Rising Groundwater Levels Research Articles

Sustainable groundwater management through an optimal water supply system using a coupled simulation-optimization approach.

Meeting people's water supply needs in cities is an urgent challenge. Especially in coastal cities, surface water sources are usually inadequate and so groundwater is frequently over-exploited, resulting in its rapid decrease and intrusion of saltwater. Conjunctive use of surface water and groundwater is the best alternative approach to mitigate the overuse of groundwater through effective distribution of surface water sources. It requires numerous runs of the simulation-optimization model to select an optimal pattern of water distribution by keeping the groundwater levels under control. In this study, a new simulation-optimization model is developed using wavelet support vector regression (WSVR) and genetic algorithm (GA) to propose an optimal water distribution system to Visakhapatnam city on the East Coast of India, fulfilling the constraints of surface water quantity, aquifer pumping, and drawdown. Estimation of groundwater pumping and groundwater level variation in spatial context is challenging in urban environment. To overcome this, the calibrated modular finite-difference flow (MODFLOW) model for this study area has been used to prepare the spatial and temporal variation of model inputs such as groundwater pumping and groundwater levels. The WSVR-GA model's performance to reduce the groundwater pumping is evaluated in three distinct cases. The surface water resources from three sources are distributed to different wards in the city source-wise in case I and centralized in cases II and III, while the source-wise surface water constraints are limited to monthly in cases I and II and annual in case III. The WSVR-GA management model suggested ward-wise groundwater pumping restrictions, resulting in 9.57 MCM, 11.64 MCM, and 12.54 MCM increase in total groundwater storage capacity in cases I, II, and III respectively. Cases II and III offer 21% and 25%, respectively, more storage than case I. Thus, centralized distribution systems have increased the sustainability of groundwater supplies by preventing overdrafts caused by a lack of surface water resources. Validation of results using MODFLOW indicates a substantial rise in groundwater levels in the study area.

Influence of the Gyeongju Earthquake on Observed Groundwater Levels at a Power Plant

Groundwater levels at a power plant site were analyzed using statistical techniques to ascertain if there was any influence from an earthquake that occurred approximately 27 km away. This earthquake was the Mw 5.5 Gyeongju earthquake that occurred on 12 September 2016 at 11:32 UTC in South Korea. Groundwater levels at five groundwater monitoring wells were examined against the 2016 Gyeongju earthquake, local precipitation, and local tide levels. A visual examination of the groundwater monitoring well data suggested no real effect or influence from the earthquake. However, precipitation data implied a rise in groundwater levels. Cross-correlation analyses also showed no significant relationship between groundwater levels and the earthquake in question. Interestingly, three of the five groundwater monitoring wells suggested a low-to-moderate correlation between groundwater and tide levels while the remaining two groundwater monitoring wells showed a low-to-moderate correlation between groundwater levels and precipitation. Granger causality tests suggested a closer relationship between tide and groundwater levels for two of the wells, questionable results describing precipitation for another two wells, and no relationship with the earthquake for four of the wells. Data resolution plays an important role in the analyses.

The Effect of Controlled Tile Drainage on Growth and Grain Yield of Spring Barley as Detected by UAV Images, Yield Map and Soil Moisture Content

