Numerous hydrological projects have been carried out using isotopic methods over the last two decades in the ESCWA region, which includes the Arabian Peninsula, the Arabian countries to the north, and Egypt. The large amount of data obtained from groundwater samples has been evaluated together with the hydrogeological, hydrochemical and water management data available for the area. Analyses of the stable isotopes of oxygen, hydrogen, and carbon in the groundwater samples, as well as the naturally occurring radioactive isotopes of hydrogen and carbon are used for the localization of groundwater recharge areas; determination and quantification of mixtures of groundwater from different sources; reconstruction of groundwater flow systems on regional and local scales; determination of the paleoclimatic effects on the geohydraulic conditions; determination of groundwater ages, i.e., residence times; and distinguishing between renewable and fossil groundwater resources. Extensive hydrological studies using isotopic methods have been conducted in the ESCWA region on the following aquifer systems and topics: isotopic composition of precipitation in Jordan and Syria; groundwater turnover in karst aquifers in the highlands of western Jordan, the mountains in western Syria and the West Bank; groundwater recharge from precipitation and surface water on the Damascus plain; origin and age of groundwater in the basalt aquifer system in Jordan and Syria; recently recharged freshwater lenses and fossil groundwater in Badiye and Hamad (steppe and desert regions in Syria and eastern Jordan and the adjacent areas in Iraq and Saudi Arabia); low of fossil groundwater and local, recently recharged groundwater in Paleogene carbonate aquifers in eastern Saudi Arabia, the Golf region, and southern Oman; groundwater recharge from flash floods in the aquifers in unconsolidated rock in wadis and coastal plains of the Arabian Peninsula; age and origin of groundwater in aquifers in consolidated rock in the mountains of Oman. The discussion of the hydrogeological significance of isotope data is supplemented by comments on the most important current hydrogeological problems in the ESCWA region that could be investigated using isotopic methods. These include problems of groundwater recharge, the provenance of groundwater, groundwater flow systems on regional and local scales, paleohydrological conditions, and groundwater quality, particularly contamination by human activities. All available publications on the isotope hydrology of the ESCWA region are listed in the bibliography, as well as basic publications on isotope hydrology in arid regions. (Isotope geochemistry, isotope ratios, stable isotopes, O16, O18, O18/O16, C14, radioactive isotopes, iritium, absolute age, atmospheric precipitation, groundwater, currents, groundwater provinces, groundwater quality, sampling, groundwater recharge, climate, paleoclimate, aquifer, sandstone, limestone, dolomite, volcanic rocks, quaternary aquifer, unconsolidated sediments Bahrain, Jemen, Jordan, Lebanon, Qatar, Kuwait, Saudi Arabia, Syria, Oman, United Arabic Emirates)weiterlesen