Impact of climate change and human activities on the spatiotemporal dynamics of surface water area in Gansu Province, China

Understanding the dynamics of surface water area and their drivers is crucial for human survival and ecosystem stability in inland arid and semi-arid areas.This study took Gansu Province,China,a typical area with complex terrain and variable climate,as the research subject.Based on Google Earth Engine,we used Landsat data and the Open-surface Water Detection Method with Enhanced Impurity Control method to monitor the spatiotemporal dynamics of surface water area in Gansu Province from 1985 to 2022,and quantitatively analyzed the main causes of regional differences in surface water area.The findings revealed that surface water area in Gansu Province expanded by 406.88 km2 from 1985 to 2022.Seasonal surface water area exhibited significant fluctuations,while permanent surface water area showed a steady increase.Notably,terrestrial water storage exhibited a trend of first decreasing and then increasing,correlated with the dynamics of surface water area.Climate change and human activities jointly affected surface hydrological processes,with the impact of climate change being slightly higher than that of human activities.Spatially,climate change affected the'source'of surface water to a greater extent,while human activities tended to affect the'destination'of surface water.Challenges of surface water resources faced by inland arid and semi-arid areas like Gansu Province are multifaceted.Therefore,we summarized the surface hydrology patterns typical in inland arid and semi-arid areas and tailored surface water'supply-demand'balance strategies.The study not only sheds light on the dynamics of surface water area in Gansu Province,but also offers valuable insights for ecological protection and surface water resource management in inland arid and semi-arid areas facing water scarcity.

Impacts of Comorbidity and Mental Shock on Organic Micropollutants in Surface Water During and After the First Wave of COVID-19 Pandemic in Wuhan (2019–2021), China

The first pandemic wave of coronavirus disease 2019(COVID-19)induced a considerable increase in several antivirals and antibiotics in surface water.The common symptoms of COVID-19 are viral and bacterial infections,while comorbidities(e.g.,hypertension and diabetes)and mental shock(e.g.,insomnia and anxiety)are nonnegligible.Nevertheless,little is known about the long-term impacts of comorbidities and mental shock on organic micropollutants(OMPs)in surface waters.Herein,we monitored 114 OMPs in surface water and wastewater treatment plants(WWTPs)in Wuhan,China,between 2019 and 2021.The pandemic-induced OMP pollution in surface water was confirmed by significant increases in 26 OMP concentrations.Significant increases in four antihypertensives and one diabetic drug suggest that the treatment of comorbidities may induce OMP pollution.Notably,cotinine(a metabolite of nicotine)increased 155 times to 187 ngL1,which might be associated with increased smoking.Additionally,the increases in zolpidem and sulpiride might be the result of worsened insomnia and depression.Hence,it is reasonable to note that mental-health protecting drugs/behavior also contributed to OMP pollution.Among the observed OMPs,telmisartan,lopinavir,and ritonavir were associated with significantly higher ecological risks because of their limited WWTP-removal rate and high ecotoxicity.This study provides new insights into the effects of comorbidities and mental shock on OMPs in surface water during a pandemic and highlights the need to monitor the fate of related pharmaceuticals in the aquatic environment and to improve their removal efficiencies in WWTPs。

Monitoring Surface Water Change in Northeast China in 1999–2020:Evidence from Satellite Observation and Refined Classification

As a typical region with high water demand for agricultural production,understanding the spatiotemporal surface water changes in Northeast China is critical for water resources management and sustainable development.However,the long-term variation characteristics of surface water of different water body types in Northeast China remain rarely explored.This study investigated how surface water bodies of different types(e.g.,lake,reservoir,river,coastal aquaculture,marsh wetland,ephemeral water) changed during1999–2020 in Northeast China based on various remote sensing-based datasets.The results showed that surface water in Northeast China grew dramatically in the past two decades,with an equivalent area increasing from 24 394 km^(2) in 1999 to 34 595 km^(2) in 2020.The surge of ephemeral water is the primary driver of surface water expansion,which could ascribe to shifted precipitation pattern.Marsh wetlands,rivers,and reservoirs experienced a similar trend,with an approximate 20% increase at the interdecadal scale.By contrast,coastal aquacultures and natural lakes remain relatively stable.This study is expected to provide a more comprehensive investigation of the surface water variability in Northeast China and has important practical significance for the scientific management of different types of surface water.