Controlled tile drainage (CTD) practices are a promising tool for improving water balance, water quality and increasing crop yield by raising shallow groundwater level and capillary rise due to drainage flow retardation. We tested the effect of CTD on growth and grain yield of spring barley, at a study site in central Bohemia using vegetation indices from unmanned aerial vehicle (UAV) imagery and Sentinel-2 satellite imagery. Tile drainage flow was slowed by fixed water level control structures that increased soil moisture in the surrounding area according to the terrain slope. Vegetation indices based on red-edge spectral bands in combination with near-infrared and red bands were selected, of which the Normalized Red Edge-Red Index (NRERI) showed the closest relationships with shoot biomass parameters (dry biomass, nitrogen concentration and uptake, nitrogen nutrition index) from point sampling at the tillering stage. The CTD sites showed significantly more biomass using NRERI compared to free tile drainage (FTD) sites. In contrast, in the period prior to the implementation of CTD practices, Sentinel-2 satellite imagery did not demonstrate higher biomass based on NRERI at CTD sites compared to FTD sites. The grain yields of spring barley as determined from the yield map also increased due to CTD (by 0.3 t/ha, i.e., by 4%). The positive impact of CTD on biomass development and grain yield of spring barley was confirmed by the increase in soil moisture at depths of 20, 40 and 60 cm compared to FTD. The largest increase in soil water content of 3.5 vol% due to CTD occurred at the depth of 40 cm, which also had a higher degree of saturation of available water capacity and the occurrence of crop water stress was delayed by 14 days compared to FTD.

Public health threats of diminished treatment of onsite sewage

Public health threats of diminished treatment of onsite sewage

Design of groundwater monitoring network for coastal aquifers based on seawater intrusion vulnerability: A case study of Mandaue City, Philippines

Groundwater is an essential source of freshwater. However, this natural resource exhibits high vulnerability to contamination due to human activities and natural phenomena. Over extraction of groundwater and sea level rise have hastened seawater intrusion in aquifers that lie along the coasts. This has led to the accelerated deterioration of groundwater quality in coastal aquifers. Thus, there is an urgent need to develop tools to monitor groundwater resources. In this study, a framework of selecting priority areas for monitoring was applied to Mandaue City, Philippines. The monitoring areas were selected based on their vulnerability to seawater intrusion using the GALDIT-index. A collection of 77 initial public sites were investigated as potential locations of monitoring wells. The resulting network determined 45 priority areas located across the study area wherein monitoring wells should be located for the long-term observation of groundwater quality. These sites are composed of 28 from the initially investigated locations and 17 proposed sites which were determined to satisfy the required number of wells lacking in certain areas. The results of this study are intended to aid decision makers in creating groundwater management plans.

Case analysis of sudden cracking in buildings near a landfill pit in China

The causes of cracks in a six-storey building are studied. Based on analyses of crack morphology, settlement observation and geological survey, it is determined that the landfill pit and uneven settlement are the main cause of cracks. The 20 July Zhengzhou rainstorm in China caused a sharp rise in groundwater level, so that the uneven settlement of the office building near the landfill pit intensified, and then, wall cracking followed. The interaction between buildings and landfill pits under different water levels is studied by three-dimensional numerical simulation. As the water level rises, the horizontal displacement of soil in the landfill pit increases, and the lateral constraint of landfill soil to foundation soil decreases. The result is that the settlement of the column foundation near the landfill pits increases and the differential settlement intensifies. Based on the analysis results, the further development of differential settlement and cracks are evaluated and treatment suggestions are given.

Characterization of basaltic rock aquifer parameters using hydraulic parameters, Theis’s method and aquifer test software in the hard rock area of Buchakewadi watershed Maharashtra, India

The twelve wells were selected to carry out the various test, duration of pumping (min), maximum draw drown (m), duration of recovery (min), residual drawdown, and aquifer type in the basaltic rock aquifer parameters of Buchakewadi watershed. The source and flow of groundwater are essential concerns in hydrological systems that concern both spatially and temporally components of groundwater discharge and water supply problems. The content and temperature of groundwater flowing through an aquifer might change depending on the aquifer environment. As a result, hydrodynamic analyses can provide valuable information about a region's subsurface geology. The present research attempts of aquifer variables such as transmissivity (T) and storativity (S) estimation are significant for groundwater resource development and evaluation. There are numerous approaches for calculating precise aquifer characteristics (i.e., hydrograph analysis, pumping test, etc.). A most frequent in situ analysis is a well-pumping test, which accurately measures the decline and rise of groundwater levels. During an aquifer pumping test, to characterize aquifer properties in an undiscovered location to forecast the rate of depletion of the groundwater table/potentiometric surface. The shallow, weathering subsurface water accessible above the Deccan traps in an unconfined state is insufficient to satisfy the ever-increasing pressure on water supplies. Maharashtra is similarly dominated by hard rocks, whose rainfall susceptibility is limited by weathering and primary porosity, as is their volume to store and convey water. Based on the hydraulic parameters and Theis method, results are optimized. Aquifer mapping and pumping test results can be more important for solving problems such as water scarcity, nonpolluting water, health issues, and source of fresh water on the earth surface. However, the characterization of aquifer parameters should be significant role in the scientific planning and engineering practices.

