Land Cover Change and Its Impact on Groundwater Resources: Findings and Recommendations

Abstract

Globally, the climate is becoming drier and wetter because of climate change. Variations in land use and land cover (LULC) brought on by humans have impacted hydrological elements, including recharge and runoff, throughout the past few decades. Agriculture, forestry, urbanization, recreational activities, and industrialization are all land uses that impact groundwater resources. For example, anthropogenic activities have an increased impact on impervious surfaces and storm drains, which divert precipitation away from highways. Similarly, groundwater resources are negatively impacted by the increased urbanization of areas in two fundamental ways: first, by blocking up aquifers with concrete, which prevents natural recharge; second, by polluting groundwater through drainage leaks and industrial waste and effluents. Therefore, the long-term temporal and seasonal variations in LULC change significantly impact groundwater flow dynamics. Numerous factors influence LULC change, including hard-to-follow social and biophysical processes, that ultimately lead to a complex and dynamic system. As a result, an evaluation of the effects of LULC changes on recharge is required to manage groundwater resources to be sustainable.

1. Introduction

Groundwater is the major water source on Earth [1]. It is an essential source of fresh water for domestic and agricultural usage [2, 3], and it is crucial for the sustainability of the economy and the supply of food [4]. It also plays a crucial role in aquatic ecosystems that have interconnections with surface water [5]. In many parts of the world, the groundwater table is dropping, and the water quality is degrading [6]. Because of excessive groundwater use for agriculture and other unsustainable purposes, groundwater depletion has been rising globally [7, 8] and groundwater contamination is becoming prominent. Groundwater is freshwater that is found in the underground layers of water-bearing porous rock or unconsolidated materials in the aquifer systems [9]. Groundwater formation and flow are influenced by a number of variables, including lithology, topography, geological structures, weathering depth, the size of fractures, slope, drainage, landforms, LULC, elevation, rainfall, and other climatic conditions [10, 11, 12].

Approximately 2 billion people throughout the world depend primarily on groundwater for domestic and agricultural needs [13]. As a result, groundwater is crucial for irrigated agriculture and for ensuring the safety of the world’s food security. Compared to other economic sectors, agriculture utilizes the most freshwater. It accounts for 90% of freshwater consumption and nearly 70% of the world’s freshwater withdrawals [14, 15]. The annual groundwater use for irrigation is 545 km³ of which 43% of the water used annually comes from groundwater [3]. In many areas, groundwater may be the sole supply of water that is always present. When energy and pumping resources are readily accessible, groundwater is frequently the only source of water. Additionally, it serves as a buffer against short- and long-term fluctuations in surface water availability brought on by climatic variability. The usage of groundwater is influenced by variables, including accessibility, transportability, cost-effectiveness, and availability. The main reasons why people choose to use groundwater water are reliable supplies and reasonable prices [16].

However, groundwater quality is declining due to rising water demand, urbanization, changing land use and land cover, and climate change. Changes in land use and land cover (LULC) are among the most significant anthropogenic interventions LULC reflects the characteristics that are spread both naturally and intentionally on the surface of the Earth, such as vegetation in forests, water bodies, and human structures [17]. Groundwater is affected by LULC changes via changes in the composition of the water balance [18, 19]. Agricultural expansion is one of the major LULC change the world has witnessed in the last few decades. Globally, around 5% of the land has been converted to agricultural land [20]. For instance, growing agricultural irrigation in the Texas High Plains of the United States has enhanced output but at the expense of falling water levels, endangering the long-term viability of the Ogallala Aquifer as a major source of water for irrigation [21]. In a single county in the High Plains of Kansas in the United States [22, 23], looked at the link between groundwater depletion and agricultural land use change and concluded that groundwater depletion was caused by land use change. In the southwestern United States [24], distinguished between irrigated and nonirrigated agricultural ecosystems and established many tiers of groundwater recharge rates as a function of LULC change. Further, the area of irrigated cropland has expanded by 460% globally over the previous three centuries [25], while the quantity of groundwater used for agricultural irrigation each year is 3300 km³ [26] and the amount of evapotranspiration drawdown has decreased by a factor of 2 [25]. The effects of LULC change on groundwater hydrology have previously been studied using both field experiments [24] and hydrologic modeling applications [27, 28]. The benefit of spatially dispersed hydrologic models is that they can take into consideration the geographical patterns of LULC’s hydrological impact [29]. Few studies take future land use change into consideration, despite the fact that the hydrological models may offer predictions about the future.

