Decline Of Groundwater Table Research Articles

The role of farm subsidies in changing India’s water footprint

Dwindling groundwater supplies threaten food security and livelihoods. Output subsidies for farmers are a ubiquitous agricultural policy tool, yet their contribution to growing groundwater stress remains poorly quantified. We show how output subsidies guaranteeing the purchase of crops at higher than market prices may have contributed substantially to declining water tables in India. Our analysis suggests that these policies may have led to a 30% over-production of water intensive crops. In the northwestern state of Punjab, rice procurement can potentially account for at least 50% of the groundwater table decline over 34 years. In the central state of Madhya Pradesh, wheat procurement adopted in the late 2000s appears to have driven a 5.3 percentage point increase in dry wells and a consequent 3.4 percentage point increase in deep tubewells. These results suggest that well-intentioned but poorly designed subsidies can impose harmful externalities on the environment and undermine long-term sustainable development.

Geospatial distribution of qanats in middle eastern countries: Potential for sustainable groundwater system

Serious concerns have arisen regarding the depletion of groundwater aquifers and water shortage, particularly in the Middle East. The utilization of qanat, subterranean tunnel-wells, may serve as a solution to addressing water scarcity and present targeted strategies toward sustainable groundwater management. This research presents an analysis of the spatial distribution of active qanats in Afghanistan, Iran, Iraq, and Syria, considering the annual rainfall rate, the elevation from sea level, water stress risks, and groundwater table decline. It aims to identify the qanat sites that may be maintained and utilized. The findings reveal distinct geographical clusters of qanats, with a concentration in mountainous regions characterized by consistently high elevations ranging from 1500 to 2500 m above sea level and annual rainfall rates between 200 and 300 mm. In contrast, a more sporadic presence is observed in low-lying plains with elevations ranging from sea level to 1000 m, where the annual rainfall ranges between 300 and 600 mm. Participation in the restoration, maintenance, and utilization of qanats in regions facing high water stress and the risk of groundwater table decline, such as the central plateau of Iran, may offer a sustainable solution to water risk challenges.

Assessment of modern irrigation versus flood irrigation on groundwater potentiality in old clayey lands

Groundwater management in semiarid and arid regions, like northern Egypt, is essential for the sustainability of scarce resources through monitoring groundwater status and sources of recharge to the aquifer. In the Qalyubia Governorate, Nile Delta, Egypt, the study examined the recharge of groundwater in lands subject to flood irrigation and compared it with water-saving irrigation methods to detect how irrigation practices influence the potentiality of groundwater. A simulation of the two irrigation techniques, flood irrigation, and water-saving irrigation, was performed. Using GMS, simulations are done to calculate the water balance in the main 8 districts of Qalyubia Governorate. In comparison to flood irrigation, it was found that water-saving irrigation has less recharge intensity, which in turn causes a lowering in groundwater levels. The decline in groundwater table ranges between 10 and 50 cm. Modern irrigation influences the potentiality of the Nile Delta aquifer, which can’t be underestimated.

Using the Hydraulic Properties of Zeolite to Grow Desert Willow—A Case Study to Rehabilitate Riparian Areas of Semi-Arid Environments

Plants in riparian areas are well known for their beneficial functions such as providing biodiverse habitats, maintaining water quality, and stabilizing streambanks. However, riparian plants are declining in semi-arid environments due to long-term drought, a decline in groundwater table, and an increase in soil salinity. A new technique using clinoptilolite zeolite (CZ) as a wicking material with minimum artificial irrigation to grow desert willow [Chilopsis linearis (Cav.) Sweet] under field conditions is introduced; desert willow is native to riparian regions of the southwestern United States. For this study’s experiment, desert willow seedlings were planted in boreholes filled with clinoptilolite zeolite (CZ) as a substrate and in situ riparian sandy loam soil (RS) as a control. The boreholes extended to the groundwater table at two distinctive depths, shallow (avg. depth = 1.21 m) and deep (avg. depth = 2.14 m). The plants’ viability was then assessed by measuring their midday water potential (Ψmd) as an indicator of water stress. There was no significant difference in Ψmd (p > 0.05) between the plants grown in CZ and RS (mean Ψmd = −0.91 vs. −0.81 MPa) where the groundwater was shallow and a significant difference (mean Ψmd = −0.75 vs. −2.03 MPa) where the groundwater was deep. The proposed method is promising as an alternative method for growing desert willow or other plants for riparian rehabilitation with no artificial irrigation. However, its effectiveness depends on groundwater being accessible at the base of the boreholes used for planting.

