Water is the lifeblood of sustainable habitation, and no more so is it crucial than in desert societies. One of this year's winners of the Aga Khan Award for Architecture is not a building complex, but remarkably, an entire ecosystem. Located in Riyadh, the capital of Saudi Arabia, is the Wadi Hanifa watershed, a 4,000 square kilometer drainage that has become key to the capital's environmental sustainability. After many years of neglect, a long term reclamation plan was put underway, and is now being recognized worldwide for its size and aesthetic. The safe use of the river was one of the most visually compelling design features, but it was water reclamation, habitat restoration and industrial clean up throughout the river basin that really exemplifies how profound the project's scope is.
Years of laissez-faire development led to damaging floods, mounds of construction waste and polluted water in the basin which serves a burgeoning population that grows increasingly dependent the source. The plan, a joint venture between Moriyama & Teshima Planners Limited and Buro Happold was to turn the basin into a thriving natural reserve that not only would restore wildlife, but serve to provide benefits for the community. Water quality was paramount in the restoration for both the water upstream and for the city’s wastewater which is intended to be stored and reused. To accomplish this 1.25 million cubic meters of construction debris were removed, and the haphazard roads and power lines were reorganized to reduce surface impact. Side water inlets have been reclaimed or added to aid in flood control and habitation.
Situated adjacent to the city, the basin is a major local and tourist attraction thus recreational facilities were combined with habitat enhancement and water quality infrastructure. Natural stone weirs were installed to create a habitat for micro-organisms as well as to increase oxygen levels to reduce chloroform bacteria. The large bio-remediation facility is a one of a kind design which recreates a complex habitat, in turn treating the city and river water naturally. Downstream large Periphyton Benthic Substrate Devices (APBS) have been installed, which have given way to an underwater habitat.
The complex is also a large park which provides area to explore and interact with the water environment. Moreover, Wadi Bed Naturalized Parkland and Recreational and Interpretative Trail are also great examples of how answers to the challenges of water quality management and public access can be woven together.
The parks use will only increase over time and anticipated to provide one million cubic meters of water per day by 2021 to meet a third of the city’s total water demand.