While it is a significant supply of freshwater for household, agricultural, and commercial applications, the effects of LULC change on groundwater recharge are not adequately understood, which leads to groundwater depletion [30]. Land use change is a complex, dynamic process, which has direct impacts on soil, water, and the atmosphere [31]. The most urgent problem of the twenty-first century in terms of groundwater monitoring and accurate projections is the rapidly changing LULC. LULC change is becoming a major ecological concern, particularly the conversion of natural vegetation into croplands or the deterioration of land into barren. Therefore, understanding the impacts of LULC change on the groundwater is needed for the optimal management of natural resources [24]. This chapter review the current status, prospects, and challenge of land cover change and its impact on groundwater resources. The effects of human climate change on groundwater resources are the subject of this review [32], hence they are not discussed in this chapter.

2. Literature review

It is becoming more widely accepted that changes in LULC have an impact on groundwater. Various forms of land-use categories and subcategories that have the potential to impact groundwater resource are presented in Figure 1. Understanding how LULC interacts with growing natural and human activities is crucial because it significantly impacts groundwater resources. The worldwide groundwater scenario has been altered by LULC change, with reports of irregular recharging [35], declining groundwater quality [36, 37], and solute transfer in the unsaturated or vadose zone [24]. Particularly, the fundamental nature of the global water cycle has been greatly altered by climate-LULC interaction brought on by human-induced fast LULC change [38]. Further, changes in LULC are known to have an effect on the relationship between groundwater and surface water. Urbanization, overgrazing by animals, subsistence agriculture, commercial agricultural growth, and the removal of forests for firewood are some of the changes that have a significant influence on groundwater resources, land productivity, and ecosystem degradation [39]. However, these effects are poorly understood [24, 40].

Figure 1.

Major land-use categories that have implications for groundwater resources (adapted from [33, 34]).

Numerous studies have attempted to estimate the possible influence of LULC on groundwater processes. Dams et al. [41] used the CLUE-S (the Conversion of Land Use and its Effects at Small regional scale) model coupled with WetSpass and MODFLOW to demonstrate the effects of land use change on the groundwater system of the Kleine Nete watershed, Belgium. Near the largest cities in their research region, they discovered significant alterations in the groundwater. Using the SWAT model Mkaya et al. [42], assessed the influence of land use change on catchment hydrology in Taita Hills, Kenya. Their study showed that the impact of LULC increased surface runoff and sediment output within the watershed. Eckhardt et al. [43] employed the SWAT-G model in the Dill catchment in southeast Germany and demonstrated a 50% drop in mean groundwater recharge and streamflow.

Groundwater recharge rates and mechanisms are significantly altered when land is converted for agriculture, whether it be irrigated or rain-fed [25, 44]. Many parts of the world have experienced substantial changes in water balances, including groundwater recharge, as a result of the removal of native vegetation and establishment of crops, which often have shorter root systems than the plants they replace [45, 46]. This often leads to increases in groundwater recharge rates of one to two orders of magnitude in dry and semiarid regions [25, 47, 48]. Significant negative effects on soil and water quality result from increased recharge brought on by irrigation and clearance of land. These changes have caused enormous sections of land and water to become waterlogged and salinized in various parts of Australia, China, India, and the United States, making it impossible for adequate drainage to take place [46, 47, 48, 49]. This process has a detrimental effect on agriculture, especially in low-lying or low-topographic relief locations where drainage is constrained, limiting the amount of arable land, reducing the growing season, and diminishing crop yields [50, 51].

On the other hand, the nature of recharge to underlying aquifers is considerably changed by urban contexts [52]. Groundwater resources are negatively impacted by the increased urbanization of areas in two fundamental ways: first, by preventing natural recharging of aquifers by covering the earth with concrete; second, by contaminating groundwater through drainage leaks and industrial waste and effluents [53]. Compared to clearing land for agriculture, the impact of urbanization on groundwater recharge is more complicated, and the impact on overall recharge rates varies depending on several site-specific factors related to the style and density of urban construction, as well as the type of infrastructure used to manage stormwater, sewage, and water supply [33, 54]. Urbanization always results in major changes to groundwater quality, recharge processes, and locations, although the total net change in recharge volume varies and is a subject of considerable ambiguity [55, 56]. It is well acknowledged that an increase in impermeable surfaces brought on by urbanization can locally diminish the rate of ground-water recharge and increase surface runoff, which then discharges to the urban drainage system [57, 58]. The excess run-off is often directed into storm-water management systems, including drains, pipelines, and retention basins along urban streams, even if pervious surfaces like roads and pavements may reduce groundwater recharge in their immediate proximity [59, 60].