Integrating SBAS-InSAR and Random Forest for Identifying and Controlling Land Subsidence and Uplift in a Multi-Layered Porous System of North China Plain

Controlling groundwater table decline could mitigate land subsidence and induced environmental hazards in over-explored areas. Nevertheless, this becomes a challenge in the multi-layered porous system as (in)elastic deformation simultaneously occurs due to vast spatiotemporal variability in the groundwater table. In this study, SBAS-InSAR was used to estimate annual land deformation during 2017–2022 in a specific region of North China Plain, in which aquifers are composed of many layers of fine-grained compressible sediments and the groundwater table has experienced a prolonged decline. The random forest (RF) was applied to establish the nonlinear relationship between accumulated deformation and its potential driving factors, including the depth to the groundwater table (GWD) and its change rate, and the compressible sediment thickness. Results show that the marked subsidence and uplift co-exist in the region even though the groundwater table has risen widely since the South–North Water Diversion Project. The land subsidence is attributed to inelastic compaction of the thick compressible deposits in depression cone centers, where the GWD is over 40 m and 90 m in the shallow and deep aquifers, respectively. In contrast, the marked uplift is primarily attributed to fast rising of the groundwater table (e.g., −2.44 m/a). The RF predictions suggest that, to control the subsidence, the GWD should be less than 20 and 70 m in the shallow and deep aquifers, respectively, and the rising rate of the GWD should increase to 2–5 times of current rates in the depression cones. To mitigate the marked uplift, the rising rate of the GWD should reduce to 1/2–1/5 of the current rates in the shallow aquifers. The uneven deformations of sediments in the depression cone centers and uplift in their boundaries may exacerbate geohazards. Therefore, it is vital to implement appropriate governance of groundwater recovery in the multi-layered porous system.

Changing water sources and extraction methods in Bangladesh: Challenges, consequences, and sustainable solutions

The quest for safe water in Bangladesh has resulted in the shift of water sources and extraction methods throughout history. The study aims to investigate the factors driving these changes, assess the consequences of current water consumption trends, and propose solutions for sustainable water management. The research highlights the historical shift from surface water to tube-wells for accessing groundwater, driven by their affordability and user-friendly nature. However, the discovery of arsenic contamination in tube-well water raised serious public health concerns, leading to the exploration of alternative water sources and extraction techniques. Various methods such as dug wells, pond sand filters, piped water supply, rainwater harvesting, and well-sharing have been adopted by communities and indigenous groups to ensure access to safe and clean water. The study reveals disparities in the installation of deep tube-wells by the government and NGOs, often overlooking safer water sources available at shallower depths. Furthermore, the study discusses the consequences of high-yielding technologies and increased water consumption in Sonargaon Upazila, leading to groundwater-related disasters and a decline in the groundwater table. Private irrigation facilities have become more popular among people, contributing to the declining groundwater table. This study provides insights into the changing water sources and extraction methods in Bangladesh, identifies the consequences of current water consumption trends, and proposes strategies for sustainable water management. The findings underline the importance of informed decision-making, government intervention, and community involvement to address the challenges of groundwater depletion and contamination in the region.

Differential eco-physiological performance to declining groundwater depth in Central Asian C3 and C4 shrubs in the Gurbantunggut Desert.

