Excessive Exploitation Of Groundwater Research Articles

Applying an Analytic Hierarchy Process and a Geographic Information System for Assessment of Land Subsidence Risk Due to Drought: A Case Study in Ca Mau Peninsula, Vietnam

The increase in extreme weather events causes secondary hazards that can influence people and the environment enormously. The Ca Mau Peninsula is known as one of the areas most severely affected by drought, and excessive groundwater exploitation is one of the reasons leading to a higher risk of land subsidence. This study uses the Delphi method and the KAMET rule table to analyze and select indicators that affect subsidence. The study uses the analytic hierarchy process (AHP) analytical hierarchy method to evaluate the weights of influencing factors, combined with geographic information system (GIS) technology to overlay the map layers of the main influencing factors and build a subsidence risk warning zoning map of the study area. The influencing factors selected to evaluate the impact on land subsidence in the study area during the drought period included geological structure, soil characteristics, groundwater flow exploitation, water flow in the dry season, current land use status, and evaporation in the dry season. The weights of these factors were evaluated based on the synthesis of relevant documents as well as consultation with experts. The results indicate that nearly two-thirds of the Ca Mau Peninsula area is currently at very low or low risk of subsidence. Meanwhile, 23% of the area is at medium risk, nearly 9% is at high risk, and 0.1% of the study area is at very high risk. Subsidence risk warning zoning maps can provide a visual and general overview of areas with high subsidence risk, supporting managers in making reference plans for socio-economic development in the Ca Mau Peninsula.

Integrated approach to water resource management in Mashhad Plain, Iran: actor analysis, cognitive mapping, and roadmap development.

Iran's Mashhad Plain faces a severe water crisis due to the excessive exploitation of groundwater, leading to the depletion of its aquifer. While water demand management is recognized as a superior solution compared to supply projects, its implementation presents notable challenges. This study addresses the urgent necessity to curtail water demand in the Mashhad Plain by alleviating conflicts among various stakeholders, including water resource managers and consumers. Initially, the research identifies key water resource actors who collaborate in devising a comprehensive roadmap and conceptual model for efficient water resource management. An analysis uncovers significant conflicts among actors, representing approximately 6% of identified issues, with minor conflicts in 30% of cases. Encouragingly, stakeholders demonstrate potential for consensus on the remaining conflict items, with specific actors emerging as pivotal in conflict resolution. Efficient water resource management in regions facing scarcity, diverse interests, and sustainability challenges demands a multifaceted strategy. Future endeavors involve developing a dynamic system model to simulate policy impacts and strengthen conflict resolution efforts. This research introduces a roadmap-driven approach aimed at resolving conflicts and implementing water demand management in the Mashhad Plain. It emphasizes the critical need to address water scarcity challenges while effectively mitigating conflicts among water resource stakeholders.

InSAR time series analysis of natural and anthropogenic coastal plain subsidence: A case of Hangjiahu plain

The early excessive groundwater exploitation caused extensive land subsidence in the Hangjiahu Plain (HJHP), threatening geological stability and infrastructure. Government restrictions on groundwater exploitation led to considerable changes in surface subsidence. To explore the distribution and causes of surface deformation after restrictions on groundwater exploitation, we used 46 Sentinel-1A TOPS images to detect the spatiotemporal distribution of surface deformation in the HJHP area from January 2019 to October 2022 by SBAS-InSAR technique and verified it with leveling results. Results indicated the following: (1) The uneven surface subsidence in the HJHP was relatively apparent, with the localized subsidence concentrated in a few areas. During InSAR monitoring, the maximum subsidence velocity reached −21.0 mm/yr. The most severe subsidence area was in the Shengze town industrial park, with remarkable subsidence bowls and a maximum subsidence of −85.8 mm. (2) Results were verified by comparing the InSAR results with leveling, and the results were in good agreement, indicating the reliability of the InSAR results. (3) Comprehensive analysis of the spatial distribution characteristics of surface subsidence, geological data and rainfall changes revealed that fault activity and rainfall changes had varying degrees of effect on surface subsidence in the HJHP area. (4) The comparison with land use data indicated that the built area was the dominant mechanism of surface subsidence in the study area. In addition, the effect of industrial activities on the surface cannot be ignored. The study results provide scientific data support for emergency disaster prevention work in the HJHP.