Modifications to the current groundwater recharge process are frequently caused by unplanned urbanization and the increased strain that human activities are placing on hydro-geomorphologic systems [61, 62]. Anthropogenic activities are the primary cause of LULC alterations [63]. Numerous studies have been conducted utilizing remote sensing (RS) and geographic information systems (GIS) to evaluate LULC change and its effects on groundwater quality and quantity [12, 64, 65, 66]. Due to its extensive geographical and temporal coverage, remote sensing is a crucial technique for the investigation of LULC changes [65, 66, 67, 68]. In addition, a variety of climatic factors also alter as urbanization replaces natural vegetation [69, 70, 71]. According to Kalnay and Cai [72], changes in land cover in the USA caused a rise in both the minimum and maximum temperatures. Additionally, groundwater condition (both quality and quantity) and its recharge are negatively impacted by urbanization [73, 74]. The hydrology of the region has been shown to have changed as a result of the conversion of natural, agricultural, and other low-population density sites into urban populations [75]. Evidence shows that when urbanization is excessive, more than half of the precipitation drains off and just a small portion is infiltrated deeply [76].

Based on the literature analysis mentioned above, it is clear that urbanization and the resulting changes in LULC have a negative impact on the local groundwater resources. However, the majority of the research to date has concentrated on analyzing bivariate correlations between urbanization and LULC changes [77, 78], urbanization and temperature changes [29, 79], urbanization and rainfall changes [80, 81], or urbanization and changes in groundwater level [82, 83]. Gebere et al. [84] investigated the effects of the dry Lake Haramaya watershed, located in the eastern region of Ethiopia. The simulated effects of future LULC were investigated using the land use change model CLUE-S (Conversion of Land Use and its Effects at Small regional extent). The WetSpass water balance model’s simulated results showed that changes in land use and land cover had a significant impact on groundwater recharge in the watershed. In 2011, the yearly groundwater recharge varied from 0 to 90 mm. The range of recharge values reduced to 0–83 and 0–87 mm, respectively, according to a land use and land cover prediction made to the year 2028 under baseline and excellent management scenarios. The level of groundwater will also keep dropping due to increasing abstraction at the same time. Using an empirical method, Patra et al. [85] investigated the effects of urbanization on groundwater resources in the Howrah Municipal Corporation (HMC) in the Indian state of West Bengal. The outcome showed signs of urban sprawl or shrinking, which indicates an increase in a built-up area and leading to environmental degradation and groundwater contamination in the urban area. In the following sections, the impact of LULC on various aspects of groundwater resources is discussed in detail.

2.1 Impact on recharge

It is evident that the change in land cover has a significant impact on the change in groundwater recharge. Estimating groundwater recharge is crucial in managing water resources, especially in regions where groundwater is essential for the local water supply. According to Healy [86], groundwater recharge is defined as the vertical flow of water that reaches the water table and increases groundwater storage. Rates of recharge vary by orders of magnitude over space and time, depending on the interaction of climate, terrain, surface hydrology, vegetation, and land use [87, 88]. LULC influences the groundwater recharge variations over the spatial and temporal scales significantly [89]. Groundwater recharge is a crucial water balancing concept that is necessary to determine sustainable extraction rates and analyze aquifer sensitivity to pollution. It plays a significant role in regulating groundwater supply [33, 90]. Globally, the quantity, locations, and timing of groundwater recharge and discharge are increasingly altered due to rising population, agricultural growth, and urban land area. For groundwater development and sustainable groundwater resource management, groundwater recharge determines the groundwater withdrawal rates in a region [91].

Groundwater recharge, which occurs primarily through rainfall-recharge and surface water and groundwater interaction processes, replenishes groundwater aquifer systems. The change in LULC impacts groundwater recharge processes by modifying the earth’s hydrological system functions. LULC consists of several subcategories as presented in Figure 1, each of which has particular effects on groundwater recharge. For instance, barren land in more populated areas inhibits groundwater penetration and lowers the pace at which groundwater systems recharge. On the other hand, based on other research, it was found that the decrease in evapotranspiration caused by surface sealing will boost groundwater recharge rates [57, 92]. For instance, in Austin, Texas, for example, [92] found that the groundwater recharge rate for the year 2000 was nearly twice as high as the pre-urban rate due to the contribution of urban recharge sources like water main leaks and excessive irrigation of, for example, gardens and agricultural areas. Similarly, in Perth, Australia, the practice of infiltrating roof and road runoff, along with decreased evaporative losses brought on by the growth of impermeable surfaces, leads to groundwater recharge rates 2–3 times greater than in pre-urban circumstances, according to research by Barron et al. [57].

