Groundwater recharge via precipitation in the Badain Jaran Desert,China

Precipitation infiltration serves as a significant source of groundwater in the Badain Jaran Desert.To investigate variations in precipitation infiltration within the desert,this study collected data on moisture content and temperature from the vadose zone through in-situ field monitoring.Utilizing these data,a numerical model is employed to explore the mechanism of groundwater recharge via precipitation.The results are as follows:(1)Moisture content and temperature in the shallow vadose zone exhibit significant seasonal variations,with moisture content diminishing with increasing depth;(2)Groundwater recharge via precipitation infiltration initially increases and then decreases with groundwater level depth(GWD).Peak groundwater recharge via precipitation occurs at a GWD of 0.75 m,decreasing to merely 0.012 cm at GWDs exceeding 2 m;(3)Groundwater is no longer susceptible to phreatic water evaporation when the GWD reaches approximately 3.7 m.Therefore,GWD plays a crucial role in governing groundwater recharge via precipitation in the Badain Jaran Desert.

Clogging caused by coupled grain migration and compaction effect during groundwater recharge for unconsolidated sandstone reservoir in groundwater-source heat pump

In unconsolidated sandstone reservoirs,presence of numerous movable grains and a complex grain size composition necessitates a clear understanding of the physical clogging process for effective groundwater recharge in groundwater-source heat pump systems.To investigate this,a series of seepage experiments was conducted under in situ stress conditions using unconsolidated sandstone samples with varying grain compositions.The clogging phenomenon arises from the combined effects of grain migration and compaction,wherein the migration of both original and secondary crushed fine-grain particles blocks the seepage channels.Notably,grain composition influences the migration and transport properties of the grains.For samples composed of smaller grains,the apparent permeability demonstrates a transition from stability to decrease.In contrast,samples with larger grains experience a skip at the stability stage and directly enter the decrease stage,with a minor exception of a slight increase observed.Furthermore,a unique failure mode characterized by diameter shrinkage in the upper part of the sample is observed due to the combined effects of grain migration and in situ stress-induced compaction.These testing results contribute to a better understanding of the clogging mechanism caused by the coupled effects of grain migration and compaction during groundwater recharge in unconsolidated sandstone reservoirs used in groundwater-source heat pump systems.

Estimation of Groundwater Recharge Using Water Table Fluctuation Method in Bamako and Surrounding Areas, Mali

Bamako’s geographic and demographic expansion is sure to increase the need for water, and the slow development of the water supply network seems unable to meet this need. The knowledge of the approximate quantity of water reaching the groundwater is crucial, given the high dependence of this city and its surrounding area on groundwater. The aim of this study is to estimate the average groundwater recharge on a monthly scale, based on measurements taken over a 24-month period by using Water Table Fluctuation (WTF). The monthly recharge values obtained from the 15 piezometers in the study area by using WTF method vary from 1.04 to 38.81 mm with an average value of 9.74 mm. As part of the precipitations, these values represent respectively 1.29%, 48.52% and 12.17% of monthly average precipitation. It appears in this study that despite the piezometers belonging to the same climatic zone, the recharge rate can be different because of many factors such as the thickness of the aquifers, the soil and geology type, the local land cover and land use activities.

Optimizing groundwater recharge plan in North China Plain to repair shallow groundwater depression zone, China

The North China Plain is one of the main grain producing areas in China. However, overexploitation has long been unsustainable since the water supply is mainly from groundwater. Since 2014,the South-to-North Water Diversion Project's central route has been charted to the integrated management of water supply and over-exploitation, which has alleviated the problem to a certain extent. Although the Ministry of Water Resources has made many efforts on groundwater recharge since 2018 most of which have been successful, the recharge has not yet been sufficiently focused on the repair of shallow groundwater depression zones. It still needs further optimization. This paper discusses this particular issue,proposes optimized recharge plan and provides the following recommendations:(1) Seven priority target areas are selected for groundwater recharge in alluvial and proluvial fans in the piedmont plain, and the storage capacity is estimated to be 181.00×10~8 m~3;(2) A recharge of 31.18×10~8 m~3/a is required by 2035 to achieve the repair target;(3) It is proposed to increase the recharge of Hutuo River, Dasha River and Tanghe River to 19.00×10~8 m~3/a and to rehabilitate Gaoliqing-Ningbailong Depression Zone;increase the recharge of Fuyang River, Zhanghe River and Anyang River to 7.05×10~8 m~3/a and rehabilitate Handan Feixiang-Guangping Depression Zone;increase the recharge of Luanhe River by 0.56×10~8 m~3/a and restore Tanghai Depression Zone and Luanan-Leting Depression Zone;moderately reduce the amount of water recharged to North Canal and Yongding River to prevent excessive rebound of groundwater;(4) Recharge through well is implemented on a pilot basis in areas of severe urban ground subsidence and coastal saltwater intrusion;(5) An early warning mechanism for groundwater quality risks in recharge areas is established to ensure the safety. The numerical groundwater flow model also proves reasonable groundwater level restoration in the depression zones by 2035.

