Evaluation of the Impact of the Ongoing Water Resource Management Plans on Nitrate Concentration in Gaza Coastal Aquifer Using Modeling Approach

Abstract

Groundwater crisis in Gaza Strip includes two major folds: shortage of water supply and contamination (Nitrate and Salinity). The main nitrate sources in the groundwater of Gaza Strip are wastewater leakage, sewage sludge, animal manure and N-fertilizers. The problem of high nitrate concentrations in drinking water exceeded the WHO standards of 50 mg/l. This constitutes a major health risk to human life. The highest level of nitrate concentration is located in the north and south parts of Gaza Strip, where it reached more than 200 mg/l. Therefore, this research aims at studying the impacts of implementing the Gaza Emergency Technical Assistance Program (GETAP) on the nitrate concentration in groundwater in Gaza Strip using modeling approach. A flow and transport model using a three dimensional, finite difference simulation model (VMODFLOW Pro.) was applied to simulate the Gaza coastal aquifer. The approach for selecting the management scenarios was carried out depending on the GETAP projects and focuses into the aquifer system during the next 24 years. Seven selected management scenarios were tested; (1) Work as usual (zero scenario), (2) Upgrading and maintaining pipe work, (3) Importing water from Israel, (4) Construction of short term low volume desalination plant (STLV), (5) Construction of two regional desalination plant, (6) Reuse of treated wastewater in addition to decrease N-fertilizer and (7) Bringing together all the previous scenarios. It was estimated that the first scenario will raise the average nitrate concentration by 8.15 mg/l annually, while the second scenario will reduce the rising of average nitrate concentration by 4.51 mg/l annually. This means that the average nitrate concentration will increase by only 3.63 mg/l annually. Also, it was estimated that scenarios (3,4,5,6) will annually increase the average nitrate concentration by only (4.67,2.78,3.87,2.15)mg/l, respectively. The results show that applying all the scenarios together will decrease the average nitrate concentration by 2.44mg/l annually. Regionally, the best scenario to solve the increasing of nitrate concentration problem is a combination of those scenarios, (Scenario 7). In domestic areas, the best scenarios is (Scenario 4) and (Scenario 2). In Agriculture areas, the best scenario and the only one that has significant effect is (Scenario 6).