Changes In Groundwater Recharge Research Articles

Indirect effects of revegetation dominate groundwater recharge change at the basin scale

Attribution of groundwater recharge (GR) change is important for understanding subsurface hydrological processes and managing regional groundwater resources. Despite vegetation change directly influencing GR, its indirect effects are mostly incorporated into other effects because of multicollinearity in environmental factors. Taking the 59 hydrological stations from 13 basins in the Loess Plateau of China as an example, GR was estimated with daily streamflow data and recession-curve-displacement method for 1961–2019. Geographical detector was employed to qualitatively attribute the spatial variability of GR, while structural equation modeling and elasticity coefficient method were utilized for qualitative and quantitative analysis of the direct and indirect impacts of environmental factors on the temporal variation of GR. The annual mean GR in 13 basins ranged from 11 to 53 mm/year, and the spatial heterogeneity of GR can be well explained by loess thickness. GR significantly decreased in 68% of hydrological stations by 38% ± 15%. Averaged over the 13 basins, the direct and indirect effects of NDVI change respectively accounted for 10% and 48% of GR reduction, which greatly exceeded other factors. The indirect effects of vegetation change dominated GR change, but they were getting smaller with increasing latitude. This study highlights the importance in considering indirect effects of vegetation change in hydrological variability, and the results can improve the understanding of hydrological variability.

Determination of groundwater conservation zones study by considering groundwater recharge changes

This paper aims to find a new groundwater conservation zone concept in Indonesia by improving groundwater zoning by considering groundwater recharge changes. The previous zoning criteria only used groundwater level decrease and selected groundwater quality parameters. The ideas of this new concept are related to actual conditions, in terms of groundwater recharge changes due to global climate changes that control the precipitation frequency and in terms of land use changes that control groundwater recharge quantity. The changes are dynamically altered due to anthropogenic interactions. Based on Decree No. 31 2018, the groundwater conservation zone is based on three criteria: the decline of the groundwater table, the groundwater’s physical quality, and the apparent effect on the environment. This research will improve the criteria by suggesting some improvements to that approach: firstly, the application of modeling in calculating the groundwater decline rate, secondly the investigation of the effect of recharge decline due to land use change, and lastly to include recommendations on each zone in the groundwater conservation zone. This new concept is expected will revise the previous Decree that according to the consensus approach is not a scientific approach

The changing nature of groundwater in the global water cycle.

In recent decades, climate change and other anthropogenic activities have substantially affected groundwater systems worldwide. These impacts include changes in groundwater recharge, discharge, flow, storage, and distribution. Climate-induced shifts are evident in altered recharge rates, greater groundwater contribution to streamflow in glacierized catchments, and enhanced groundwater flow in permafrost areas. Direct anthropogenic changes include groundwater withdrawal and injection, regional flow regime modification, water table and storage alterations, and redistribution of embedded groundwater in foods globally. Notably, groundwater extraction contributes to sea level rise, increasing the risk of groundwater inundation in coastal areas. The role of groundwater in the global water cycle is becoming more dynamic and complex. Quantifying these changes is essential to ensure sustainable supply of fresh groundwater resources for people and ecosystems.

Developing a conceptual model of groundwater – Surface water interactions in a drought sensitive lowland catchment using multi-proxy data

Frequencies and intensities of droughts have increased due to climate change, providing an urgent impetus to improve understanding of ecohydrological fluxes in drought-sensitive areas where water and food security are threatened. We used a multi-proxy approach for assessing the effects of landuse and catchment properties on recharge and groundwater – surface water interactions during a prolonged drought starting in summer 2018 in a 66 km2 lowland, mixed landuse catchment (Demnitzer Mill Creek, Germany). We used water table monitoring, water stable isotopes, tritium isotopes, hydrogeochemical tracers, streamflow observations and geophysical investigations to characterise the spatial and temporal patterns of groundwater recharge in a shallow, unconfined aquifer system. Long-term groundwater levels showed a declining trend since 2011, which accelerated after 2018 resulting in increasingly intermittent streamflow. Geophysical surveys and groundwater monitoring indicated that shallow water tables (typically < 3 m deep) in low to moderate permeability surficial deposits are generally recharged during winter, leading to higher groundwater – surface water connectivity in riparian alluvial aquifers, which is the first order control on streamflow generation. This was supported by similar geochemical characteristics of groundwater and streamflow. Water stable isotopes indicated a high damping in groundwater with a bias towards winter precipitation and direct recharge. Groundwater age estimates using tritium showed high uncertainty but indicated that shallow groundwater was < 10 years old and generally similar to streamflow. Such multi-proxy approaches help understand changes in groundwater recharge and stream-aquifer interactions during droughts and contribute to the development of sustainable land and water management strategies for groundwater systems that are sensitive to climate change.