Unveiling three-dimensional sea surface signatures caused by internal solitary waves:insights from the surface water ocean topography mission

Internal solitary waves(ISW),characterized by large amplitude and long propagation distance,are widespread in global oceans.While remote sensing images have played an essential role in studying ISWs,they mainly exploit two-dimensional image information.However,with the launch of the surface water ocean topography(SWOT)satellite on December 16,2022,a unique opportunity has emerged to capture wide-swath three-dimensional ISW-induced sea surface information.In this study,we examine ISWs in the Andaman Sea using data from the Ka-band Radar Interferometer(KaRIN),a crucial sensor onboard SWOT.KaRIN not only provides backscattering satellite images but also employs synthetic aperture interferometry techniques to retrieve wide-swath two-dimensional sea surface height measurements.Our observations in the Andaman Sea revealed the presence of ISWs characterized by dark-bright strips and surface elevation solitons.The surface soliton has an amplitude of 0.32 m,resulting in an estimation of ISW amplitude of approximately 60 m.In contrast to traditional two-dimensional satellite images or nadir-looking altimetry data,the SWOT mission’s capability to capture threedimensional sea surface information represents a significant advancement.This breakthrough holds substantial promise for ISW studies,particularly in the context of ISW amplitude inversion.

Isotope Tracking of Surface Water Groundwater Interaction in the Beninese Part of the Iullemeden Aquifer System

The Kandi basin is located in northeast Benin (West Africa). This study is focused on the estimation of water fluxes exchanged between the river Niger (and its tributaries) and the transboundary Iullemeden Aquifer System. In that framework, an innovative approach based on the application of the Bayesian Mixing Model (MixSIAR) analysis on water isotopes (oxygen-18, deuterium and tritium) was performed. Moreover, to assess the relevance of the model outputs, Pearson’s correlation and Principal Component Analysis (PCA) have been done. A complex relationship between surface water and groundwater has been found. Sixty percent (60%) of groundwater samples are made of more than 70% river water and rainwater;while 31.25% of surface water samples are made of about 84% groundwater. To safeguard sustainable water resources for the well-being of the local communities, surface water and groundwater must be managed as a unique component in the Kandi basin.

Surface Water Quality Profiling Using Physicochemical Parameters in Open Defecation Free and Non-Open Defecation Free Local Government Areas in Benue State, Nigeria

Physicochemical parameters of surface water sources in the study of local government areas (LGAs) were assessed using standard procedures. The mean physicochemical parameters for pH (5.49), NO2 (0.23 mg/L), SO4 (0.77 mg/L), Na (28.72 mg/L), Ca (28.94 mg/L), Mg (17.50 mg/L), Cl (11.65 mg/L), TSS (6.27 mg/L), TDS (104.23 mg/L), BOD (2.83 mg/L) and F (0.87 mg/L) were below WHO standards irrespective of their defecation status. The values for electrical conductivity (EC) (2770.50 µs/cm, turbidity (481.24 NTU), dissolved oxygen (DO) (5.32 mg/L), chemical oxygen demand (COD) (445.50 mg/L), K (125.06 mg/L), PO4 (0.78 mg/L) and Fe (0.57 mg/L) were above the WHO limits for safe water. Higher EC and COD values obtained in the study is evidence of pollution of the water sources by organic matter.

Agricultural Contamination of the Surface Waters of the Upper Ouémé in Benin: The Case of Heavy Metals and Pesticides

