St.Laurent *et al*. (2001) Canada, Sih et al. (1985) and China among others.

Despite that fluvial system adjustments to new climatic and hydrological regimes are able to produce major responses at upstream levels, the effects of base level control in downstream levels (in response to Glacio-eustatic fluctuations) effectively can produce clear paleodrainage records in continental margins and coastal plains, and the significance of these characteristics can be very elucidating for understanding geomorphic processes associated with sea level changes. The paleodrainage characteristics is one of the main geoindicators of continental margin evolution over the Glacial periods when most of the world´s shelves were exposed to sub aerial incision during relative sea level low-stands, and the cross-shelf valleys were directly connected to the continental slope and deep marine environments. From a sequence stratigraphy point of view (see Van Wagoner *et al*. 1990), an understanding of how, when, and where incised valleys are excavated in response to sea level variations remains a topic of considerable interest since the basal surface of paleovalley fills is commonly taken to define the sequence boundary, the most commonly used bounding surface for the identification of allostratigraphic units (Tronqvist *et al.* 2005).

Models developed by Koss *et al.* (1994), Ashley and Sheridan (1994), Meijer (2001); Gutierrez *et al*. (2003), Weber *et al*. (2004) and Hori *et al*. (2002) Strong and Paola (2006) suggest that, despite continental shelves, paleovalleys can be correlated with the paleo-hydrological regime in which the channel was formed; they also can be associated with submerging processes in the incised valleys during marine transgressions, reflecting the interaction between the autogenic and allogenic forcings. Still, the relative and absolute effect of these mechanisms remains unclear (Wellner and Bartek, 2003).

Paleodrainage Systems 11

Examples of using of integrated methods based on multi parameter investigation of paleodrainage can be related to drying and desertification processes in which the original landform still lies only a few meters above the sand sheet, still remaining recognizable. Ghoneim & Elbaz (2007), based on SRTM elevation data obtained on a near-global scale (3 arcsec resolution) in combination with Radarsat-1 Synthetic Aperture Radar Images and Landsat TM satellite images, made a complete paleoenvironmental analysis of the Tushka basin between Egypt and Sudan (figure 3). Similar methods were used by Sultan *et al* (2004), Marinangeli (2005) Gaber *et al.* (2008) Blumberg *et al*., (2004); Griffin, (2006); Pachur and Altmann, (2006) demonstrating good potential for recognizing topographic patterns of

Fig. 3. (a) typical example of multi data INTEGRATED to characterize paleodrainage networks - Landsat ETM+ color composite (bands 7, 4, 2) covering an area in NW Sudan showing the dominance of surface sand deposits. (b) Radarsat-1 image showing a distinct subsurface drainage network trending eastward; note the absence of the surface sand deposits. (c) The SRTM DEM (90 m) with the delineated drainage network overlain; note the good correspondence between the SRTM-generated channels and the Radarsat-1 subsurface

paleodrainage in semi arid or arid areas.

channels (after Ghoneim & Elbaz, 2007).

A quite thorough review on the fluvial systems response to sea level variations can be found in Bloom and Tronquvist, 2000: According to the authors, fluvial responses to climate and sea-level change can be disaggregated into stratigraphic, morphological and sedimentological components: The stratigraphic responses are produced by aggradation due to increasing accumulation space, degradation as accumulation space decreases and lateral migration when there is no change in accumulation space and the fluvial systems in fluvial systems in subsiding basins. These are characterized by long-term net aggradation, punctuated by relatively short periods (103 - 104 years) of incision and/or lateral migration (in opposition to typical upstream valleys). Morphological responses reflect changes in channel system geometry and sedimentological responses are associated with changes along with the spatial distribution of depositional environments and proprieties of lithofacies.

#### **3. Method of analysis – tracking ancient rivers**

Paleodrainage systems, as previously mentioned, can be a powerful tool for modeling paleoenvironmental scenarios and understanding the geological and climatic dynamics in time scales that ranges from seasons to millions of years, even though the identification and characterization of such features is usually indirect and quite often requiring a detailed process of analysis and integration of data from multiple sources. Perhaps the most comprehensive review of general principles on this topic is provided by Andersen (1962) who previously recognized the main geological aspects of mapping paleodrainage distribution maps. According to the author,

*" […] paleodrainage maps can be constructed in several ways: 1) by making a structural contour map of the erosion surface at the base of the valley fill; 2) by making a number of stratigraphic crosssections which intersect the valley trends - valley axes are approximated by connecting consecutive valley low-points which have been plotted on a map; 3) by making a paleogeologic map of the surface at the base of the valley-fill - valley axes are drawn in the middle of the areas where the oldest rocks are represented; 4) by isopaching the interval between the valley floor and some datum- valley axes are where the valley floor is farthest from or closest to the datum\* depending on whether the datum is above or below the valley floor; and 3) by making an isopach# map of the valley-fill - valley axes are where the fill is the thickest. Knowledge of paleodrainage patterns in a given area allows the geologist to conclude the direction of paleoslope, local paleotopography, the approximate direction of the source area from the study area, the character of the surface into which the valleys were cut, and whether or not there was any structural activity in the study area during the time of valley carving."*

The development of new methods in geomorphology to record and quantify past and recent geomorphic processes allied with the implementation of techniques of geoprocessing and Geographic Information Systems have permitted increased accuracy in reconstructions of past environments. This new "geomorphological" approach has also provided valuable insights into the formation and evolution of fluvial systems. Mapping topographical attributes, for example, can still be the simplest and most intuitive method to recognize some aspects of the ancient fluvial geomorphology and usually can reveal several characteristics of the fluvial system. In practice, however, the original local landform is rarely preserved after morphodynamic processes that caused the changes in the fluvial patterns, so the use of elevation data (obtained from different sources) should be accompanied by further geophysical investigations, in order to track aspects of the original landform configuration.