Investigation of groundwater induced land subsidence in Ludhiana City using InSAR and Sentinel-1 data

Land Subsidence (LS) is a vertically downward motion of land surface due to various reasons such as natural processes and anthropogenic activities especially excessive exploitation of groundwater. LS has adverse effects on substantial infrastructural damage, severe environmental problems, extensive economic losses, and significant societal impacts. In this study, we investigated the LS of Ludhiana city, a densely populated, largest and major industrial city of Punjab state, India. We presented a comprehensive methodology of Short BAseline Subset Interferometric Synthetic Aperture Radar (SBASInSAR) for LS measurement using an open-source computational environment. We generated 197 interferograms from 65 Sentinel-1A images acquired in descending pass between September 2019–July 2022 for deriving radar line of sight (LOS) displacement time-series and mean LOS velocity. Deformation results showed that the southern, and south-eastern parts of the city had been consistently moving downward with a mean subsidence rate of 24.7 mm/yr, while in western, few small patches in eastern and northern regions it ranges from 2 to 21 mm/yr, 3–20 mm/yr and 4–16 mm/yr respectively. The standard deviation of mean LOS velocity was observed between 0.7 and 3.3 mm/yr with majority values < 2 mm/yr. SBASInSAR results were compared with six Groundwater Level (GWL) wells observations, and both measurements generally agreed well at GWL locations (W1–W6) except W1–W2. For assessing the influence of groundwater change on LS, a correlation analysis was performed, and correlation of 0.50, 0.47, 0.81, 0.77, 0.84, and 0.64 was observed at GWL stations (W1–W6) respectively. Overall comparison of InSAR and GWL measurements are found in good agreement and significantly correlated, which can provide sufficiently detailed information about LS.

DAMPAK EKSPLOITASI AIR TANAH SECARA BERLEBIHAN TERHADAP PEMENUHAN KEBUTUHAN AIR PENDUDUK DI DESA RAENYALE, KECAMATAN SABU BARAT KABUPATEN SABU RAIJUA

This study aims to determine (1) the impact of excessive exploitation of groundwater on the fulfillment of groundwater for residents in Raenyale Village (2) Strategies for overcoming the impact of excessive exploitation of groundwater on meeting the water needs of residents in Raenyale Village.The method used in this study is a quantitative descriptive research method to test hypotheses using statistical data tests. In this study there were 103 people who became the research sample consisting of people who used drilled wells, people who used dug wells and the head of Raenyale Village. Data collection methods used are questionnaires, interviews, observation and documentation. The results showed that (1). The impact of groundwater exploitation in Raenyale Village is that there are 17 dug wells which are experiencing drought due to excessive use of drilled wells which means that the community is forced to incur additional expenses by buying tanked water to meet the population's water needs. (2). The strategy for overcoming the impact of groundwater exploitation is that there are 13 people who make infiltration wells, plant trees around the well area and with community awareness and understanding of the importance of sustainable development and use of groundwater.

Analysis of the Potential of Watersheds as a Source of Raw Water in the Batang Integrated Industrial Area (KITB) in Cluster 1

The Batang Integrated Industrial Area (KITB) is located in Banyuputih District, Batang Regency, Central Java, with a total area of 4,300 Ha and currently what has been developed is cluster 1 covering an area of 3100 Ha. Water has a central role in human and industrial activities, with potential impacts on health, worker safety, and the environment. The main problem is the uncertainty of raw water supply which poses a risk to Environment Health Safety (EHS). Therefore, this research aims to identify and analyze water sources, by EHS objectives, because safe water supply is key to environmental and worker safety. The water balance method is used to analyze water needs and availability. Analyze water needs in industrial areas by taking into account data for each type of industry. Water availability analysis includes the identification of raw water sources, including groundwater and surface water, taking into account that excessive exploitation of groundwater can hurt EHS. In contrast, surface water and rainwater collection are sustainable alternatives that are relevant to environmental and safety concerns. The research involved calculations using rainfall data from the Subah Rain Station and climatology data from the Central Java Climatology Station during the 2021-2022 period, as well as discharge analysis using the Mock Method. The research results display the potential of the river basin and show that rainwater collection can effectively overcome EHS challenges related to water availability in the Batang Integrated Industrial Area.