Additionally, concrete structures caused by streets and buildings, flood control, forest management, and irrigation are examples of manmade activities that alter the infiltration and transport of water [93]. Groundwater supplies frequently deteriorate because of these alterations [34, 94]. Compared to the natural condition, urbanization alters the sources and flow routes of groundwater recharge [95]. Two urbanization-related processes have an impact on groundwater recharge on a quantitative level: (i) the growth of impervious surfaces, which reduces evapotranspiration and increases runoff [96]; and (ii) the construction of water supply and sewer networks, which boosts groundwater recharge rates because of leaks [97]. Compared to natural landscapes, urban environments’ recharge declines since surface sealing limits infiltration and increases surface water runoff [98, 99]. According to Rose and Peters [100] study, urban wells’ water levels noticeably dropped when compared to nonurban wells in the study region near Atlanta, US. In Dresden, Germany, Grischek et al. [98] discovered a 23% reduction in groundwater recharge as a result of surface sealing. Overall, all studies noted that because every city has a unique environment and frequently a distinct climate, therefore, it is challenging to anticipate the overall impact of urbanization on groundwater recharge.

Besides, urbanization and urban structure, natural vegetation has also various degrees of impact on groundwater recharge. For example, deep-rooted vegetation, like woods, has a lower rate of groundwater recharge than shallow-rooted vegetation, such as annual crops, according to Geist and Lambin [101]. Increased groundwater recharge rates are shown when natural deep-rooted native vegetation, such as trees and bushes, are replaced with shallow-rooted agricultural crops, based on field data [25, 47, 48] and modeling results [102]. But if the conversion of natural forests to cultivated crops lowers evapotranspiration losses, surplus water is available for boosting groundwater recharge and streamflow [24, 88]. In the past several decades, 80% of the woods in southwest Niger, which has a semiarid to an arid environment, have been turned into agriculture, increasing recharge from 2 to 25 + −7 mm year-1 [103]. For areas like these, where water is a limiting issue for sustainable development, it is crucial to look at the connections between LULC and groundwater change.

Similarly, the impact of deforestation on groundwater recharge has also been reported by many studies [104]. Deforestation increased the recharge and deep drainage by 1–2 times in Argentina [105], where the transition from grasslands to trees caused a 38 cm decrease in the water table [106]. Consequently, converting agricultural land back to “natural” vegetation may result in lower runoff and decreased in-stream sediment loads owing to reduced erosion, all essential components for sustainable water resource management [25, 35]. According to Brown et al., conversions to forests have decreased streamflow, changed the hydraulic characteristics of the soil, decreased soil moisture, and decreased recharge rates [104]. The considerably greater evapotranspiration rates of the planted woody plants are responsible for the decreases in groundwater recharge and soil moisture loss [107]. Other studies have also connected the decreases in soil moisture and recharge rates to vegetation-induced soil water repellency and increased rainfall interception of the plants that were planted [108, 109, 110].

For the purpose of assessing groundwater recharge, a number of techniques exist. They are roughly divided into physical, chemical, tracer, and numerical modeling techniques [111]. Studies have used a variety of methodologies to estimate groundwater recharge, including tracer methods, methods based on changes in the water table, lysimeter methods, and straightforward water balance procedures. In some of this research, recharge is incorporated into numerical groundwater models or dynamically linked to hydrological models to assess fluctuations under various climatic and land cover conditions [112, 113]. Lvovich [114] made the first effort at a world-scale study by producing a global recharge map using baseflow generated from river discharge hydrographs. The second large-scale groundwater recharge estimate was made by Döll [115], who used the WaterGAP Global Hydrological Predict [115, 116] to model global groundwater recharge at a spatial resolution of 0.50.

The impact of LULC on groundwater recharge has been monitored and studied using GIS and remote sensing data. Manap et al. [117] calculated the groundwater potential index in Malaysia using a number of geographical layers and remote-sensing photos. Based on the study of multi-temporal satellite and field survey data, Verma et al. [118] evaluated the effects of LULC on quaternary aquifer groundwater supplies in the Lucknow region of the Ganga plain, India. The findings showed that during the 10 years period, changes in LULC, hydro-geomorphic characteristics, and widespread groundwater research methods had led to significant changes in groundwater reservoirs.

Using remote sensing and GIS techniques, Waked et al. [83] investigated the effects of urbanization on groundwater recharge in the city of Hyderabad, India. According to the findings, the urban component of groundwater recharge was more than 10 times bigger than the natural component. Tam et al. [119] used a coupled hydrological simulation of rainfall-runoff and groundwater flow with WetSpa and MODFLOW to investigate the effects of urbanization on groundwater resources in Hanoi, Vietnam. According to the simulation’s findings, seepage from rivers and lakes makes up 31% of the recharge of Hanoi City’s groundwater system, while infiltration from rainfall provides 53.6%. The municipal water supply and sewage networks were responsible for the remaining 15.4% of the leakage. In the northwest of Bangladesh, Siddik et al. [120] investigated the impact of LULC changes on groundwater recharge. A semi-physically based water balance model was used to simulate spatially dispersed monthly groundwater recharge. The findings indicate that over the research period, the impervious built-up area rose by 80.3% while the vegetated land cover dropped by 16.4%. Because of this, groundwater recharge in 2016 was lower than it was in 2006. However, the reduction in recharge brought on by long-term temporal LULC changes is extremely negligible at the basin size (2.6 mm/year), even if urbanization has a bigger influence at the regional level (17.1 mm/year). Zomlot et al. [121, 122] used a change trajectory technique to examine the effects of land use change on groundwater recharge in Flanders, Belgium, and identified spatiotemporal LULC change trajectories.

