Decrease In Groundwater Level Research Articles

Comparison of the disturbance of soil physical quality indices between different underground mining stages in semi-arid regions of Western China

Based on soil sampling, lab experiment and support resistance monitoring, the disturbance of soil physical quality indices between different underground mining stages of No 52303 working face was studied in semi-arid region of western China. Soil sampling was conducted in same locations before and after mining in 2014. This study proved that soil water content, soil cohesion and soil porosity were greatly decreased, while bulk density and dry density were increased by coal mining. In comparison, coal mining had slight effect on organic matter, internal fraction angle, and D1 and D2 percent. Underground pressure monitoring showed that P1 during stage 2 was significantly greater than that during stage 1, indicating the large difference of pressure characteristics in tail areas of working face between two stages. Both soil water content and soil cohesion were decreased during two stages in two sites. Soil cohesion was strongly correlated to soil water content, and D1 and D2 percent in 2013 and 2014. Coal mining subsidence increased the cumulative probability to reach the same value of soil water content and soil cohesion. The cover depth produced different elastic and plastic zone widths between sites by theoretical model calculation, consistent with the support resistances in tail areas of working face. Higher pressure might cause a more serious destructive rock-soil body and a larger groundwater level decrease. The dryer and more serious erosive soil column induced by coal mining is a non negligible matter for the semi-arid region.

Analysis of Groundwater Flow on Hydrogeological for Sustainable Development and Environment in the Ternate Basin, North Maluku Province, Indonesia

The sustainability of water and sanitation management is an important point in the 2021 SDGs program. To support the program, it is important to understand Indonesia's water cycle. Given the variety of characters, topography, and geology between islands in Indonesia can distinguish hydrogeological systems and their interactions with the surrounding environment. The design and management of water resources, especially groundwater, has an important role, considering the basin area is 106 km2, the character of a volcanic island with the name of an active volcano. Topography from 0-8% is a built-up zone, 8-14% is a cultivation zone, 14-45% is a protected forest, and >45% is a stratovolcano peak zone. Island morphology affects groundwater flow patterns. This study aimed to determine the characteristics of groundwater flow in the Ternate basin. Purposive sampling of 56 production wells, transmissivity value, conductivity, aquifer thickness, and topography was analyzed using the Cubic spline interpolation method. The results showed that the direction of flow and groundwater accumulation based on groundwater modeling using the kriging interpolation technique resulted in the interaction of groundwater flow and depression cones in 56 production wells due to the concentration and massive groundwater abstraction in the Ternate Basin. The decrease in groundwater level is fluctuating, from groundwater flows that occur radially-centrifugally, the total reserves of 56 production wells are 46 million m3/day, the average transmissivity value is 2.17 m2/day, production discharge is 51,710 m3/day.

Artificial Groundwater Recharge Zones Mapping using Remote Sensing and GIS for Sub-Watersheds of Krishna Basin

The exacerbated exploitation of groundwater resources has led to an alarming decrease in groundwater levels. It is necessary to identify areas that allow for efficient recharge so that implementation of artificial groundwater recharge can be conducted in such areas with better efficiency. This study maps zones with their varying degrees of affinity for groundwater recharge in two of the sub-watersheds of the Krishna Basin.The factors affecting the potential of groundwater recharge were determined and then thematic maps for each factor were generated in ArcGIS 10.8. Remote sensing data from sources like ‘Bhuvan’ and ‘Bhukosh’ were used for the generation of the thematic layers. The Analytic Hierarchy Process (AHP) was used while deciding the relative and subsequently overall importance of each layer. The weights derived from the AHP were applied to the thematic layers and the mapping of zones for artificial groundwater recharge was done.

Effects of groundwater level decline to soil and vegetation in arid grassland: a case study of Hulunbuir open pit coal mine.