Rainfall intensity affects the recharge mechanisms of groundwater in a headwater basin of the North China plain

Understanding the origins of groundwater and its movement from mountain to plain during different high intensity rainfall events is critical for conserving water supplies, determining water-use policies and controlling pollution. These factors are also the keys for understanding the dominant processes in hydrological models. In this study, groundwater resources and recharge processes during heavy precipitation were explored by using stable isotope tracers in the hilly area of Taihang Mountain. It was found that the δ2H and δ18O values of precipitation exhibited obvious precipitation amount effect during different precipitation intensity events. The stable isotopic values in groundwater and river water showed significantly varied during the single extreme heavy precipitation and the continuous heavy precipitation events. In the rainy season, precipitation amounts greater than 40 mm/d could effectively recharge the shallow groundwater in the study area. By comparing the spatial isotopic distribution of groundwater, soil water, and river water with precipitation, we showed distinct groundwater recharge patterns in terms of their water resources, timing, and the degree of river water and groundwater interaction during the single extreme heavy precipitation and the continuous heavy precipitation. After the single extreme heavy precipitation, the δ2H and δ18O values of groundwater, soil water, and river water showed stable over time and had the same similar variations, suggested that the groundwater recharge was mainly dominated by precipitation with preferential flow or bypass flow. While after the continuous heavy precipitation, the variation of δ2H and δ18O in all water is consistent with the previous precipitation, which shown a mixing effect of previous enrich precipitation and depleted heavy precipitation, suggested that groundwater source was dominated by a continuous recharge of previous heavier precipitation with translatory flow. The groundwater main recharge mechanism is not constant, but changes with rainfall intensity. The rainfall intensity play an important role in groundwater recharge change affecting runoff process. Overall, this paper presents a new insight to understand the effect of rainfall intensity on hydrological process, which could be used to provide vital information in the semi-humid and semi-arid regions where water resources are critical in climate change adaptation strategies.

Climate elasticity assessment on groundwater recharge to the Edwards Balcones Fault Zone Aquifer, United States

AbstractThis study presents a comprehensive analysis of the characteristics of precipitation, temperature, and groundwater recharge in the recharge zone of the nine basins of the San Antonio segment of the Edwards Balcones Fault Zone Aquifer, which is one of the major groundwater systems in the United States and serves as primary water sources for approximately 1.7 million people in south‐central Texas. Datasets of monthly precipitation and average temperature (1895–2019) and groundwater recharge (1934–2019) are used to examine the decadal variability in precipitation, temperature, and groundwater recharge on the annual scale with a normalized 20‐year moving average of variance. Climate elasticity (precipitation and potential evapotranspiration) of groundwater recharge is estimated to evaluate impacts of climate change on groundwater recharge. The results of this study show that precipitation and temperature variability exhibit decadal cyclic patterns. Elasticity analysis of groundwater recharge indicates that a 1% change in annual precipitation may result in 2%, with a likely range of 0.15%–2.8%, change in groundwater recharge, and a 1% change in annual potential evapotranspiration may lead to −3.3% change in groundwater recharge with a likely range of −8.9% to 4% in the study area. This study suggests that climate elasticity of groundwater recharge may provide an alternative means for evaluating climate impacts on groundwater recharge to an aquifer.