Effects of subsidy and regulation policy on soil and water resources of cotton planted lands in Harran Plain, Turkey

Cotton (Gossypium hirsutum L.) provides essential raw material used in the textile, feed, and vegetable oil sectors. Therefore, it is a strategic crop for agricultural, economic, and political strategies around the world. Accurate monitoring of the changes in the cotton production patterns is crucial for decision-makers. Turkey is among the top ten cotton producers and ranks fourth in the world for cotton imports. One third of the total cotton production in Turkey comes from the southeastern Anatolia region of the country. This study analyzed the impact of subsidy and regulation policies on fluctuations in cotton production areas and soil and water quality in Harran Plains, southeastern Anatolia region Turkey. Time-series (between 2016 and 2021) satellite images were utilized to determine actual crop rotation in the study area. Turkish Government implemented a new rule for crop subsidies in 2020 which stated that a farmer will be eligible for subsidy for two consecutive years; however the subsidy will not be paid if the same crop is planted in the third year. Cotton was cultivated in 83 % of the Harran plains prior to new subsidy regulation, which decreased to 26 % after the new regulation. Sudden decrease in cotton cultivation area clearly indicated that farmers need public support to cover the costs in agricultural production. The Gross Production Value (BPV) for each crop was calculated to determine the impact of subsidy regulation on economic value of crops in the rotation.The GPV in 2020 was 2.903,7 $ ha−1 that was 33.6 % and 20.5 % lower than 2019 and 2021, respectively. The results indicated that crop subsidies significantly altered the crop selection behavior of farmers. Water requirement of crops in rotation between 2016 and 2021 was calculated to assess the effects of subsidy changes on water consumption. Cotton cultivation over a large part of the plains during the same season caused excessive water consumption, rise in groundwater level over time, soil salinity and severe water erosion. However, cotton cultivation area as well as water consumption in Harran plain new significantly decreased with the new subsidy regulation; therefore, water consumption in 2020 was the lowest among the time frame evaluated. Total sediment losses through surface runoff from the Harran Plain was estimated as 0.83 tons ha−1 per year. The results revealed that subsidies exert significant impacts on the gross production value in the region, amount of irrigation water consumed, and quality of soil and water resources in addition to the impact on the decision of farmers for crop selection.

Combining river replenishment and restrictions on groundwater pumping to achieve groundwater balance in the Juma River Plain, North China Plain

In recent years, to alleviate the decline in groundwater levels, extensive restrictions on groundwater pumping have been implemented in the North China Plain (NCP). In September 2018, a large-scale ecological water replenishment project was executed involving 22 rivers and lakes. How to adjust the layout of reduction on groundwater pumping within the context of ecological water replenishment is a key issue to be addressed in the study of groundwater level recovery in the NCP. This study adopted the Juma River Plain in Baoding city as a case study, established a numerical model of river replenishment of groundwater, predicted groundwater level changes over the next 15 years (2021–2035) and quantitatively calculated the impact of river replenishment on groundwater levels. To achieve the goal of an overall groundwater balance by 2035, a suitable groundwater pumping restriction scenario was defined based on the impact of river replenishment on groundwater levels. The results indicated that by 2035, the relative rise in groundwater levels attributed to river replenishment and restrictions on groundwater pumping could reach 3.51 and 2.28 m, respectively. River replenishment significantly impacts groundwater levels, especially those near the river. Under the current groundwater exploitation conditions, river replenishment could ensure groundwater level recovery near the river, which accounts for 15% of the total study area. The goal of an overall groundwater balance by 2035 could be achieved if restrictions on groundwater pumping were superimposed, with an average annual reduction of 56 million m3. This study provides valuable insights into groundwater management across the NCP. The proposed methods are useful for the management of other depleted aquifers recharged via ecological water replenishment.