Coal mine in arid and semi-arid area is one of the most severely degraded ecosystems on the earth. The continuous decrease in groundwater level caused by coal mining will inevitably affect biogeochemical environment of the vadose zone, and then lead to the replacement of surface vegetation. Yimin open-pit coal mine was taken as an example to reveal the relationship between the groundwater depth and soil water content (SWC), soil salt content, soil electrical conductivity (SEC), soil organic matter (SOM), soil available potassium (SAK), soil available nitrogen (SAN), vegetation coverage, aboveground biomass and species richness. The results show that, the change of groundwater depth can affect soil properties and then change the characteristics of surface vegetation, and the change of surface vegetation can also react on soil properties. Vegetation coverage and aboveground biomass are negatively correlated with groundwater depth, and positively correlated with SWC, SEC, SOM and SAK. The shallow groundwater table is conducive to the accumulation of SOM, so that the surface biomass and vegetation coverage are high. The higher the surface biomass, the more the SAN is absorbed. Under natural conditions, the relative strength of biological nitrogen fixation and plant absorption determine the content of SAN. In the research area, when the depth of groundwater is less than 0.4m will cause soil salinization, then lead to low species richness; Species richness is exponentially correlated with groundwater depth and decreases with the increase in groundwater depth.

Radial increment and defoliation of Pinus sylvestris (L.) on sandy soils relate to summer temperatures and ground water level

Abstract The study deals with the analysis of the impact of climate and ground water table level on radial increment and defoliation of Scots pine (Pinus sylvestris L.) growing on sandy soils. The research was performed in the area of the Borska nížina (i.e. Borská Lowland, situated in southwest of Slovakia), where a substantial die-back of pine trees has been observed in the last decade. Increment measurements and defoliation assessment were performed at 150 adult trees of Scots pine growing at three permanent monitoring plots within the international network of ICP Forests during the years 1989–2018. We examined the impact of climatic and hydrological factors on selected features of pine using the methods of correlation analysis and linear mixed models. Statistical analyses confirmed that the annual radial increment of Scots pine significantly depended on the mean air temperature from June to August, and mean ground water level in the mentioned months. These two factors also significantly correlated with crown defoliation. The factors explained 26% and 32% of increment and defoliation variability, respectively. From the long-term perspective, our analyses indicated that the decrease of ground water level by 0.5 m in summer resulted in the increase of defoliation by 10%. The obtained results indicate a further increase of Scots pine die-back on easy-to-dry sandy soils in regions with low precipitation totals, particularly considering the ongoing climate change and its inherent factors.

Aquatic Weeds Diversity in India and its Management by Composting: A Review

According to UNDP, about 70% of the global natural wetlands have been lost during the last decade. The continual decrease in the amount of fresh water available to humans for use is a cause of major concern today. In India also, diminishing freshwater bodies, decreasing ground water levels, increasing anthropogenic activities and pollution are posing challenges to the management of water bodies. In recent years, lot of research and efforts have been made worldwide to reclaim the depleting water resources. Continuous and increasing infestation of water bodies with aquatic weeds is one of the leading causes of its deterioration and vanishing. Within this context the present review was undertaken with the aim to understand the diversity of the aquatic weeds in India and composting as a management option to control the growth of the aquatic weeds.