A quite thorough review on the fluvial systems response to sea level variations can be found in Bloom and Tronquvist, 2000: According to the authors, fluvial responses to climate and sea-level change can be disaggregated into stratigraphic, morphological and sedimentological components: The stratigraphic responses are produced by aggradation due to increasing accumulation space, degradation as accumulation space decreases and lateral migration when there is no change in accumulation space and the fluvial systems in fluvial systems in subsiding basins. These are characterized by long-term net aggradation, punctuated by relatively short periods (103 - 104 years) of incision and/or lateral migration (in opposition to typical upstream valleys). Morphological responses reflect changes in channel system geometry and sedimentological responses are associated with changes along with the spatial distribution of depositional environments and proprieties of

Paleodrainage systems, as previously mentioned, can be a powerful tool for modeling paleoenvironmental scenarios and understanding the geological and climatic dynamics in time scales that ranges from seasons to millions of years, even though the identification and characterization of such features is usually indirect and quite often requiring a detailed process of analysis and integration of data from multiple sources. Perhaps the most comprehensive review of general principles on this topic is provided by Andersen (1962) who previously recognized the main geological aspects of mapping paleodrainage

*" […] paleodrainage maps can be constructed in several ways: 1) by making a structural contour map of the erosion surface at the base of the valley fill; 2) by making a number of stratigraphic crosssections which intersect the valley trends - valley axes are approximated by connecting consecutive valley low-points which have been plotted on a map; 3) by making a paleogeologic map of the surface at the base of the valley-fill - valley axes are drawn in the middle of the areas where the oldest rocks are represented; 4) by isopaching the interval between the valley floor and some datum- valley axes are where the valley floor is farthest from or closest to the datum\* depending on whether the datum is above or below the valley floor; and 3) by making an isopach# map of the valley-fill - valley axes are where the fill is the thickest. Knowledge of paleodrainage patterns in a given area allows the geologist to conclude the direction of paleoslope, local paleotopography, the approximate direction of the source area from the study area, the character of the surface into which the valleys were cut, and whether or*

*not there was any structural activity in the study area during the time of valley carving."*

The development of new methods in geomorphology to record and quantify past and recent geomorphic processes allied with the implementation of techniques of geoprocessing and Geographic Information Systems have permitted increased accuracy in reconstructions of past environments. This new "geomorphological" approach has also provided valuable insights into the formation and evolution of fluvial systems. Mapping topographical attributes, for example, can still be the simplest and most intuitive method to recognize some aspects of the ancient fluvial geomorphology and usually can reveal several characteristics of the fluvial system. In practice, however, the original local landform is rarely preserved after morphodynamic processes that caused the changes in the fluvial patterns, so the use of elevation data (obtained from different sources) should be accompanied by further geophysical investigations, in order to track aspects of the original

lithofacies.

**3. Method of analysis – tracking ancient rivers**

distribution maps. According to the author,

landform configuration.

Examples of using of integrated methods based on multi parameter investigation of paleodrainage can be related to drying and desertification processes in which the original landform still lies only a few meters above the sand sheet, still remaining recognizable. Ghoneim & Elbaz (2007), based on SRTM elevation data obtained on a near-global scale (3 arcsec resolution) in combination with Radarsat-1 Synthetic Aperture Radar Images and Landsat TM satellite images, made a complete paleoenvironmental analysis of the Tushka basin between Egypt and Sudan (figure 3). Similar methods were used by Sultan *et al* (2004), Marinangeli (2005) Gaber *et al.* (2008) Blumberg *et al*., (2004); Griffin, (2006); Pachur and Altmann, (2006) demonstrating good potential for recognizing topographic patterns of paleodrainage in semi arid or arid areas.

Fig. 3. (a) typical example of multi data INTEGRATED to characterize paleodrainage networks - Landsat ETM+ color composite (bands 7, 4, 2) covering an area in NW Sudan showing the dominance of surface sand deposits. (b) Radarsat-1 image showing a distinct subsurface drainage network trending eastward; note the absence of the surface sand deposits. (c) The SRTM DEM (90 m) with the delineated drainage network overlain; note the good correspondence between the SRTM-generated channels and the Radarsat-1 subsurface channels (after Ghoneim & Elbaz, 2007).

Paleodrainage Systems 13

In downstream systems, the subsurface mapping for locating and analyzing cut and fill structures associated with buried incised channels across continental shelves is probably one of the most widespread applications involving paleodrainage studies. Several studies have considered these factors as indicators of the paleogeography of the subaerial surface as well as the fluvial and hydrological regime during regressive events (see Reynaud *et al.,* 1999;

Despite the focus on direct analysis of channel incision surfaces and their relation to quaternary stratigraphy based on high resolution seismic data (e.g. Thorne, 1994; Lericolais *et al*., 2001; Hori *et al*., 2002; Nordfjord *et al*. 2005, Ashley and Sheridan, 1994; Zaitlin *et al*., 1994), along with the fact that they are covered by marine sediments deposited during and after rises in sea levels (Correa, 1996; Harris and O'Brien, 1996; Collina-Girard, 1999; Abreu and Cagliari, 2005; Finkl *et al*., 2005) and the small number of studies characterizing the topographic expression of the paleo-drainage registers (Strong and Paola, 2008;), it is still

possible to identify and classify the main paleo-valley axis in the surface topography.

paleovalley features in the coastal plain and on the continental shelf.

