Abstract: The gravest environmental challenge that Jordan faces today is the scarcity of water. Indeed, water is the decisive factor in the population/resources equation Various techniques are available to quantify recharge; however, most of these are lumped and/or empirical approaches. The best alternative approach for such purposes is the use of a physically based hydrological model integrating all hydrological processes on basin scale. In this study GIS and RS technologies are applied to assist the simulation of the water balance components of the Hasa catchment, Jordan. The study area consists of 2,800 km2. It includes the well known phosphate mines. Wadi Hasa is the main perennial stream within the area. The techniques have been used to develop the land use and other necessary maps of the basin. A flexible, physically and GIS based, distributed recharge methodology, WetSpass, has been used for the estimation of long-term average spatially varying annual and seasonal water balance components: surface runoff, actual evapotranspiration and groundwater recharge. The simulated hydrological variables are made on pixel basis using a 90 m grid size. The groundwater recharge and surface runoff show mean values of 0.98 mm and 23.64 mm per year, respectively. The results show about 0.64 and 15.4% of the mean annual precipitation is effective in producing groundwater recharge and surface runoff respectively, while the rest and the major part is lost as evapotranspiration which is estimated 128.68 mm per year. Analysis of the simulated results shows that WetSpass is good enough to simulate the hydrological water balance components of the Hasa basin.