Objective: The main objective of this study was to assess the degree of contamination of surface waters by heavy metals and pesticides. Method: To this end, data were collected in December 2022 from four specific sampling stations: Okpara, Térou, Affon and Adjiro. Levels of heavy metals, including cadmium, chromium, copper, iron, mercury, nickel and lead, were measured and subjected to in-depth statistical analysis using graphical summation models. In addition, the concentrations of pesticide active ingredients present in the samples were interpreted and evaluated. The statistical data collected during this study were processed using R software, version 3.5.0. Results: The values obtained at the different stations Okpara, Térou, Affon and Adjiro are respectively Arsenic (2 × 10-4 mg/L;2.2 × 10-1 mg/L;1.2 × 10-4 mg/L;2 × 10-4 mg/L), Cadmium (4.4 × 10-5 mg/L;1.1 × 10-2 mg/L;10-4 mg/L;4 × 10-4 mg/L). Then Copper (7 × 10-4 mg/L;3 × 10-3 mg/L;7 × 10-4 mg/L;1 × 10-4 mg/L), Iron (1.51 mg/L;6.4 × 10-1 mg/L;2.0012 mg/L;2.9 × 10-1 mg/L), Lead (0 mg/L;0 mg/L;1.5 × 10-3 mg/L;1.5 × 10-3 mg/L). Mercury, nickel and chromium were not detected in surface waters. It is important to note that the values obtained for trace metals (Cadmium, Chromium, Copper, Iron, Mercury, nickel and chromium were not detected in surface waters. It is important to note that the values obtained for trace metals (cadmium, chromium, copper, iron, mercury, nickel and lead) were all below the guideline standards set by the WHO in 2006 for uncontaminated surface waters. This indicates that the surface waters of the Upper Ouémé were below acceptable contamination thresholds in terms of heavy metals. However, the presence of pesticide active ingredients such as cyfluthrin, endosulfan-alpha, endosulfan-beta, profenosfos, tihan, atrazine, gala super and glycel clearly indicates that these surface waters are subject to agricultural contamination.

Estimation of surface water content at the Tianwen-1 Zhurong landing site

China’s first Mars rover,Zhurong,successfully landed in the south of Utopia Planitia.The surface water content at the landing area can provide constraints on mineral formation conditions and help us better understand the evolution of the Martian aqueous and geological environment.In this work,the surface kinetic temperature of the Zhurong landing area was derived by analyzing data from the Mars Express Observatoire pour la Minéralogie,l’Eau,les Glaces et l’Activité(OMEGA)spectrometer.Using the Discrete Ordinate Radiative Transfer(DISORT)model,we performed atmospheric correction and thermal correction for the OMEGA data to obtain the surface effective single-particle absorption thickness(ESPAT)parameter to evaluate the surface water content.The surface water content distribution at the landing area was relatively uniform at a lateral scale of~10 km.At the Zhurong landing site,the surface water content in the topmost layer(a few hundred micrometers)of the regolith was 5−8 weight percent water(wt%H_(2)O),assuming surface particle sizes of<45μm,or 1.6−2.5 wt%H_(2)O,assuming surface particle sizes in the range of 125−250μm.The Mars Surface Composition Detector(MarSCoDe)onboard Zhurong also observed significant H_(2)O/OH signals in the landing area.Our results provide an important regional context for the hydration state of the area and can be further verified by the H content derived from the Laser-Induced Breakdown Spectrometer(LIBS)data of MarSCoDe.

Current Situation and Countermeasures of Antibiotic Pollu-tion in the Surface Water of the Yangtze River Basin in a Province of Central China

Antibiotics are widely used in the process of human medical treatment,livestock and poultry breeding,and aquaculture.With the excretion of urine and feces,they enter the water environment of human life and become an important source of water environment pollution.Antibiotic residues in the environment have high ecological and health risks.Through the pilot monitoring of antibiotics in the main stream of the Yangtze River,Chaohu Lake and the drinking water source of Hefei City,the current situation and impact of antibiotic pollution were analyzed.The results show that 32 kinds of antibiotics and their derivatives of the six major categories involved were detected to varying degrees,and the concentrations at some points reached 1.26μg/L.Finally,the prevention and control of antibiotic pollution in the surface water of the Yangtze River basin in a province of central China were summarized,and relevant suggestions were given.

Spatio-temporal variation of trace elements distributed over surface water of Upper Ganga River Basin in Western Himalayan Region