Incised valleys are also often associated with large-scale sediment bypass zones that feed downdip into large sandy deltas, so the stratigraphic characterizing of these features can provide reliable information on the general characteristics of a paleofluvial regime (Dalrymple *et al.,* 1994). Different sedimentation models based on the fluvial and marine deposition during relative rises and falls of sea level can be constructed based on direct (biostratigraphic, isotopic, and geochemistry data) and indirect (seismic data) analysis of such submarine fans. Examples in the Amazon (Mikkelsen *et al.* 1997 and Figueredo *et al.*

Conti and Furtado 2009, having studied the paleodrainage registers of the southeastern Brazilian continental shelf, observed that the paleo-valley features present diverse topographical expressions and are related differently to the drainage system that generated them. Some of those identified by the Digital Terrain Model (DEM) were quite conspicuous and easily detected, while others could only be distinguished by using enhanced filters on the topography DEM; however, there is no direct relation between the size and dimension of the paleo-valleys and the shape, form, outflow or basin characteristics of the modern rivers. A particularly interesting example of how the use of multi data in a Geographic Information System framework proved to be valuable in understanding the paleo drainage records is the case of the downstream of Ribeira de Iguape River – RIR (southeastern São Paulo state – Brazil). The analysis of remote sensing images (Landsat TM), in particular near infrared bands of the coastal plain of the river, reveal areas with high wetness index values indicating an abandoned channel feature with a divergent orientation in relation to the modern RIR position (figure 4a). A bathymetry digital terrain model (DTM) of the adjacent Continental Shelf mapped two channel-like structures in submarine topography; one clearly related to the present estuary of the RIR and another, more than 15 km southward, apparently connected to the paleochannel have been identified on satellite images (figure 4b). High-resolution seismic profiling data on the supposed point of convergence of these two features (satellite images and DTM) revealed the presence of a prominent cut and fill structure indicative of channel incision (figure 4c). The body of evidence points to two distinct positions of the RIR during two low-stand periods: one associated with the actual position of the river at the north and another one, probably older, diverging more than 30 km from the present estuary, headed seaward in a mostly direct path, forming the

Lericolais *et al*., 2003; Tesson *et al*., 2005; Meijer, 2002).

Furthermore, some of the most interesting studies in paleodrainage recognition have been developed by applying topographical analysis in conjunction with spectral information in tropical/equatorial forests. Haywakawa *et al*. (2010) has analyzed the ancient drainage complex of the Madeira River, one of the main Amazon tributaries and was able to delineate a complex system of abandoned channels due to avulsion processes during the Late Pleistocene- Holocene, despite the area being covered by dense forests (figure 4). Rossetti (2010), after analyzing topographic and spectral data has also produced satisfactory results in understanding the resulting drainage rearrangement in the Amazonian lowlands.

Fig. 4. DEM-SRTM with the regional view of the study area and the location of the paleodrainage network (dashed lines) detected in the Madeira-Manicoré Rivers. B) Topograhic profile (i–i) derived from DEM-SRTM. Observe that paleodrainage occurs in an area topographically higher than the modern Madeira valley (after Haywakawa *et al.* 2010).

Furthermore, some of the most interesting studies in paleodrainage recognition have been developed by applying topographical analysis in conjunction with spectral information in tropical/equatorial forests. Haywakawa *et al*. (2010) has analyzed the ancient drainage complex of the Madeira River, one of the main Amazon tributaries and was able to delineate a complex system of abandoned channels due to avulsion processes during the Late Pleistocene- Holocene, despite the area being covered by dense forests (figure 4). Rossetti (2010), after analyzing topographic and spectral data has also produced satisfactory results

in understanding the resulting drainage rearrangement in the Amazonian lowlands.

Fig. 4. DEM-SRTM with the regional view of the study area and the location of the paleodrainage network (dashed lines) detected in the Madeira-Manicoré Rivers. B)

Topograhic profile (i–i) derived from DEM-SRTM. Observe that paleodrainage occurs in an area topographically higher than the modern Madeira valley (after Haywakawa *et al.* 2010).

In downstream systems, the subsurface mapping for locating and analyzing cut and fill structures associated with buried incised channels across continental shelves is probably one of the most widespread applications involving paleodrainage studies. Several studies have considered these factors as indicators of the paleogeography of the subaerial surface as well as the fluvial and hydrological regime during regressive events (see Reynaud *et al.,* 1999; Lericolais *et al*., 2003; Tesson *et al*., 2005; Meijer, 2002).

Despite the focus on direct analysis of channel incision surfaces and their relation to quaternary stratigraphy based on high resolution seismic data (e.g. Thorne, 1994; Lericolais *et al*., 2001; Hori *et al*., 2002; Nordfjord *et al*. 2005, Ashley and Sheridan, 1994; Zaitlin *et al*., 1994), along with the fact that they are covered by marine sediments deposited during and after rises in sea levels (Correa, 1996; Harris and O'Brien, 1996; Collina-Girard, 1999; Abreu and Cagliari, 2005; Finkl *et al*., 2005) and the small number of studies characterizing the topographic expression of the paleo-drainage registers (Strong and Paola, 2008;), it is still possible to identify and classify the main paleo-valley axis in the surface topography.

Conti and Furtado 2009, having studied the paleodrainage registers of the southeastern Brazilian continental shelf, observed that the paleo-valley features present diverse topographical expressions and are related differently to the drainage system that generated them. Some of those identified by the Digital Terrain Model (DEM) were quite conspicuous and easily detected, while others could only be distinguished by using enhanced filters on the topography DEM; however, there is no direct relation between the size and dimension of the paleo-valleys and the shape, form, outflow or basin characteristics of the modern rivers.

A particularly interesting example of how the use of multi data in a Geographic Information System framework proved to be valuable in understanding the paleo drainage records is the case of the downstream of Ribeira de Iguape River – RIR (southeastern São Paulo state – Brazil). The analysis of remote sensing images (Landsat TM), in particular near infrared bands of the coastal plain of the river, reveal areas with high wetness index values indicating an abandoned channel feature with a divergent orientation in relation to the modern RIR position (figure 4a). A bathymetry digital terrain model (DTM) of the adjacent Continental Shelf mapped two channel-like structures in submarine topography; one clearly related to the present estuary of the RIR and another, more than 15 km southward, apparently connected to the paleochannel have been identified on satellite images (figure 4b). High-resolution seismic profiling data on the supposed point of convergence of these two features (satellite images and DTM) revealed the presence of a prominent cut and fill structure indicative of channel incision (figure 4c). The body of evidence points to two distinct positions of the RIR during two low-stand periods: one associated with the actual position of the river at the north and another one, probably older, diverging more than 30 km from the present estuary, headed seaward in a mostly direct path, forming the paleovalley features in the coastal plain and on the continental shelf.