Fresh Water availability and Its Global challenge

Water is prime natural resources fulfilling our needs in a precisious assets.we must acts to preserve and utilize every drop of water.water resources can be assessed on the basis of surface and subsurface water bodies.Climate change impact on ground Water the impact of climate change on ground water has been studied much less than the impact on surface waters. Ground water reacts to climate change mainly due to change in ground water recharge,but also change in river level in response to increase in mean Temperature,precipitation ,variability and sea level as mean precipitations.Changing land use pattern due to increasing ,urbanization, industrialization and agriculture activities are serious issues that causing increase ground water with drawal resulting in depletion of ground water resources and mining of ground water resources,along with deterioration of water quality.Rainfall is highly irregular and erratic and declining year to year due to change climatic conditions as result of serious deforestation global warming etc.Human health is affected by change in biodiversity and ecosystem.Climate change will affect the quality of drinking water and impact of fresh water availability and impact on public health. About 70% of Earth’s surface is water of which 97.5% is salty water and 2.5% is fresh water. Less than 1% of this 2.5% amount of freshwater is accessible. As sea water rise’s , salt water of ocean in filtrate as coastal fresh water due heavy rainfall and flooding waste more fertilizer and municipal sewage mixed with costal fresh water and change alter into more oxygen dead zone. Weather extreme and climate variability is main driver of food production in recent global challenge. Recent global challenge food security, fresh water availability, increase incidence of extreme high sea level. Loss of agriculture reproduction and increase in food prices and changes in weather patterns and alter availability and quality of water in many part of world. Climate change is an on-going phenomenon. This will inevitably bring about numerous environmental problems, including alterations to the hydrological cycle, which is already heavily influenced by anthropogenic activity.Chemical fertlizer’s has been adversely affecting the flora, fauna as well as soil quality . more ever every year plant pathogen are causing loss of 10 to 20% of agricultural production worldwide. Ground water will be vital to alleviate some of the worst drought situations. flooding and contaiminated water supplies, more intense weather events are likely to increase to risk of infectious disease epidemics and erosion of low-lying and costal land. Climate Chang will affect the quality of drinking Water and impact of fresh water availlablity and impact on public health it’s better to use UV Water purifiers.This paper will explore what climate change. Water is prime natural resources fulfilling our needs in a precisious assets.we must acts to preserve and utilize every drop of water.water resources can be assessed on the basis of surface and subsurface water bodies.Climate change imapact on ground Water the impact of climate change on ground water has been studied much less than the impact on surface waters. Ground water reacts to climate change mainly due to change in ground water recharge,but also change in river level in response to increase in mean Temperature,precipitation ,variability and sea level as mean precipitations.Changing land use pattern due to increasing ,urbanization, industrialization and agriculture activities are serious issues that causing increase ground water with drawal resulting in depletion of ground water resources and mining of ground water resources,along with deterioration of water quality.Rainfall is highly irregular and erratic and declining year to year due to change climatic conditions as result of serious global warming .Impacts of sea level rise on salinity intrusion global climate change has resulted in gradual sea level rise. sea level rise can cause saline water to migrate up stream in estuaries and rivers,thereby threating fresh water habitat and drinking- water supplies.Hydrology all the costal margin; fresh ground water flowing in land areas meets with saline ground water from the ocean. the fresh ground water flows from in land areas towards the coast where elevation and groundwater level are lower because salt water has higher content of dissolved salt and minerals. it denser the fresh water,causing it to have hydraulic head than freshwater. hydraulic head refers to the liquid pressure exerted by water column. the higher pressure density of salt water causes it to move into costal aquifiers in a a wedge shape under the freshwater. the salt water and fresh water meets in a transition zone where mixing occurs through dispersion and diffusion.

Urbanization effects on the groundwater potential recharge of the aquifers in the southern part of the Basin of Mexico

Abstract Collection, processing, and analysis of GIS and satellite data were performed in this work to estimate temporal groundwater recharge changes, which are needed as input in numerical groundwater-flow models. Layers of geological alignments, land use, drainage network, lithology, topography, and precipitation were collected. This information was spatialized, then layer importance was calculated using an Analytic Hierarchy Process (AHP) based on infiltration capacity to define Potential Recharge (PR) regions. A water budget equation was used to calculate PR volumes. The analysis was done every five years from 1970-19, considering average urban area changes. For all study periods, an increase in urban area was calculated from 16 to 28% of the total study area, while potential recharge decreased from 23 to 19% of the mean precipitation values for each 5-year period. The most significant urban expansion was from 1980-94 and 2010-19, which match periods of potential recharge decrease. However, a slight increase in PR from 2000-09, unrelated to urban area change, may be due to temperature variations. The results account for the spatial and temporal dynamics of the recharge in the study area and can be used as input data to calibrate the actual recharge in a groundwater numerical model.

