The arid and semi-arid regions, such as the West Bank, have its own properties in the hydrological processes as a response to rainfall. Extreme rainfall events and accompanied floods have higher probability in these regions compared to other regions. So, the floods occurrence has become more predictable and the risk of these floods has increased. As such, the importance of rainfall-runoff modeling becomes more challenging in such regions not only to predict the catchment response to these extreme rainfall events but also to be able to produce a more reliable infrastructure designs. This in turn will facilitate the development of proper mitigation measures to reduce its impacts on the surrounding environment.
This study aims to model rainfall-runoff response in Al-Faria catchment, which is located in the northeastern part of the West Bank with a total area of about 320 km2 and drains into the Jordan River. The HEC-HMS was used to simulate the rainfall-runoff response in the catchment based on single events. The GIS tools were utilized to prepare some gridded input data (e.g. land use, soil) whereas, MS excel was used to prepare some time series data (e.g. rainfall, runoff). Model performance was evaluated based on two major rainfall events. The storm of February (8-9), 2006 was used to calibrate the model while the storm of February (4-8), 2005 was used for model validation.
The observed flow data from the runoff flumes in the upper part of the catchment were used to calibrate and validate the model. The model performance was tested statistically using both the root mean square error (RMSE) and the Nash-Sutcliffe efficiency (NSE). Results showed that the model was quite good in simulating the single rainfall event response and thus it can be used for further modeling of single rainfall event in the Faria.