Incised valleys are also often associated with large-scale sediment bypass zones that feed downdip into large sandy deltas, so the stratigraphic characterizing of these features can provide reliable information on the general characteristics of a paleofluvial regime (Dalrymple *et al.,* 1994). Different sedimentation models based on the fluvial and marine deposition during relative rises and falls of sea level can be constructed based on direct (biostratigraphic, isotopic, and geochemistry data) and indirect (seismic data) analysis of such submarine fans. Examples in the Amazon (Mikkelsen *et al.* 1997 and Figueredo *et al.*

Paleodrainage Systems 15

history of the ancient drainage systems. Freshwater fish, in particular, have indicated strong relationships between historical river connections and phylogeographic patterns since changes in fluvial patterns might have been the source of isolation and divergence for aquatic species, forming barriers to gene flow. In this context, a large number of studies have been suggesting even the influence of the paleodrainage on species evolution and vicariance processes as well as the other way around, resorting to biodiversity in order to reconstruct fluvial paleoenvironments (see Waters, 2001, Cook *et al.*, 2006; Ribeiro, 2006;

There are several open questions involving the evolution of drainage in response to longterm environmental changes. Some of these questions have been debated since the mid 20th century after the publication of major quantitative studies on dynamic fluvial geomorphology (e.g. Horton, 1945; Strahler, 1952; Shreve, 1969; Schumm, 1972; 1977 and 1987). Perhaps one of the most intriguing questions related to the evolution of fluvial systems is the relationship with base level low-stands. The models for incised valleys assume that relative sea-level fall produces an upstream propagating wave of rejuvenation, but how far reaching and how impacting are these processes, is still a matter for discussion. Other key aspects of paleohydrological and paleoenvironmental sciences remains unclear and uncertain, for example, the role of feedback effects on the climatic forcing (such as peak precipitation) to indirect (such as permafrost melting) and partial forcing (such as vegetation suppression) on the evolution of fluvial systems (Vandenberghe, 2003) and the temporal scales, time lapses and coupling of different stages of the geomorphic processes (Harvey, A.M., 2002)*.* In fact, most of the models for reconstructing the morphology and hydrology dynamics in response to climate change (either in continental upstream or continental shelves downstreams) are quite incomplete in delivering quantitative descriptions and predictions, therefore, the development of integrated frameworks is fundamental to

Considering further development of global warming, intense urbanization, deforestation and need for hydroelectric energy, there is no option for the near future, but to develop integrated and multidisciplinary research focused on the study of geomorphological and geological mechanisms of evolution of landscapes, in particular for fluvial systems, and it is very clear that the same uncertainties and achievements can be broadly applied to artificial drainage systems, independent of the temporal and spatial scale. Today, at least one billion people live along or near rivers and channels worldwide (Palmer *et al.* 2008) and only a complete synergy between observation and understanding of empirical evidence of paleodrainages on the local and general scale and theoretical models based on rigorous physical assumptions will provide a robust scientific body of knowledge capable of improving the accuracy and reliability of broader and better-integrated models and theories

The author would also like to acknowledge the financial support of FAPESP (Fundação de

increasing their usability for forecasting, simulating, and planning proposals.

Amparo a Pesquisa do Estado de São Paulo) – Grant: 2011/20563-4

Burridge *et al.* 2007; Flinstone *et al.* 2007).

understanding such relationships.

**5. Acknowledgments**

**4. Final remarks**

Fig. 5. Indicators of the paleo Ribeira de Iguape River – Southeastern Brazil. (a) Position of a wet lowlands indicated by vegetation indices from Landsat Images. (b) Digital Terrain Model from the continental shelf bathymetry indicating the presence of two paleovalleys (c) cut and fill structure in a high resolution seismic profile.

2009), Indus (Qayyum *et al.* 1997), Danube (Panin *et al.* 1998), and Pearl River (Pang *et al.* 2006) among others, have proven that the sediment load variability respond not only to climate changes that affect the river discharges but also to processes within the basin such as tectonic and autogenic processes.

Recent improvements in genetic analysis involving biogeography paleoenvironmental reconstructions have been making important contributions to the understanding of the

Fig. 5. Indicators of the paleo Ribeira de Iguape River – Southeastern Brazil. (a) Position of a wet lowlands indicated by vegetation indices from Landsat Images. (b) Digital Terrain Model from the continental shelf bathymetry indicating the presence of two paleovalleys (c)

2009), Indus (Qayyum *et al.* 1997), Danube (Panin *et al.* 1998), and Pearl River (Pang *et al.* 2006) among others, have proven that the sediment load variability respond not only to climate changes that affect the river discharges but also to processes within the basin such as

Recent improvements in genetic analysis involving biogeography paleoenvironmental reconstructions have been making important contributions to the understanding of the

cut and fill structure in a high resolution seismic profile.

tectonic and autogenic processes.

history of the ancient drainage systems. Freshwater fish, in particular, have indicated strong relationships between historical river connections and phylogeographic patterns since changes in fluvial patterns might have been the source of isolation and divergence for aquatic species, forming barriers to gene flow. In this context, a large number of studies have been suggesting even the influence of the paleodrainage on species evolution and vicariance processes as well as the other way around, resorting to biodiversity in order to reconstruct fluvial paleoenvironments (see Waters, 2001, Cook *et al.*, 2006; Ribeiro, 2006; Burridge *et al.* 2007; Flinstone *et al.* 2007).

### **4. Final remarks**

There are several open questions involving the evolution of drainage in response to longterm environmental changes. Some of these questions have been debated since the mid 20th century after the publication of major quantitative studies on dynamic fluvial geomorphology (e.g. Horton, 1945; Strahler, 1952; Shreve, 1969; Schumm, 1972; 1977 and 1987). Perhaps one of the most intriguing questions related to the evolution of fluvial systems is the relationship with base level low-stands. The models for incised valleys assume that relative sea-level fall produces an upstream propagating wave of rejuvenation, but how far reaching and how impacting are these processes, is still a matter for discussion. Other key aspects of paleohydrological and paleoenvironmental sciences remains unclear and uncertain, for example, the role of feedback effects on the climatic forcing (such as peak precipitation) to indirect (such as permafrost melting) and partial forcing (such as vegetation suppression) on the evolution of fluvial systems (Vandenberghe, 2003) and the temporal scales, time lapses and coupling of different stages of the geomorphic processes (Harvey, A.M., 2002)*.* In fact, most of the models for reconstructing the morphology and hydrology dynamics in response to climate change (either in continental upstream or continental shelves downstreams) are quite incomplete in delivering quantitative descriptions and predictions, therefore, the development of integrated frameworks is fundamental to understanding such relationships.