Impact of Temperature Changes on Groundwater Levels in Nzoia River Basin, Kenya

Climate change poses uncertainties to the supply and management of water resources under the observed increase in surface temperatures all over Africa. The aim of this study is to assess the impact of temperature changes on groundwater levels in Nzoia River Basin. Temperature and groundwater level variability and trends has been analyzed using the parametric test of Linear regression and the non-parametric Mann-Kendall statistical test. Temperature data was obtained from the Kenya meteorological department (KMD) whereas groundwater level data was collected from Water resources management agency (WRMA). Linear regression of the annual groundwater levels in Nzoia River Basin between 2011 and 2017 revealed a decreasing trend ranging from -0.49 ft/year (Kitale Golf Club) to -0.03 ft/year (Kakamega Tande School). Mann-Kendall statistical test also showed decreasing groundwater levels for all observation wells with the results for Kitale Golf Club and Mois Bridge Quarry observation wells being statistically significant, whereas those for Kapsabet Boys High School, Kakamega Mwikalikha School, Kakamega Tande School and Busia Town Prison were statistically insignificant at 5% significance level. The highest decline in groundwater levels was observed in the upper catchment of the basin.There are significant increases in annual tempratures for Kitale and Kakamega stations in the period 1979 - 2014. Kitale showed annual maximum temprature rising at 0.0006260C/year; annual minimum temperature rising at 0.0011630C/year and the annual mean temprature rising at 0.0008940C/year. Kakamega had annual maximum temprature rising at 0.0007710C/year; annual minimum tempratures rising at 0.0004710C/year and the annual mean tempratures rising at 0.0006230C/year. Eldoret showed falling maximum temprature at - 0.002020C/year; rising minimum temperature at 0.0008130C/year and falling mean temperatures at - 0.001420C/year. The results for Kitale and Eldoret stations showed statistically significant trends whereas those for Kakamega station had a statistically insignificant trend. In Nzoia River Basin, Kitale and Eldoret, annual minimum tempratures are rising faster than the maximum whereas in Kakamega it’s the annual maximum tempratures that are rising faster than the minimum. Kitale and Kakamega stations showed rising annual mean temperatures whereas Eldoret showed falling annual mean tempratures. As one would expect, temperatures in Nzoia River Basin are expected to be rising; however, the case of falling temperatures recorded at Eldoret international airport might occur because this region of Rift valley has highly protected natural resources and a high forest cover is available all the year round. Another possible explanation to this could be the changing cloudness around Eldoret station. Kitale and Kakamega showed annual mean tempratures rising at about 0.10C per century and Eldoret showed mean temperatures falling at about -1.40C per century. The findings for Kitale and Kakamega stations compare well with IPCC Third Assessment Report estimated global warming rate of 0.60C during the twentieth century and other studies from the African continent and East African region.The decreasing trend in groundwater levels in the basin appears to be linked to climate change. Increases in temperature have an impact on the hydrologic cycle because they enhance evaporation of accessible surface water and vegetation transpiration. As a result, these changes have an impact on precipitation volumes, timings, and intensity rates, as well as indirect effects on water flux and storage in surface and subsurface reservoirs. While changes in important long-term climatic factors such as air temperature, precipitation, and evapotranspiration directly affect surface water supplies, the interaction between changing climate variables and groundwater is more intricate and little understood. For efficient and long-term groundwater resource management, understanding long-term temperature variability and trends, as well as the corresponding reaction of groundwater levels, is critical. Despite the fact that groundwater level records are only available for a short period of time, they include essential information that may be utilized to establish strategies for managing the basin's limited groundwater resources.

The impact of irrigation return flow on seasonal groundwater recharge in northwestern Bangladesh

Irrigation is vital in Bangladesh in order to meet the growing food demand as a result of the increasing population. During the dry season, groundwater irrigation is the main source of water for agriculture. However, excessive abstraction of groundwater for irrigation causes groundwater level depletion. At the same time, the loss from excessive irrigation could end up contributing to aquifer recharge as return flow. Therefore, investigating the influence of irrigation on groundwater is important for the sustainable management of this resource. This study aims to assess the impact of irrigation on groundwater recharge in the northwest Rajshahi district in Bangladesh. A semi-physically based water balance model was used to simulate spatially distributed groundwater recharge with two scenarios (with and without irrigation). To evaluate the effect of irrigation, groundwater recharges from these two scenarios were compared. The result showed that the use of groundwater for irrigation increased over the study period whereas, there was a persistent trend of decrease in groundwater level during the study period. Groundwater provides 91% of overall irrigation in the study area. However, on average, about 33% of the total irrigation becomes return flow and contributes to groundwater recharge in the dry season. Irrigation return flow is around 98% of the total recharge during the dry season in this region. The spatially distributed seasonal return flow varies from 305 to 401 mm. In brief, irrigation has a significant role in groundwater recharge in the study area during the dry season. Hence, proper irrigation water measurement and management are necessary for sustainable groundwater resource management in this region.

Opportunity or catastrophe? effect of sea salt on host-parasite survival and reproduction.

Seawater intrusion associated with decreasing groundwater levels and rising seawater levels may affect freshwater species and their parasites. While brackish water certainly impacts freshwater systems globally, its impact on disease transmission is largely unknown. This study examined the effect of artificial seawater on host-parasite interactions using a freshwater snail host, Biomphalaria alexandrina, and the human trematode parasite Schistosoma mansoni. To evaluate the impact of increasing salinity on disease transmission four variables were analyzed: snail survival, snail reproduction, infection prevalence, and the survival of the parasite infective stage (cercariae). We found a decrease in snail survival, snail egg mass production, and snail infection prevalence as salinity increases. However, cercarial survival peaked at an intermediate salinity value. Our results suggest that seawater intrusion into freshwaters has the potential to decrease schistosome transmission to humans.