Evolution of groundwater recharge-discharge balance in the Turpan Basin of China during 1959-2021

Groundwater overexploitation is a serious problem in the Turpan Basin,Xinjiang Uygur Autonomous Region of China,causing groundwater level declines and ecological and environmental problems such as the desiccation of karez wells and the shrinkage of lakes.Based on historical groundwater data and field survey data from 1959 to 2021,we comprehensively studied the evolution of groundwater recharge and discharge terms in the Turpan Basin using the groundwater equilibrium method,mathematical statistics,and GIS spatial analysis.The reasons for groundwater overexploitation were also discussed.The results indicated that groundwater recharge increased from 14.58×10^(8)m^(3)in 1959 to 15.69×10^(8)m^(3)in 1980,then continued to decrease to 6.77×10^(8)m^(3)in 2021.Groundwater discharge increased from 14.49×10^(8)m^(3)in 1959 to 16.02×10^(8)m^(3)in 1989,while continued to decrease to 9.97×10^(8)m^(3)in 2021.Since 1980,groundwater recharge-discharge balance has been broken,the decrease rate of groundwater recharge exceeded that of groundwater discharge and groundwater recharge was always lower than groundwater discharge,showing in a negative equilibrium,which caused the continuous decrease in groundwater level in the Turpan Basin.From 1980 to 2002,groundwater overexploitation increased rapidly,peaking from 2003 to 2011 with an average overexploitation rate of 4.79×10^(8)m^(3)/a;then,it slowed slightly from 2012 to 2021,and the cumulative groundwater overexploitation was 99.21×10^(8)m^(3)during 1980-2021.This research can provide a scientific foundation for the restoration and sustainable use of groundwater in the overexploited areas of the Turpan Basin.

Groundwater Flow Simulation and its Application in Groundwater Resource Evaluation in the North China Plain,China

The purpose of this study is to establish a 3D groundwater flow modelling for evaluating groundwater resources of the North China Plain. First, the North China Plain was divided into three aquifers vertically through a characterization of hydrogeological conditions. Groundwater model software GMS was used for modeling to divide the area of simulation into a regular network of 164 rows and 148 lines. This model was verified through fitting of the observed and the simulated groundwater flow fields at deep and shallow layers and comparison between the observed and simulated hydrographs at 64 typical observation wells. Furthermore, water budget analysis was also performed during the simulation period （2002-2003）. Results of the established groundwater flow model showed that the average annual groundwater recharge of the North China Plain during 1991 to 2003 was 256.68x10s m3/yr with safe yield of groundwater resources up to 213.49x10s m3/yr, in which safe yield of shallow groundwater and that of deep groundwater was up to 191.65x10s m3/yr and 22.64x10s m~/yr respectively. Finally, this model was integrated with proposal for groundwater withdrawal in the study area after commencement of water supply by South-North Water Transfer Project, aiming to predict the changing trend of groundwater regime. As indicated by prediction results, South-North Water Transfer Project, which is favorable for effective control of expansion and intensification of existing depression cone, would play a positive role in alleviation of short supply of groundwater in the North China Plain as well as maintenance and protection of groundwater.

Isotope Method for Confined Groundwater Recharge of the Lower Reaches of the Heihe River,Inner Mongolia,China

Environmental isotopes have been appfied to analyze confined groundwater recharge in the lower reaches of the Heihe River, Inner Mongolia. CFC is regarded as a tracer that determines the date of groundwater, the date being less than 45 a. The confined groundwater within the Gurinai area and Ejin Basin other than the surface water of Heihe River might have originated from precipitation from Qilian Mountain or/and the Tibetan Plateau. The deep confined groundwater overflows into an upper aquifer and emerges into the ground, forming springs and lakes within the low-lying area. The recharge volume is estimated to be around 400 million-cubic meters.