Considering further development of global warming, intense urbanization, deforestation and need for hydroelectric energy, there is no option for the near future, but to develop integrated and multidisciplinary research focused on the study of geomorphological and geological mechanisms of evolution of landscapes, in particular for fluvial systems, and it is very clear that the same uncertainties and achievements can be broadly applied to artificial drainage systems, independent of the temporal and spatial scale. Today, at least one billion people live along or near rivers and channels worldwide (Palmer *et al.* 2008) and only a complete synergy between observation and understanding of empirical evidence of paleodrainages on the local and general scale and theoretical models based on rigorous physical assumptions will provide a robust scientific body of knowledge capable of improving the accuracy and reliability of broader and better-integrated models and theories increasing their usability for forecasting, simulating, and planning proposals.

### **5. Acknowledgments**

The author would also like to acknowledge the financial support of FAPESP (Fundação de Amparo a Pesquisa do Estado de São Paulo) – Grant: 2011/20563-4

Paleodrainage Systems 17

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**2**

*Brazil*

**Sustainable Drainage Systems: An Integrated**

**Approach, Combining Hydraulic Engineering**

Floods are natural and seasonal phenomena, which play an important environmental role, but when they take place at the built environments, many losses of different kinds occur. By its side, urban growth is one of the main causes of urban floods aggravation. Changes in land use occupation, with vegetation removal and increasing of impervious rates lead to greater run-off volumes flowing faster. Intense urbanisation is a relatively recent process; however, floods and drainage concerns are related to city development since ancient times. Drainage systems are part of a city infrastructure and they are an important key in urban life. If the drainage system fails, cities become subjected to floods, to possible environmental degradation, to sanitation and health problems and to city services disruption. On the other hand, urban rivers, in different moments of cities development history, have been considered as important sources of water supply, as possible defences for urban areas, as a

Thus, there is a paradox in the relation between the water and the cities: water is a fundamental element to city life, but urbanisation is not always accompanied by the adequate planning and the necessary infrastructure is generally not provided, leading both to urban spaces and water resources degradation. An interesting historical register illustrates the problem of urban land occupation. In the 16th Century, the architect Giovani Fontana studied the Tiber River flood in the Christmas of 1598, in Rome (Biswas, 1970). Fontana's conclusions stated that the severe consequences of that flood were related to the occupation of the riparian areas near the confluences of Tiber River with different tributaries and channels, as well as to the lack of information of the people that settled their houses at those places. This situation is pretty similar to what still occurs today: lack of urbanisation planning and control, poor environmental education and the absence of a major framework to unite technical and socio-economic aspects. The main proposition of Fontana to control floods in Rome referred to the enlargement of Tiber River, in order to improve the general flow conditions – a classic view focusing on fast conveying floods to a safe downstream

way of transporting goods, and as a means of waste conveying.

**1. Introduction**

discharge.

**Design, Urban Land Control and River**

**Revitalisation Aspects**

and Paulo Roberto Ferreira Carneiro

*Federal University of Rio de Janeiro*

Marcelo Gomes Miguez, Aline Pires Veról

### **Sustainable Drainage Systems: An Integrated Approach, Combining Hydraulic Engineering Design, Urban Land Control and River Revitalisation Aspects**

Marcelo Gomes Miguez, Aline Pires Veról and Paulo Roberto Ferreira Carneiro *Federal University of Rio de Janeiro Brazil*

#### **1. Introduction**

20 Drainage Systems

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1218.

*Reviews*, 22 . 1123–1129

Floods are natural and seasonal phenomena, which play an important environmental role, but when they take place at the built environments, many losses of different kinds occur. By its side, urban growth is one of the main causes of urban floods aggravation. Changes in land use occupation, with vegetation removal and increasing of impervious rates lead to greater run-off volumes flowing faster. Intense urbanisation is a relatively recent process; however, floods and drainage concerns are related to city development since ancient times. Drainage systems are part of a city infrastructure and they are an important key in urban life. If the drainage system fails, cities become subjected to floods, to possible environmental degradation, to sanitation and health problems and to city services disruption. On the other hand, urban rivers, in different moments of cities development history, have been considered as important sources of water supply, as possible defences for urban areas, as a way of transporting goods, and as a means of waste conveying.

Thus, there is a paradox in the relation between the water and the cities: water is a fundamental element to city life, but urbanisation is not always accompanied by the adequate planning and the necessary infrastructure is generally not provided, leading both to urban spaces and water resources degradation. An interesting historical register illustrates the problem of urban land occupation. In the 16th Century, the architect Giovani Fontana studied the Tiber River flood in the Christmas of 1598, in Rome (Biswas, 1970). Fontana's conclusions stated that the severe consequences of that flood were related to the occupation of the riparian areas near the confluences of Tiber River with different tributaries and channels, as well as to the lack of information of the people that settled their houses at those places. This situation is pretty similar to what still occurs today: lack of urbanisation planning and control, poor environmental education and the absence of a major framework to unite technical and socio-economic aspects. The main proposition of Fontana to control floods in Rome referred to the enlargement of Tiber River, in order to improve the general flow conditions – a classic view focusing on fast conveying floods to a safe downstream discharge.