Resources in water-limited ecosystems are highly variable and unpredictable, and the maintenance of functional diversity among coexisting species is a crucial ecological strategy through which plants mitigate environmental stress. The comparison of differential eco-physiological responses among co-occurring plants in harsh environments could help provide deep insights into the coexistence mechanisms of competing species. Two coexisting desert shrubs with different photosynthetic pathways (Haloxylon ammodendron and Tamarix ramosissima) were selected in the Gurbantunggut Desert located in northwest China. This study detected variations in the water sources, photosynthetic parameters, stem water status, and non-structural carbohydrates of the two shrubs at three sites with different groundwater table depths during the growing seasons of 2015 and 2016 to identify distinct eco-physiological performances in coexisting plants with different functional types under fluctuating water conditions. The water sources of H. ammodendron shifted from soil water to groundwater, while T. ramosissima extracted water mainly from deep soil layers at both sites. Significant reductions in carbon assimilation and stomatal conductance in H. ammodendron with deeper groundwater table depth were detected during most drought periods, but no significant decreases in transpiration rate were detected with declining groundwater table depth. For T. ramosissima, all of these gas exchange parameters decreased with the progression of summer drought, and their relative reduction rates were larger compared with those of H. ammodendron. The stem water status of H. ammodendron deteriorated, and the relative reduction rates of water potential increased with deeper groundwater, whereas those of T. ramosissima did not differ with greater groundwater depth. These findings indicated that prolonged drought would intensify the impact of declining groundwater depth on the eco-physiology of both shrubs, but the extent to which the shrubs would respond differed. The two shrubs were segregated along the water-carbon balance continuum: the C3 shrub T. ramosissima maximized its carbon fixation at an enormous cost of water, while greater carbon fixation was achieved with far greater water economy for H. ammodendron. These results demonstrated that the two shrubs prioritized carbon gain and water loss differently when faced with limited water sources. These mechanisms might mitigate competitive stress and enable their coexistence.

Soil extracellular enzyme activity and microbial resource limitation exhibited close relationships with groundwater table decline in desert wetlands

In groundwater-fed desert wetlands, groundwater table (GWT) decline leads to the loss of carbon and nutrients, followed by the expansion of desertification. How the GWT decline affects soil nutrient cycling and microbial resource limitation is still unclear. Here, we sampled soils along a steep GWT decline gradient in desert wetlands and surroundings traversing marshland (ML), sandy grassland (SG) and bare sandy land (SL) in the southern margin of Mu Us Sandy Land, China, then determined the extracellular enzyme activity (EEA, including carbon (C)-, nitrogen (N)- and phosphorus (P)-acquiring enzymes) and related soil environmental variables, and quantified the relative value of microbial metabolic limitation by vector analysis. Results showed that GWT decline eventually inhibited the activities of soil C-, N- and P-acquiring enzymes, which might be unfavourable for nutrient cycling. The relationship between soil microbial C limitation and GWT showed a downwards unimodal trend, despite the largest SOC value observed in ML. However, microbial P limitation was relieved by a slight GWT decline, and the continuous decline in GWT eventually shifted microorganisms from P to N limitation. We further provide evidence that DOC and C:P were the key factors explaining the variations in microbial C and nutrient limitations along the decline in GWT, respectively. Altogether, these findings suggest that soil EEA and microbial resource limitation exhibit close relationships with GWT decline in desert wetlands. Moreover, they highlight that alleviating microbial N limitation may be the primary solution for vegetation restoration and carbon sequestration in sandy land around wetlands.