Monitoring Oasis Cotton Fields Expansion in Arid Zones Using the Google Earth Engine: A Case Study in the Ogan-Kucha River Oasis, Xinjiang, China

Rapid and accurate mapping of the spatial distribution of cotton fields is helpful to ensure safe production of cotton fields and the rationalization of land-resource planning. As cotton is an important economic pillar in Xinjiang, accurate and efficient mapping of cotton fields helps the implementation of rural revitalization strategy in Xinjiang region. In this paper, based on the Google Earth Engine cloud computing platform, we use a random forest machine-learning algorithm to classify Landsat 5 and 8 and Sentinel 2 satellite images to obtain the spatial distribution characteristics of cotton fields in 2011, 2015 and 2020 in the Ogan-Kucha River oasis, Xinjiang. Unlike previous studies, the mulching process was considered when using cotton field phenology information as a classification feature. The results show that both Landsat 5, Landsat 8 and Sentinel 2 satellites can successfully classify cotton field information when the mulching process is considered, but Sentinel 2 satellite classification results have the best user accuracy of 0.947. Sentinel 2 images can distinguish some cotton fields from roads well because they have higher spatial resolution than Landsat 8. After the cotton fields were mulched, there was a significant increase in spectral reflectance in the visible, red-edge and near-infrared bands, and a decrease in the short-wave infrared band. The increase in the area of oasis cotton fields and the extensive use of mulched drip-irrigation water saving facilities may lead to a decrease in the groundwater level. Overall, the use of mulch as a phenological feature for classification mapping is a good indicator in cotton-growing areas covered by mulch, and mulch drip irrigation may lead to a decrease in groundwater levels in oases in arid areas.

What are the dynamics of hydrometeorological parameters on peatlands during the 2019 extreme dry season?

Peatlands in Indonesia are generally flammable, including peatlands in Kalimantan. The Indonesian government has made efforts to prevent fires on peatlands in Indonesia. One of them is by establishing several stations for measuring hydrometeorological parameters which are managed by the Peat Restoration Agency (BRG). This study utilizes BRG data, especially rainfall and groundwater levels, combined with hotspots data from MODIS satellite measurements during the 2019 extreme dry season at two research locations, namely at BRG stations in Central Kalimantan and West Kalimantan. The objectives of this research is to study the dynamics of these three parameters and find their relationship during the 2019 extreme dry season. To achieve the objectives of this study, an analysis of the time series graphs of these three parameters was carried out during the 2019 extreme dry season. It is hoped that the results of this research will help to prevent severe fires on peatlands, especially in Kalimantan. The results of this study indicate that during this period there was a decrease in rainfall, a decrease in groundwater level, and the emergence of a large number of hotspots. It can be concluded that the hotspots that appear are closely related to the low groundwater level due to low rainfall.

ESTIMATION OF POSSIBLE DIRECTION OF THE USE OF CUT-AWAY USYAZH PEATLAND (MINSK REGION)

Bogs play an important role in biosphere sustainability ensuring. During the development of a peatland for peat extract, significant changes occur in the bog ecosystem: a decrease in groundwater level, vegetation cover destruction, a decrease in peat deposit surface, animals migration, etc. These anthropogenic transformations lead to disruption of all biospheric functions inherent to a bog only in a natural state.
 As a result of the research, the general ecological situation of Logoisk district of Minsk region was analyzed, a number of developed peat deposits, reclaimed areas, as well as environmental objects of the region were estimated, and, taking into account the geomorphological and hydrological features of the bog and qualitative characteristics of remaining peat deposit, the further more rational direction of the developed section use of the peat deposit was determined. It has been established that the subsequent agricultural use of the worked-out area of Usyazh peatland is futile and, over time, leads to irreversible environmental and economic consequences.
 It is recommended after the end of the peat deposit exploitation: to carry out the procedure of changing the direction of its use to nature protection in accordance to the current legislation; to develop the remaining layer of peat deposits to maximum possible depth and take measures for environmental rehabilitation. The nature conservation direction of the use of the rehabilitated territory will lead to the restoration of the biosphere and natural and economic functions of the bog, as well as stabilization of the ecological situation in Logoisk district.