The aforementioned studies have made significant headway in understanding the impact of various ULC types on groundwater resources however, there is a pertinent need to explore an in-depth analysis of the impact of grassland conversions to forest and grassland conversions to agricultural land. Similarly, the groundwater management plan and afforestation efforts, and future forest restoration plans around the globe need to be addressed in the current and future studies. Currently, significant efforts are being made to recover degraded forests in the United States [24, 104], China [95, 107], and India [123].

2.2 Impact on quality and quantity

Since LULC occurs globally and affects both water quantity and quality, its effects on groundwater are crucial [24]. Studies around the world have reported LULC’s impact on groundwater recharge [124]. According to Valle et al. [125], groundwater quality changes are caused by people’s direct or indirect associations with specific land uses. Numerous research has investigated the connection between LULC and groundwater contamination during the last few decades [126, 127, 128]. Barber et al. evaluated the effects of urbanization on groundwater quality related to LULC change using GIS-based techniques [1996]. Low NO3-N concentrations were found in forests and natural waterways and high NO3-N concentrations in croplands, according to research by Liu et al. [129] on the association between groundwater NO₃-N pollution and LULC types. The findings of Khan and Jhariya’s [130] evaluation of the effect of LULC changes on groundwater quality using remote sensing, GIS, and field research revealed a 16.2% increase in the overall area of settlement from 1999 to 2016, which resulted in an increase in NO3 concentrations. He et al. [131] utilized the random forest (RF) method to forecast groundwater NO₃ concentrations in the Yinchuan region and concluded that the primary LULC categories influencing groundwater NO₃ concentrations were urban and agriculture.

GIS has been extensively used to study the effects of urban and land development on groundwater quality [132]. The geographical relationship between LULC changes and trends in groundwater quality has been explored by numerous studies [133, 134]. Most of these studies have been conducted to evaluate the effects of fast changes in LULC mapped using manual screen digitizing, which introduces bias and is prone to subjectivity [135]. Singh et al. [136] examined the effects of LULC in the lower Shiwalik hills in Rupnagar, Punjab, India, with a focus on groundwater quality and quantity. They discovered that changes in the LULC pattern led to an increase in groundwater quantity through both natural and artificial recharge. Due to the use of fertilizers intended to increase short-term soil fertility, the quality of groundwater has declined.

In the Pearl River Delta of China, urbanization coupled with the infiltration of domestic sewage was one of the main driving forces for groundwater quality in fissured aquifers in urbanized and peri-urban areas. Industrialization coupled with the infiltration of industrial wastewater was one of the main driving forces for groundwater quality in granular and fissured aquifers in peri-urban areas. Using a fuzzy synthetic assessment approach, it was determined that 83% of groundwater was drinkable with excellent quality. Compared to granular and fissured aquifers, groundwater in karst aquifers was drinkable and of higher quality. Groundwater quality in non-urbanized areas of the latter two aquifer types was much higher than that in peri-urban and urbanized areas [137].

According to Alqurashi and Kumar [138], recent fast urban growth has changed the original LULC patterns, modifying the groundwater circulation system and reducing groundwater quality owing to the leaching of contaminants from numerous sources (such as wastewater and fertilizers) [57, 139, 140, 141]. According to Townsend and Young [142], human causes, including urban and agricultural activities, were responsible for the groundwater nitrate (NO3-N) concentrations above 3 mg/L recorded in Kansas. On the other hand, urbanization, and industry greatly enriched sulfates (SO42), chlorides (Cl), and fluorides (F) in the shallow aquifers of Punjab, Pakistan, and Kharkiv, Ukraine [143, 144]. Elmahdy and Mohamed [145] discovered a connection between groundwater Cl, sodium (Na), and NO3 concentrations and animal waste, specifically from poultry.

Xu et al. [146] used statistical models and a curved streamline searchlight-shaped model to explore the geographical distribution patterns of groundwater hydro-chemical parameters in the Guanzhong Basin and evaluate the correlations between the groundwater parameters and LULC (CS-SLM). The findings demonstrated that the north of the plain had greater groundwater parameter concentrations than the south. Most hydrochemical parameters, such as Na+, Cl-, SO₄2-, F-, and Cr6-, were positively influenced by forests and water bodies, while negatively impacted by barren land and crops. Using Landsat pictures and hydrological data in a GIS, Elmahdy et al. [147] investigated the effects of LULC on groundwater level and quality in the northern United Arab Emirates. The findings demonstrated that the groundwater quality and level depletion across the research region, from the Oman Mountains to the coastal areas, is strongly correlated with the observed variations in LULC.

