GIS Techniques to Choose Best Location To Drill Wells in the Yarmouk basin (Jordan)

Summary

This study is about the recharge origin of the groundwater resources in Yarmouk Basin.

In order to characterize the groundwater hydrochemistry and the type of water, several wells tapping these three aquifer systems were sampled and analyzed for their chemical (TDS, Ca++, Mg++, Na+, K+, HCO3-, Cl-, SO4-2, and NO3-) and isotopes [stable (18O, 2H) and radioactive (3H)] constituents periodically for the last 5 years from around 50 wells.

The stable isotope data indicated that the groundwater in the first deep sandstone aquifer is paleowater, recharged during the Pleistocene. The groundwater of this aquifer is depleted in deuterium by ~ -20 ‰ in comparison to present precipitation in the study area.

The stable isotopic composition of groundwater of second aquifer in Ajloun mountains shows a similar pattern to the stable isotope composition of precipitation. In addition the tritium concentration (3.5 to 9.9 T.U.) of the groundwater indicates a significant contribution from bomb-tritium, which means recent infiltration from precipitation to the aquifer system.

The stable isotope content of the third aquifer is more enriched than the second aquifer, due to altitude and mechanism of recharge. The second aquifer is recharged from an elevation close to 1200 m above sea level (asl), while the recharge elevation of the third aquifer is close to 550 m asl. The third aquifer also reveals a relatively high tritium level (5.4 to 9.3) similar to the value of groundwater in the second aquifer and precipitation which indicates recent recharge events. The isotopic composition of groundwater in the second and third aquifer signifying recharge under the climate regime that dominate today in Jordan.

Significant variations were recorded for the TDS and NO3- concentration in second and third aquifers. The elevated NO3- level attributed to anthropogenic sources, which clearly classify the location of the second and third aquifers as recharge areas.

A fuzzy logic model in SPANS-GIS was applied using the TDS, NO3-, and tritium maps. The results indicates that the Ajloun mountains and Ramtha area are defined as a recharge areas and they are the most suitable locations for a potential drilling for future development.