Fresh Water availability and It’s Global challenge

Water is prime natural resources fulfilling our needs in a precisious assets. We must acts to preserve and utilize every drop of water. Water resources can be assessed on the basis of surface and subsurface water bodies. Climate change impact on ground Water the impact of climate change on ground water has been studied much less than the impact on surface waters. Ground water reacts to climate change mainly due to change in ground water recharge, but also change in river level in response to increase in mean Temperature, precipitation ,variability and sea level as mean precipitations. Changing land use pattern due to increasing, urbanization, industrialization and agriculture activities are serious issues that causing increase ground water with drawal resulting in depletion of ground water resources and mining of ground water resources, along with deterioration of water quality. Rainfall is highly irregular and erratic and declining year to year due to change climatic conditions as result of serious deforestation global warming etc. Human health is affected by change in biodiversity and ecosystem. Climate change will affect the quality of drinking water and impact of fresh water availability and impact on public health. About 70% of Earth’s surface is water of which 97.5% is salty water and 2.5% is fresh water. Less than 1% of this 2.5% amount of freshwater is accessible. As sea water rise’s, salt water of ocean in filtrate as coastal fresh water due heavy rainfall and flooding waste more fertilizer and municipal sewage mixed with coastal fresh water and change alter into more oxygen dead zone. Weather extreme and climate variability is main driver of food production in recent global challenge. Recent global challenge food security, fresh water availability, increase incidence of extreme high sea level. Loss of agriculture reproduction and increase in food prices and changes in weather patterns and alter availability and quality of water in many part of world. Climate change is an on-going phenomenon. This will inevitably bring about numerous environmental problems, including alterations to the hydrological cycle, which is already heavily influenced by anthropogenic activity. Chemical fertlizer’s has been adversely affecting the flora, fauna as well as soil quality . more ever every year plant pathogen are causing loss of 10 to 20% of agricultural production world wide. Ground water will be vital to alleviate some of the worst drought situations. flooding and contaiminated water supplies, more intense weather events are likely to increase to risk of infectious disease epidemics and erosion of low-lying and costal land. Climate Chang will affect the quality of drinking Water and impact of fresh water availlablity and impact on public health it’s better to use UV Water purifiers. This paper will explore what climate change. Water is prime natural resources fulfilling our needs in a precisious assets.we must acts to preserve and utilize every drop of water. water resources can be assessed on the basis of surface and subsurface water bodies. Climate change imapact on ground Water the impact of climate change on ground water has been studied much less than the impact on surface waters. Ground water reacts to climate change mainly due to change in ground water recharge, but also change in river level in response to increase in mean Temperature, precipitation, variability and sea level as mean precipitations. Changing land use pattern due to increasing, urbanization, industrialization and agriculture activities are serious issues that causing increase ground water with drawal resulting in depletion of ground water resources and mining of ground water resources, along with deterioration of water quality. Rainfall is highly irregular and erratic and declining year to year due to change climatic conditions as result of serious global warming .Impacts of sea level rise on salinity intrusion global climate change has resulted in gradual sea level rise. sea level rise can cause saline water to migrate up stream in estuaries and rivers, thereby threating fresh water habitat and drinking- water supplies. Hydrology all the costal margin; fresh ground water flowing in land areas meets with saline ground water from the ocean. the fresh ground water flows from in land areas towards the coast where elevation and groundwater level are lower because salt water has higher content of dissolved salt and minerals. it denser the fresh water, causing it to have hydraulic head than freshwater. hydraulic head refers to the liquid pressure exerted by water column. the higher pressure density of salt water cause it to move into costal aquifiers in a wedge shape under the freshwater. the salt water and fresh water meets in a transition zone where mixing occurs through dispersion and diffusion.