Harrington et al. and Xu et al. [23, 148] looked at the important connections between groundwater level decline and land use change. According to their findings, there is a clear connection between agricultural land-use change and groundwater depletion. In the Southern US, [24] looked at how LUCC affected groundwater recharge and soil quality. Their findings demonstrated the need for a quantitative understanding of the relationships between land change and groundwater recharge for sustainable land use. The substantial association between changes in land use and groundwater level was demonstrated by Chen et al. [149] using statistical analysis. Excessive aquifer withdrawal can have long-term effects on the land surface and the amount of groundwater.

The above studies depicted that, fertilizers, sewage disposal, and landfills are providing a possible source of groundwater pollution along with population growth and intensive agricultural practices, frequently affecting the groundwater quality. However, due to the wide variation in pollution concentrations throughout the landscape, it is challenging to measure and identify the relationship between human activities and groundwater quality and land use changes [13]. Also, there is a lack of assessment of the drivers of groundwater pollution in the transboundary groundwater system and land use conflicts on the quality of groundwater [125].

2.3 Impact on groundwater storage

Groundwater storage is another factor that is affected by the change in LULC. Various studies have assessed the impact of LULC on groundwater storage [11, 150, 151]. Groundwater recharge, groundwater outflow, and groundwater level all show a positive spatial association with LULC variations. According to Haddeland et al. [151], the human population directly affects the terrestrial water cycle, thus impacting the groundwater resource.

Land factors and their non-hydrological equivalents, such as temperature and LULC, have an influence on groundwater storage. For instance, in the Ganga basin, rising demand from the agricultural and industrial sectors as well as population growth have had a significant impact on groundwater storage, geochemical properties, and the type and extent of water exchange with the river [152, 153]. The negative effects may be seen as a long-term decline in groundwater levels, desaturation of aquifer zones, higher energy need to raise water from deeper levels, and quality degradation brought on by saline water intrusion in coastal areas in various sections of the nation [154].

The effects of LULC variations on evapotranspiration and groundwater storage were examined by Dias et al. [150]. The increased impermeable surface has been a significant contributor to decreased infiltration, which leads to decreased groundwater storage [155]. Groundwater is a vital component that significantly affects the well-being of people, animals, and aquatic environments. However, anthropogenic activities, including intensive agricultural crop production, urbanization, mining, and industrial developments, pose significant pollution threats to the sustainability of groundwater resources [156]. The main factor for groundwater pollution is human activity. Because of the excessive use of pesticides, herbicides, and large-scale applications of nitrogenous fertilizer, more agricultural operations will have a greater probability of contaminating the groundwater [157].

A thorough understanding of groundwater inputs and outputs is needed to inform water management decisions for future planning and policy. Due to population increase and the effects it has on built-up expansion, impermeable surfaces impede groundwater recharge and other hydro-climatic factors [158, 159]. However, because of the impact of social, environmental, and economic issues, it is challenging to determine land-use trends [33]. Furthermore, combining knowledge and modeling capabilities across biophysical responses, environmental issues, policies, economies, data, and computer capabilities is necessary to fully understand the long-term effects of natural and human causes in river basin interactions [160].

3. Complexity of groundwater management

Groundwater supports drinking water for the population and irrigation for agriculture. However, the excessive use of groundwater resources has become a major issue on a worldwide scale and needs an immediate response [161, 162]. Despite being a vitally significant global water resource, groundwater receives less attention from management systems than readily accessible surface water resources, as stated by Famiglietti [163]. This is especially true in nations with poor or nonexistent water administration and insufficient aquifer monitoring. As a result, there is a paucity of information about (i) how groundwater storage responds to different drivers such as point sources of pollution (ii) how storage variations relate to aquifer heterogeneity and transboundary aquifer, and (iii) how future changes in groundwater levels may be expected and mitigated based on these different drivers. Such knowledge is essential for management, particularly if the heterogeneity of the aquifer system causes noticeably varied reactions to future stresses in various sections of a region.

Assessing LULC change and its effects on groundwater quality have been done extremely effectively using remote sensing and GIS [164, 165, 166]. The capacity of remote sensing data to provide information on geographical and temporal domains, which is crucial for effective analysis and prediction, is one of the biggest benefits of employing it for hydrogeological research and monitoring [61, 166]. Further research needs to be done, to collect greater precision data. Therefore, there is a need to integrate remote sensing photos, field surveys, and visual interpretations to collect more precise data and further examine the danger of groundwater contamination influenced by LULC in future studies.

