Potential impacts of urban area expansion on groundwater level in the Gaza Strip: a spatial-temporal assessment

Abstract

In this study, a 3-D groundwater flow model was developed using MODFLOW-USG to investigate the groundwater levels within the Gaza coastal aquifer. Recharge estimation is based on a comprehensive approach including the connection to a surface water model (SWAT) for determining percolation from rainfall as well as detailed approaches regarding further recharge components. An unstructured grid (Voronoi cells) generated by MODFLOW-USG engine was used to reduce run time within complicated aquifer boundary conditions. The results indicate a very good fit between measured and simulated heads. Long-term forecasting of the groundwater levels was carried out as an essential step to support realistic and sustainable water resources planning and decision making. The increasing built-up area was linked to the potential impacts of urban expansion relating to water supply quantities and groundwater recharge components. The percolation was reduced temporally and spatially in the forecasting period based on the projected built-up area as well as an urban-percolation index. Considering the current management situation, the annual groundwater level correlated negatively with the increasing built-up area; the regression line slope was −0.056 m/km 2 for the average groundwater levels while it became steeper at −0.23 m/km 2 in sensitive locations in the southern part of the Gaza Strip. The groundwater level trend index was developed as a spatial indicator for the appropriate management alternatives that can achieve less negative trend index.

Integrated hydrologic modeling as a key for sustainable urban water resources planning

“…The agricultural sector in the Gaza Strip on average consumes around 75e85 hm 3 of water annually (PWA, 2013). The spatial monthly estimation of agricultural return flow is based on various factors (Eshtawi et al, 2015b), namely the monthly pattern of crop water requirements (CEP and FCG, 2010), annual irrigated crop area through governorates (in Gaza region) and zones (outside Gaza region), and estimated overall annual irrigation returned flow (PWA, 2013).…”

“…The initial hydraulic head is based on previous work (Eshtawi et al, 2015b) and drawn in November 2004 based on 138 observed water wells distributed through the model domain. The hydraulic conductivity, specific storage and porosity of the Gaza coastal aquifer system are based on the calibrated groundwater flow model (Eshtawi et al, 2015b).…”

“…The hydraulic conductivity, specific storage and porosity of the Gaza coastal aquifer system are based on the calibrated groundwater flow model (Eshtawi et al, 2015b). The initial flow concentrations of NO 3 and Cl were drawn in November 2004 based on 96 and 114 observed water wells, respectively, distributed through the model domain.…”

“…Model forecasting is based on the population projection (2010e2030) and the linear prediction of the built-up area (km 2 ) developed by Eshtawi et al (2015b). Increasing water demand due to population growth is based on the current per capita consumption (around 100 l/d), and the related water and wastewater leakage was estimated.…”

Evaluating Spatiotemporal Variation of Groundwater Depth/Level in Beijing Plain, a Groundwater-Fed Area from 2001 to 2010

“…Given that a number of researches of spatiotemporal variation of groundwater level in Beijing Plain have been initiated [8][9][10], it is of great importance to seek the possible causes to the variation. Recent researches showed that the groundwater depletion could be attributed to decreasing precipitation, increasing water demand, water extravagancy, poor utility ratio, and other unpredicted problems [11][12][13][14][15]. Numerical models have been proven to be an effective way to investigate the relationship between groundwater level and environmental-social factors [16,17].…”