The rivers draining from the Himalayan range distribute enormous amount of fresh water to the people living in downstream regions.Trace metals flowed with river water can lead to serious impact on ecological system and human health.Nevertheless,the documentation on trace elements of Himalayan rivers is inadequately documented.The current study deals with the spatial and temporal variability of the major and trace elements of Ganga river water in epirhithron,metarhithron and hyporhithron zone belonging to Himalayan segment.Water samples from nineteen monitoring locations were collected in pre-monsoon(May-June),monsoon(AugustSeptember)and post-monsoon(December)seasons and subjected to be assessed for 20 elements(Ag,Al,Ba,Cd,Ca,Cr,Cu,Fe,Ga,K,Mn,Mg,Na,Ni,Pb,Sr,Th,U,Zn,and Zr)using ICP-OES(Inductively Coupled Plasma-Optical Emission Spectrometer).Different water pollution indexes such as HPI(Heavy Metal Pollution Index),MI(Metal Index)and PI(Pollution Index)were used to describe current water quality status at each monitoring station under particular classified ecological zone.The studied stations in hyporhithron zone had the value of Metal Index(MI>1),indicating threshold of warning.Further,the highest values of HPI in hyporhithron zone correspond to poor water quality status.Sites with poor water quality were also found to be contaminated as per the Pollution Index(PI),exhibiting high concentrations for element(Fe).However,the epirhithron and metarhithron zone in Himalayan segment showed excellent water quality mainly contributed from natural sources.Cluster Analysis(CA)and Principal Component Analysis(PCA)were applied to identify the main influential sources for Ganga river water pollution.The Kriging interpolation method was also applied to prepare spatial distribution map of computed indexes(HPI,MI,and PI).With the help of index of local Moran’s I(LMI),identified spatial clusters and spatial outliers revealed the elevated concentration of most elements in hyporhithron zone.The dataset presented in this study would be convenient for government officials in developing more effective management policies and necessary steps to check and monitor the Ganga river water quality.It was also suggested that further investigations in terms of trace elemental sources and their role in self-purification properties of Ganga water can be addressed in future.

Linking bacterial and archaeal community dynamics to related hydrological,geochemical and environmental characteristics between surface water and groundwater in a karstic estuary

Subterranean estuaries(STEs)are characterized by the mixing of terrestrial fresh groundwater and seawater in coastal aquifers.Although microorganisms are important components of coastal groundwater ecosystems and play critical roles in biogeochemical transformations in STEs,limited information is available about how their community dynamics interact with hydrological,geochemical and environmental characteristics in STEs.Here,we studied bacterial and archaeal diversities and distributions with 16S rRNA-based Illumina MiSeq sequencing technology between surface water and groundwater in a karstic STE.Principal-coordinate analysis found that the bacterial and archaeal communities in the areas where algal blooms occurred were significantly separated from those in other stations without algal bloom occurrence.Canonical correspondence analysis showed that nutrients and salinity can explain the patterns of bacterial and archaeal community dynamics.The results suggest that hydrological,geochemical and environmental characteristics between surface water and groundwater likely control the bacterial and archaeal diversities and distributions in STEs.Furthermore,we found that some key species can utilize terrestrial pollutants such as nitrate and ammonia in STEs,indicating that these species(e.g.,Nitrosopumilus maritimus,Limnohabitans parvus and Simplicispira limi)may be excellent candidates for in situ degradation/remediation of coastal groundwater contaminations concerned with the nitrate and ammonia.Overall,this study reveals the coupling relationship between the microbial communities and hydrochemical environments in STEs,and provides a perspective of in situ degradation/remediation for coastal groundwater quality management.

Trace Metal Levels of Groundwater,Surface Water and Sediments in Kinsevere Industrial Zone and Its Surroundings,Southeastern Democratic Republic of Congo

Arsenic,barium,bismuth,cadmium,cesium,chromium,cobalt,copper,iron,lead,manganese,molybdenum,nickel,strontium,thallium,tungsten,uranium,vanadium,and zinc concentrations were investigated in forty-two groundwater samples,twenty-four surface water and six surface sediment samples in Kinsevere industrial zone and its surroundings in February and march 2017,January,February and March 2018 to evaluate the potential human health risk.Chemical analyses were carried out by using ICP-SF-MS(Inductively Coupled Plasma-Sector Field Mass Spectrometry,Thermo Scientific Element II).The trace metals were detected at various concentrations in all the analyzed samples.Pb,Mn and Fe concentrations exceeded the European Union acceptable maximum limits for water intended for human consumption in 4.76%,28.57%and 61.90%of the groundwater samples,respectively and in 0%,50%and 100%of the surface water samples,respectively.As,Cr,Cu and Ni concentrations exceeded the recommended lower sediment quality guideline values in 33.33%,50%,83.33%and 83.33%of the surface sediment samples,respectively.All those elevated trace metal concentrations in the groundwater,surface water and sediments represent a risk for the health of local population as well as for aquatic organisms.

