Flash Floods in Oman – A Sase Study of Alhamrya Catchment in Oman

Sultanate of Oman is an arid country where flash floods are common. The country experienced severe flash flood events in years 1989, 1997, 2002, 2003, 2005, 2006, 2007, 2010 and 2013, including several cyclones. The impact of floods has increased greatly in the recent years due to poor infrastructure planning, increasing urbanization and lack of emergency operation plans. Flood risk maps based on accurate hydrologic and hydraulic molding need to be updated to manage similar floods in future. In the present study, Alhamrya wadi catchment is considered (wadi is an Arabic term for an ephemeral stream). Muscat downtown area is part of this catchment and experienced destructive floods, causing loss of life and damage to public infrastructure. To evaluate and reduce the flood risk, field monitoring, rainfall analysis and numerical models (HEC-HMS and HEC-RAS) have been applied to simulate the flow propagation of different scenarios of return periods. The areas that are frequently flooded are accurately identified and suitable mitigation measures are proposed.