Monitoring of continuous GNSS stations at Central Anatolia region

In this study, the linear behaviors in the North, East and Up directions of 30 CORS-TR stations in the Central Anatolian Region were obtained by the trend component analysis which is the time series component. The time series of the stations between 2017-2020 years were calculated in the Eurasia-fixed frame with the GAMIT/GLOBK software. As a result of the analysis, the average horizontal velocity of the stations in the east of the Central Anatolian Region is 17.59 mm/year in the northwest direction, and the average horizontal velocity of the stations in the west is 18.66 mm/year in the southwest direction. This movement shows the movement of the Anatolian plate in the southwest direction in terms of direction and velocity and is in agreement with other research results. In the linear changes in the up coordinates of the stations, the greatest linear change was detected at the KNY1 (-48.22 mm/year) station. It is thought that this change at station KNY1 is due to the decrease in groundwater level in this region (Konya Closed Basin). In addition, in the standard deviation (m0) values of the time series that obtained as a result of the analysis, linear changes were approximately the same for the north and east directions, and about 2-3 times larger for the up values compared to the north or east directions.

Mechanism of Saline–Alkali land improvement using subsurface pipe and vertical well drainage measures and its response to agricultural soil ecosystem

Salinization is recognized as a threat to agricultural productivity and land resources in global arid desert regions. To date, field soil improvement schemes have met with minimal success to date. We aimed to improve saline–alkali soils by assessing the effects of combining subsurface pipe (Pa) and vertical well (Sa) drainage measures on agricultural soils ecosystem. In a five-year field experiment, soil was sampled 0.5 m, 5 m, 7.5 m horizontally away from the Pa, and 0.5 m, 30 m, 60 m horizontally away from the Sa. Findings indicate that the soil electrical conductivity (EC) decreased from 16 dS m−1 to 3 dS m−1 at a 0–80 cm depth, and the soil desalination efficiency was great at the 0–300 cm depths (≥ 32%) than at the 400–700 cm depths (−14%–74.7%). The combined Pa and Sa drainage measures significantly decreased the species richness and quantity of soil microbial communities, and their negative impact on observed species was irreversible within 1 year. The farther the horizontal sampling conducted from the Pa and Sa, the greater the structural similarity of the microbial community at the genus level, higher the catalase, acidic protease, and neutral phosphatase activities, and lower the alkaline phosphatase activity. The overall decrease in groundwater level from 2016 to 2020 was 5.7 m. The seed cotton yield increased by 3.2 t ha−1. The results suggest that the value of saline–alkali soil can be improved by combining Pa and Sa drainage measures. Our research provides guidance for further effective utilization of agricultural water and soil resources and the sustainable development of the soil ecosystem in arid desert areas.

Assessing climate change effects on declining groundwater levels using wavelet entropy (case study of Khorramabad city)

Abstract Changing global climate suggests a warmer future which may alter the hydrological cycle, affecting surface water as well as groundwater resources. The wavelet entropy (WE) criterion is a new indicator for analyzing time series fluctuations. In this study, effective factors decreasing the groundwater level in Khorramabad city during the years 2005–2018 were evaluated by the use of WE criterion. In general, it can be said that the decreasing WE criterion or time series complexity of a phenomenon shows the time series decrease of natural fluctuation, which leads to an unfavorable trend. In this regard, in order to identify the factors affecting groundwater level decrease in Khorramabad, the groundwater level was divided into 4 time periods, and after being investigated, the monthly time series of runoff, temperature, and precipitation of this city were also divided into 4 periods. Each of these subsets were decomposed into several other subsets at different time scales under the wavelet transform, and finally, after calculation of the normalized wavelet energy for this subset, the WE criterion was calculated for each period. Investigation of WE complexity shows a 21.3% decrease in groundwater level in the second period, but in the third and fourth periods, it increased by 145 and 272%, respectively. Also, according to the results of analysis of WE changes for the precipitation time series, 35.2, 32.8, and 10.06% decrease in the second, third, and fourth periods were shown, respectively. The air temperature time series complexity decreased by 26.8% only in the third time period and in the second and fourth period, it shows an increase of 29.65 and 34.7%, respectively. However, the runoff time series did not show any reduction complexity according to the WE criterion. These results indicate that the impact of climatic factors has been more effective than human factors in reducing the groundwater level of Khorramabad.