Dynamic process, influence, and triggering mechanism of slope remodelling by landslide clusters in the South Jingyang Tableland, China

Recently, the concept of landslide path dependence has been proposed and well confirmed in landslide studies in central Italy and the Nepal Himalaya, providing a novel perspective for understanding landslide activity patterns and assessing susceptibility. Previous studies have shown that landslides in some loess tableland regions of China have obvious clustering effect, but whether landslides in these regions also have path dependence have not been well discussed. From the perspective of landslide path dependence, multidisciplinary survey methods (including remote sensing, satellite interpreting and monitoring, geographic information system mapping, terrestrial laser scanner survey, electrical resistivity tomography survey, remote online monitoring, physical experiments, numerical simulations, mathematical statistical analysis, and geomorphic change detection, etc.) were jointly applied in the study of landslide clusters in the South Jingyang Tableland, Shaanxi Province, China. We reveal the temporal-spatial distribution and deformation law of landslide clusters in the study area, analyze the effect of consecutive landsliding on the geomorphic evolution of the loess tableland and its triggering mechanism, and find the evidence of the existence of landslide path dependence in loess environment. The results show that the rise of groundwater level caused by human activities is the main culprit for the landslide clusters formation in the study area. Different path dependent models (reactivation or continuation landsliding, local activation landsliding, and remote activation landsliding) repeatedly acted alone or interacted with each other, leading to the formation of large-scale landslide clusters, and continuously remodeled the landscape of the loess tableland, thus accelerating the evolution process of the loess tableland. This study provides a scientific basis for further understanding the distribution law, sliding mode, clustering effect and formation mechanism of landslide clusters in loess tableland.

Groundwater-level recovery following closure of open-pit mines

Open-pit mining has increased substantially over the past two decades. Many currently operating open-pit mines are facing the end of mine-life over the next few decades and, increasingly, focus is shifting towards mine-closure planning that provides evidence on available closure options under the given geological, hydro(geo)logical and climatic conditions. This study uses synthetic groundwater modelling to build basic process understanding of closure options and how these will determine the formation of pit lakes. This governs the long-term pit lake water quality and how postmining landscapes may be utilised. Simulations show that the recovery time of postmining groundwater levels increases with decreasing aquifer transmissivity. Final postmining water tables are predominantly controlled by the implemented mine closure options and climatic conditions. The most important decision is, thereby, whether to backfill the pit to above the water table or allow a pit lake to develop. Under moderately transmissive aquifer settings, backfilling of pits leads to rapidly rising groundwater levels within the first decade after mining, with water-table recoveries of above 70%. If mine voids remain unfilled, evaporation from the pit lake surface becomes a governing factor in determining whether the unfilled mine pit becomes a terminal sink for groundwater. Lake levels may remain subdued by several 10s of metres in arid to semiarid climates. If surplus surface water can be diverted into open pits, rapid filling can accelerate groundwater recovery of open pits in regions of low permeability. This is a less successful management option in transmissive aquifers.