Impact of land cover changes on Long‐Term Regional‐Scale groundwater recharge simulation in cold and humid climates

AbstractIn cold and humid climates, warming temperatures will result in longer growing seasons, leading to land cover changes that could have long‐term impacts on groundwater recharge (GWR), in addition to the direct impacts of climate change. The objective of this study was therefore to investigate whether land cover (LC) changes need to be considered when simulating long‐term regional‐scale potential GWR in cold and humid climates by (1) quantifying how LC changes impact simulated GWR and (2) quantifying the combined impacts of LC and climate changes on the future GWR changes. Using the region of southern Quebec (Canada) as a case study and a water budget model, this work proposes an innovative coupling of land cover change scenarios and specific future climate conditions to simulate spatially distributed transient GWR over the 1951–2100 period. The results showed that including LC changes in long‐term GWR simulations produced statistically significant increases in GWR compared to using a constant LC through time (average of +13 mm). Massive afforestation taking place on agricultural lands simulated for one of the scenario chains (RCP4.5) increased GWR by reducing runoff during the snow‐dominated period (average − 17 mm). The results also showed that GWR was more sensitive to climate change for scenarios that included intense land cover changes. Additionally, the spatial distribution of the LC changes influenced their simulated impacts on GWR. Considering that the methodology was computationally feasible and entirely transferrable to the new CMIP6 ensemble, LC changes should be considered systematically in long‐term groundwater resources simulations.

Surface Morphologies in a Mars-Analog Ca-Sulfate Salar, High Andes, Northern Chile

Salar de Pajonales, a Ca-sulfate salt flat in the Chilean High Andes, showcases the type of polyextreme environment recognized as one of the best terrestrial analogs for early Mars because of its aridity, high solar irradiance, salinity, and oxidation. The surface of the salar represents a natural climate-transition experiment where contemporary lagoons transition into infrequently inundated areas, salt crusts, and lastly dry exposed paleoterraces. These surface features represent different evolutionary stages in the transition from previously wetter climatic conditions to much drier conditions today. These same stages closely mirror the climate transition on Mars from a wetter early Noachian to the Noachian/Hesperian. Salar de Pajonales thus provides a unique window into what the last near-surface oases for microbial life on Mars could have been like in hypersaline environments as the climate changed and water disappeared from the surface. Here we open that climatological window by evaluating the narrative recorded in the salar surface morphology and microenvironments and extrapolating to similar paleosettings on Mars. Our observations suggest a strong inter-dependence between small and large scale features that we interpret to be controlled by extrabasinal changes in environmental conditions, such as precipitation-evaporation-balance changes and thermal cycles, and most importantly, by internal processes, such as hydration/dehydration, efflorescence/deliquescence, and recrystallization brought about by physical and chemical processes related to changes in groundwater recharge and volcanic processes. Surface structures and textures record a history of hydrological changes that impact the mineralogy and volume of Ca-sulfate layers comprising most of the salar surface. Similar surface features on Mars, interpreted as products of freeze-thaw cycles, could, instead, be products of water-driven, volume changes in salt deposits. On Mars, surface manifestations of such salt-related processes would point to potential water sources. Because hygroscopic salts have been invoked as sources of localized, transient water sufficient to support terrestrial life, such structures might be good targets for biosignature exploration on Mars.

Climate Change Impacts on Groundwater Recharge in Cold and Humid Climates: Controlling Processes and Thresholds

Long-term changes in precipitation and temperature indirectly impact aquifers through groundwater recharge (GWR). Although estimates of future GWR are needed for water resource management, they are uncertain in cold and humid climates due to the wide range in possible future climatic conditions. This work aims to (1) simulate the impacts of climate change on regional GWR for a cold and humid climate and (2) identify precipitation and temperature changes leading to significant long-term changes in GWR. Spatially distributed GWR is simulated in a case study for the southern Province of Quebec (Canada, 36,000 km2) using a water budget model. Climate scenarios from global climate models indicate warming temperatures and wetter conditions (RCP4.5 and RCP8.5; 1951–2100). The results show that annual precipitation increases of &gt;+150 mm/yr or winter precipitation increases of &gt;+25 mm will lead to significantly higher GWR. GWR is expected to decrease if the precipitation changes are lower than these thresholds. Significant GWR changes are produced only when the temperature change exceeds +2 °C. Temperature changes of &gt;+4.5 °C limit the GWR increase to +30 mm/yr. This work provides useful insights into the regional assessment of future GWR in cold and humid climates, thus helping in planning decisions as climate change unfolds. The results are expected to be comparable to those in other regions with similar climates in post-glacial geological environments and future climate change conditions.