The absence of surface water monitoring is lacking which typically helps to constrain catchment water balances and improve recharge estimates. It is crucial to gather a range of independent field data to support and improve conceptual models and measure groundwater recharge [167]. Without such information, mapping, and analysis, it would be challenging to identify the spatial dependencies and major variables influencing recharge, which would leave room for uncertainty regarding how future water budgets and water quality may change as land-use change occurs.

Evaluating changes due to LULC, and the consequences for processes like aquifer depletion, land subsidence, and land and water salinization, are important scientific challenges resulting from the complexity of recharging processes and difficulty in accurately estimating recharge even in relatively undisturbed environments [168, 169]. Further, things are complicated by time lags that are typical of groundwater systems’ reactions to hydrological change at the surface [170, 171, 172], as well as feedback between changes in recharge and other elements of the eco-hydrological system [173]. To successfully understand, predict, and manage groundwater systems, analysis, and assessment of the effects of human-induced activities on recharge processes and rates are necessary [174, 175] because groundwater recharge negatively and positively impacts people’s quality of life through a complex social-ecological hydrologic system [45]. Hence, it is essential for sustainable land and water management to have a thorough understanding of the connections between vegetation and groundwater recharge as well as the water balance consequences of agricultural land use. Moreover, due to increased groundwater recharge sources and widely dispersed new abstraction points in the urbanized area, the water balancing of an urban aquifer is complicated. Understanding the effects of changing land uses on groundwater recharge is crucial, particularly in areas where urbanization is taking place rapidly with limited surface water [176].

Due to the challenges of assessing groundwater recharge, previous studies on groundwater recharge have concentrated on limited points in space [177]. In order to quantify the spatiotemporal variability of groundwater recharge, numerical modeling is an alternative [178, 179]. It is important to note that there were various levels of variance between studies which can be attributed to many factors. First, the major cause of the variance may be a mismatch in the spatial size. Although the simulation is point-based, the vegetation data were typical of a large pixel scale, therefore the simulated groundwater recharge should be evaluated in the context of a broad scale [107] Second, inconsistent temporal scales between studies may contribute to the underestimating of groundwater recharge [180]. Third, management techniques, such as irrigation and soil diversity, would also have an impact on the outcomes. Irrigated agriculture typically receives more water input than rainfed crops and produces greater groundwater recharge [181]. On the other hand, the influence of irrigation on groundwater recharge is less pronounced at the regional level if the irrigation water’s primary source is the same region’s rainfall, which is presumably the case in most cases.

Even though the loss of groundwater supplies is extremely localized, coarser satellite data like Gravity Recovery and Climate Experiment (GRACE) frequently mask it [182]. Because of the limitations of groundwater data and their coarse spatiotemporal resolution, it can be difficult to understand the spatiotemporal variability of groundwater. Studies of groundwater variability now rely on two primary data sources: (i) local in situ data from borehole data, such as those from [183]; and (ii) satellite-based GRACE data paired with hydrological or reanalysis models [33, 184, 185]. Likewise, the resulting groundwater outputs from the associated hydrological models are lowered due to the uncertainty of the meteorological forcing inputs [186]. For instance, mean annual precipitation in the southwest of the United States accounts for 80% of the variance in ground recharge [102, 103]. The impact of climatic conditions on groundwater recharge, however, varies greatly depending on the site [187]. The impact of meteorological elements can also change depending on the kind of aquifer, irrigation intensity, and seasonal variability of precipitation [188, 189]. Extreme precipitation was discovered to have a substantial influence in influencing groundwater recharge across the Northern High Plains in the United States, contrary to the conventional hypothesis that claims groundwater recharge was controlled by low-intensity precipitation over extended periods of time [190, 191]. It is unknown how the groundwater recharge dynamics were impacted by these temporal variations in the rainfall pattern [192]. Additionally, the seasonality of precipitation was said to have a big impact on groundwater recharge [193].

Groundwater, the biggest distributed reservoir of fresh water on Earth, is crucial for maintaining ecosystems and allowing for human adaptability to climate change [194]. In order to maintain a robust and sustainable economy in the future, an accurate evaluation of groundwater resources is essential. But groundwater supply and quality are influenced by a variety of social, economic, and environmental factors, and these systems are frequently unpredictable. Therefore, they make managing groundwater more difficult. Groundwater is used by populations in every part of the world to varying degrees. Groundwater is a complicated system that, once damaged, is particularly challenging to restore [195]. In addition, the effects of future land-use changes on the groundwater system have not been well studied. Groundwater extraction for irrigation will rise by 39% by 2050 [196], despite the fact that the world’s population, Gross Domestic Product (GDP), and water demand would be unequal, posing difficulties to around 30% of the world’s major groundwater systems [197].