An approach to delineate groundwater recharge potential sites in Ambalantota,Sri Lanka using GIS techniques

The demand for fresh water in Hambantota District, Sri Lanka is rapidly increasing with the enormous amount of ongoing development projects in the region. Nevertheless, the district experiences periodic water stress conditions due to seasonal precipitation patterns and scarcity of surface water resources.Therefore, management of available groundwater resources is critical, to fulfil potable water requirements in the area. However, exploitation of groundwater should be carried out together with artificial recharging in order to maintain the long term sustainability of water resources. In this study, a GIS approach was used to delineate potential artificial recharge sites in Ambalantota area within Hambantota. Influential thematic layers such as rainfall, lineament, slope, drainage, land use/land cover, lithology, geomorphology and soil characteristics were integrated by using a weighted linear combination method. Results of the study reveal high to moderate groundwater recharge potential in approximately 49% of Ambalantota area.

A field study of advanced municipal wastewater treatment technology for artificial groundwater recharge

Field studies were conducted to investigate the advanced treatment of the municipal secondary effluent and a subsequent artificial groundwater recharge at Gaobeidian Wastewater Treatment Plant, Beijing. To improve the secondary effluent quality, the combined process of powdered activated carbon adsorption, flocculation and rapid sand filtration was applied, which could remove about 400 dissolved organic carbon （DOC） and 70% adsorbable organic halogens. The results of liquid size exclusion chromatography indicate that in the adsorption unit the removed organic fraction was mainly low molecular weight compounds. The fractions removed by the flocculation unit were polysaccharides and high molecular weight compounds. The retention of water in summer in the open recharge basins resulted in a growth of algae. Consequently, DOC increased in the polysaccharide and high molecular weight humic substances fraction. The majority of the DOC removal during soil passage took place in the unsaturated area. A limited reduction of DOC was observed in the aquifer zone.

Natural water purification and water management by artificial groundwater recharge

Worldwide,several regions suffer from water scarcity and contamination.The infiltration and subsurface storage of rain and river water can reduce water stress.Artificial groundwater recharge,possibly combined with bank filtration,plant purification and/or the use of subsurface dams and artificial aquifers,is especially advantageous in areas where layers of gravel and sand exist below the earth's surface.Artificial infiltration of surface water into the uppermost aquifer has qualitative and quantitative advantages.The contamination of infiltrated river water will be reduced by natural attenuation.Clay minerals,iron hydroxide and humic matter as well as microorganisms located in the subsurface have high decontamination capacities.By this,a final water treatment,if necessary,becomes much easier and cheaper.The quantitative effect concerns the seasonally changing river discharge that influences the possibility of water extraction for drinking water purposes.Such changes can be equalised by seasonally adapted infiltration/extraction of water in/out of the aquifer according to the river discharge and the water need.This method enables a continuous water supply over the whole year.Generally,artificially recharged groundwater is better protected against pollution than surface water,and the delimitation of water protection zones makes it even more save.

Impact of Land Use Change on Groundwater Recharge in Guishui River Basin,China

It is important to understand how land use change impacts groundwater recharge, especially for regions that are undergoing rapid urbanization and there is limited surface water. In this study, the hydrological processes and re- charge ability of various land use types in Guishui River Basin, China （in Beijing Municipality） were analyzed. The impact of land use change was investigated based on water balance modeling, WetSpass and GIS. The results indicate that groundwater recharge accounts for only 21.16% of the precipitation, while 72.54% is lost in the form of evapotranspiration. The annual-lumped groundwater recharge rate decreases in the order of cropland, grassland, urban land, and forest. Land use change has resulted in a decrease of 4 x 106 m3 of yearly groundwater recharge in the study area, with a spatially averaged rate of 100.48 mm/yr and 98.41 mm/yr in 1980 and 2005, respectively. This variation has primarily come from an increase of urban area and rural settlements, as well as a decrease of cropland.