Sustainable Drainage Systems: An Integrated Approach,

adding value to the city itself.

roughness;

new option at the end of the 1970s (Andoh & Iwugo, 2002).

approach may be briefly described by the following points:

Combining Hydraulic Engineering Design, Urban Land Control and River Revitalisation Aspects 23

Focus on the consequences of the urbanisation process, that is, the increase of flow generation, which concentrates on storm drains, should be changed. Source control, acting on the causes of flooding and focusing on storage and infiltration measures, emerged as a

An integrated approach, considering the watershed as the planning unit, may be considered the initial basis for a sustainable system design. The design of an urban drainage system integrated with city development, aiming to reduce impacts on the hydrological cycle, acting on infiltration processes and allowing detention on artificial urban reservoirs, joining concerns, restrictions and synergies from Hydraulic Engineering and Urbanism appears as a fundamental option to treat urban floods. Besides the quantity aspects, the water quality became also a main issue and waste waters and solid waste disposal became matters to be treated together. The first flush and the washing of the catchment also introduced a new perception related to the diffuse pollution. At last, and in a complementarily way, rain water harvesting appears as an opportunity to increase water resources availability in urban environments. Several different conceptions have been proposed in the last decades, with some minor differences among them. All of them, however, tend to consider those questions in an integrated way, trying to rescue natural characteristics of the hydrological cycle, while

Coffman et al. (1998) proposed a design concept of Low Impact Development (LID). LID design adopts a set of procedures that try to understand and reproduce hydrological behaviour prior to urbanisation. In this context, the use of functional landscapes appear as useful elements in the urban mesh, in order to allow the recovering of infiltration and detention characteristics of the natural watershed. It is a change in the traditional design concepts, moving towards a site design that mimics natural watershed hydrological functions, involving volume, discharge, recharge and frequency. The main principles of this

 minimise runoff, acting on impervious rates reduction and maintaining green areas; preserve concentration times of pre-development, by increasing flow paths and surface

In a similar way, another early trend in the drainage system design evolution involved the use of stormwater Best Management Practices (BMP). The term Best Management Practices is frequently used in the USA and Canada and its origin is related with pollution control in the field of industrial wastewaters. Later, it was also referred as a possibility of nonpoint source pollution control and then associated with stormwater management. This way, stormwater BMPs are supposed to work in a distributed way over the watershed, integrating water quantity and water quality control aiming to mitigate effects generated by land use changes, with optimised costs. BMPs are designed to reduce stormwater volume, peak flows, and nonpoint source pollution through infiltration, filtration, biological or chemical processes, retention, and detention. They also may be classified into structural, when referring to installed devices and engineering solutions, or non-structural, when related to procedures changes, like limitations on landscaping practices (US EPA, 2004).

use of retention reservoir for peak discharge control and improve water quality;

use of additional detention reservoirs to prevent flooding, if necessary.

LID and BMP are very often used together and may complement each other.

As cities started to grow, especially after the Industrial Era, urbanisation problems became greater and urban floods increased in magnitude and frequency. The traditional approach for the drainage systems, which were important as a sanitation measure in the first times of the cities development, conveying stormwaters and wastewaters, turned unsustainable. Flow generation increased and end-of-pipe solutions tended to just transfer problems to downstream. In this context, in the last decades, several approaches were developed, in order to better equate flow patterns in space and time. However, not only the hydraulics aspects are important. Technical measures do not stand alone. The water in the city needs to be considered in an integrated way and sustainable solutions for drainage systems have to account for urban revitalisation and river rehabilitation, better quality of communities' life, participatory processes and institutional arrangements to allow the acceptance, support and continuity of these proposed solutions.

#### **2. Historical aspects and background of urban floods and drainage solutions**

Several ancient civilisations showed great care when constructing urban drainage systems, combining the objectives of collecting rainwater, preventing nuisance flooding, and conveying wastes. During the Roman Empire Age, significant advances were introduced in urban drainage systems. Concerns on urban flooding mitigation and low lands drainage were very important to the city of Rome, which arose among the hills of Lazio region, on the margins of Tiber River. To meet urban drainage needs, a complex network of open channels and underground pipes were constructed. This system was also used to convey people's waste from their living areas (Burian and Edwards, 2002).

During the Middle Ages, urban centres suffered a great decay and people tended to live in communities sparsely established in rural areas, near rivers, with minor concerns about urban drainage. Sanitation practices have deteriorated after the decline of the Roman Empire and surface drains and streets were used indiscriminately as the only means of disposal and conveyance of all wastewaters (Chocat *et al.*, 2001). Later, when cities started to grow significantly again, in the Industrial Era, urban drainage found itself regretted to a second plane. The industrial city grew with very few guidelines. The Liberalism influenced urban growth and there was a certain lack of control on the public perspective for city development (Benevolo, 2001). Sanitation, then, became a great problem and inadequate waste disposal led to several sort of diseases and deterioration of public health. The role of urban drainage became very important in helping to solve this problem and, more than often, it was important to fast collect, conduct and dispose securely stormwater and wastewater. Focus was driven to improve conveyance and this was the main goal of urban drainage, until some decades ago. However, considering the fast urban growth of the last two centuries, and the fact that the world population profile is changing from rural to urban, it became hard to simply look at urban drainage and propose channel corrections, rectifications and other similar sort of interventions. Canalisation could not answer for all urban flood problems and, in fact, this isolated action, in a local approach, was responsible for transferring problems more than solving them. The increasing flood problems that the cities were forced to face showed the unsustainability of the traditional urban drainage conception and new solutions started to be researched.

A sustainable approach for drainage systems became an important challenge to be dealt with. Drainage engineers became aware that the existing infrastructure was overloaded.

