ORIGINAL PAPER Strategic groundwater resources planning in arid regions Zekai Şen & Saleh A. Al Sefry & Saleh A. Al Ghamdi & Wahib A. Ashi & Wael A. Bardi Received: 13 August 2012 / Accepted: 23 September 2012 # Saudi Society for Geosciences 2012 Abstract A strategic approach is presented for future ground- water reservoir planning in arid regions where the evaluation of groundwater resources is restricted by scarcity of rainfall, data paucity, restrictive and unrepresentative methodologies, weak economies, almost nonexisting management and optimization programs, frequent groundwater quality variables along short distances, etc. This paper explains the necessary steps in prepar- ing an effective strategic planning program that is expected to provide all the necessary data for identifying alternative solution scenarios especially in arid regions. It is shown on the basis of available scarce data that the risk model of these factors appears as the logarithmic normal probability distribution. The basic decision variables in groundwater storage and recharge planning are furnished with application to Wadi Fatimah in the western central part of the Kingdom of Saudi Arabia along the Red Sea coast. The approach given in this paper provides a basic example for future groundwater reservoir strategic use and management studies in the Kingdom in particular and in any part of the arid regions of the world, in general. Keywords Arid region . Aridity index . Groundwater . Management . Risk . Strategy . Wadi Introduction There are three basic water problems faced by human beings: having too much, too little, or too dirty water (Kundzewich 2001). The primary manifestation in the arid regions is the amount of groundwater that is too little to serve different human activities in a local development plan. The intensity and range of groundwater scarcity in arid regions differ from location to other, but it is necessary to have a unified method- ology for the evaluation and decision making against different alternative risky situations. Although there are a bundle of methodologies that can be applied in humid areas, unfortu- nately their implementation in arid regions is hindered basi- cally due to data paucity and different hydrological and geological environments. In cases of emergency, the scarcity and little volume of groundwater might be exploited in an irrational manner due to ignorance of the future circumstan- ces. This is basically true if there are no preplanned strategic rules, regulations, and evaluation methodologies in exploiting the available water volumes. A common feature in any arid region is the frequent water deficit occurrence due to either dry years or over-exploitation or mismanagement. In arid regions, there are two distinctive groundwater resources lying in shallow and deep aquifers. By defini- tion, shallow aquifers are in contact with the present-day hydrological cycle whereas deep aquifers were in contact with paleogeologic hydrological cycles except insignifi- cantly through outcrop areas. Accordingly, strategic groundwater resources planning methodology differs in shallow aquifers than deep ones. Shallow aquifers are almost completely unsaturated and have the possibility of occasional recharge after infrequent but intensive rain- fall. Hence, rainfall component of the hydrological cycle is the most important variable in arid-region strategic planning. There are no perennial streams and this shows that most of the groundwater recharge is through the infiltration, which takes place during a storm period. Hence, the runoff and evaporation components can be overlooked in strategic groundwater resources. In this manner, the most strategic case is considered with reliable consequences (Sefry et al. 2003). Z. Şen (*) Civil Engineering Faculty, Hydraulics and Water Resources Division, Istanbul Technical University, Maslak, 34469, Istanbul, Turkey e-mail: zsen@itu.edu.tr S. A. Al Sefry : S. A. Al Ghamdi : W. A. Ashi : W. A. Bardi Hydrogeological projects-Saudi Geological Survey, PO Box 54141, Jeddah 21514, Kingdom of Saudi Arabia Arab J Geosci DOI 10.1007/s12517-012-0701-8