Forecasting groundwater rise in the historic downtown area of Irkutsk city

The purpose of this investigation is to develop an analytical model for predicting the groundwater level rise due to the barrage effect. Processing of a significant volume of production decisions for multiple objects has resulted an analytical model that allows predicting the dynamics of groundwater rise due to the barrage effect when building deep foundation structures. The study has been conducted for the downtown areas of Irkutsk and other cities of Eastern Siberia. Prediction schemes for the groundwater level formation have been made, and an assessment of the study areas by their underflooding conditions has been carried out. Being adequately simple and multi-purpose. The analysis of the research results shows that the hydraulic gradient of the underground water flow and the project structure width have the biggest effect on the groundwater rise. Vertical planning of the territory and the use of pile foundations play a significant role in the formation of the groundwater level. Besides, when evaluating the depth of the underground water formation level and developing the prevention and protection measures, it is necessary to take into account the seasonal rise of the underground waters. The developed model can be applied in the corresponding geological and hydrogeological conditions.

The Effect of the Water Table on the Bearing Capacity of a Shallow Foundation

Immersion is an important part of reservoir engineering investigation and evaluation. Determining the reasonable and effective burial depth of the critical immersion water table is one of the key scientific issues in the impact assessment of the bearing capacity of reservoir immersion foundations. In this study, basic physical and mechanical property tests were carried out on the soil in the typical immersion area of Xiaonanhai Hydropower Station, and the influence mechanism of saturation on the mechanical properties of building foundation soil and immersion on the bearing capacity of a shallow foundation was obtained. According to the test results, the influence depth of the rising groundwater level on the stability of the building foundation is analyzed, and a method to determine the critical depth of immersion groundwater in the reservoir is proposed. Taking the typical building foundation of Luohuang Town in the immersion area of Xiaonanhai Reservoir as an example, the validity of the critical water depth is further verified. The results show that the safety limit depth of the independent foundation affected by the rise of the water table increases with the increase of the width of the foundation and decreases with the increase of the buried depth of the foundation. Considering the safety limit depth, the critical depth of building immersion is 4.830 m, and without considering the safety limit depth, the critical depth of building immersion is 4.05 m. To a certain extent, it can reduce the impact of water table changes on the bearing capacity of shallow foundations.

Land Use/Land Cover change detection in the wetlands. A case study: Al-Aba Oasis, west of Ras Tanura, Kingdom of Saudi Arabia

In addition to unthinking anthropogenic meddling with the subtle ecological balance, the territories of Al-Aba Oasis are witnessing various Land Use and Land Cover (LULC) changes. Comprehending LULC is a central facet of upholding a sustainable, friendly, and fit environment. This paper presents a spatiotemporal study of land use and land cover trends in the wetlands of Al-Aba Oasis, an ecologically sensitive area in the west of Ras Tanura in the east of the Kingdom of Saudi Arabia. The study area faces several environmental problems, including the rise in groundwater levels, expansion of agricultural land, urban expansion, and anthropogenic interference with the ecological balance. In this paper, a verified representation of the changes in each LULC class has been made using satellite images. Remote sensing imagery is helpful for studying temporal changes in LULC and providing environmental monitoring data. We analysed Landsat-5 and Sentinel-2 imagery for 1985, 2000, and 2021. The overall precision besides the kappa coefficient for precision assessment indicates the relevance of the LULC classification. LULC map products were overlaid and interpreted based on post-classification change detection methods. The LULC aspects were classified into six classes: water body, waterlogged area, sabkha soil, sandy area, cultivated area, and built- up area. The results prove that from 2001 to 2021, the extension of the built-up area (2.6%) and agricultural land (6.85%) is directly proportional to the population growth (36.5% between 1992 and 2004) and the sabkhas are subject to constant metamorphosis under the joint influence of urban and agricultural land expansion. 100 samples were collected for the years 1986, 2001, and 2021 to assess the accuracy. We reviewed the outcomes of this study by evaluating the accuracy (77, 81, and 84% for 1986, 2001, and 2021 respectively) and comparing the field truth using a GPS (Global Positioning System) sensor. The results of this study are useful in the development of environmental policies during the development of sustainable territorial development programmes of the oasis.

