With a yearly precipitation of 200 mm in most of the country, Jordan is considered one of the least water-endowed regions in the world. Water scarcity in Jordan is exacerbated by growing demands driven by population and industrial growth and rising living standards. Major urban and industrial centers in Jordan including the Capital Amman are concentrated in the northern highlands, mostly contained within the boundaries of the Zarqa River Watershed (ZRW). The ZRW is the third most productive basin in the greater Jordan River System. King Talal Dam was built a few kilometers upstream of the Zarqa-Jordan confluence to regulate its input mostly for the benefit of agricultural activities in the Jordan Valley. Concerns regarding the sensitivity of the ZRW to potential climate change have prompted the authors to carry out the current study. The methodology adopted is based on simulating the hydrological response of the basin under alternative climate change scenarios. Utilizing the BASINS-HSPF modeling environment, scenarios representing climate conditions with ±20% change in rainfall, and 1 • C, 2 • C and 3.5 • C increases in average temperature were simulated and assessed. The HSPF model was calibrated for the ZRW using records spanning from 1980 through 1994. The model was validated against an independent data record extending from 1995 through 2002. Calibration and verification results were assessed based on linear regression fitting of monthly and daily flows. Monthly calibration and verifications produced good fit with regression coefficient r values equal to 0.928 and 0.923, respectively. Assessment based on daily records show much more modest r value of 0.785. The study shows that climate warming can dramatically impact runoffs and groundwater recharge in

In this surface water modeling study, a new spatial evaluation for assessing the impact of urbanization was applied for the semi-arid watersheds intersecting with the Gaza coastal aquifer. The SWAT model was calibrated and validated in a semi-automated approach for stream flow in the main watersheds. The results show that the model could simulate water budget components adequately within the complex semi-arid watersheds.Linear relationships between the change in urban area and the corresponding change in surface runoff or percolation were concluded for the urbanized subbasins. The urbansurface runoff index (USI) and the urban-percolation index (UPI) were developed to represent a micro-level evaluation of different urban change scenarios in the subbasins.The global urban-surface runoff index (GUSI) and the global urban-percolation index (GUPI) were derived as macro-level factors reflecting the influence on the overall Gaza coastal aquifer due to urban area expansion.

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.

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Gaza has a water crisis and faces serious challenges for the future sustainability of its water resources. Land-use change has an expected effect on water budget of the Gaza Strip. Three different land cover scenarios; the and cover of 2007, land cover of 2020, and full urbanization land cover were simulated independently using The Automated Geospatial Watershed Assessment (AGWA) tool which work under the umbrella of GIS. In general, the simulation results indicate that land-cover changes will significantly alter the hydrologic response of Gaza region. Percolation is expected to decrease in all options as urban areas are expanded where as the simulated surface runoff reflected a relative departure from the first scenario comparing with other scenarios. In the baseline scenario (2007), the simulated surface runoff and percolation represent 12% and 41% respectively from the water budget components of the Gaza Strip. In year 2020, these values were expected by the simulation results to be 20% and 27% respectively. A unique linear relationship between the relative change in urban area and the corresponding relative change in surface water has been investigated from the simulation results. The analysis of the three urbanization scenarios can give decision makers better understand for the future situation and assist them to advance towards achieving sustainable development planning for water resources system in the Gaza Strip