Many developing countries experience widespread groundwater declination. Sustainable management actions include generation of an accurate groundwater distribution based on an extensive groundwater monitoring network which is often cost prohibiting in the context of a developing country such as Bangladesh. Further, such knowledge is lacking for the Sylhet region where groundwater was documented to be under tremendous pressure. Specifically, the gap in the current literature exists regarding groundwater trends and its areal extent for this region. This paper bridges the gap in research by focusing on trends and spatial and temporal variation of groundwater level changes for this area. This study addresses this problem by creating groundwater level predictions at the ungauged areas using geostatistical methods applied to a detailed set of data. In this study, the spatial variability of annual-average depth to the water table at 46 observation wells in the Sylhet division in Bangladesh is analyzed for 2000, 2005, 2010, and 2015. The geostatistical analysis applies the ordinary kriging method with cross-validation to create the water table maps for the study area. The results indicate a substantial increase in groundwater depths during the studied period from 2000 to 2015 in some locations in the study area. Importantly, this work identifies the vulnerable zones in the area due to the groundwater lowering trend. The study adds to the groundwater management research in developing countries and focuses on the spatial and temporal groundwater variation. The findings from the modeling exercise contribute to identification of the vulnerable areas and therefore help policymakers in making informed decisions to manage groundwater resources in this sensitive region sustainably.

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The dry season irrigation primarily depends on groundwater in Bangladesh. The over-abstraction, along with decreasing recharge, is depleting the groundwater resource across the country. Consequently, the government of Bangladesh is planning to switch from groundwater to surface water irrigation. In line with this, Bangladesh Water Development Board has proposed to construct a rubber dam on the Mohananda river at the Chapai Nawabganj district. This work investigated the impact of the proposed reservoir facilitated surface water irrigation on the adjacent groundwater in the study area. A coupled river–groundwater modeling technique was used to predict the long-term groundwater condition. Results showed that the groundwater lowering rate reduced to 50 mm/year inside the irrigation zone compared to 87 mm/year outside the zone. Also, the augmented surface water irrigation raised the groundwater over an area of 141 km2 and 242 km2 in 2029 relative to the base condition of 2013 and existing irrigation practice if continued, respectively. Besides, the raised groundwater resulted in a higher discharge from the aquifer to the river. The study concludes that increased surface water irrigation successfully lowered the groundwater declination rate, especially in the surface water irrigation zone.

The shallow, Memphis, and Fort Pillow aquifers are the three major water‐bearing strata beneath Memphis, Tennessee, where the Memphis aquifer serves as the primary groundwater source. The upper Claiborne confining unit (UCCU) separates shallow and Memphis aquifers across the majority of Shelby County, acting as an upper protective layer for the Memphis aquifer. However, hydrogeologic breaches within the UCCU create a hydraulic connection and provide an avenue for potential contaminant migration from the shallow to the Memphis aquifer. This research aims to minimize contaminant migration, mitigate risks, extend existing wells' life that may face water contamination, and find suitable locations for future well construction. Several strategies are developed addressing well depth, seasonal well operation, and mapping no‐drilling or red zones to provide practical solutions. A numerical groundwater modeling technique is developed for each strategy that includes stochastic simulation–optimization and customized simulation models depending on the strategy. The models result in thousands of numerical simulations for each scenario to identify recurring patterns of contaminant movement to and through the Memphis aquifer. The results indicate that optimum well positions (spatially and vertically) and modification to pumping can increase the life expectancy of wellfields, offer sustainable management of the Memphis aquifer, and reduce contaminant migration through 2050.