Typification of Kherson region by water availability for irrigation and its environmental consequences

. The article presents the results of regional typification for the Kherson region by water availability for irrigation, taking into account the possible environmental risk as a result of the increase in irrigated area. The grouping of the territories previously differentiated by water availability into the following subtypes was performed: low rate of natural surface and groundwater water availability; sufficient rate of groundwater availability variously suitable for irrigation; high level of transit river flow availability; provided water supply of different quality from irrigation sources. Also, the territory grouping was made by the zones of ecological risk according to ecological and amelioration qualifications along with the separation of admissible ecological risk zones (potentially conditionally unstable areas with good ecological and reclamation conditions), zones of increased ecological or potentially unstable areas with the satisfactory and endangered condition), zones of sustainable ecological risk (potentially unstable areas with the unsatisfactory or very unsatisfactory land condition), zones of ecological crises development (potentially very unstable with the very unsatisfactory land condition). 
 It was specified that within the Kherson region predominate the areas with low natural water supply from local surface flow in combination with the zones of increased ecological risk (Kakhovka irrigation zone) or with the zones of stable ecological risk (Oleksandrivska irrigation zone, Kalanchak irrigation system). Additional surface water supply for irrigation is provided by the main canals from the Kakhovka reservoir. Further increase in irrigation areas within these typological territories, on the one hand, can be provided with available resources on the other hand, may lead to deterioration of ecological and reclamation condition of irrigated land and aggravation of water and ecological situation, first of all, rising groundwater level.

Precipitation Amounts Triggering Landslide Processes in the Western Part of the Nałęczów Plateau (Lublin Upland, Poland)

Abstract This study covers the western part of Poland’s loess Nałęczów Plateau (Kazimierz Dolny, Zbędowice). Mass movements in the Lublin Upland occur during periods of increased precipitation or after a snowy and cold winter. To date, there are no comprehensive studies on active (precipitation, hydrology, vegetation, land use, anthropogenic factors) or passive factors (lithology, slope angle) causing such geohazards in this region. This area’s formations are characterised by high sensitivity to even small changes in moisture content; thus, their geotechnical parameters deteriorate as a result of precipitation or rising groundwater levels. The calculations in this study were chosen to determine the time necessary for ground response to external factors, in addition to determining the impact of these factors on decreases in the factor of safety (FS). Based on calculations in GeoStudio software, the impacts of rainfall totals and duration on slope failure, interpreted as an event where the FS falls below 1.0, were analysed. Accordingly, the threshold rainfall value was determined as the total rainfall at the time of slope failure. The study’s results indicate that loess covers are characterised by average water permeability, relatively high internal friction angles and low cohesion, which, combined with high slope inclination, favour landslide formation even when the slope is only partially saturated. The most unfavourable stability conditions occur at the beginning of spring, indicating that loess stability is significantly affected by snowmelt and precipitation at the beginning of the vegetation season, as well as the occurrence of episodic intense precipitation during the summer.

Spatiotemporal Distribution and Statistical Analysis of Abnormal Groundwater Level Rising in Poyang Lake Basin

Studies on groundwater have traditionally been based on declining groundwater levels and associated ecological, environmental, and geological problems. However, due to extreme hydrometeorological events and human activities, rising groundwater levels have been observed in many areas. The daily groundwater levels from 2018 to 2020 for the Poyang Lake Basin (PLB) in Jiangxi Province were recorded. The statistical characteristics of abnormal groundwater level rising (AGLR) events and the factors influencing the dynamic changes in groundwater level were analyzed using geostatistical methods and outlier identification methods. The groundwater level in the lower terrain of the PLB has increased significantly in recent years. AGLR events identified by the median absolute deviation and interquartile range methods showed that AGLR events mainly occurred in the spring and summer and were mainly distributed near the surface water bodies. Correlation analysis of the factors influencing the groundwater level revealed that the correlation between precipitation and groundwater level was related to topography. In contrast, the correlation between river stage and groundwater level was related to runoff volume.