Level of Bacteriological and Physicochemical Pollution of Surface Waters in Rural Area: The Case of Mbankomo Municipality (Center Region, Cameroon)

A study aimed at evaluating the physicochemical and bacteriological quality of surface water was therefore carried out in a few watercourses in the municipality of Mbankomo, located in the Center Region (Cameroon). The physico-chemical parameters were measured according to the standard method. The organic pollution index (OPI) was determined from the contents of nitrates, phosphates, and ammoniacal nitrogen to characterize the level of organic pollution of the water. The microorganisms sought were total flora, indicators of faecal contamination like total coliforms, faecal coliforms, feacal streptococci and Escherichia coli, as well as the species Clostridium perfringens. The organic pollution index indicates a high-level organic pollution level during the small rainy season and high to moderate during the small dry season. High concentrations of the total and fecal coliforms, streptococci fecal, Escherichia coli and Clostridium perfringens respectively of 1712 × 105 CFU/100mL;82 × 105 CFU/100mL;10 × 105 CFU/100mL;27 × 105 and 40 × 103 CFU/100mL, all higher than WHO standards, indicate that the waterways of Mbankomo are subject to feacal pollution and harbor pathogenic microflora. The cell densities of main bacteria were significantly correlated with main abiotic parameters, such as Escherichia coli, which was significantly correlated with the pH of the water (r = 0.35;p < 0.05). The variation of organic pollution index category means correspond to a high level of organic pollution during the small rainy season and a high to moderate level during the small dry season. The deterioration of the quality of these waters is favored by their proximity to sources of pollution (toilets, plantation), the runoff of the waters contaminated, the use of detergents and wrong maintenance. These waters without any treatment are not recommendable for human consumption according to standards of the World Health Organization.

Hydrogeological Investigations of Groundwater and Surface Water Interactions in the Berg River Catchment, Western Cape, South Africa

The Berg River Catchment based in the Western Cape Province,South Africa services the greater Cape Town area with water,subsequent to supplying the vast agricultural activities that exist in the middle and the lower reaches.This study thus investigates the hydrogeochemical interactions between surface and groundwater in the Berg River Catchment with the aim of establishing trends and transfer of constituents between the surface and groundwater systems,investigates the role that geology plays in water chemistry as well as identifies the geochemical processes controlling surface and groundwater chemistry in the catchment.This study was carried out using three types of research designs namely i)experimental research design;ii)field research design and meta-analysis research design.Furthermore,the study made use of hydrochemical data ranging from 2003 to 2013 obtained from the National Water Monitoring Database owned and maintained by the Department of Water and Sanitation and data that were sampled in 2016 by authors and analyzed using the ICP-MS Technique Ground Water Chart,Arc-GIS and Geosoft(Oasis Montaj)were further employed to model the data.The results indicated that:i)in the Upper Berg there is not much interaction and transfer of constituents between surface and groundwater;ii)the Middle Berg,however,indicated a degree of interaction with the sharing of constituents between the two water systems and iii)the Lower Berg indicated only NaCl water type also noting that the area situated near the river mouth whereby there is the mixing of river and seawater.

Assessment of Nitrogen Pollutant Sources in Surface Waters of Taihu Lake Region

The nitrogen （N） pollution status of the 12 most important rivers in Changshu, Taihu Lake region was investigated. Water samples were collected from depths of 0.5-1.0 m with the aid of the global positioning system （GPS）. The seasonal variations in the concentrations of different N components in the rivers were measured. Using tension-free monolith lysimeters and ^15N-labeled fertilizer, field experiments were carried out in this region to determine variations of iSN abundance of NO3^- in the leachate during the rice and wheat growing seasons, respectively. Results showed that the main source of N pollution of surface waters in the Taihu Lake region was not the N fertilizer applied in the farmland but the urban domestic sewage and rural human and animal excreta directly discharged into the water bodies without treatment. Atmospheric dry and wet N deposition was another evident source of N pollutant of the surface waters. In conclusion, it would not be correct to attribute the N applied to farmlands as the source of N pollution of the surface waters in this region.

Impact of climate change on the surface water of Kaidu River Basin

To reveal the changing trend and annual distribution of the surface water hydrology and the local climate in the Bayanbuluk alpine-cold wetlands in the past 50 years, we used temperature, precipitation, different rank precipitation days, evaporation, water vapor pressure, relative humidity, dust storm days and snow depth to analyze their temporal variations. We conclude that there were no distinct changes in annual mean temperature, and no obvious changes in the maximum or minimum temperatures. Precipitation in warm season was the main water source in the wetlands of the study area and accounted for 92.0% of the annual total. Precipitation dropped to the lowest in the mid-1980s in the past 50 years and then increased gradually. The runoff of the Kaidu River has increased since 1987 which has a good linear response to the annual precipitation and mean temperature in Bayanbuluk alpine-cold wetland. Climate change also affected ecosystems in this area due to its direct relations to the surface water environment.

