Case studies

This project will cover the following study areas and reservoirs:

1. Gepatsch Reservoir, Austria

Gepatsch Reservoir Austria in Winter

The Gepatsch Reservoir is a seasonal reservoir located in the Kaunertal valley in southwest-Tyrol, Austria. It supplies the Kaunertal power station built by the Tiroler Wasserkraft AG (TIWAG) in 1961 – 1964, holds a maximum capacity of 138 Mio m³ at an area of 2.6km². The dam itself rises up to a height of 153m with a crest width of 600m. The water from the reservoir is led through a 13km long pressure tunnel and a 1.9km long pressure shaft to the powerhouse in Prutz. With a gross head of roundabout 900m before it is discharged to the Inn river and a design discharge of 52 m3/s the power generating capacity is 325-392 MW. The mean annual generated capacity adds up to 696 GWh.
The reservoir is naturally fed by the Faggenbach, which drains an area of 107km². Additionally, three diversion systems channel runoff from ten streams originating in the upper Pitztal Valley, the Radurschelbach area in the southwest and the catchments northeast of the reservoir. The total size of catchments contributing to the reservoir inflow add to area of 279km². From the dam crest at the Gepatsch reservoir located at 1770m a.s.l. the catchment spans to the peak of Wildspitz at 3770m a.s.l. It is characterized by highly glaciated terrain, steep moraine and scree slopes interspersed with pastures and woodland. As part of the Ötztal massif the catchment is made up of gneisses and granite.
A large number of measurements, time series of long-term data on sediment transport in that area were collected over the periods since the construction. This includes data sets at the reservoirs as well as at water intake struktures. Those data will among others be used to model the sediment in the reservoir catchment.

Schöber, J and Hofer, B. (2018) The sediment budget of the glacial streams in the catchment area of the Gepatsch Reservoir in the Ötztal Alps in the period 1965-2015, ICOLD 2018,

Kraftswerkspark der TIWAG [power plant park of TIWAG]

TIWAG – Tiroler Wasserkraft

TIWAG is the major hydropower operator in Tirol with more than 1400 employees. It maintains several hydropower plants, located in lower to upper alpine areas. Since the TIWAG is an enterprise with long history, a broad experience regarding hydrology of alpine catchments is available. With respect to the increasing importance of renewable energy resources and its efficient and ecologic development, climate change and its consequences on hydropower utilization are of great interest, as it is found to be a valuable contribution regarding the alteration of the fluvial systems in the alpine area connected to climate change.

2. Banja Reservoir, Albania

Devoll River Catchment

The Devoll river is located South-East of the capital in Albania, Tirana, and the catchment of the river is as the rest of the country characterized by varying topography. It covers an area of approximately 3,140 km2 with steep hills and valleys with low. Since the catchment is of such magnitude, the climate and hydrology describing the 196 km long river is also varying. The area of interest for the project is from upstream the Kokel area until the Banja reservoir.

The flow regime is characterized by snowmelt in the upstream part, while precipitation dominates the lower regions. As to peak events during the year, the flow maximums are usually located in March/April and November/December, whereas high flood values span from September to April (Pano and Frasheri, n.d.). Albania is divided into different climate zones, but the year in general can be described as having cold and wet winters and dry, warm summers (Shundi, 2006).

banja dam site
Photo: Nils Rüther, NTNU
Devoll River catchment

More information on the Devoll HPP project of Statkraft can be found here

3. Orust/Tjörn drainage area, Sweden

The Orust-Tjörn fjord system is located on the Swedish west coast, adjacent to the Skagerrak, the most eastern part of the North Sea. The major part of the Swedish aqua culture industry is located here and thus it is an ideal location to investigate effects of climate change on the phytoplankton community composition and potential effects on the aqua culture industry. The main focus of this case study is to answer:

  • Will a change of silicate input and sediment to the Orust-Tjörn area modify the phytoplankton composition?
  • Will harmful algae be favoured?
  • What effect on the aquaculture industry are likely?


map of north sea and skagerrak and orust

The case study focusses on effects of changed sediment content in river run-off and changed nutrient ratios on the phytoplankton community, both of which are likely effects of future climate changes. Long term monitoring data on water transparency, temperature, salinity, inorganic nutrients and phytoplankton will be used to understand the general dynamics of the phytoplankton community with regard to both water transparency and silicate concentrations. This will allow us to investigate what climate impacts on the community we can expect if a certain future scenario is realised.  Fresh water enters the Orust-Tjörn system through river Bäveån with river mouth in the town of Uddevalla at the By fjord. There are also many smaller creeks that brings fresh water to the system. To the south of the fjord system, the large river Göta Älv, with river mouths at the city of Göteborg and the town of Kungälv, is found.

Orust and Tjörn are two large islands surrounded by smaller islands and fjords. Blue mussels (Mytilus edulis) is the main aqua culture product but also oysters are harvested.

mussel farm

 The bivalves feed on phytoplankton, some of these produce biotoxins that can accumulate in shellfish and pose a threat to human health and a problem to the aqua culture industry.The water from this river influences the fjord system. In the Skagerrak the ocean is usually strongly stratified as a result of the brackish surface water being brought to the area by the Baltic current which, on average, goes northward towards Norway along the Swedish coast. This current also brings nutrients to the case study area and it is thus another cause of climate change impact on the Orust-Tjörn area.

4. Europe

Cross-scale comparison and determination of CIIs at regional and global levels takes advantage of the SMHI’s existing HYPE models with two different spatial resolutions covering the whole pan-European domain with the aim of identifying limitations and uncertainties and improving the process representation. E-HYPE will be used to simulate the hydrological impacts of different shared socio-economic pathways (SSPs). In combination of an energy system model, this enables to assess the interactions between reservoirs, runoff and the energy system. The focus is on the role and operation of hydropower plants that provide flexibility services for short-term balancing, seasonal storage and long-term backup. In addition, cross-sectoral interdependencies of water use in different economic sectors and the energy sector will be investigated with respect to how they can potentially affected by changes in runoff and reservoirs.