Effects of Groundwater Table Decline on Vegetation in Groundwater-Dependent Ecosystems

The distribution map of groundwater-dependent ecosystems (GDEs) is generally used for the scientific management of vegetation and groundwater resources, and is instructive for forest resource conservation. The groundwater table in the Loess zone has declined over the past few years, but no study has yet been conducted to assess the impact of this decline on GDEs. This study used data from the GRACE gravity satellite to delineate groundwater fluctuation periods from 2002 to 2021, to develop a method to identify whether vegetation is potentially associated with groundwater using three criteria, and to verify the accuracy of this method. Study results show that the groundwater changes in the Loess zone can be divided into two periods, 2002–2014 and 2015–2021, with groundwater declines becoming more rapid after 2015. We did not observe the spatial variation pattern of GDEs in the Loess areas, but there was a significant change in the area of GDEs during the two periods studied, with a 13.56% decrease in the very likely GDEs’ group area and an 11.68% increase in the unlikely GDEs’ group area between 2015 and 2021 compared to 2002–2014, with little change in the neutral, likely, and very unlikely group areas. This study provides a reference for exploring the relationship between vegetation and groundwater, as well as for the scientific management of water resources.

Estimation of groundwater level and storage changes using innovative trend analysis (ITA), GRACE data, and google earth engine (GEE)

Groundwater is the supreme source of fresh water and the third-largest water resource around the world. But in recent decades, groundwater-related issues in Manbhum Singhbhum Plateau have been significantly increasing day by day. In this plateau region, overuse of groundwater and inappropriate irrigation has greatly harmed the ecosystem, triggering salinity, increasing contamination of groundwater. Therefore, it is essential to estimate the magnitude of groundwater storage changes and water table fluctuation in both pre and post-monsoon seasons in this plateau fringe. The principal objectives of this study are i) to investigate groundwater level changes in the last two decades using observed water level data and ii) to estimate groundwater storage changes using satellite-derived datasets in a hard rock terrain region of India. The Innovative Trend Analysis (ITA) technique has been applied for its better visual interpretation and advantage in serial correlation than the traditional Mann-Kendell test. Gravity Recovery and Climate Experiment (GRACE) gridded data have been processed to obtain a time series trend of mean Equivalent Water Thickness (EWT) and soil moisture has been estimated in Google Earth Engine (GEE). Therefore, soil moisture is subtracted from terrestrial water storage (TWS) to estimate the changes in groundwater storage (GWS) in this plateau fringe. ITA result indicates that approximately 40% and 67.5% of monitoring sites had seriously dropping tendencies of groundwater table in pre and post-monsoon seasons respectively. Simultaneously, maximum groundwater storage (9.484 cm) occurred in Jul 2004 (wet months) whereas a minimum of −30.21 in March 2016 (dry months). Overall results indicate massive decline in groundwater table and groundwater storage. The main reasons for these alarming challenges are geological structure and excessive extraction of groundwater for drinking and irrigation purposes. These research findings will help to further investigations and perform crucial well-organized management of water resources in this part of Manbhum-Singhbhum Plateau.

Study of Spatio-temporal Variability of Groundwater Table in Semi-arid Agrarian District of Haryana

Abstract The increase in the number of tubewells and associated irrigated area is increasing pressure on the groundwater resource. Therefore, present study focuses on detailed elaboration on spatio-temporal variations in groundwater level and its relation with rainfall and other corresponding factors in Jind district of Haryana. Study area contributes nearly 10% of food grain production to the state. Present study utilizes secondary data acquired from various departments of state government of Haryana. The temporal variability is studied by calculating minimum, maximum, average depth and yearly rise/fall of groundwater table from 1987 to 2017. The non-parametric tests like Mann-Kendall, Sen’s slope and parametric tests like linear regression are used to understand the behavior of groundwater table. The rate of depletion is 19 cm per year in pre-monsoon season and 24 cm per year during post-monsoon season. The central, north and north-western part of the study area is facing sharp decline in groundwater table. This decline of groundwater table is found to be correlated with the cultivation of rice crop and increase in tubewell irrigated areas. Contrary to this, the southern and south-western part of the study area is becoming more vulnerable to waterlogging.