Evaluation of spatial-temporal dynamics in surface water temperature of Qinghai Lake from 2001 to 2010 by using MODIS data

Lake surface water temperature （SWT） is an important indicator of lake state relative to its water chemistry and aquatic ecosystem,in addition to being an important regional climate indicator.However,few literatures involving spatial-temporal changes of lake SWT in the Qinghai-Tibet Plateau,including Qinghai Lake,are available.Our objective is to study the spatial-temporal changes in SWT of Qinghai Lake from 2001 to 2010,using Moderate-resolution Imaging Spectroradiometer （MODIS） data.Based on each pixel,we calculated the temporal SWT variations and long-term trends,compared the spatial patterns of annual average SWT in different years,and mapped and analyzed the seasonal cycles of the spatial patterns of SWT.The results revealed that the differences between the average daily SWT and air temperature during the temperature decreasing phase were relatively larger than those during the temperature increasing phase.The increasing rate of the annual average SWT during the study period was about 0.01℃/a,followed by an increasing rate of about 0.05℃/a in annual average air temperature.The annual average SWT from 2001 to 2010 showed similar spatial patterns,while the SWT spatial changes from January to December demonstrated an interesting seasonal reversion pattern.The high-temperature area transformed stepwise from the south to the north regions and then back to the south region from January to December,whereas the low-temperature area demonstrated a reversed annual cyclical trace.The spatial-temporal patterns of SWTs were shaped by the topography of the lake basin and the distribution of drainages.

Surface Water Pollution in the Yangtze River Delta:Patterns and Countermeasures

On the basis of field investigations, observations andexperimental data combined with environmental monitoring information,the status and the spatial and temporal patterns of surface waterpollution over the past ten years in the Yangtze River Delta havebeen assessed. The water quality of large rivers is still very goodbut most of the medium-sized and small rivers have been veryseriously polluted. The appearance of black and odorous conditions inrivers in the urban areas has increased due to serious pollution byorganic matter with consequent high oxygen demand. Annual increasesin N and P concentrations in lakes have accelerated eutrophication.The water quality of river sin small towns is rapidly deteriorating.The main sources of surface water pollution include industrial anddomestic sewage, animal manures, chemical fertilizers in farmland,and polluted sediments in rivers and lakes.

Concentration level and geographical distribution of nitrobenzene in Chinese surface waters

Nitrobenzene was reported to occur at relatively high concentrations in some Chinese surface water and to cause an environmental pollution event in 2005.To map the distribution of nitrobenzene in the Chinese surface water throughout China,surface water samples were collected from over 600 sites in the 7 major watersheds and three drainage areas.The samples were analyzed for concentration of nitrobenzene.Overall,nitrobenzene was more frequently detected at higher concentrations in the rivers of North China,i...

Impact of transferred water on the hydrochemistry and water quality of surface water and groundwater in Baiyangdian Lake,North China

The hydrochemical composition of surface water and groundwater is a key parameter for understanding the evolution of water and its quality.In particular,little is known about the impact of transferred water on surface water and groundwater.In this study,Baiyangdian Lake was selected as a typical area for extensive groundwater exploration and surface water transfer in the North China Plain.Surface water and groundwater samples were sampled in dry/wet seasons and then analyzed before/after the water transfer,respectively.Generally,surface water and groundwater are extensively hydrologically connected based on hydrochemical evidence.It was found that the hydrochemical composition of the shallow groundwater is affected by the surface water and that the water quality of the deep groundwater is stable.However,inter-aquifer recharge processes from the shallow groundwater to the deep groundwater existed in the anthropogenic region impacted with high nitrate-ion concentrations.Also,the hydrochemical composition of the surface water and groundwater was dominated by rock-weathering and evaporation-precipitation processes.Due to the existence of the deep vadose zone in the alluvial fan,Na^(+)was exchanged into soil matrices during the leakage of the surface water.In addition,the transferred water resulted in surface water with good quality,and it also played as an important recharge source to groundwater.As the most important water resource for irrigation and drinking,deep groundwater should be paid more attention in the alluvial fan with frequent water transfer and extensive groundwater exploration.