Water Use Efficiency

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Al-Quds University Water Use Efficiency Research Group

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Browsing Water Use Efficiency by Author "Rawan Zaid Ahmad Khader"

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    Assessing the Effects of Climate Change and Land Use on the Runoff Generation: Case Study Zomar Watershed
    (Al-Quds University, 2025-05-27) Rawan Zaid Ahmad Khader; روان زياد احمد خضر
    Surface runoff constitutes a critical component of the hydrological cycle, influenced by climate variability, land use changes, and topographical characteristics. In arid and semi-arid regions such as the West Bank, understanding the complex interplay between climate change and land use changes on runoff generation is important for implementing sustainable water resource management strategies and mitigating flood risks. The effects of climate change directly influence surface runoff through variations in temperature, evaporation, and the intensity, frequency, and distribution of precipitation. Additionally, urbanization and changes in land use result in a rise in impervious surfaces, which contributes to an increase in surface runoff and heightens the risk of flash floods. This study aims to assess the effect of climate change and land use transformations on surface runoff generation within the Zomar watershed, especially as it is situated between Nablus and Tulkarm cities, which are considered among the most densely populated cities. Given the urban expansion and the increasing frequency and intensity of extreme rainfall events in the region, this comprehensive analysis quantifies these impacts and proposes evidence-based water management strategies. The research developed a hydrological model using the Watershed Modeling System (WMS) integrated with the Hydrologic Modeling System (HEC-HMS). The Zomar watershed was divided into three sub-catchments: Nablus, Tulkarm, and Burqa. To build the model, the study used a wide range of data, including daily rainfall records from 2000 to 2023, high-resolution land use maps generated from aerial imagery, and detailed information about soil and topography. The model was calibrated and validated using rainfall-runoff data that were observed during 2005–2006. For simulating infiltration, the Deficit and Constant method was applied, while the Clark Unit Hydrograph method was used to model the runoff process accurately. The findings demonstrate that the effects of climate change and land use changes have substantially increased runoff generation patterns throughout the Zomar watershed. Quantitative analysis showed that urbanization increased impervious surface coverage by 6.27% in the Nablus subcatchment, 5.03% in the Tulkarm subcatchment, and 1.94% in the Burqa subcatchment between 2000 and 2023, consequently reducing infiltration capacity and amplifying surface runoff volumes. The total surface runoff volume over 23 years is 12.5 MCM, with a surface runoff coefficient of 13.2%. The hydrological modeling established that rainfall intensity distribution patterns have a greater effect on runoff generation than cumulative seasonal precipitation. This was illustrated in the 2013-2014 season, in which rainfall was concentrated on specific days with high intensity, which produced significantly elevated runoff coefficients and peak discharges compared to seasons with comparable or greater total rainfall but more temporally distributed precipitation patterns. Spatial analysis revealed pronounced heterogeneity among the sub-catchments, with the Nablus sub-catchment generating the highest average runoff coefficient (20.6%) due to urban expansion, compared to Tulkarm (14.5%) and Burqa (5.72%). The study indicates that future urban expansion will increase surface runoff, heightening flood risks. This research conclusively establishes that the cumulative impact of climate change and land use changes significantly increases the risk of surface runoff and flash flooding within the Zomar watershed. The findings emphasize the urgent necessity for implementing integrated watershed management approaches, encompassing sustainable urban development policies, strategic enhancement of green infrastructure networks, and innovative water harvesting initiatives. These strategies are essential not only for effective flood risk reduction but also for optimizing water resource utilization in alignment with the United Nations Sustainable Development Goals (SDGs), particularly those addressing water security, climate resilience, and sustainable communities in vulnerable regions.