Study on the Variation in Coastal Groundwater Levels under High-Intensity Brine Extraction Conditions

The excessive exploitation of groundwater is becoming a serious global issue. Different from other regions, groundwater extraction in coastal areas usually stops and moves inland after causing seawater intrusion. The abundant salt fields in the Laizhou Bay area of China provide a unique case of maintaining high-intensity underground brine mining even after seawater intrusion. The intensive exploitation of underground brine has led to significant changes in the groundwater flow field. However, there is still a lack of research on how different factors affect the groundwater level in this mining situation. In this paper, time series analysis methods were used to investigate the impact of brine water extraction, tidal fluctuations, and precipitation on the groundwater level in the Laizhou Bay area. The results indicate that brine extraction is the main factor controlling the changes in groundwater level, with the cessation and resumption of extraction resulting in a 93.4 cm increase and a 122.5 cm decrease, respectively. Different rainfall patterns can also lead to an increase in groundwater levels, especially when a heavy rainfall event can cause a 61.2 cm increase. Tidal fluctuations can cause periodic fluctuations in the groundwater level, with a variation amplitude of approximately 11% of the tide itself.

Prediction of groundwater level under the influence of groundwater exploitation using a data-driven method with the combination of time series analysis and long short-term memory: a case study of a coastal aquifer in Rizhao City, Northern China

The excessive exploitation of groundwater not only destroys the dynamic balance between coastal aquifer and seawater but also causes a series of geological and environmental problems. Groundwater level prediction provides an efficient way to solve these intractable ecological problems. Although several hydrological numerical models have been employed to conduct prediction, no study has accurately predicted the groundwater level change under the consideration of groundwater exploitation, especially in coastal aquifers. This is due to the characteristics of spatially and temporally complex hydrological processes. This study proposes a novel data-driven method based on the combination of time series analysis and a machine learning method for accurately predicting the variation of groundwater level in a coastal aquifer under the influence of groundwater exploitation. The partial autocorrelation function and continuous wavelet coherence were used to analyze the monitoring data of groundwater level at three wells, which indicated that the historical monitored data and the dataset of precipitation could be considered as the input variables to construct the hydrological model. Then, three models based on the different inputs were constructed, namely, the LSTM, PACF-LSTM, and PACF-WC-LSTM models. The performances of the three models were compared by the calculation of four error metrics. The results showed that the performance of the PACF-LSTM and PACF-WC-LSTM models was better than that of the LSTM model and that the PACF-WC-LSTM model achieved the best prediction performance. Accurately predicting the variation of groundwater level provides the basis for managing groundwater resources and preserving the ecological environment.

Bi-LSTM and partial mutual information selection-based forecasting groundwater salinization levels

Abstract Fresh-saline groundwater is distributed in a highly heterogeneous way throughout the world. Groundwater salinization is a serious environmental issue that harms ecosystems and public health in coastal regions worldwide. Because of the complexities of groundwater salinization processes and the variables that influence them, it is challenging to predict groundwater salinity concentrations precisely. It compares cutting-edge machine learning (ML) algorithms for predicting groundwater salinity and identifying contributing factors. It employs bi-directional long short-term memory (BiLSTM) to indicate groundwater salinity. The input variable selection problem has attracted attention in the time series modeling community because it has been shown that information-theoretic input variable selection algorithms provide a more accurate representation of the modeled process than linear alternatives. To generate sample combinations for training multiple BiLSTM models, PMIS-selected predictors are used, and the predicted values from various BiLSTM models are also used to calculate the degree of prediction uncertainty for groundwater levels. The findings give policymakers insights for recommending groundwater salinity remediation and management strategies in the context of excessive groundwater exploitation in coastal lowland regions. To ensure sustainable groundwater management in coastal areas, it is essential to recognize the significant impact of human-caused factors on groundwater salinization.