Groundwater regulation for coordinated mitigation of salinization and desertification in arid areas

Desertification and salinization are both threats to the ecosystem services in inland river oases of arid regions. Previous studies focus on either desertification or salinization, and there is a lack of joint studies on the two issues. The essential cause of desertification in a transition zone is usually concentrated irrigation water use, which leads to shrink of the subsurface flow field of groundwater, decline of the groundwater level, and loss of groundwater supply to the vegetation. The salinization problem in an oasis area is mainly caused by the local excess groundwater in the oasis, referring to secondary salinization, which leads to salt migration with the groundwater level rise to form salt crystallization at the land surface. Thus, the processes of desertification and secondary salinization are connected, and the solutions to the two problems can be complementary, i.e., by transporting the excess groundwater in the local secondary salinization area to the transition zone area where water is scarce. This paper, taking Luocheng Irrigation District in the Heihe River Basin of northwestern China as an example, estimates 1.76–4.70 million m3 of excess groundwater that can be extracted in the salinized area. Using this amount of water through engineering regulation, it is estimated that the transition zone nearby the irrigation district, which is under desertification threat, can be restored with an area of 23–212 km2. An engineering system is designed for coordinated groundwater regulation and the implementation with an experimental farm in the irrigation district is demonstrated.

Application of double lifting method for river water irrigation in the water stressed Barind Tract of northwest Bangladesh

Groundwater has become the prime source of drinking and irrigation use in drought-prone Barind Tract (BT) of Bangladesh as the surface water sources are minimal. Continuous groundwater withdrawals for irrigation, drinking, domestics, industries and other uses deplete groundwater levels (GWL). So, the study aims to compute the quantity of river water extracted for irrigation by double lifting and rubber dam irrigation systems of Barind Multipurpose Development Authority (BMDA) in BT area and evaluate their impacts on reducing groundwater exploitation. To carry out the study, bore log lithology, rainfall, GWL, and water irrigation data have been collected from BMDA and field investigation and analyzed the Groundwater depletion due to over-extraction than the potential recharge, lower rainfall than the national average, and thick top clay that limits the natural recharge. Lifted water by the pumps of 11 pontoons placed on the river Padma (Ganges), Mohanonda, and Atrai can reduce 7.08% of groundwater extraction for irrigation in the study area. Groundwater exploitation for Puthia Upazila can be reduced by 10.11% with conserved water upstream of the rubber dam constructed in the Barnai river. Also, a continuous rise in GWL was observed due to storing of river water at a 4 km long section by the rubber dam.

Beijing Land Subsidence Revealed Using PS-InSAR with Long Time Series TerraSAR-X SAR Data

Beijing is a major city suffering from land subsidence due to long-term over-exploitation of groundwater. The South-to-North Water Diversion Project (SNWDP), however, has had a significant impact on the structure of water consumption since the end of 2014, and it is changing the status of land subsidence in Beijing. In this study, we employed Persistent Scatterers Synthetic Aperture Radar Interferometric (PS-InSAR) to investigate the decadal evolution of land subsidence in Beijing with 100 TerraSAR-X stripmap images collected from April 2010 to December 2019. The water resources, historic climate and urban construction data were compiled for the years of 2010 to 2019 to analyze changes in groundwater level, human activity, surface geology, active faults and land subsidence patterns. The results show that the changes in the water supply structure are correlated to a rise in groundwater level after 2015. These changes include an increase in the water supply from the SNWDP, a reduction in groundwater exploitation, the optimization of water consumption, replacing recycled water for environmental water and a reduction in the use of water for agriculture. Land subsidence in the study area was concentrated in the eastern regions, trending towards a decreasing velocity starting about two years after the commencement of SNWDP in 2015. Uneven subsidence in the land subsidence area was related to excavations of underground soil, and the construction of Line 6 and Line 7 led to rapid nonlinear subsidence. Our results have scientific significance for reducing subsidence hazards in the context of SNWDP and urban expansion.