Estimation of Groundwater Recharge in Kumamoto Area, Japan in 2016 by Mapping Land Cover Using GIS Data and SPOT 6/7 Satellite Images

Agricultural fields, grasslands, and forests are very important areas for groundwater recharge. However, these types of land cover in the Kumamoto area, Japan, were damaged by the Kumamoto earthquake and heavy rains in 2016. In this region, where groundwater provides almost 100% of the domestic water supply for a population of about 1 million, quantitative evaluation of changes in groundwater recharge due to land cover changes induced by natural disasters is important for the sustainable use of groundwater in the future. The objective of this study was to create a land cover map and estimate the groundwater recharge in 2016. Geographic information system (GIS) data and SPOT 6/7 satellite images were used to classify the Kumamoto area into nine categories. The maximum likelihood classifier of supervised classification was applied in ENVI 5.6. Eventually, the map was cleaned up with a 21 × 21 kernel filter, which is larger than the common size of 3 × 3. The created land cover map showed good performance of the larger filter size and sufficient validity, with overall accuracy of 91.7% and a kappa coefficient of 0.88. The estimated total groundwater recharge amount reached 757.56 million m3. However, if areas of paddy field, grassland, and forest had not been reduced due to the natural disasters, it is estimated that the total groundwater recharge amount would have been 759.86 million m3, meaning a decrease of 2.30 million m3 in total. The decrease of 2.13 million m3 in the paddy fields is temporary, because the paddy fields and irrigation channels have been improved and the recharge amount will recover. On the other hand, since the topsoil on the landslide scars will not recover easily in natural conditions, it is expected to take at least 100 years for the groundwater recharge to return to its original state. The recharge amount was estimated to decrease by 0.17 million m3 due to landslides. This amount is quite small compared to the total recharge amount. However, since the reduced recharge amount accounts for the annual water consumption for 1362 people, and 12.1% of the recharge decrease of 1.41 million m3 each year to fiscal year 2024 is expected by municipalities, we conclude that efforts should be made to compensate for the reduced amount due to the disasters.

Simulation of long-term spatiotemporal variations in regional-scale groundwater recharge: contributions of a water budget approach in cold and humid climates

Abstract. Groundwater recharge (GWR) is a strategic hydrologic variable, and its estimate is necessary to implement sustainable groundwater management. This is especially true in a global warming context that highly impacts key winter conditions in cold and humid climates. For this reason, long-term simulations are particularly useful for understanding past changes in GWR associated with changing climatic conditions. However, GWR simulation at the regional scale and for long-term conditions is challenging, especially due to the limited availability of spatially distributed calibration data and due to generally short observed time series. The objective of this study is to demonstrate the relevance of using a water budget model to understand long-term transient and regional-scale GWR in cold and humid climates where groundwater observations are scarce. The HydroBudget model was specifically developed for regional-scale simulations in cold and humid climate conditions. The model uses commonly available data such as runoff curve numbers to describe the study area, precipitation and temperature time series to run the model, and river flow rates and baseflow estimates for its automatic calibration. A typical case study is presented for the southern portion of the Province of Quebec (Canada, 36 000 km2). With the model simultaneously calibrated on 51 gauging stations, the first GWR estimate for the region was simulated between 1961 and 2017 with very little uncertainty (≤ 10 mm/yr). The simulated water budget was divided into 41 % runoff (444 mm/yr), 47 % evapotranspiration (501 mm/yr), and 12 % GWR (139 mm/yr), with preferential GWR periods during spring and winter (44 % and 32 % of the annual GWR, respectively), values that are typical of other cold and humid climates. Snowpack evolution and soil frost were shown to be a key feature for GWR simulation in these environments. One of the contributions of the study was to show that the model sensitivity to its parameters was correlated with the average air temperature, with colder watersheds more sensitive to snow-related parameters than warmer watersheds. Interestingly, the results showed that the significant increase in precipitation and temperature since the early 1960s did not lead to significant changes in the annual GWR but resulted in increased runoff and evapotranspiration. In contrast to previous studies of past GWR trends in cold and humid climates, this work has shown that changes in past climatic conditions have not yet produced significant changes in annual GWR. Because of their relative ease of use, water budget models are a useful approach for scientists, modelers, and stakeholders alike to understand regional-scale groundwater renewal rates in cold and humid climates, especially if they can be easily adapted to specific study needs and environments.