Alternative cropping systems and optimized management practices for saving groundwater and enhancing economic and environmental sustainability

Rapid decline in groundwater table due to excessive withdrawal of water for irrigation has been posing a serious threat to sustainable agricultural production in hot arid region of India. Alternative cropping systems having low irrigation requirement have been proposed to resolve unsustainable groundwater use but trade-off with other dimensions such as yield, profitability, and environmental impacts is not well-documented. An integrated analysis of amount of groundwater use, productivity, profitability, resource-use efficiency (RUE), and environmental impacts of three cluster bean-based cropping systems [conventional cluster bean (Cyamopsis tetragonoloba)–wheat (Triticum aestivum) (CB–W), and two alternative cropping systems, namely cluster bean-Indian mustard (Brassica juncea) (CB–IM) and cluster bean–blond psyllium (Plantago ovata) (CB–BP)] under different soil management practices [two tillage types, i.e., conventional (CT), and deep tillage (DT); and three farmyard manure (FYM) application rates, i.e., 0, 5, 10 Mg ha-1] was carried out. Based on a three-year field experiment, compared to conventional CB–W, alternative cropping systems produced 28.6–47.4 % lower seed yield, but enhanced economic returns (7.6–31.1 %), while reduced amount of irrigation (− 27.9 to − 37.2 %), energy (− 22.4 to − 37.0 %), and nutrient (− 17.4 to − 46.1 %) used, global warming potential (− 20.2 to − 45.9 %) and greenhouse gas intensity (− 27.3 to − 57.7 %). Alternative cropping systems saved 1.87–2.50 × 103 m3 per year per hectare of groundwater than conventional cropping systems. Soil management practices influenced agro-economic and environmental dimensions of cropping systems. Deep tillage (DT) enhanced yield (14.0 %), economic profit (18.8 %), RUE (13.2 %, 13.8 % and 8.5 % for nutrient, water and energy use efficiency, respectively). Addition of FYM increased yield (up to 23.0 %), economic net return (up to 21.8 %), RUE (up to 22.7 %, 16.5 %, 91.0 % in water, energy and nutrient use efficiency), and reduced global warming potential (up to − 7.9 %). The CB-BP cropping system with DT and FYM addition offered the best balance of yield, profit, saving of irrigation water, energy and nutrient, while minimizing GWP. This study provides empirical evidence of the opportunities for alternative cropping systems which balance the multiple objectives of sustainable groundwater use, farmer profitability and environmental sustainability for arid region of India. The results have direct implications for sustainable utilization of underground water for similar regions of the world facing water shortage.

Groundwater potential and recharge zones mapping using remote sensing and GIS for Kadegaon Taluka, Maharashtra, India

Year by year the water is becoming the scare source all over the world. Water resources available on earth are in the two forms namely surface water and ground water. According to the study of scientist the total volume of the ground water is very less as compared to the total water available in the globe. There are many areas in our country that are facing scarcity of water, and this is due to the no proper planning of the ground water development, results in the fall of water levels, drying of wells, etc. The over exploration of ground water in certain parts of the country may also leads in the lowering of ground water table, and this requires the scientific resource management and conservation. The source of water available below the surface of earth and that can be used as the prime source of water for water supply system majorly for agriculture, and also used for domestic and commercial uses. Groundwater has crucial importance and value for human life and economic development. The ground water has major contribution in the earth’s water circulatory system known as hydrologic cycle.Keeping in mind the growing rate of the population and as result of it the needs of the society could not be satisfied by the available surface water resources. Thus the man has started massive search of water resources. Such massive mining of ground water has leads to drastic decline of ground water table. Thus the ground water has become the precious resources for the agriculture and domestic use. Hence in order to ensure a sensible use of ground water the proper evaluation and management is required.