Hydrochemical and Isotopic Explanations of the Interaction between Surface Water and Groundwater in a Typical-Desertified Steppe of Northern China

The Tabu catchment, a typical-desertified steppe in China, was selected as the study area to qualitatively analyze the interaction between surface water (SW) and groundwater (GW), and an integration of hydrochemical analysis and isotopic techniques was applied. The results show that the ion contents in SW and GW increased from upstream to downstream, and the hydrochemical evolutions were both controlled by rock weathering and influenced by evaporation. The δD–δ18O lines of SW and GW were δD = 5.14δ18O − 24.68 and δD = 6.89δ18O − 5.81, respectively. Along the I–I′ profile, the contents of most indices, δD and δ18O in SW and GW both showed increasing tendencies. All of the similarities in the hydrochemical characteristics and isotopic techniques indicated that SW was recharged by GW. The δD–δ18O inconsistency in SW and GW samples from midstream and downstream areas indicated that SW did not recharge to GW in these areas and was consumed by evaporation or replenished the moisture in the vadose zones. The runoff decreased, which was mainly caused by excessive exploitation of GW and a decline in the GW level. This study deepens the understanding of the hydrological cycle and provides guidance for the optimal combined utilization of SW and GW.

Optimizing the Cropland Fallow for Water Resource Security in the Groundwater Funnel Area of China

Excessive exploitation of groundwater for agricultural irrigation has resulted in groundwater funnel, causing land subsidence, water pollution, and vegetation degradation. The cropland fallow is an effective tool to maintain groundwater by reducing water consumption from agricultural irrigation. However, the cropland fallow program of fallow areas and fallow locations based on the protection of water resources at county level is unclear. The objective of this study is to improve the efficiency of cropland fallows under the premise of ensuring regional food security. In this study, we assessed the fallow urgency using IPLI (irrigation profit/loss index) and SGDCR (shallow groundwater depth change rate) and analyzed the cropland fallow areas and cropland fallow locations in Quzhou County, which is located in the world’s largest groundwater funnel area. The results showed that winter wheat’s irrigation water is in short supply (IPLI value is 0.1173), while that of summer maize and cotton’s irrigation water are in excessive supply (−0.9849 and −0.0071, respectively), and the depth to groundwater is deeper in the south and east in Quzhou County. The GM (1,1) gray prediction model showed that the cropland area that can be fallowed is 4089.288 hm2, 1189.288 hm2 larger than the current cropland fallow area (2900 hm2) according to official figures. In addition, two townships in southeast Quzhou county (Yizhuang and Houcun town) should be given high priority for cropland fallow; this is different from the current fallow cropland plots, distributed in eight townships (Yizhuang, Houcun, Nanliyue, Huaiqiao, Disituan, Henantuan, Baizhai, and Quzhou town). These results were useful to improve the cropland fallow program with the actual needs of the groundwater funnel area and develop the cropland fallow program from the aspects of “quality”, “quantity”, and “positioning” at county level.