Environmental Isotopic Characterization of Groundwater and Surface Water in Northeast Missan Province,South Iraq

The present work studies the environmental isotopes assess groundwater characteristics of the different parts of the main aquifer in the northeast Missan Province in south of Iraq. Water samples of groundwater and surface water were collected for two dry and wet seasons during the water year of 2011-2012. The study shows that most of the groundwater in the aquifer falls above the global meteoric water line, and all the samples fall below the Mediterranean meteoric water line, indicating that these samples are a mixture of two water types. The tritium content of these samples supports this conclusion. The overall conclusion of this study indicates that there are two sources of groundwater recharge in the studied area： the ephemeral streams （Teeb and Dewerge） and major precipitation sources. According to the tritium levels at or below one tritium unit （TU） obtained from the water, supply wells are highly confined or ＂not vulnerable＂. Overall, the 3^H results imply that recent recharge has taken place during the last four to five decades. In the recharge area, the high tritium content in the southern part of the Teeb area suggests that the recharge originates from rapid infiltration of surface runoff. Therefore, the groundwater resources in the study area should be protected from contamination, because it will influence the aquifer in a relatively short period of time if any contamination enters the recharge areas of the aquifer.

Groundwater Recharge and Mixing in Arid and Semiarid Regions:Heihe River Basin,Northwest China

A sound understanding of groundwater recharged from various sources occurring at different time scales is crucial for water management in arid and semi-arid river basins. Groundwater recharge sources and their geochemical evolution are investigated for the Heihe River Basin （HRB） in northwest China on the basis of a comprehensive compilation of geochemical and isotopic data. Geochemical mass- balance modeling indicates that mountain-block recharge accounts for a small fraction （generally less than 5%） of the shallow and deep groundwater sustaining the oasis, whereas infiltration of rivers and irrigation water contribute most of the groundwater recharge. Dedolomitization is the primary process responsible for the changes in groundwater chemical and carbon isotope compositions from the piedmont to the groundwater discharge zone, where the dedolomitization is very likely enhanced by modern agricultural activities affecting the shallow groundwater quality. Analysis of radioactive isotopes suggests that these primary recharge sources occur at two different time scales. Radiocarbon-derived groundwater age profiles indicate a recharge rate of approximately 12 mm/year, which probably occurred during 2000-7000 years B.P., corresponding to the mid-Holocene humid period. The recharge of young groundwater on the tritium-dated time scale is much higher, about 360 mm/year in the oasis region. Infiltration from irrigation canals and irrigation return flow are the primary contributors to the increased young groundwater recharge. This study suggests that groundwater chemistry in the HRB has been influenced by the complex interaction between natural and human-induced geochemical processes and that anthropogenic effects have played a more significant role in terms of both groundwater quantity and quality.

Mapping favorable groundwater potential recharge zones using a GIS-based analytical hierarchical process and probability frequency ratio model:A case study from an agro-urban region of Pakistan

In Punjab(Pakistan),the increasing population and expansion of land use for agriculture have severely exploited the regional groundwater resources.Intensive pumping has resulted in a rapid decline in the level of the water table as well as its quality.Better management practices and artificial recharge are needed for the development of sustainable groundwater resources.This study proposes a methodology to delineate favorable groundwater potential recharge zones(FPRI)by integrating maps of groundwater potential recharge index(PRI)with the DRASTIC-based groundwater vulnerability index(VI).In order to evaluate both indexes,different thematic layers corresponding to each index were overlaid in ArcGIS.In the overlay analysis,the weights(for various thematic layers)and rating values(for sub-classes)were allocated based on a review of published literature.Both were then normalized and modified using the analytical hierarchical process(AHP)and a frequency ratio model respectively.After evaluating PRI and FPRI,these maps were validated using the area under the curve(AUC)method.The PRI map indicates that 53%of the area assessed exists in very low to low recharge zones,22%in moderate,and 25%in high to excellent potential recharge zones.The VI map indicates that 38%of the area assessed exists in very low to low vulnerability,33%in moderate,and 29%in high to very high vulnerability zones.The FPRI map shows that the central region of Punjab is moderately-to-highly favorable for recharge due to its low vulnerability and high recharge potential.During the validation process,it was found that the AUC estimated with modified weights and rating values was 79%and 67%,for PRI and VI indexes,respectively.The AUC was less when evaluated using original weights and rating values taken from published literature.Maps of favorable groundwater potential recharge zones are helpful for planning and implementation of wells and hydraulic structures in this region.