Examining the groundwater level in a semi-arid district of eastern India: spatiotemporal trends, determinants, and future prospects

The present study aims to examine the spatio-temporal and seasonal fluctuation of groundwater levels in an eastern Indian semi-arid region. Also, it attempted to investigate the involvement of different significant groundwater usage factors in causing such variations and trends. Furthermore, by evaluating temporal patterns and the influence of the crucial drivers, generate meaningful predictions for raising community awareness about the future. A combination of statistical, spatial analysis, and machine learning techniques were used to fulfill the objectives. Overall, the findings revealed that the south-eastern corner (consisting of Bundwan and Barabazar Blocks), the far western region (especially Jhalda I and II Blocks), and some of the eastern Blocks are most vulnerable to groundwater scarcity. The monitoring stations in this region are typically suffering a significant declining trend in groundwater level, with a substantial amount of Sen's Slope. In contrast, the centrally positioned Blocks have lesser susceptibility. The MLR analysis and spatial thematic maps demonstrate a strong association between this spatial pattern of declining groundwater table and the groundwater drivers in consideration. Thus, it is acceptable to suggest that drivers from the human world must be included in the groundwater management planning of the Purulia district. Finally, the predictions from the time series confirm that if no interventions are implemented, the average groundwater level will decline by 2.5 m by 2030. Therefore, Purulia urgently requires a realistic plan to prevent future generations from becoming refugees in their own land.

Development of subsurface drainage systems: Discharge – retention – recharge

Sufficient freshwater is needed for water dependent sectors such as agriculture, nature, drinking water, and industry. However, even in low-lying, flood prone countries like the Netherlands, climate change, weather extremes, economic growth, urbanization, land subsidence and increased food production will make it more complex to guarantee sufficient freshwater for all sectors. Furthermore, the frequency and amplitude of extremely dry and wet weather conditions is expected to increase. The current Dutch water management system is not designed to anticipate these extremes. Over the last decades, drained Dutch agricultural fields, land consolidation and urbanization resulted in declining groundwater tables. Additionally, the fresh water demand of different sectors (agriculture, industry, drinking water) increased, causing an increased pressure on the regional groundwater system. As a consequence, the annual groundwater table in sandy soil areas dropped over time with the effect that, nowadays, fresh water is becoming scarce in dry periods. In this paper we provide insight in the shifting water management strategy in the Netherlands (1950–2020), with the corresponding drainage systems, developing from conventional drainage (approx. 1950–1990), to controlled drainage (1990’s onwards), climate adaptive drainage (2010 onwards) and subirrigation systems (2018 onwards). Furthermore, we provide insight in the effect of subirrigation on groundwater levels and crop yields, based on both international literature and measurements of Dutch field pilots. Although subirrigation can contribute to improved soil moisture conditions for crop growth on field scale, we show that the water volume needed for subirrigation can be large and could put a significant pressure on the available regional water sources. Therefore, efficient and responsible use of the available external water sources for subirrigation (e.g. surface water, treated waste water, or groundwater) is required. Finally, the implementation of controlled drainage with subirrigation asks for correct implementation in the regional balance: it requires an integral, catchment-wide approach.

Sustainability of groundwater resources of weathered and fractured schists in the rural areas of Galicia (Spain)

Water supply deficits in droughts, groundwater pollution and climate change are the main challenges for the sustainability of groundwater resources from hard-rock aquifers in rural areas of Galicia (Spain). Here, we address the sustainability of groundwater resources of weathered and fractured schists in the rural areas of the Abegondo municipality. The conceptualization of the hydrogeology of the study area includes: (1) The weathered schist (regolith), (2) The decompressed highly fractured schist layer; and (3) An underlying slightly fractured schist. Groundwater flows mostly through the regolith and the highly fractured rock. Rainfall infiltration is the source of aquifer recharge. Groundwater discharges in seepage areas, springs and along creeks and valleys. The water table is generally shallow and shows seasonal oscillations of up to 4 m. The equivalent transmissivity of the regolith and the highly fractured schist ranges from 15 to 35 m2/days. The electrical resistivity tomography identifies a shallow water table and attests that the contact of the highly fractured schist and the slightly fractured schist is highly heterogeneous. Groundwater resources were quantified with a hydrological water balance model. The mean annual recharge is about 185 mm. Groundwater recharge at the end of the twenty-first century could decrease from 6 to 10% due to climate change. The decline in groundwater table could aggravate the shortages during droughts. Groundwater quality data show bacteriological and nitrate contamination due to the poor management of the manure in the fields and occasional discharges of slurry from pig and mink farms. Groundwater management and protection actions are proposed to prevent groundwater pollution and achieve a sustainable groundwater supply in the study area.

