An-Najah Staff

Extreme events, such as severe storms, floods, and droughts are the main features characterizing the hydrological system of a region. In the West Bank, which is characterized as semiarid; little work has been carried out about hydrological modeling. This thesis is an attempt to model the rainfall-runoff process in Faria catchment, which is considered as one of the most important catchments of the West Bank. Faria catchment dominating the north eastern slopes of the West Bank is a catchment of about 334 km2 and has the semiarid characteristics of the region. The catchment is gauged by six rainfall stations and two runoff flumes. Statistical analysis including annual average, standard deviation, maximum and minimum rainfall was carried out for the rainfall stations. The internal consistency of rainfall measurements of the six stations was examined by using the double mass curve technique. The results show that all station measurements are internally consistent. Gumbel distribution fits well the annual rainfall and can be used for future estimations. It provides means to understand and evaluate the distribution characteristics of the rainfall in the Faria catchment. Trend analysis of the rainfall has shown an increasing trend for the stations with high elevations and a decreasing trend for low elevated ones. The multiple regression analysis applied to the six rainfall stations proved to be strongly correlated. GIS-based KW-GIUH hydrological model was used to simulate the rainfall-runoff process in the Faria catchment. GIUH unit hydrographs were derived for the three sub-catchments of Faria namely Al-Badan, Al-Faria and Al-Malaqi. The KW-GIUH model is tested by comparing the simulated and observed hydrographs of Al-Badan sub-catchment for two rainstorms with good results. Sensitivity of the KW-GIUH model parameters was also investigated. The simulated runoff hydrographs proved that the GIS-based KW-GIUH model is applicable to semiarid regions and can be used to estimate the unit hydrographs in the West Bank catchments.