Dams planned in Wadi Samayil upper catchment. Al Khoudh recharge dam to be upgraded. Consultant to carry out feasibility study, engineering design
MUSCAT -- The Government will shortly commission a study for the development of a major flood management scheme that will protect vast swathes of Muscat Governorate's suburbs from flooding. Envisaged is an elaborate system involving the construction of one or more flood protection dams in the upper catchment of Wadi Samayil, one of the Oman's biggest wadis that cuts through the capital region en route to the sea. Also planned is a major upgrade of the existing recharge dam at Wadi al Khoudh and its conversion into a flood protection dam.
The project is the latest in a series of ambitious flood protection schemes drawn up by the Ministry of Regional Municipalities, Environment and Water Resources (MRME&WR) in an effort to prevent severe flooding in flood-prone areas of Muscat Governorate, and the Batinah and Sharqiya regions. On behalf of the ministry, the Tender Board has launched the process of selecting a competent engineering consultant to carry out a feasibility study, as well as prepare a detailed design of the most economically advantageous engineering solution for protecting flood prone area of Al Khoudh, Seeb and Maabelah from flooding.
The selected consultant will identify suitable sites for the construction of flood protection structures in the entire Wadi Samayil catchment, including the development of one or more flood protection dams. The dams will be designed with a large reservoir capacity catering to a flood frequency of a 1-in 200-year event or more. In designing the dam capacity, the consultant will be required to take into account the latest hydrological data gleaned from the recent unusual weather conditions in the Sultanate. Experts point out that 2 or more dams will be necessary in the upper catchment if habited areas downstream of Wadi Samayil are to be secured from possible flooding.
Furthermore, the Wadi al Khoudh recharge dam will be considerably strengthened and expanded. The height of the dam is proposed to be raised by a few metres to roughly double its reservoir capacity. Additionally, the dam's length will be increased from the present 5.1km to more than 6.2km. These improvements are designed not only to enhance the overall safety of the structure, but also to give the function of a full-fledged flood protection dam. Besides identifying the need for repairs to damage caused by the recent weather conditions, the consultant will also design an improved dyke complete with suitable discharge channels to ensure that any overflow will run off into the main wadi channel and not flood habited areas downstream.
Muscat Governorate, situated for the most part at the northern foot of the Hajar Mountains, is crisscrossed by a number of major and minor wadis. With increased urban development over the years, authorities undertook a number of flood protection measures to alleviate flooding in flood-prone areas. In 1985 the Ministry of Agriculture and Fisheries constructed Wadi al Khoudh recharge dam as a pilot project, while Muscat Municipality constructed three flood retention dams and six check dams in the governorate during 1992-1993 to control the flooding.
The comprehensive study will cover a huge catchment area, which includes the entire Wadi al Khoudh catchment (flood plain) starting from the moutains in the upper catchment in Samayil, Fanja and Bid-bid to the downstream reaches in Al Khoudh and Seeb in Muscat Governorate.
It also includes the area around Wadi al Khoudh dam located some 5 km upstream of the Muscat-Sohar highway from the Al Khoudh roundabout. The total catchment area of the entire Wadi Samayil stretch is about 1,700 km2, while that of the existing Al Khoudh dam is 1,635 km2. Last month, the ministry unveiled the Wadi Adai Dams Project an ambitious initiative aimed at protecting the Qurum area of Muscat from severe flooding, as well as enhancing water resources thorugh groundwater recharge. The project calls for the construction of three dams along Wadi Adai.
By Conrad Prabhu
© Oman Daily Observer 2007