Identifying the facts and driving factors of deceleration of groundwater table decline in Beijing during 1999–2018

Domestic water supply and agricultural irrigation are highly dependent on groundwater in Beijing. Groundwater table (GWT) decline and ecological issues caused by groundwater overexploitation have been of growing concern. However, some positive measures such as groundwater extraction control, improvement of water use efficiency, and South-to-North Water Diversion Middle Route Project (SNWDMRP) have alleviated severe groundwater shortage situation in recent years. Therefore, quantifying the contributions of different factors to the deceleration of groundwater table decline contributes to guide groundwater resources. In this study, in-situ groundwater table data, climate data, and water use data were used to identify the deceleration and driving factors of GWT decline by comprehensively using water table fluctuation (WTF) method, Mann-Kendall (MK) trend test, wavelet analysis methods, and Random Forest Regression (RFR). Firstly, the MK trend test evaluated the trend of the defined groundwater stress index (GSI) and groundwater table decline rate (GTDR) changes, indicating the fact that GWT decline was decelerated during 1999–2018. Then, the WTF method combined with in-situ groundwater level data and specific yield were used to derive the monthly groundwater storage anomalies (GWSA), which revealed a slight GWS recovery in the past decade, especially a significant increase of GWS with a rate of 5.76 mm/month since the operation of South-to-North Water Diversion Middle Route Project (SNWDMRP). Wavelet analysis identified a correlation and coherence between GWSA and precipitation in the time–frequency domain. Furthermore, correlation analysis indicated that the deceleration of GWT decline may be attributed to climatic factors (e.g., precipitation, temperature), the SNWDMRP, and water supply and use structure. The RFR quantitatively identified the greatest contribution of water use (e.g., agricultural and domestic water use) to GWT dynamics. Moreover, the effect of SNWDMRP is greater than climatic factors (e.g., precipitation, temperature). These findings have important implications for groundwater resource management in Beijing and other areas suffering from severe groundwater depletion.

Reduced groundwater use and increased grain production by optimized irrigation scheduling in winter wheat–summer maize double cropping system—A 16-year field study in North China Plain

Optimizing irrigation strategies to increase water utilization efficiency and achieve higher yield is vital for balancing groundwater use and improving food security during water shortage in the North China Plain (NCP). Based on a 16-year field experiment (2003–2018) using seven irrigation schedules from W0M0 to W4M3 (numbers are irrigation times in wheat (W) and maize (M) season, 75 mm each) in the winter wheat–summer maize double cropping system, we analyzed annual total water consumption ( ET a ) and groundwater table change in terms of net groundwater depletion, annual total grain yield, water productivity (WP), irrigation water productivity (IWP) and marginal benefit of the whole wheat–maize system. Relationship between yield or WP and irrigation or ET a were also revealed. Results showed that (1) total ET a increased as irrigation input increased, ranging from 427.3 mm (Rainfed, W0M0) to 891.0 mm (W4M3). Soil water storage contributed nearly 30% to ET a for winter wheat under water deficit conditions. Pre-sowing soil water storage played an important role in improving the annual yield and WP of both wheat and maize by promoting germination, seedling emergence and root growth; (2) the rainfed treatment (W0M0) was best for mitigating the groundwater table decline (0.1 m yr -1 ), followed by W1M1 (0.5 m yr -1 ) and W2M1 (0.8 m yr -1 ). Groundwater table decline in M2W2 almost overlapped the observed data at the station (1.1 m yr -1 ). In W3M2, the farmers’ traditional practice, the groundwater table declined by 1.4 m yr -1 , obviously over exploitation, while W4M2 and W4M3 declined by almost 2.0 m yr -1 ; (3) the relationship between total annual yield and irrigation (or ET a ) followed a quadratic curve. Total annual yield significantly increased from W0M0 to M1W1 (25%) to M2M1 (5%) and then kept stable. Average annual WP decreased as irrigation increased, from 2.4 kg m -3 (W0M0) to 1.6 kg m -3 (W4M3). Average annual IWP and marginal benefit also declined as irrigation increased. These results over 16 years indicated that the W2M1 is the most balanced irrigation regime for wheat– maize rotation to mitigate groundwater decline, maintain grain production, and improve water use efficiency in the NCP. ● A 16 - year field experiment of seven irrigation regimes for wheat-maize was conducted. ● ET a increased and water productivity decreased with increasing irrigation amount. ● W2M1 was the best optimized irrigation regime for balancing groundwater use and yield.

