The groundwater resources of the Lower Jordan Valley and its tributaries in Israel, Palestine and Jordan are strongly limited by the semi-arid conditions. In addition, the extreme population growth intensifies the lack of available and high quality water resources in the region, where overexploitation of surface- and groundwater is usual. References are the intense drawdown of groundwater levels, the disappearance of springs and saltwater intrusions. To solve that complex issue a smart and integrated strategy to manage all available water resources (IWRM) will be developed. Such an IWRM is the aim of the multilateral SMART-project in the Lower Jordan Valley (www.iwrm-smart.org), where all water resources (groundwater, surface runoff, waste water) will be quanti- and qualitatively evaluated. One major topic of SMART is the generation of a trans-boundary numerical flow model in the scale of the Lower Jordan Valley. Different sub-projects on the local scale were necessary for the achievement of this goal. The study area of the here presented sub-project is one of the northernmost tributaries of the Lower Jordan Valley, the Wadi Al Arab (Jordan). The aim of the sub-project is to evaluate natural resources on catchment scale by combining hydrochemical and hydraulical methods to develop a high precision model. Concerning the quantification of the system, two separated models will be linked: a numerical finite element flow-model for the groundwater passage and a new developed hydrological model JAMS. The challenge of the investigation were the deployment of a conceptional groundwater model based on scarce data and adjustment of empirical equations and input parameters of JAMS onto the semiarid conditions. The results lead to a better understanding of the processes, which are important and necessary for the implementation in the trans-boundary model.