EVALUATION OF GROUNDWATER STORAGE CHANGES USING SATELLITE GRAVIMETRY MISSION IN PENINSULAR MALAYSIA

Abstract. Water stored beneath the Earth’s surface, known as groundwater is a major water supply for living things. The increase in human population leading to high urban development and industrial needs in Malaysia has made the use of groundwater more critical. The current issue faced by Malaysia is the limitation of freshwater source from dam resulting in increasing demand to gather the source of fresh water from groundwater; hence, leading to the crucial exploitation of groundwater. Therefore, this study aims to evaluate groundwater storage (GWS) using Gravity Recovery and Climate Experiment (GRACE) and Global Land Data Assimilation System (GLDAS) data in Peninsular Malaysia. GRACE data consist information on the liquid water equivalent thickness covering terrestrial water storage (TWS) of GWS, soil moisture (SM), snow water equivalent (SWE), and surface water (SW). In comparison with GLDAS data, they only consist hydrological products of SM, SWE, and SW. Therefore, the differences between the GRACE and GLDAS data are most likely to reflect the information of GWS. Due to the seasonal monsoon, the changes in GWS can also be seen in specific months. In addition, the data can also be used to identify important areas that need improvement and attention. The output of this study is expected to help authorities monitoring the changes in GWS in recharge and discharge areas for future preservation of groundwater quality. Moreover, the excessive exploitation of groundwater can also be observed for the prevention of land hazard phenomena, such land subsidence.

Understanding the effects of subsidence on unconfined aquifer parameters by integration of Lattice Boltzmann Method (LBM) and Genetic Algorithm (GA)

Excessive exploitation of groundwater has hitherto led to a significant land subsidence in a considerable number of plains in Iran. The compaction of aquifer layers ends up with changes in aquifer parameters, including hydraulic conductivity (Kx), specific yield (Sy), and compressibility (α). Accordingly, a precise estimation of aquifer parameters, Kx, Sy, and α seems essential for future water resources planning and management. In this study, an innovative inversion solution based on the combination of lattice Boltzmann method (LBM) and genetic algorithm (GA) was developed to determine the aquifer parameters, Kx, Sy, and α in Darab plain (in Fars province, Iran), which is highly subject to land subsidence. Herein, a newly developed LBM for unconfined groundwater flow was employed by incorporating the amount of subsidence measured by synthetic aperture radar interferometry (InSAR) spanning from 2010 to 2016. In order to optimize the aquifer parameters, the whole process of inverse modeling is replicated on the annual basis from 2010 to 2016 which leads to the temporal estimation of the aquifer parameters. Due to the compaction occurring in the aquifer system, a declining temporal trend is observed in the aquifer parameters in most parts of the plain. By fitting a function to time-dependent aquifer parameters, Kx, Sy, and α, their corresponding values and consequently the amount of subsidence in the near future, i.e., 2017, are predicted. The small average relative error (~ 3.5%) between the predicted land subsidence and the InSAR measurements demonstrates the high performance of the proposed inverse modeling approach.

La vulnérabilité des oasis de la délégation de Kébili Sud face aux risques naturels et aux pressions anthropiques : impacts des changements climatiques et de la pénurie d’eau

Les oasis de Kébili Sud subissent des problèmes importants liés au changement climatique et à la pénurie d’eau résultant de l’élévation de la température et de la diminution des précipitations. Ainsi, la région souffre d’une pénurie importante d’eau d’irrigation en raison de longues périodes de sécheresses affectant cette zone déjà fragile, mais aussi et surtout du comportement humain. Notre étude a pour objectif de discuter et d’analyser la question liée aux impacts du changement climatique et des changements sociaux sur la pénurie d’eau dans les oasis de Kébili Sud, ainsi de contribuer à l’évauation de l’impact de ces changements sur la productivité des palmiers et la qualité des eaux souterraines. Les résultats obtenus lors du suivi spatiotemporel des indicateurs climatiques et des données hydrogéologiques ont montré une augmentation de la vulnérabilité des oasis. En particulier, la fragilité du secteur de l’eau par l’exploitation excessive des eaux souterraines a conduit à la détérioration de la qualité des eaux d’irrigation et à la perte de biodiversité. D’autre part, les taux élevés de dégradation qui ont été observés dans la zone d’étude indiquent une autre source de vulnérabilité en plus de la pollution, qui est l’activité agricole. La pénurie en eau, due à différents facteurs tant climatiques qu’anthropiques, nécessite de définir une stratégie de gestion des ressources en eau dans les oasis de cette région. Certains des résultats des activités de recherche et développement dans la zone d’étude qui visent principalement à soutenir la préservation et le développement durable des oasis de la région de Kébili seront présentés.

