Although there is no diffuse groundwater recharge at many semiarid sites, evidence for diffuse recharge exists at some locations where mean annual precipitation is much less than mean annual potential evapotranspiration , particularly where soils are coarse and rainfall variable is substantial. We investigate the climatic controls on diffuse recharge using a one‐dimensional, variably saturated flow model. The model is driven by a stochastic parameterization of climate that includes storm size distribution and seasonality of precipitation (P) and potential evapotranspiration (PET), constrained by data from 536 weather stations in the southwestern United States. Storm size distribution and seasonality determine the frequency and duration of intervals when P exceeds PET, which controls the flux of water past the root zone. For coarse soils, climates with large, infrequent storms yield recharge when / exceeds 0.4, compared with 0.7 for a typical climate. Recharge through fine soils is insensitive to storm size and occurs at / > 0.8. Seasonality has a stronger influence on recharge than storm size distribution, and the effects are similar for coarse and fine soils. Recharge is relatively insensitive to rainfall seasonality. In contrast, the typical PET annual cycle lowers / of the recharge threshold by 0.3. The relative timing of P and PET maxima is critical: Recharge occurs at / values that are lower by 0.2 when the rainy season occurs during winter instead of summer. Over the range of climate and soils examined, / values at the recharge threshold varied from 0.2 to 0.7. Therefore and alone are insufficient to predict where recharge will occur.

Abstract Low‐impact development (LID) technology for stormwater control has a number of forms, some of which relate to managed aquifer recharge to provide adequate safe water to communities. Stormwater collected through LID for managed aquifer recharge shifts water quantity and quality effects from surface waters to groundwater. Factors affecting quantity and quality of recharge influence and are influenced by state/local land development policy, state/local groundwater policy, regulation and codes and climate change effects, as well as pretreatment requirements. Groundwater quality effects of untreated stormwater infiltration by LID in a range of hydrogeologic settings are not well understood. Site selection for LID will include hydrogeologic considerations, onsite footprint and construction factors. Cost of the technology has a wide range of typically low‐cost options. Lessons learned include: matching technology to hydrogeologic setting; state/local policy should serve to avoid hydraulic and pollutant effects, particularly high water impacts; representative groundwater monitoring adds safeguard to water supply; and LID systems designs should consider life cycle costing including vulnerable geology, not just low installation cost.

Abstract. Reviews of field studies of groundwater recharge have attempted to investigate how climate characteristics control recharge, but due to a lack of data have not been able to draw any strong conclusions beyond that rainfall is the major determinant. This study has used numerical modeling for a range of Köppen-Geiger climate types (tropical, arid and temperate) to investigate the effect of climate variables on recharge for different soil and vegetation types. For the majority of climate types the total annual rainfall had a weaker correlation with recharge than the rainfall parameters reflecting rainfall intensity. In regions with winter-dominated rainfall, annual recharge under the same annual rainfall, soils and vegetation conditions is greater than in regions with summer-dominated rainfall. The relative importance of climate parameters other than rainfall is higher for recharge under annual vegetation, but overall is highest in the tropical climate type. Solar radiation and vapour pressure deficit show a greater relative importance than mean annual daily mean temperature. Climate parameters have lowest relative importance in the arid climate type (with cold winters) and the temperate climate type. For 75% of all considered cases of soil, vegetation and climate types recharge elasticity varies between 2 and 4, indicating a 20% to 40% change in recharge for a 10% change in annual rainfall Understanding how climate controls recharge under the observed historical climate allows more informed choices of analogue sites if they are to be used for climate change impact assessments.

The Bahariya Oasis in Egypt’s Western Desert faces critical water security challenges due to intensive groundwater exploitation and limited renewable recharge. To address this challenge, this study integrates a GIS-AHP model for the first time in the Bahariya area and incorporates high-resolution aeromagnetic data to enhance the prediction of groundwater potential zones. Nine groundwater-controlling thematic layers were compiled from multi-source datasets, classified, and weighted using the AHP model: structural geology (lineament density), terrain (slope), hydrology (drainage density and rainfall), hydrogeology (lithology and soil moisture), land-surface conditions (NDVI and LU/LC), and the RTP aeromagnetic signal. The resulting groundwater potential map delineates coherent “very-high” potential corridors concentrated in the southern and southeastern sectors, where high lineament density, low-relief topography, and permeable Quaternary alluvial deposits coincide and correlate with known productive wells, suggesting favorable conditions for enhanced recharge and storage. Potential patterns also show strong spatial correlation with the drainage network and mapped structural trends. Model validation against well occurrences yields an AUC of 93.4%, indicating excellent predictive accuracy. Aeromagnetic interpretation further resolves the subsurface structural architecture and constrains the basement configuration, revealing a marked deepening of the basement toward the south and southeast. This is where a thick sedimentary cover suggests enhanced groundwater storage potential, providing additional support for the groundwater potential zoning results. This integrated workflow offers a robust tool for groundwater prediction and planning, with direct utility for prioritizing drilling locations and supporting sustainable water resources planning in arid environments.