Effect of groundwater on the ecological water environment of typical inland lakes in the Inner Mongolian Plateau

To explore the causes of the ecological environment deterioration of lakes in the Inner Mongolia Plateau,this study took a typical inland lake Daihai as an example,and investigated the groundwater recharge in the process of lake shrinkage and eutrophication.Using the radon isotope(^(222)Rn)as the main means of investigation,the ^(222)Rn mass balance equation was established to evaluate the groundwater recharge in Daihai.The spatial variability of ^(222)Rn activity in lake water and groundwater,the contribution of groundwater recharge to lake water balance and its effect on nitrogen and phosphorus pollution in lake water were discussed.The analysis showed that,mainly controlled by the fault structure,the activity of ^(222)Rn in groundwater north and south of Daihai is higher than that in the east and west,and the difference in lithology and hydraulic gradient may also be the influencing factors of this phenomenon.The ^(222)Rn activity of the middle and southeast of the underlying lake is greater,indicating that the ^(222)Rn flux of groundwater inflow is higher,and the runoff intensity is greater,which is the main groundwater recharge area for the lake.The estimated groundwater recharge in 2021 was 3017×10^(4) m^(3),which was 57%of the total recharge to the lake,or 1.6 times and 8.1 times that of precipitation and surface runoff.The TN and TP contents in Daihai have been rising continuously,and the average TN and TP concentrations in the lake water in 2021 were 4.21 mg·L^(−1) and 0.12 mg·L^(−1),respectively.The TN and TP contents entering the lake with groundwater recharge were 6.8 times and 8.7 times above those of runoff,accounting for 87%and 90%of the total input,respectively.The calculation results showed that groundwater is not only the main source of recharge for Daihai,but also the main source of exogenous nutrients.In recent years,the pressurized exploitation of groundwater in the basin is beneficial in increasing the groundwater recharge to the lake,reducing the water balance difference of the lake,and slowing down the shrinking degree of the lake surface.However,under the action of high evaporation,nitrogen and phosphorus brought by groundwater recharge would become more concentrated in the lake,leading to a continuous increase in the content of nutrients and degree of eutrophication.Therefore,the impact of changes in regional groundwater quantity and quality on Daihai is an important issue that needs further assessment.

Characteristics of karst groundwater system in the northern basin of Laiyuan Spring area

Guided by the theory of groundwater system, based on the groundwater level data from the northern basin of Laiyuan Spring area, the authors took into account factors such as the lithology, geological structure and topography to study the relationship between groundwater recharge, runoff and drainage in this area. It was concluded that the infiltration of atmospheric precipitation is the main source of groundwater supply in this area; the upper layer of the Spring area is distributed with the Cambrian-Lower Ordovician karst water, and the lower layer is filled with the Jixian system karst water. The upper layer of karst water supplies to the lower layer of karst water or the pore water in loose strata through the fault while the lower layer of karst water runs to the three strong runoff belts from the east and west sides of the watershed, southwards into the basin, partially replenishing the pore water in loose strata, or forming fault Springs(e.g. Nanguan Spring, Beihai Spring) when dolomite movement encounters faults. Replenished by atmospheric precipitation and the upper and lower layers of karst waters, the pore water in loose strata joins the groundwater in the southern basin and then flows eastwards, in the end it flows out of the system in Shangfanpu. Through the analyses of groundwater level data and hydrogeological drilling data, based on groundwater D and ^(18) O isotope test results, the karst groundwater circulation system in the northern basin of Laiyuan Spring area is further verified, which provides hydrogeological basis for water resources development and utilization as well as protection in this area.