Characterization of Shallow Groundwater Circulation Based on Chemical Kinetics: A Case Study of Xiong’an New Area, China

Xiong’an New Area, located in the middle of the North China Plain, will have been built as a “city of the future.” Urban planning and construction need to comprehensively consider the constraints of hydrogeological conditions such as aquifer structure and parameters. As the main aquifer in this area, the paleo-channel is heterogeneous and anisotropic, and the two-dimensional hydraulic conductivity in each horizontal direction cannot be obtained from aquifer tests. Therefore, this study adopts a chemical kinetics method to calculate the ionic activity and mineral saturation indices of shallow groundwater, determine the groundwater chemical potential field, and construct a horizontal two-dimensional groundwater chemical kinetics model. This model is used to calculate the hydraulic conductivity, flow rate and retention time of groundwater in areas of different chemical kinetics, as well as evaluate horizontal heterogeneity of the Quaternary paleo-channel aquifer. The results indicate that the groundwater chemical potential field can reflect the characteristics of the groundwater seepage field in each horizontal direction. The paleo-channel is the main channel of groundwater circulation, which shows the statistical difference of its permeability. Alluvial and lacustrine strata affect groundwater circulation due to their different hydrogeological structures and permeability. The groundwater chemical kinetics results of hydraulic conductivity along the paleo-channel are approximately consistent with traditional hydrogeological calculation results derived from aquifer test data. Hydraulic conductivity is higher in the extension direction of the paleo-channel, and lower if the path crosscuts multiple paleo-channels. This feature can be used to build a hydrogeological structure model combined with drilling data. Furthermore, excessive groundwater exploitation will change the actual flow rate and retention time of groundwater, thereby affecting the groundwater circulation conditions. This study of groundwater circulation in Xiong’an New Area by means of chemical kinetics makes up for the deficiency in the study of the unconsolidated sedimentary aquifer anisotropy within the paleo-channel.

Integrating the impact of large-scale hydraulic engineering with a sustainable groundwater development strategy: A case study of Zhengzhou City, China

With the rapid growth of China's economy, the increase in water demand has threatened the sustainable development of groundwater. Construction of the South-to-North Water Diversion Project alleviated this problem. Zhengzhou, with a large population and high-intensity energy consumption, is a water-receiving city of the South-to-North Water Diversion Central Line Project (CLP). A series of ecological risks caused by the excessive exploitation of groundwater have been exposed. It is urgent to strengthen the assessment and management of groundwater to ensure sustainable development. In this study, the multi-criteria decision analysis (MCDA) underpinned the assessment of the sustainable groundwater development (ASGD) framework. Eight assessment factors were established based on the resource supply function (RSF) and eco-environment stability function (ESF). The novelty of this study lies in the integration of ASGD results with the impact of the CLP on the evolution of groundwater levels in Zhengzhou. Thus, more comprehensive and scientific management suggestions for groundwater development in Zhengzhou were obtained. GIS technology was integrated with the ASGD framework to identify five visualized areas: centralized groundwater supply area (8.61%), decentralized groundwater supply area (27.91%), vulnerable eco-environment area (14.34%), recharge protection area (45.67%), and unsuitable exploitation area (3.47%). The CLP changed the groundwater evolution pattern in Zhengzhou. The results showed that the operation of the CLP effectively slowed the decline in groundwater levels, thus confirming that the CLP has a positive impact on the rational utilization of groundwater. The disuse of two groundwater sources (G1 and G9) were able to enhance sustainable groundwater development. Meanwhile, five groundwater sources in the plain area proved unsuitable. Overall, this study provides a scientific basis for groundwater management in Zhengzhou City, while generating new ideas for sustainable groundwater development in cities affected by large-scale hydraulic projects worldwide.

