Saudi Cultural Missions Theses & Dissertations
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Item Restricted Hydrochemical assessment of an urban groundwater-fed wetland at Sweet Briar Marsh(University of East Anglia, 2024) BinTani, Sharifah Ahmed; Hiscock, Kevinتتعمق هذه الأطروحة بعمق في النظام البيئي المعقد لمستنقع سويت براير، بهدف فهم العوامل العديدة التي تؤثر على جودة المياه. ستكشف الأطروحة عن التفاعلات والتأثيرات المعقدة التي تشكل التوازن الدقيق للمستنقعات من خلال فحص شامل لدرجة الحموضة والأكسجين المذاب والتوصيل ودرجة الحرارة ومستويات المغذيات. يسلط التحقيق الضوء على أن الجريان الزراعي والتوسع الحضري والأنشطة الصناعية تلعب دورًا مهمًا في رفع مستويات النترات والفوسفات، ويرجع ذلك أساسًا إلى الاستخدام المكثف للأسمدة وممارسات إدارة الثروة الحيوانية غير الكافية. تؤدي مستويات المغذيات المرتفعة هذه إلى تلوث المغذيات، مما يزيد من خطر التغذية الزائدة، حيث تحفز المغذيات الزائدة ازدهار الطحالب الضارة وتدهور جودة المياه. تم اقتراح استراتيجيات مختلفة لإدارة المياه لمكافحة هذه التحديات الملحة، بما في ذلك إدارة المغذيات الدقيقة وتدابير مكافحة التلوث. وتؤكد الدراسة على الحاجة الماسة إلى خطط إدارة مصممة خصيصًا والرصد المستمر لحماية الأراضي الرطبة. ويساهم هذا البحث في المعرفة الأوسع بممارسات إدارة الأراضي الرطبة الفعّالة من خلال توفير رؤى متعمقة من الملاحظات الميدانية، مع التأكيد على أهمية مواجهة قضايا جودة المياه المحلية.21 0Item Restricted GIS-Based Modeling of Shallow Groundwater Potential in Arid Regions under changing Climate and Future Water Demands: a case study of Al-Madinah, Saudi Arabia.(University of York, 2024-06-14) Alharbi, Ohood; McClean, Colin; Sakai, MarcoInvestigating water resources in arid regions is essential for managing water scarcity's unique challenges in these environments. GIS and remote sensing approaches have been applied here to model and analyse three main aspects: mapping potential groundwater zones, assessing climate change impacts, and examining future water needs under socio-economic scenarios. A fuzzy-frequency ratio model and a logistic regression model successfully delineated the potential groundwater zones. An ensemble of models performed well (Best model AUC = 0.943). Soil type was the most important factor in driving both models. The spatial distribution of very high potential groundwater areas in Al-Madinah is primarily compatible with volcanic lava areas with Lithosols and Calcic Yermosols soils. Assessing climate change under IPCC RCPs scenarios (2021-2100, RCP4.5 and RCP8.5) revealed that the temperature and Reference Evapotranspiration (ET0) rate of Al-Madinah is expected to continue to increase although rainfall may also increase by around 18.74% or 22.81 mm (2081-2100, RCP8.5) compared to 1970-2018. Such an increase might not have a pronounced effect on enhancing groundwater availability due to raising temperature (2°C) and ET0 (359.70 mm) with a higher probability of drought events indicated by the Standardised Precipitation Evapotranspiration Index (SPEI). Increases with higher water accumulation opportunities are predicted at 2081-2100 (RCP8.5). However, changes in potential groundwater zones using the Topographic Wetness Index (TWI) weighted by Rainfall are expected to show a small quantitative increase with the greatest addition of suitable potential zones also estimated for 2081-2100 under RCP8.5 (logistic regression = 19296km²) Analysing water needs in Al-Madinah city under the Impact of Population, Affluence, and Technology (IPAT) model confirmed that population was the most important factor in explaining water consumption trends. Water demand is projected to increase by up to 28% under IPCC_ SSP scenarios. These findings should aid in developing water resources management strategies and sustainable decision-making.34 0Item Restricted MODELING NONPOINT-SOURCE URANIUM POLLUTION IN AN IRRIGATED STREAM-AQUIFER SYSTEM: CALIBRATION AND SIMULATION(Colorado State Univeristy, 2024-05-15) Qurban, Ibraheem; Gates, TimothyThe Lower Arkansas River Valley (LARV) in southeastern Colorado has been a source of significant agricultural productivity for well over a century, primarily due to extensive irrigation practices. Mirroring trends seen in other semi-arid irrigated areas globally, however, irrigated agriculture in the LARV has resulted in several challenges for the region. In addition to the emergence of waterlogging and soil salinization, leading to decreased crop yields, elevated levels of nutrients and trace elements have appeared in the soil and water. Among these constituents, uranium (U), along with co-contaminants selenium (Se) and nitrate (NO3), has shown particularly high concentrations in groundwater, surface water, and soils. These heightened concentrations pose environmental concerns, impacting human health and the well-being of aquatic life such as fish and waterfowl. Careful monitoring and management practices are crucial to prevent potential harm to water resources. The main goal of this research is to develop a comprehensive numerical model for assessing U pollution in a stream-aquifer system within a large irrigated area. To achieve this, a computational model is built and tested that can predict with reasonable accuracy how U, along with Se and NO3, are mobilized and move within a coupled system of streams and groundwater. The approach combines two key modeling components: a MODFLOW package, which handles the simulation of groundwater and stream flow dynamics, and an RT3D package, which addresses the reactive transport of U, Se, and nitrogen (N) species in both groundwater and interconnected streams. RT3D relies on the simulated flows generated by MODFLOW to track the movement of U, Se, and N species between streams and the aquifer in the irrigated landscape, updating daily to adequately capture changes over time. This integrated model provides an understanding of how these contaminants behave and interact within the stream-aquifer system, aiding in effective pollution assessment and providing insights valuable to the planning of management strategies. The coupled MODFLOW-RT3D flow and reactive transport model is applied to a 550 km² area within the LARV, stretching from Lamar, Colorado, to the Colorado-Kansas border and spanning a period of 14 years. The flow package is compared with observations of groundwater hydraulic head and stream flow, along with estimates of return flow along the Arkansas River. The reactive transport package is assessed by comparing predicted U, Se, and NO3 concentrations against data collected from groundwater monitoring wells and stream sampling sites along with estimates of solute mass loads to the river. To calibrate and refine the model, the PESTPP-iES iterative ensemble smoother (iES) software is employed. This calibration process is dedicated to enhancing the model's accuracy in predicting both flow and transport dynamics. PESTPP-iES addresses calibration uncertainty by establishing prior frequency distributions for key model parameters based on data and expertise, then iteratively adjusts these parameters during calibration to align model predictions with observed data. Post-calibration, posterior distributions reflect updated parameter values and reduced uncertainties. Demonstrating a strong alignment with concentrations of values found in groundwater, streams, and the mass loading entering the Arkansas River, outcomes of the model-based simulations reveal a substantial violation of the Colorado chronic standard (85th percentile = 30 μg/L) for CU throughout the study region. On average, simulated values for groundwater in non-riparian areas in the region are 3.6 mg/L, 41 µg/L, and 126 µg/L, compared to respective averages of 4 mg/L, 53 µg/L, and 112 µg/L observed in monitoring wells. When considering the 85th percentile of simulated values, the figures for non-riparian groundwater are 6 mg/L, 50 µg/L, and 218 µg/L, respectively. Groundwater in riparian areas shows lower average simulated values of 3 mg/L, 26 µg/L, and 72 µg/L, respectively, and 85th percentile values of 5 mg/L, 41 µg/L, and 152 µg/L. Additionally, simulated average mass loading rates for NO3, Se, and U along the river are 8.8 kg/day per km, 0.05 kg/day per km, and 0.27 kg/day/km respectively, compared to stochastic mass balance estimates of 9.2 kg/day per km , 0.06 kg/day per km , and 0.23 kg/day per km. The simulated 85th percentile values in the Arkansas River are 1 mg/L, 11 μg/L, and 87 μg/L, respectively. Notably, the simulated U levels in groundwater exceed the chronic standard across 44% of the region. Along the Arkansas River, concentrations consistently surpass the chronic standard, averaging 2.9 times higher. Predicted Se concentrations also show significant exceedances of the chronic standard, while NO3 violations are slight to moderate. The varying pollutant levels across the region highlight specific areas of concern that require targeted attention, indicating potential contributing factors to these hotspots. Findings outline how serious and widespread the problem is in the LARV, providing a starting point for comparing potential pollution reduction from alternative water and land best management strategies (BMPs) to be explored in future applications of the calibrated model.18 0Item Restricted DELINEATING GROUNDWATER POTENTIAL ZONES IN JAZAN REGION, SAUDI ARABIA: A GIS AND REMOTE SENSING APPROACH USING ANALYTIC HIERARCHY PROCESS(Saudi Digital Library, 2023-11-22) Aljehani, Naif; Tansey, KevinIn arid countries such as Saudi Arabia, groundwater is an essential source of fresh water. The Jazan region is one of the Saudi Arabian regions and has the highest population density in the country. This region relies on groundwater as a source of fresh water, and the demand for this source has increased by 11,000 m3/day over the past 13 years. To meet this demand, identifying groundwater potential zones (GWPZ) becomes crucial. This dissertation aims to delineate GWPZ in 94% of the Jazan region using remote sensing, GIS, and the analytic hierarchy process (AHP), and ten thematic layers were generated for this purpose. Notably, incorrect classification and ranking of vegetation and water spectral indices (e.g., NDVI, NDWI, and NDMI) and a spatial correlation between them and the LULC thematic layer were observed in recent published studies. To address this, two thematic layers, CVWI (a combination of these indices) and MLULC (CVWI merged with land use/ land cover), were suggested. Two methods, AHP and weighted overlay analysis, were conducted, resulting in two GWPZ maps that were validated against regional observation well data. Findings revealed that merging vegetation and water indices with land use/ land cover in a single thematic layer yielded a better performing model compared to using them separately in the overlay analysis. It was determined that 62% of the study area in the Jazan region is categorised as a high potential zone. This differed from earlier studies, which allocated more area to zones of very high potential.35 0