Quantification of groundwater recharge and evapotranspiration along a semi-arid wetland transect using diurnal water table fluctuations

Groundwater is a vital water resource in arid and semi-arid areas.Diurnal groundwater table fluctuations are widely used to quantify rainfall recharge and groundwater evapotranspiration(ET_(g)).To assess groundwater resources for sustainable use,we estimated groundwater recharge and ET_(g) using the diurnal water table fluctuations at three sites along a section with different depths to water table(DWT)within a wetland of the Mukai Lake in the Ordos Plateau,Northwest China.The water table level was monitored at an hourly resolution using a Keller DCX-22 A data logger that measured both the total pressure and barometric pressure,so that the effect of barometric pressure could be removed.At this study site,a rapid water table response to rainfall was observed in two shallow wells(i.e.,Obs1 and Obs2),at which diurnal water table fluctuations were also observed over the study period during rainless days,indicating that the main factors influencing water table variation are rainfall and ET_(g).However,at the deep-water table site(Obs3),the groundwater level only reacted to the heaviest rainfalls and showed no diurnal variations.Groundwater recharge and ET_(g) were quantified for the entire hydrological year(June 2017–June 2018)using the water table fluctuation method and the Loheide method,respectively,with depth-dependent specific yields.The results show that the total annual groundwater recharge was approximately 207 mm,accounting for 52%of rainfall at Obs1,while groundwater recharge was approximately 250 and 21 mm at Obs2 and Obs3,accounting for 63%and 5%of rainfall,respectively.In addition,the rates of groundwater recharge were mainly determined by rainfall intensity and DWT.The daily mean ET_(g) at Obs1 and Obs2 over the study period was 4.3 and 2.5 mm,respectively,and the main determining factors were DWT and net radiation.

Spatial and temporal variation of groundwater recharge in shallow aquifer in the Thepkasattri of Phuket,Thailand

Whether groundwater resources can be sustainably utilized is largely determined and characterized by hydrogeological parameters.Estimating the groundwater recharge is one of the essential parameters for managing water resources and protecting water resources from contamination.This study researched the spatial and temporal variation of groundwater recharge in the Thepkasattri sub-district through integrating chloride mass balance(CMB)and water table fluctuation(WTF)methods.The chloride content of representative rainfall and groundwater samples was analyzed.Besides,WTF method was adopted from groundwater level data from 2012 to 2015.According to the CMB method,the mean recharge was estimated to be 1172 mm per year,accounting for 47%of the annual rainfall.Moreover,the estimated recharge from the WTF method took 26%of annual rainfall in 2015.The recharge was underestimated according to the WTF method,because of the uncertainty in specific yield estimates and the number of representative wells in the study area.Moreover,the correlation between rainfall and water table fluctuation data indicated the positive linear relationship between two parameters.The spatial recharge prediction indicated that recharge was higher(1200-1400 mm/yr)in the eastern and western catchment,while that in the central floodplains was between 800 mm/yr and 1100 mm/yr.In addition,low recharge value between 450 mm/yr and 800 mm/yr was observed in the south-west part of Thepkasattri.The spatial variation of recharge partly reflects the influences of land use and land cover of the study area.

Groundwater recharge site suitability analysis through multiinfluencing factors(MIF)in West Bengal dry-land areas,West Bengal,India

Groundwater levels are gradually declining in basins around the world due to anthropogenic and natural factors.Climate is not the only factor contributing to change in groundwater levels,population growth and economic progress are leading to increased water demand.Areas used for agricultural irrigation are expanding,necessitating the use of artificial groundwater recharge as a method to sustain pumping and enhance storage.The present study delineates potential locations of significant groundwater resources that already exist using a geostatistical approach as a method to identify potential groundwater recharge zones.The Multi-Influencing Factors(MIF)technique was applied to determine the relationship between different landscape and climatic factors that influence groundwater recharge.Factors include topography,climate,hydrogeology,population,economic change,and geology.Integration of these factors enabled the identification of potential locations of groundwater suitable for artificial recharge efforts based on weights derived through the MIF technique.We applied these weights to derive a groundwater recharge index(GRI)map.The map was delineated into three groundwater recharge zones classified by their potential areal coverage as a metric for recharge suitability,namely low,medium and high suitability,occupying areas of 8625 km2(30.06%),9082 km2(31.65%),and 10,989 km~2(38.29%),respectively.Our findings have important implications for designing sustainable groundwater development and land-use plans for the coming century.

The Source of Groundwater Recharge Based on Entropy Theory in the Arid Areas of North China

Objective Any natural system is constantly exchanging material, energy and information with the environment, and all tkese processes follow the basic law of thermodynamics, with no exception of groundwater recharge and discharge process. On the basis of the principle of the first law of thermodynamics, the reverse geochemical simulation method is widely used in the study of groundwater recharge, runoff and drainage process. However, some studies only consider the material conservation in theprocess, but ignore the probability of the transformation.