As cities started to grow, especially after the Industrial Era, urbanisation problems became greater and urban floods increased in magnitude and frequency. The traditional approach for the drainage systems, which were important as a sanitation measure in the first times of the cities development, conveying stormwaters and wastewaters, turned unsustainable. Flow generation increased and end-of-pipe solutions tended to just transfer problems to downstream. In this context, in the last decades, several approaches were developed, in order to better equate flow patterns in space and time. However, not only the hydraulics aspects are important. Technical measures do not stand alone. The water in the city needs to be considered in an integrated way and sustainable solutions for drainage systems have to account for urban revitalisation and river rehabilitation, better quality of communities' life, participatory processes and institutional arrangements to allow the acceptance, support and

**2. Historical aspects and background of urban floods and drainage solutions**  Several ancient civilisations showed great care when constructing urban drainage systems, combining the objectives of collecting rainwater, preventing nuisance flooding, and conveying wastes. During the Roman Empire Age, significant advances were introduced in urban drainage systems. Concerns on urban flooding mitigation and low lands drainage were very important to the city of Rome, which arose among the hills of Lazio region, on the margins of Tiber River. To meet urban drainage needs, a complex network of open channels and underground pipes were constructed. This system was also used to convey people's

During the Middle Ages, urban centres suffered a great decay and people tended to live in communities sparsely established in rural areas, near rivers, with minor concerns about urban drainage. Sanitation practices have deteriorated after the decline of the Roman Empire and surface drains and streets were used indiscriminately as the only means of disposal and conveyance of all wastewaters (Chocat *et al.*, 2001). Later, when cities started to grow significantly again, in the Industrial Era, urban drainage found itself regretted to a second plane. The industrial city grew with very few guidelines. The Liberalism influenced urban growth and there was a certain lack of control on the public perspective for city development (Benevolo, 2001). Sanitation, then, became a great problem and inadequate waste disposal led to several sort of diseases and deterioration of public health. The role of urban drainage became very important in helping to solve this problem and, more than often, it was important to fast collect, conduct and dispose securely stormwater and wastewater. Focus was driven to improve conveyance and this was the main goal of urban drainage, until some decades ago. However, considering the fast urban growth of the last two centuries, and the fact that the world population profile is changing from rural to urban, it became hard to simply look at urban drainage and propose channel corrections, rectifications and other similar sort of interventions. Canalisation could not answer for all urban flood problems and, in fact, this isolated action, in a local approach, was responsible for transferring problems more than solving them. The increasing flood problems that the cities were forced to face showed the unsustainability of the traditional urban drainage

A sustainable approach for drainage systems became an important challenge to be dealt with. Drainage engineers became aware that the existing infrastructure was overloaded.

continuity of these proposed solutions.

waste from their living areas (Burian and Edwards, 2002).

conception and new solutions started to be researched.

Focus on the consequences of the urbanisation process, that is, the increase of flow generation, which concentrates on storm drains, should be changed. Source control, acting on the causes of flooding and focusing on storage and infiltration measures, emerged as a new option at the end of the 1970s (Andoh & Iwugo, 2002).

An integrated approach, considering the watershed as the planning unit, may be considered the initial basis for a sustainable system design. The design of an urban drainage system integrated with city development, aiming to reduce impacts on the hydrological cycle, acting on infiltration processes and allowing detention on artificial urban reservoirs, joining concerns, restrictions and synergies from Hydraulic Engineering and Urbanism appears as a fundamental option to treat urban floods. Besides the quantity aspects, the water quality became also a main issue and waste waters and solid waste disposal became matters to be treated together. The first flush and the washing of the catchment also introduced a new perception related to the diffuse pollution. At last, and in a complementarily way, rain water harvesting appears as an opportunity to increase water resources availability in urban environments. Several different conceptions have been proposed in the last decades, with some minor differences among them. All of them, however, tend to consider those questions in an integrated way, trying to rescue natural characteristics of the hydrological cycle, while adding value to the city itself.

Coffman et al. (1998) proposed a design concept of Low Impact Development (LID). LID design adopts a set of procedures that try to understand and reproduce hydrological behaviour prior to urbanisation. In this context, the use of functional landscapes appear as useful elements in the urban mesh, in order to allow the recovering of infiltration and detention characteristics of the natural watershed. It is a change in the traditional design concepts, moving towards a site design that mimics natural watershed hydrological functions, involving volume, discharge, recharge and frequency. The main principles of this approach may be briefly described by the following points:

In a similar way, another early trend in the drainage system design evolution involved the use of stormwater Best Management Practices (BMP). The term Best Management Practices is frequently used in the USA and Canada and its origin is related with pollution control in the field of industrial wastewaters. Later, it was also referred as a possibility of nonpoint source pollution control and then associated with stormwater management. This way, stormwater BMPs are supposed to work in a distributed way over the watershed, integrating water quantity and water quality control aiming to mitigate effects generated by land use changes, with optimised costs. BMPs are designed to reduce stormwater volume, peak flows, and nonpoint source pollution through infiltration, filtration, biological or chemical processes, retention, and detention. They also may be classified into structural, when referring to installed devices and engineering solutions, or non-structural, when related to procedures changes, like limitations on landscaping practices (US EPA, 2004).

LID and BMP are very often used together and may complement each other.

Sustainable Drainage Systems: An Integrated Approach,

the regional scale;

landscaping;

initiatives.

that direction.

growth as a result.

**3. Interface between rain waters and the city**

Combining Hydraulic Engineering Design, Urban Land Control and River Revitalisation Aspects 25

the integration of the urban water management from the individual allotment scale to

the integration of sustainable urban water management with building architecture and

the integration of structural and non-structural sustainable urban water management

Integration of urban water uses in different spatial scales, with the involvement of different knowledge areas, encompassing hydraulic engineering, urbanism, architecture, social sciences and economy, trying to preserve natural environment and adding value to the built environment, in a participative framework where communities play an important role, seems to be the main point to characterise the WSUD concept. The institutional

Furthermore, actions on urban rivers revitalisation or, in a more optimistic sense, actions to allow urban rivers rehabilitation, also arise as a new possibility. The river revitalisation usually includes solutions for the built environment, reconnecting it to the city, but not necessarily recovering natural patterns. The concept of river rehabilitation, however, tries to integrate the river hydrology and morphology, the hydraulic risks associated to the flood control, the quality of waters and the ecological state of the river. These are very complex tasks to be dealt in urban environments, due to several constraints accumulated over time. River canalisation, flood plains disconnection, lack of free spaces, combined sewers (or even uncontrolled wastewaters disposal, as it happens frequently in developing countries), social pressures and other questions appear as difficulties in the way of a river rehabilitation. By the way, one possible decision in urban development may be to state a vision for the river and how to integrate it with the built environment and try to do the best possible to walk in