Assessing Long‐Term Changes in Regional Groundwater Recharge Using a Water Balance Model for New Mexico

AbstractIn New Mexico in the arid southwestern United States, groundwater recharge is crucial to sustain groundwater (GW), which is vitally important to life, agriculture, industry, and ecosystems. To better understand the changes in recharge statewide, we explored the changes in groundwater recharge (RE), precipitation (P), surface water inflow (SWin), outflow (SWout), diversions (SWdiv), returns (SWret), and surface water and GW evapotranspiration (SWE and GWET) in five New Mexico counties: Taos, Torrance, Doña Ana, Eddy, and Lea during 1975–2015. The results show that the change‐point of RE was in the 1990s, leading to contrasting tendencies in RE before and after the change‐point with a decreasing rate during the latter one. There was a significant positive relationship between RE and P for Taos. The highest contribution rate (CR) to RE was SWout for Taos, whereas GWET ranked as the top CR for the other counties. Furthermore, the annual CR of GWET to RE increased significantly in all counties except Lea. The above results reveal that P and surface water flows played the dominant role in impacting RE in northern New Mexico where surface water is the primary local water resources, whereas GWET had the highest and increasingly continuous influence in central and southern New Mexico where the surface water is much less than that in northern New Mexico. This study shows that water budgets are important to identify differences in regional hydrological regimes that affect planning to maintain RE to groundwater.

Assessment of groundwater quantitative vulnerability to climate change in Slovenia

Assessment ofthe potential impact of climate change on groundwater recharge and availability of groundwater resources is as essential in Slovenia as it is elsewhere. Adaptive planning is of immense importance when aiming for reduction of negative impacts, even more so in areas with the highest groundwater exploitation levels and the lowest adaptive capacity. We have assessed quantitative groundwater vulnerability to climate change through potential impact and adaptive capacity indicators for all groundwater bodies in Slovenia. High and moderatly high quantitative groundwater vulnerability can be observed in merely 9 % of Slovenian territory. The highest quantitative vulnerability was accounted to shallow alluvial groundwater bodies in the northeastern part of the country, where the annual change in groundwater recharge due to climate change until the middle of this century is expected to represent more than a quarter of the current average annual groundwater extraction.

Effects of land-cover and watershed protection futures on sustainable groundwater management in a heavily utilized aquifer in Hawai\u2018i (USA)

Groundwater sustainability initiatives, including sustainable yield and watershed policy protection policies, are growing globally in response to increasing demand for groundwater, coupled with concerns about the effects of climate and land-cover change on groundwater supply. Improved understanding of the impacts of watershed management on groundwater yields and management costs—particularly in the broader context of climate and land-cover change—is critical to inform these initiatives and facilitate integrated land and water management. This study develops a novel, spatially explicit groundwater hydrologic ecosystem services framework, which combines stakeholder-defined land-cover scenarios, sustainable yield estimation using a groundwater simulation optimization approach, and economic valuation, and applies it in the most heavily utilized aquifer Hawai‘i (USA). Sustainable yield estimates and resulting differences in replacement costs are estimated for six land-cover scenarios (with varying levels of urban development and watershed management) crossed with two water demand scenarios in a context of a dry future climate (Representative Concentration Pathway [RCP] 8.5 mid-century). Land-cover change is found to be an important, though less significant drive of changes in groundwater recharge than climate change. The degree of watershed protection, through preventing the spread of high-water-use, invasive plant species, is projected to be a much stronger land-cover signal than urban development. Specifically, full forest protection increases sustainable yield by 7–11% (30–45 million liters per day) and substantially decreases treatment costs compared with no forest protection. Collectively, this study demonstrates the hydrologic and economic value of watershed protection in a context of a dry future climate, providing insights for integrated land and water policy and management in Hawai‘i and other regions, particularly where species invasions threaten source watersheds.

