Groundwater Resources Isotope Study of Eastern and Southeastern Areas of Jordan

Since Jordan depends on the groundwater resources especially for municipal use so, water resources studies and development takes priority on the national level. For this reason the environmental isotope technique and application contributed and supported the hydrological studies as a research tool confirmed some scientific facts including natural and environmental changes of water resources. The isotope analyses has been implemented for upper and deep aquifer systems in the eastern and southeastern areas of Jordan for Hamad, Sirhan, Azraq and Jafr basins. The analyses included the stable isotopes for 18O, Deuterium (2H) and 13C also the radioactive isotopes for Tritium (3H ) and 14C in nineties of the last century until 2002 and this indicates the following: * The origin and mechanism of the nonrenewable groundwater recharge in the deep aquifer systems of (B2/A7) Campanian and Turonian age for Hamad and Azraq basins has been defined. This refers that the groundwater recharge existed within humid, cold and wet climatologic conditions which is completely different from the present climate where the groundwater age exceeds thirty thousand years. * Also this indicates that the stable isotopic composition of the upper aquifers in Hamad and Sirhan basins in Shallala and Rijam aquifers (B5/B4) of Eocene and Paleocene age lie on the Global Meteoric Water Line (GMWL) where the deuterium excess (d) is 10 %. Actually this water is not tritiated and the 14C content in the groundwater is close to zero which is a strong indication of humid and wet climate where the age of the groundwater range between 20000 and exceeds 300000 years. In comparison this situation with the same aquifer in Jafr basin located in the southeastern part of Jordan, there are differences in the deuterium excess (d), Tritium and 14C content which depends on the climatologic conditions existed during the recharge period. Also the isotopic signaure for the middle groundwater system (B2/A7) and the deep Ram sandstone aquifer (D) in Jafr basin as follows: The isotopic content and deuterium excess (d) in Shediya well field tapping the middle aquifer system (B2/A7) range from 10.1-16.2 % with an average of 14 % for the samples representing the beginning of eighties of the last century.This is closer to the Global Meteoric Water Line (GMWL), in comparison of this with the isotopic content of five wells sampled in 2000 and 2001, an average deuterium excess (d) of these wells is 17.2 %. Concerning the deep sandstone of Ram group aquifer which belongs to the Cambrian and Ordovician age, it is indicated in Shediya deep well of total depth 1960 meters. The deuterium excess (d) as 7.8 % is completely different from the middle and upper aquifer systems in Jafr basin, it is also highly depleted in the stable isotopes, in addition of that both deep and middle aquifers has very old water. This requires application a convenient advanced isotope analyses as 36CL to define the exact age of deep and nonrenewable groundwater with comparison on the paleohydrological history. (author)