Groundwater is the only fresh water resource in the semi-arid to hyper-arid Western Dead Sea catchment. Due to exploitation of groundwater the water level is decreasing in the surrounding Cretaceous aquifer system and sustainable water management is needed in order to prevent the progressive yields and contamination of those water resources. In addition, the water level of the Dead Sea decreases dramatically by at least one meter per year. This is connected to channel off the water from the Jordan River to supply intensive agriculture in the semi-arid to hyper-arid region. Hydrological and hydro-geological analysis and modelling in arid regions, like the study area, frequently suffer from data scarcity and uncertainties regarding rainfall and discharge measurements. The study showed that spatial and temporal interpolations as well as additional methods (e.g. empirical relationships and simultaneous numerical approaches) were suitable tools to overcome data shortage for modelling. Water balances are the result of a calibrated model and are the basis for sustainable management of surface and subsurface water resources. The present study investigates beside the hydrological characterisation of selected sub-catchments (wadis) also the hydro-geology of the Judean limestone aquifer and calculates a comprehensive water balance of the entire western flank of the Dead Sea by the application of two numerical open source codes: OpenGeoSys (OGS) and J2000g. The calibrated two-dimensional hydrological model J2000g provides a 33 years time series of temporal and spatial distributed groundwater recharge for the numerical groundwater flow model of OGS. The mean annual groundwater recharge of 139.9 · 10^6 m^3ˑ a^-1 is nearly completely depleted by abstractions from pumping wells close to the replenishment area in the Judea Mountains.