Meta-analysis of uranium contamination in groundwater of the alluvial plains of Punjab, northwest India: Status, health risk, and hydrogeochemical processes

Despite numerous studies, there are many knowledge gaps in our understanding of uranium (U) contamination in the alluvial aquifers of Punjab, India. In this study, a large hydrogeochemical dataset was compiled to better understand the major factors controlling the mobility and enrichment of uranium (U) in this groundwater system. The results showed that shallow groundwaters (<60 m) are more contaminated with U than from deeper depths (>60 m). This effect was predominant in the Southwest districts of the Malwa, facing significant risk due to chemical toxicity of U. Groundwaters are mostly oxidizing and alkaline (median pH: 7.25 to 7.33) in nature. Spearman correlation analysis showed that U concentrations are more closely related to total dissolved solids (TDS), salinity, Na, K, HCO3−, NO3− Cl−, and F− in shallow water than deep water, but TDS and salinity remained highly correlated (U-TDS: ρ = 0.5 to 0.6; U-salinity: ρ = 0.5). This correlation suggests that the salt effect due to high competition between ions is the principal cause of U mobilization. This effect is evident when the U level increased with increasing mixed water species (Na-Cl, Mg-Cl, and Na-HCO3). Speciation data showed that the most dominant U species are Ca2UO2(CO3)2− and CaUO2(CO3)3−, which are responsible for the U mobility. Based on the field parameters, TDS along with pH and oxidation-reduction potential (ORP) were better fitted to U concentration above the WHO guideline value (30 μg.L−1), thus this combination could be used as a quick indicator of U contamination. The strong positive correlation of U with F− (ρ = 0.5) in shallow waters indicates that their primary source is geogenic, while anthropogenic factors such as canal irrigation, groundwater table decline, and use of agrochemicals (mainly nitrate fertilizers) as well as climate-related factors i.e., high evaporation under arid/semi-arid climatic conditions, which result in higher redox and TDS/salinity levels, may greatly affect enrichment of U. The geochemical rationale of this study will provide Science-based-policy implications for U health risk assessment in this region and further extrapolate these findings to other arid/semi-arid areas worldwide.

Analysis of surface water utilization for restoration of the groundwater table case study: Dayeuhkolot, Bandung-Soreang groundwater basin

Groundwater utilization as a source of clean water for the community increases, both for domestic and non-domestic needs, thus lowering the groundwater table. The Dayeuhkolot area is part of the Bandung-Soreang Groundwater Basin, which has a groundwater table decline resulting from excessive groundwater utilization. The Experimental Station of Groundwater modeled the groundwater condition in 2010-2020 concluded that the groundwater decline for a particular area reaches up to 50 m. This study aims to analyze the potential for groundwater table restoration that can be carried out at the research location by reducing groundwater utilization through the substitution of surface water use. The prospect of surface water that can be utilized can be identified by identifying its quantity and quality for the feasibility of using surface water as a substitute for groundwater utilization to implement the concept of conjunctive use. Groundwater modeling is carried out with a substitution scheme for groundwater utilization with surface water. Modeling results show that the reduction in groundwater utilization positively impacts the restoration of the water table level. Based on the model result, the groundwater level can recover as high as 2.37 m from 2020 conditions.