Groundwater Potentiality in Jefara Plain

Abstract

Jefara Plain located at western north of Libya. Jefara Plain influenced by arid desert areas to the south and Mediterranean Sea to the north. Groundwater is the main source of water in the Plain where the scarcity of water is major issue. Current groundwater resources are not covering the rapid development in the plain. The thesis consists of eight chapters as following; 1. Introduction: in this section the problem of seawater intrusion (SWI) was described, research objectives, research motivation, methodology, and Thesis Organization. 2. Review of Previous Studies: previous studies were mentioned and discussed to illustrate the problem history and find out the reasons led to SWI problem. 3. Describing Study Area (Jefara Plain): the study area was studied in terms of location, climate, geology, population, location, recharge, discharge, and hydrogeology. 4. Mathematical Approach: 5. Model Description: Numerical modeling is an effective tool for managing groundwater resources and predicting future responses, MODFLOW and MT3DMS used to simulate groundwater flow and solute transport in Jefara Plain. 6. Model calibration: Calibration steps were explained in this chapter 7. Model predictions: seven scenarios were applied to the model. These scenarios include: first, model will run without abstraction from the aquifers; second, Pumping of agriculture assumed constant in this scenario, and the pumping of municipal are varied depending on population demand; third, running of the model under 1993 situation where the pumping rate for agriculture and municipal remaining constant during the interval 1993-2040 without any management or climate change effects.; fourth, pumping of municipal and agriculture are varied depending on future predictions; fifth, this scenario studies the impact of SLR onSWI with no consideration to climate change through recharge; sixth, this scenario deals with the extreme impacts of climate change by combining both the maximum rates of SLR (59 cm/100 yr) and the minimum recharge rate (-10%) and finally, the actual imported waters from Man-Made River Project will take in account. An additional study was done to produce safe maps for recommended wells depths to pump water from without getting salty water by upconing. 8. Conclusion and Recommendations The results indicated that recent & previous studies indicate that there is progress problem of saltwater intrusion in Jefara Plain, the decline in groundwater heads below MSL and high salinity are the main indicators of SWI problem, in all scenarios the area south of Tripoli in Bin Ghashir and Al Swani are dried up for an unconfined aquifer, in Tripoli area the worst scenario for the unconfined aquifer is scenario No.6 where the inland SWI reached 10961m, and for the confined aquifer the worst scenario is scenario No. 4, the maximum inland SWI in unconfined aquifer at Tripoli area happened at Ain Zara section, while the minimum inland SWI happened at Gergaresh section, the maximum GW levels lowering values for all the scenarios considered indicated that the fourth and sixth scenarios have similar effect on GW levels lowering. Also the second and fifth scenarios have similar effect on GW levels lowering. In all scenarios considered, the sixth scenario has the worst effect on GW levels lowering. Key words: Jefara Plain, Groundwater, Modflow, MT3D, TDS, SWI, Abstractions