Gusmaroli et al. (2011) propose the adoption of an ecosystem approach, in order to supplement or replace the concept of Waterfront Design. The Waterfront Design mainly aims to recover the relationship between river and city around the line where they meet. Stepping ahead brings the opportunity to propose the river rehabilitation concept from the point of view of an environmental improvement, looking at the city as an organism in constant transformation and, therefore, capable of modelling and adapting itself (even only in part) to the demands of recovering more natural features of the watercourses. In this sense, it is a challenge to find ways to recover more natural rivers and rethink the city's

The urbanisation process changes significantly the natural water balance equilibrium. Vegetation removal and its substitution by impervious surfaces reduces the infiltration possibilities, increasing superficial flow volumes. Besides, natural retention is reduced and the runoff is able to travel faster over regularised urban surfaces. In general terms, even when the urbanisation process is conducted within planning standards, the superficial volumes are greater. If the urbanisation does not account for more sustainable patterns, the

peak flow is much greater than the natural one and the peak time occurs early.

arrangements are key elements here, in order to manage this process

Batista *et al.* (2005), in Brazil, consolidated the concepts of Compensatory Techniques in urban drainage design, which meant the introduction of several different measures, focusing on infiltration and storage capacity, with the aim of compensating urban impacts on the hydrological cycle.

Another possibility of improving urban drainage solutions concerns the Sustainable Urban Drainage System (SUDS) concept. In this case, the ideals of sustainable development are included in the drainage system design process, that is, impacts on the watershed due to drainage solutions may not be transferred in space or time. Moreover, besides contributing to sustainable development, drainage systems can be developed to improve urban design, managing environmental risks and enhancing built environment. SUDS objectives account both for reducing quantity and quality problems and maximising amenities and biodiversity opportunities, which form the three way concept: quantity – quality – amenity & biodiversity. All of them have to be managed collectively and the desired solution appears in the interface of these three objectives (CIRIA, 2007). The philosophy of SUDS, similar to LID, is also to replicate, as well as possible, the natural conditions of pre-development site.

The key elements for a more sustainable drainage system consider to:

The continuous evolution of all these concepts and the seek for new urban drainage system solution led also to the Water Sensitive Urban Design (WSUD) concept, initially developed in Australia.

Wong (2006) states that the definition of WSUD appears to be confusing among practioners because of its wide range of applications. WSUD tries to integrate social and physical sciences in a holistic management proposition for urban waters.

Langenbach et al. (2008) define WSUD as the "interdisciplinary cooperation of water management, urban design and landscape architecture which considers all parts of the urban water cycle, combines water management function and urban design approaches and facilitates synergies for the ecological, economical, social and cultural sustainability."

According to Wong (2006): "WSUD brings 'sensitivity to water' into urban design. The words 'water sensitive' define a new paradigm in integrated urban water cycle management that combines the various disciplines of engineering and environmental sciences associated with the provision of water services, including the protection of aquatic environments in urban areas. Community values and aspirations of urban places necessarily govern urban design decisions and therefore water management practices".

WSUD is centred on integration at a number of levels (*ibid*):

the integrated management of potable water, wastewater and stormwater;

Batista *et al.* (2005), in Brazil, consolidated the concepts of Compensatory Techniques in urban drainage design, which meant the introduction of several different measures, focusing on infiltration and storage capacity, with the aim of compensating urban impacts

Another possibility of improving urban drainage solutions concerns the Sustainable Urban Drainage System (SUDS) concept. In this case, the ideals of sustainable development are included in the drainage system design process, that is, impacts on the watershed due to drainage solutions may not be transferred in space or time. Moreover, besides contributing to sustainable development, drainage systems can be developed to improve urban design, managing environmental risks and enhancing built environment. SUDS objectives account both for reducing quantity and quality problems and maximising amenities and biodiversity opportunities, which form the three way concept: quantity – quality – amenity & biodiversity. All of them have to be managed collectively and the desired solution appears in the interface of these three objectives (CIRIA, 2007). The philosophy of SUDS, similar to LID, is also to replicate, as well as possible, the

on the hydrological cycle.

natural conditions of pre-development site.

protect or enhance water quality;

enhancement;

in Australia.

The key elements for a more sustainable drainage system consider to:

encourage natural groundwater recharge (where appropriate);

enhance amenity and aesthetic value of developed areas;

meet the environmental and the local community needs.

sciences in a holistic management proposition for urban waters.

design decisions and therefore water management practices". WSUD is centred on integration at a number of levels (*ibid*):

manage runoff volumes and rates, reducing the impact of urbanisation on flooding;

provide a habitat for wildlife in urban areas, creating opportunities for biodiversity

The continuous evolution of all these concepts and the seek for new urban drainage system solution led also to the Water Sensitive Urban Design (WSUD) concept, initially developed

Wong (2006) states that the definition of WSUD appears to be confusing among practioners because of its wide range of applications. WSUD tries to integrate social and physical

Langenbach et al. (2008) define WSUD as the "interdisciplinary cooperation of water management, urban design and landscape architecture which considers all parts of the urban water cycle, combines water management function and urban design approaches and

According to Wong (2006): "WSUD brings 'sensitivity to water' into urban design. The words 'water sensitive' define a new paradigm in integrated urban water cycle management that combines the various disciplines of engineering and environmental sciences associated with the provision of water services, including the protection of aquatic environments in urban areas. Community values and aspirations of urban places necessarily govern urban

facilitates synergies for the ecological, economical, social and cultural sustainability."

the integrated management of potable water, wastewater and stormwater;

Integration of urban water uses in different spatial scales, with the involvement of different knowledge areas, encompassing hydraulic engineering, urbanism, architecture, social sciences and economy, trying to preserve natural environment and adding value to the built environment, in a participative framework where communities play an important role, seems to be the main point to characterise the WSUD concept. The institutional arrangements are key elements here, in order to manage this process