Paleogroundwater in Jordan

Introduction

The importance of groundwater for development in Jordan is proceeding from different aquifers, even though there is uncertainty in replenishment some of these resources. There are 13 catchment areas within the territory of Jordan. Some of these basins are extended outside the territory of the country.

The continuos abstraction of groundwater from the southern Desert described as a mining process. Understanding the difference between rechargeable and non-rechargeable groundwater will asset for any further development in the groundwater resources. The application of environmental stable isotopes is a vital techniques to demonstrate the interrelation between present day and past recharge. The stable isotope technique proved to be an excellent indicator to distinguish between waters recharged in different climate conditions. Dansgaard, et al., (1982), showed that the stable isotope of the ice in the Antarctic and Greenland ice demonstrated different climate conditions prevailing in these regions in the past. The isotopic composition of the groundwater depend on the mechanism and time of recharge. Values of 18 O and D and the deuterium excess (d) defined by (Dansgaard, 1964) are taken to be an identical for climate condition.

The isotopic composition of the groundwater resources in several part of the world proved also to be a potential source of information on the climate existed in the past especially in arid areas like Jordan. Lloyd, (1980), based on the low deuterium excess (~ 10 0/00) of the stable isotope of the groundwater of the Disi sandstone aquifer in the southern desert of Jordan concluded that the recharge events into the aquifer took place in the past. Al-Sayari and Zotl, (1978), indicated that multiple changes of humid and arid phases occurred in the Arabian Peninsula during the Holocene period. Two distinguished phases was drawn from the sediments; the younger one is between 4500 to 7000 years BP and the oldest is between 8000 to 9000 years BP

Recently a wide range of isotopic composition of groundwater was encountered in different borehole of various aquifers in different part of Jordan. The isotopic composition of these water is more depleted than the ones recorded in the Disi aquifer (Lloyd, 1980). The most negative isotopic values were recorded for the deep and thermal groundwaters. This paper will examine the relationship between the isotopic composition of precipitation and various groundwater resources from different aquifers from all over the country. Comparison all the groundwater data with present day precipitation lead to some important conclusions to the climate conditions prevailed in Jordan in the past. In addition it will shed more light on the past climatological parameters which could affect the precipitation.