Integrated hydrologic modeling as a key for sustainable development planning of urban water resources in the semi-arid watersheds of the Gaza Strip

This study demonstrates the strength of using integrated hydrologic modeling in a sustainable urban water planning process. It provides a complete view of the urban water system of the Gaza Strip, quantifies the urban water budget interaction with sufficient spatial and temporal details, and supports realistic scenarios inferred from the decision-making agenda. This study comprises three main parts. The first part aims to quantify the impact of urban area expansion on groundwater recharge and surface runoff by developing surface water modeling and investigating the response of watersheds to urban development. The second part provides a spatial-temporal assessment of potential impacts of urban area expansion on groundwater level concerning the link between surface and groundwater models. The third part promotes an integrated hydrologic modeling as a key for sustainable urban water resources considering the coupling of surface water, groundwater flow, and solute transport models. In the first part, 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 urban-surface 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 the second part, 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 the 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 (2004–2030) 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 the 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/km2 for the average groundwater levels while it became steeper at -0.23 m/km2 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. In the last part of this study, a coupling of surface water (SWAT), groundwater (MODFLOW) and solute transport (MT3DMS) models was performed to quantify surface-groundwater and quantity-quality interactions under urban area expansion. The results indicate a good fit between measured and simulated nitrate and chloride concentrations. The response of groundwater level, nitrate concentrations (related to human activities) and chloride concentrations (related to seawater intrusion) to urban area expansion and corresponding changes in the urban water budget were examined on a macro-scale level (the Gaza coastal aquifer domain). The potentials of non-conventional water resources scenarios, namely desalination, stormwater harvesting and treated wastewater reuse as well as an infrastructure performance scenario were investigated. In a novel analysis, groundwater improvement and deterioration under each scenario were defined and discussed in spatial-temporal and statistical approaches. The quality deterioration cycle index was estimated as the ratio between the amounts of low and high quality recharge components within the Gaza Strip boundary predicted for year 2030. The improvement index for groundwater level (IIL) and the improvement index for groundwater quality (IIQ) were developed for the scenarios as measures of the effectiveness toward sustainable groundwater planning

Climate Change Effect on Sediment Yield at King Talal Dam (Jordan)

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 few kilometers upstream of the Zarqa-Jordan confluence to regulate its input mostly for the benefit of agricultural activities in the Jordan Valley. King Talal Dam (KTD) is the most important one in Jordan. It lies at the outlet of Zarqa River watershed (ZRW). This dam has a capacity of 86×106 m3, which serves irrigation purposes in the Jordan Valley. However, the dam suffers from accelerated annual sedimentation. 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. The Soil and Water Assessment Tool (SWAT) is a powerful time-variable hydrologic model that has rarely been applied in arid environments. In this paper, the performance of SWAT in the semi-arid Zarqa River watershed (ZRW) was assessed. The SWAT model was calibrated for Zarqa basin 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.  Annual volume predictions correlated well with measured flow in both the calibration (r = 0.94) and validation (r = 0.93) periods.  For model validation the simulation results were compared to the measured values over 12 years period.  Good agreement was obtained in some of the years. Utilizing the SWAT modeling environment, scenarios representing climate conditions with ±20% change in rainfall, and 1oC , 2oC and 3.5oC increases in average temperature were simulated and assessed. Unique relationship between the percent change in precipitation scenarios and the parallel change in sediment yield has been studied at different change in temperature to evaluate the degree of sediment sensitivity with temperature and precipitation. The study shows that climate warming can dramatically impact runoffs, groundwater recharge and sediment yield in the basin. However the impact of warming can be greatly influenced by significant changes in rainfall volume. Keywords: Zarqa River, Climate change, Sediment, SWA

Application of Automated Geospatial Watershed Assessment (AGWA) Tool to Evaluate the Sediment Yield in a Semi-arid Region: Case Study, Kufranja Basin-Jordan

Prediction of sediment yield from catchments is essential in the investigation of reservoir sedimentation and other hydrological and geological studies. Many methods have been used in the prediction of sediment yield. Soil and Water Assessment Tool (SWAT) is a newly developed model that can be applied to rural watershed. SWAT model has used Modified Universal Soil Loss Equation (MUSLE) in sediment calculation. The Automated Geospatial Watershed Assessment Tool (AGWA) is a GIS based watershed modeling tool. This paper improved a hydrological modeling using modeling environment AGWA and SWAT model to evaluate the sediment yield in Kufranja basin in Jordan. The sediment yield has been calculated at three proposed dam sites in the basin. The calibration process depended on the most sensitive parameters in SWAT model. Long term rainfall series were used in the modeling process. AGWA studies the change in the most sensitive parameter in the SWAT model. The change in this parameter can be considered as different scenarios in Kufranja basin

Urban and river flooding: Comparison of flood risk management approaches in the UK and China and an assessment of future knowledge needs

Increased urbanisation, economic growth, and long-term climate variability have made both the UK and China more susceptible to urban and river flooding, putting people and property at increased risk. This paper presents a review of the current flooding challenges that are affecting the UK and China and the actions that each country is undertaking to tackle these problems. Particular emphases in this paper are laid on (1) learning from previous flooding events in the UK and China, and (2) which management methodologies are commonly used to reduce flood risk. The paper concludes with a strategic research plan suggested by the authors, together with proposed ways to overcome identified knowledge gaps in flood management. Recommendations briefly comprise the engagement of all stakeholders to ensure a proactive approach to land use planning, early warning systems, and water-sensitive urban design or redesign through more effective policy, multi-level flood models, and data driven models of water quantity and quality

Appropriate solutions for wastewater reuse in agriculture: a pilot plant in Rafah, Gaza Strip

Water supply represents a constant worldwide challenge for people and authorities. This issue is significantly severe in semiarid regions such as Gaza Strip, where groundwater constitutes the only fresh water source. Furthermore, Gaza Strip area suffers from water scarcity due to the decrease in water recharge and a constantly groundwater over-pumping, along with seawater intrusion, which cause serious problems in fresh water supply. Treated wastewater reuse represents a sustainable approach to increase water resource availability, to alleviate stressed polluted Gaza\u2019s coastal aquifer and to contribute to local agriculture development. On this issue, a pilot-scale plant has been designed to evaluate the feasibility of a municipal wastewater recovery for agricultural purposes in Rafah (Gaza Strip), reproducing the working conditions and performances of a real plant, which will be built by summer 2020. The paper aims to describe the case study in the context of Appropriate Technology (AT) for Developing Countries approach