Uncertainty of simulated groundwater recharge at different global warming levels: a global-scale multi-model ensemble study

Abstract. Billions of people rely on groundwater as being an accessible source of drinking water and for irrigation, especially in times of drought. Its importance will likely increase with a changing climate. It is still unclear, however, how climate change will impact groundwater systems globally and, thus, the availability of this vital resource. Groundwater recharge is an important indicator for groundwater availability, but it is a water flux that is difficult to estimate as uncertainties in the water balance accumulate, leading to possibly large errors in particular in dry regions. This study investigates uncertainties in groundwater recharge projections using a multi-model ensemble of eight global hydrological models (GHMs) that are driven by the bias-adjusted output of four global circulation models (GCMs). Pre-industrial and current groundwater recharge values are compared with recharge for different global warming (GW) levels as a result of three representative concentration pathways (RCPs). Results suggest that projected changes strongly vary among the different GHM–GCM combinations, and statistically significant changes are only computed for a few regions of the world. Statistically significant GWR increases are projected for northern Europe and some parts of the Arctic, East Africa, and India. Statistically significant decreases are simulated in southern Chile, parts of Brazil, central USA, the Mediterranean, and southeastern China. In some regions, reversals of groundwater recharge trends can be observed with global warming. Because most GHMs do not simulate the impact of changing atmospheric CO2 and climate on vegetation and, thus, evapotranspiration, we investigate how estimated changes in GWR are affected by the inclusion of these processes. In some regions, inclusion leads to differences in groundwater recharge changes of up to 100 mm per year. Most GHMs with active vegetation simulate less severe decreases in groundwater recharge than GHMs without active vegetation and, in some regions, even increases instead of decreases are simulated. However, in regions where GCMs predict decreases in precipitation and where groundwater availability is the most important, model agreement among GHMs with active vegetation is the lowest. Overall, large uncertainties in the model outcomes suggest that additional research on simulating groundwater processes in GHMs is necessary.

Evolution of groundwater recharge as a result of forest development on the east coast of the province of Buenos Aires, Argentina

Changes in groundwater recharge associated with variations in land use were analysed with a focus on the role of afforestation on the east coast of Buenos Aires, Argentina. The growth of the population related to such changes was considered, linking water consumption to variations in recharge. A multi-temporal analysis was carried out using aerial photographs for the years 1957, 1975, 1981 and 2016, differentiating three types of cover: bare soil, forested soil and grassland. Water balances for each type of land use and groundwater recharge were estimated. In the forested soil, a reduction in recharge over time can be observed and it can be appreciated that forest expansion occurs at the expense of the sand-dune area, which offers the greatest possibilities for infiltration. At present, the water consumption, which depends solely on the groundwater reserves, is lower than the recharge, but this relationship is reversed during the tourist season. According to the estimated projections, the drinking water supply would be compromised in the coming decades, reaching a critical point or level of collapse as from 2070. This proves that it is essential for the policies and projects aiming at afforestation for different purposes to take into consideration the role of this change in land use when assessing the sustainability of the associated water resources.

Anthropogenic influence on monthly groundwater utilization in an irrigation dominated Ganga river Sub-Basin

In the last three decades, the low-income and highly-populated Kosi River's alluvial plain have improved its agricultural production by adapting a million groundwater pumping systems. As the farmers have less land holding for agriculture activities, site-specific water, and nutrient management are adopted for agriculture production. The study represents the impact of intensified agricultural activities aided by additional groundwater pumping system over the groundwater recharge/pumping rate. We analysed groundwater utilization variation due to farmers' empowerment through the green revolution and adaption of a million-groundwater pumping system via satellite-based Actual Evapotranspiration (AET). Throughout the year, groundwater accessibility has reduced the study area's agricultural dependency on monsoonal rainfall and allowed agricultural activities all season. In this study, hydrological modelling with spatial input data from different sources estimated monthly groundwater recharge/pumping and its variation during wet/dry years. The observed groundwater recharge/ extraction was compared with the corresponding rainfall patterns and validated using measured seasonal groundwater depths. We present the relative change in groundwater recharge or extraction statistics using a set of standardized seasonal indices. Improved socio-economic condition and the risk of recurring floods/ droughts has increased the dependency on groundwater aided irrigation in the region. Since the farmers have to pay for pumping fuel, they opt for more efficient groundwater-aided agricultural activities, especially in dry years. This additional dependency on groundwater has significantly increased the annual groundwater extraction rate and reduced the area's net recharge.