Thus, there are several factors that influence LULC change and its impact on groundwater. These factors include difficult-to-trace socioeconomic and biophysical variables, which in turn lead to a complex and changing system [198, 199]. The applicability of any particular driving factor in a particular circumstance relies on the social and geographic context. A clear division of the multiple causes is frequently challenging, given the interconnected impacts of climate and LULC change [200]. Regarding the economic drivers, it is hypothesized that urbanization and the spread of agricultural and grasslands provide advantageous economic and institutional conditions that lead to land use change. In political ecology, it is believed that the maintenance of globalization, the market forces of capital, and multinational corporations are frequently what drive changes in land usage. Possible drivers of land use change include the creation of unsustainable irrigation systems where groundwater exploration exceeds recharge rates [201], the appropriation of land and water [202], and the distribution of land to elites that marginalizes the disadvantaged communities [198].

Moreover, underlying causes of land cover change do not take place in isolation; they involve intricate interactions across these several scales [203]. Social, political, economic, demographic, technical, cultural, institutional, and biophysical variables are among the root causes of changes in land cover [204, 205]. Land use change may happen gradually or even more quickly as a result of certain occurrences like natural disasters or shifts in political power [206]. It is important that these data may be studied in the context of how local land use decisions related to both cultural and politico-economic forces, and how land cover patterns are impacted by such processes. Physical landscapes and social systems are as much the result of uneven power relations, histories of colonialism, and racial and gender inequality as they are of hydrology, ecology, and climate change, so we cannot rely on explanations based just on physical or critical human geography [207].

In order to resolve these problems, a coupled sociocultural and natural systems approach as proposed in Figure 2, as an example, is required to enable efficient interaction between social scientists, biophysical scientists, and management experts and to better comprehend how individuals interact with their surroundings to impact groundwater. Untangling the intricacies of linked human and natural systems, such as reciprocal effects, the impact of many scales of biological and social organization, and emergent features can result in innovative scientific findings that are crucial for the creation of successful regulations for ecological and socioeconomic sustainability [208]. When human and natural systems are investigated together, new and complex patterns and processes emerge that are not visible when the two disciplines are examined individually [209]. Opportunities to properly combine different disciplines are becoming available in order to address basic coupled sociocultural and natural systems issues and respond to society’s tremendous problems [209]. In other words, groundwater resources management challenges should be identified and addressed through multidisciplinary studies and initiatives. The relatively new science of coupled human-natural systems offers a promising framework to tackle the complex problems of groundwater resource management by recognizing the integrated and coupled nature of human and ecological systems [210].

Figure 2.

Coupled human-natural conceptual framework to study groundwater (adapted from [80, 81]).

This conceptual framework encourages synthesizing research approaches to foster innovative studies that advance our understanding of the complex socio-biophysical phenomena and develop socially and environmentally resilient policy outcomes for sustainable groundwater management. It will further help improve our understanding of the cause, exposures, and consequences of groundwater issues and devise appropriate strategies to combat future groundwater depletion and improvement of lives of the people. The proposed framework offers a possible course of action as an example. It can be modified to best suit the needs of a specific study and objectives.

4. Conclusion

The sustainability of groundwater resources is crucial for the areas with the highest population growth, particularly the arid and semiarid areas that depend on the resource for domestic, industrial, and agricultural requirements. Half of the world’s population relies on groundwater as their primary drinking water source. It also maintains ecosystems by providing them with access to water, nutrients, and a reasonably stable temperature. Therefore, groundwater contribution is crucial for most regions around the globe [211].

LULC change is becoming a major ecological hazard, particularly the conversion of natural vegetation into croplands or the degradation of land into barren. Intense human exploitation of land resources throughout history has led to considerable changes in land use and cover. The phenomenon of LULC has significantly intensified in many locations since the age of industrialization and high population expansion. As a result, the demand for groundwater resources is expanding, and the amount of water available per person is decreasing every day as a result of our population’s rapid growth and rising standards of living.

The growth in groundwater abstraction to meet the demand for water supply from an increasingly urban population, on the other hand, is one of the reasons leading to groundwater depletion around the world. To fulfill the demands of domestic, commercial, industrial, and public users, water must be supplied. LULC change influences the volume, forms, and patterns of groundwater recharge [89]. Such a change might impact the environment and the socioeconomic condition in a number of different ways, both directly and indirectly [33].

For the sustainable use of groundwater resources, as well as the adaptation and mitigation of climate change, LULC must be managed. To achieve this, an integrated approach to groundwater recharge is necessary to ensure a link between recharge and abstraction and to comprehend the impact of LULC and climate change on the spatiotemporal distribution of recharge [121, 122, 212, 213]. Understanding the dynamics and causes of groundwater recharge is essential for forecasting and managing groundwater systems as well as the ongoing expansion of the water supply [33, 214].