Assessment of nitrate contamination of groundwater using lumped-parameter models

In this paper, lumped-parameter models (LPMs) were developed and utilized to simulate nitrate concentration in the groundwater of Gaza City and Jabalia Camp (GCJC) in the Gaza Coastal Aquifer (GCA) in Palestine. In the GCJC area, nitrate levels exceed the maximum contaminant level (MCL) of 10 mg/L NO3-N (45 mg/L NO3) in many wells. Elevated nitrate concentrations in the groundwater of GCJC area are due to the disposal of untreated wastewater, the existence of heavy agriculture in the surrounding areas, and the use of cesspits for wastewater disposal. The developed LPMs utilize monthly time steps and take into consideration all the sources and sinks of water and nitrate in the study area. The main outcomes of the LPMs are the average temporal water table elevation and nitrate concentration. In order to demonstrate LPMs usability, a set of management options to reduce nitrate concentration in the groundwater of the study area were proposed and evaluated using the developed LPMs. Four broad management options were considered where these options tackle the reduction of nitrate concentration in the lateral inflow, rehabilitation of the wastewater collection system, reduction in cesspit usage, and the restriction on the use of nitrogen-based fertilizers. In addition, management options that encompass different combinations of the single management options were taken into account. Different scenarios that correspond to the different management options were investigated. It was found based on the LPMs that individual management options were not effective in meeting the MCL of nitrate. However, the combination of the four single management options with full rehabilitation and coverage of the wastewater collection network along with at least 60% reduction in both nitrate concentration in the lateral inflow and the use of nitrogen-based fertilizers would meet the MCL constraint by the end of the management period. 2009 Elsevier Ltd. All rights reserved.