Aquifer exploitation potential at a riverbank filtration site based on spatiotemporal variations in riverbed hydraulic conductivity

Study regionA riparian zone within the Songhua River Basin in Northeast China, characterized by a continental monsoon semi-humid climate. Study focusRiver infiltration is an important part of groundwater recharge at riverbank filtration (RBF) sites and largely depends on the riverbed hydraulic conductivity (RHC). The influence of river scouring and deposition on RHC is not completely clear, resulting in calculation inaccuracies in the rate of river water infiltration to the aquifer. Thus, the study determined the relationship between RHC and sediment particle size using stepwise regression analysis and a genetic algorithm. A hydrodynamic and sediment transport model (Delft3D) was used to simulate the spatial distribution of sediment particle sizes. A numerical groundwater flow model was also established, using Visual MODFLOW, in which the river boundary was generalized into a third type of boundary condition, and RHC zoning was performed to improve the accuracy of the simulation. New hydrological insightsThe findings showed that accurate prediction of RHC is essential for the assessment of groundwater resources in riparian zones. This is crucial for RBF managers, as they will be able to adjust the pumping rate according to the hydrological conditions of the river to either access more water resources in wet years or avoid a series of ecological and geological problems caused by excessive groundwater exploitation in dry years.

RAINWATER HARVESTING, A REVIEW

Water management is critical to any economy's growth and development, particularly in growing economies like India. However, due to excessive groundwater exploitation in the process of socioeconomic development and to meet the increased needs of the growing population, the resource is currently under stress. As a result, we should make use of this valuable resource while also conserving it. The basic goal of this study is to give a broad review of rainwater collecting systems and groundwater, as well as their possible uses in everyday life. Many countries have implemented rainwater harvesting as a long-term strategy to complement public water supplies. Many water-related issues have been overcome thanks to the RWH system. Another source of water that can be counted on is groundwater.

A System Dynamics Approach to Modeling Groundwater Dynamics: Case Study of the Choshui River Basin

Land subsidence resulting from the overexploitation of groundwater is an important issue in the Choshui River Basin, Taiwan. In the current study, we employed system dynamics simulation in modeling the supply of surface and groundwater, as well as the demand for water by industry, water deficits, and mechanisms underlying land subsidence. The proposed model was then used to estimate the magnitude of land subsidence and evaluate various management strategies. Our simulation results revealed that the vigorous enforcement of well sealing would have a modest effect on land subsidence; however, it would also have notable adverse effects on the agricultural community. We determined that reducing the demand for irrigation water (e.g., by switching to less water-intensive crops) would reduce land subsidence, while preserving profitability in those areas. In the future, this policy could be complemented by promoting the adoption of advanced irrigation technology and automatic systems to further slow the excessive exploitation of groundwater, with a corresponding effect on land subsidence.

Mapping land subsidence and aquifer system properties of the Willcox Basin, Arizona, from InSAR observations and independent component analysis

Long-term excessive groundwater exploitation for agricultural, domestic and stock applications has resulted in substantial ground subsidence in Arizona, USA, and especially in the Willcox Groundwater Basin. The land subsidence rate of the Willcox Basin has not declined but has rather increased in recent years, posing a threat to infrastructure, aquifer systems, and ecological environments. In this study, we first investigate the spatiotemporal characteristics of land subsidence in the Willcox Groundwater Basin using an interferometric synthetic aperture radar (InSAR) time series analytical approach with L-band ALOS and C-band Sentinel-1 SAR data acquired from 2006 to 2020. The overall deformation patterns are characterized by two major zones of subsidence, with the mean subsidence rate increasing with time from 2006 to 2020. An approach based on independent component analysis (ICA) was adopted to separate the mixed InSAR time series signal into a set of independent signals. The application of ICA to the Willcox Basin not only revealed that two different spatiotemporal deformation features exist in the basin but also filtered the residual errors in InSAR observations to enhance the deformation time series. Integrating the InSAR deformation and groundwater level data, the response of the aquifer skeletal system to the change in hydraulic head was quantified, and the hydromechanical properties of the aquifer system were characterized. Historical spatiotemporal storage loss from 1990 to 2020 was also estimated using InSAR measurements, hydraulic head and estimated skeletal storativity. Understanding the characteristics of land surface deformation and quantifying the response of aquifer systems in the Willcox Basin and other groundwater basins elsewhere are important in managing groundwater exploitation to sustain the mechanical health and integrity of aquifer systems.