Based on on-site review reports by Mohammad Al-Asad and Wael Al-Samhouri

The Wadi Hanifa watershed is an oasis located in the heart of the Najd Plateau in the Kingdom of Saudi Arabia. It is a natural water drainage course for an area of over 4,000 square kilometers and a unique geographical feature in this dry region. Its basin and many tributaries form a unique 120-kilometre-long ecological zone that descends from the Tuwaiq escarpment in the northwest to the open desert southeast of Riyadh. For centuries, the Wadi Hanifa watershed system provided sustenance for communities along its length, where a balance prevailed between the wadi’s resources, natural processes, and human interventions. The Wadi Hanifa is inextricably linked to Riyadh’s history.

In the late 18th century, the first Saudi state strategically located its capital at Addiriyyah on the west bank of Wadi Hanifa, taking advantage of water and arable land.
Subsequently, Riyadh (or in Arabic, Arriyadh), the new capital of the modern Saudi state, developed to the east of Wadi Hanifa, which was used as a sustainable source
of water and food for the city. Beginning in the early 1970s, Riyadh expanded westward towards Wadi Hanifa, after which it was overexploited to satisfy the increasing demand for water and mineral resources to meet the massive construction needs arising from rapid growth.

By the 1980s, Riyadh’s explosive growth towards Wadi Hanifa led to the rise of ground water, dumping, environmental degradation, and loss of natural functioning and ecosystem productivity. Illegal building, flooding, and wastewater and industrial dumping led to further deterioration exacerbated by increased urbanization and encroachment. In response, the Arriyadh
Development Authority (ADA) began the implementation of a comprehensive long-term strategy in 2004 to developWadi Hanifa into an environmental, recreational, and tourist resource, restore its natural beauty, and rehabilitate and harness its water resources.

The reclamation project has included the introduction of landscaping, conservation of the natural environment, enhancement of agricultural land in the valley, managing water quality, restoring flood performance, the construction of dams to regulate water flow, and the planting of reed to further purify water from contaminants. An environmentally sensitive wastewater treatment facility was constructed, providing additional water resources for the rural and urban inhabitants of the region. The works involved the removal of almost 1.25 million cubic metres of construction waste, along with inert and non-inert waste that had been dumped in the wadi over many years. Another component of the wadi development was the restoration of the wadi channel as preparation for a 20-year flood plan. Prior to this, there had been widespread flooding due to the rubble and illegal building within the wadi.

The bio-remediation facility is one of the most impressive features of the project. The facility incorporates a series of weirs, riffles, pools, aerating pumps, bio-remediation cells, artificial periphyton and benthic substrates, and riparian planting. Together, the elements of this design have developed the appropriate aquatic and riparian conditions to assimilate contaminants and further purify the water through a community of natural organisms that aggregate to form a food web. This has contributed to the improvement of the environmental quality of the wadi and has greatly enhanced public perception and recreational use.

Today Wadi Hanifa is a “living valley” recovered and fully integrated into the life of Riyadh. The restoration project has regenerated a clean, green, safe, and healthy environment, providing continuous parkland that connects city and wadi. Combined residential development, farming, recreation, cultural activities, and tourism inhabit an oasis that extends the full length of Riyadh and beyond, into the surrounding rural areas.

Preservation of the wetlands of the Wadi Hanifa has resulted in restoring the productive capacity of the ecosystem to provide multiple services including purifying contaminated water, restoring flood performance, providing habitat for biodiversity, and creating opportunities for recreational, educational, and aesthetic experiences. Wadi Hanifa has become a popular destination for recreational activities such as fishing and picnicking and has also become a stop for migratory birds. Use of the parks for recreation, farming, and tourism generate income and support regional employment. The Wadi Hanifa Wetlands reclamation project offers an alternative model for urban development. It demonstrates that the productive resources of an ecosystem can be balanced with the socio-economic needs of the people living around it to create a sustainable relationship.

Dr. Mohammad Al-Asad is Chairman, Center for the Study of the Built Environment, Amman.
Dr. Wael Al-Samhouri is Head of Architecture Department, International University of Science and Technology (IUST), Syria.

The text was edited by Melissa Vaughn.