In water-limited environments, quantifying the timing and frequency of erratic rainfall recharge events and its climate forcing is of critical importance for groundwater resource management. In temperate semi-arid New South Wales, SE Australia (precipitation: 615 mm/year, pan evaporation: 1679 mm/year), since 2010 we have been using a limestone cave situated at 20 m below land surface, and just above the water table, as a vadose zone observatory of potential recharge approximated by drip rate observations. Complimented since 2018 by a soil moisture probe network and using the VarKarst karst-specialized recharge model, we investigate the climatic, hydrological and karst geological controls on recharge dynamics. We observe nineteen recharge events (07.2010 to 01.2021). They cluster into two periods (1) seven events between 08.2010 and 12.2010 during a La Niña (enhanced spring rainfall is typical in eastern Australia) and (2) seven events between 06.2016 and 10.2016 associated with a negative Indian Ocean Dipole (which is associated with wet winters and springs in southern Australia). Comparison with antecedent rainfall indicates a minimum of 40 mm rainfall over 14-days is required for recharge in winter, and >120 mm rainfall over 14-days in summer. We will use the karst recharge model to simulate the observed recharge events and to quantify the threshold behavior of the soil and vadose zone above the cave. Two recharge events have occurred since the establishment of the soil moisture network (03.05.2020, 29.07.2020). For those, we can analyze the influence of antecedent soil storage on the initiation of recharge and use this understanding for an evaluation of the simulated internal fluxes and storages of karst recharge model. Providing realistic results of both recharge and soil moisture observations, the model can be used as tool to predict the impact of past and future climate changes on groundwater renewal.

Objective Geological, climatic, and topographical conditions control regional groundwater flow systems. Previous researchers have made significant advancements in developing the theory of groundwater flow systems under steady-state climatic conditions. However, there has been limited progress in comprehensively understanding transient groundwater flow systems. Methods To address this gap, we constructed a two-dimensional numerical model that couples groundwater and surface water using HydroGeoSphere. We then examined the relationships among the subsystems of transient groundwater flow systems in response to variations in rainfall. Results The results demonstrate that the areas occupied by subsystems change with rainfall fluctuations. Local groundwater flow systems may neither expand during wet seasons nor contract during dry seasons. The relationships among the penetration depths, which indicate the elevation of the lowest point in a local flow system, can be positive, negative, or unrelated. This variation mainly arises from the high activity of intermediate groundwater flow systems under transient conditions, where their inputs, outputs, flow paths, and areas of recharge and discharge vary with rainfall fluctuations. These relationships are also sensitive to factors such as geology (hydraulic conductivity, specific storage), climate (rainfall rate), and topography (local and regional). Conclusion Based on a sensitivity analysis of five scenarios, changes in local flow syste

Groundwater exploration in arid regions of the Eastern Desert of Egypt requires an integrated understanding of the structural, geomorphic, and subsurface controls governing recharge and storage. This study presents a GIS-based groundwater potentiality model for a structurally complex rift-related zone along the southern Esh El Mellaha Block, between the Gulf of Suez and northern Red Sea. Sixteen topographical, meteorological, hydrological, and surface geological factors were systematically integrated with particular magnetic basement-depth modeling and subsurface fault architecture, which were weighted using the Analytical Hierarchy Process (AHP). Results demonstrate that regional tectonic configuration and structural geometry, rather than surface geomorphic factors alone, exert the primary control on groundwater distribution. High-potential zones are concentrated within major structural lows, including the Tarboul syncline, West Hurghada trough, and El Gouna fan system, where thick Quaternary deposits and enhanced infiltration prevail. The ENE-trending Bali Shear Zone acts as a key conduit for focused recharge by enhancing fracture permeability and linking the Gulf of Suez and Red Sea structural domains. Model validation yielded an AUC of 0.80, with balanced sensitivity and specificity (0.74), indicating reliable predictive performance. Single parameter sensitivity analysis confirms the robustness of the model and indicates that structural and geological factors exert the strongest control on groundwater potential distribution. The study emphasizes the role of structural architecture in groundwater assessment and supports future sustainable water-resource development in arid extensional tectonic settings.

and karst groundwater resources by publishing examples of the human impacts on karst groundwater. A great … Concentrated (concentrated groundwater flow) 7 : allogenic Diffuse allogenic recharge from Vadose / unsaturated … objectives of groundwater management in the Yu- catan are to develop regional groundwater supplies for

degradation, and groundwater recharge. The only natural input to any surface water system is precipitation within its watershed. The total quantity of water Water resources are natural resources of water that are potentially useful for humans. For example, they serve as a source of drinking water or irrigation water. These resources may consist of freshwater from natural sources or water produced artificially from other sources, such as reclaimed water (wastewater) or desalinated water (seawater). Approximately 97% of the water on Earth is salt water Sur…