The Geoelectric Resistivity Methods to Determine the Presence or Position of Layers and the Aquifer Type in Transition and Inland Tropical Peatlands of Central Kalimantan, Indonesia

The decreasing groundwater level (GWL) in degraded tropical peatland areas during the dry season has been one source of annual peat fire disasters in Central Kalimantan. After the severe peatland fire in 2015, Peatland Restoration Agency's strategies' peatland restoration efforts enhance peat moisture and increase the groundwater level of the hundreds of deep wells and canal blocking in the burned area of 2015. This study examines the use of geoelectric resistivity methods in determining the attachment or position of layers and types of aquifers in transition and inland tropical peatland. The research was conducted on transitional peatlands in Sidodadi Village with 19 estimate points of resistivity geoelectric, nine estimate points in the inland swamp in Taruna Jaya Village, and 18 estimate points Kalampangan Village. This research used the quantitative approach is a one-dimensional (1 D) resistivity geoelectric, which using the Schlumberger array. While the qualitative process verified the result of sequences observation with two drill wells in Sidodadi, two drill wells in Taruna Jaya, 18 hand drill wells in Kalampangan, and geological stratigraphy. The research results obtained 4 (four) layers of composition with resistivities ranging from 1.224 - 661.1 Ωm in Sidodadi, ranging from 3.37 – 7,950 Ωm in Taruna Jaya Kalampangan ranging from 5.36 - 16719 Ωm. The geoelectric data and field verification interpretation show that the soil/lithology layer consists of 4 (four) layers: peat, sand, sandy clay, and clay. The type of aquifer is an unconfined aquifer. The type of aquifer is an unconfined aquifer.

Impacts of experimental decreasing groundwater levels on bacterial community composition and hydrocarbon attenuation in oil-polluted soil from Northern China

Impacts of experimental decreasing groundwater levels on bacterial community composition and hydrocarbon attenuation in oil-polluted soil from Northern China

Causes and consequences of long-term groundwater overabstraction in Jordan

In 2017, a comprehensive review of groundwater resources in Jordan was carried out for the first time since 1995. The change in groundwater levels between 1995 and 2017 was found to be dramatic: large declines have been recorded all over the country, reaching more than 100 m in some areas. The most affected areas are those with large-scale groundwater-irrigated agriculture, but areas that are only used for public water supply are also affected. The decrease of groundwater levels and saturated thickness poses a growing threat for drinking water supply and the demand has to be met from increasingly deeper and more remote sources, causing higher costs for drilling and extraction. Groundwater-level contour lines show that groundwater flow direction has completely reversed in some parts of the main aquifer. Consequently, previously established conceptual models, such as the concept of 12 “groundwater basins” often used in Jordan should be revised or replaced. Additionally, hydraulic conditions are changing from confined to unconfined; this is most likely a major driver for geogenic pollution with heavy metals through leakage from the overlying bituminous aquitard. Three exemplary case studies are presented to illustrate and discuss the main causes for the decline of the water tables (agriculture and population growth) and to show how the results of this assessment can be used on a regional scale.

Hydrogeochemical properties and the exhaustion groundwater reserve from Dammam aquifer at Al-Najaf Governorate, middle Iraq

One of Iraq’s most significant groundwater-bearing limestone aquifers is the Dammam Formation. The aquifer groundwater has been studied hydrogeochemically. It is suitable for irrigation, as indicated by sodium adsorption ratio (SAR) and total dissolved solids (TDS), which are 4.15 and 1971 ppm (in average) respectively. Through the vision of the Stiff diagram, the predominant ions are Cl-, SO4 2+ and Na+ while the HCO-3 and Mg2+ are relatively poor. There is plenty of flowing wells in the study area in Najaf Governorate producing groundwater from the Dammam aquifer. In recent years, many wells have been drilled in an irregular pattern for forming fish breeding lakes. These lakes’ water drains 4.715 m3/s into the Najaf depression by Wadi Al- Khur and artificial channels, where it mixes with brine water, rendering it useless. This lead to the exhaustion huge amount of precious groundwater resource. Many signs that confirm the Piezometric pressure drop and groundwater levels descent in the Dammam aquifer in the region. The groundwater flow has been halted in several flowing wells in the study area especially in Wadi Al-Khur due to the exhaustion of the reserve and a decrease in the level of the hydrostatic pressure of the aquifer. A significant decline in values transmissivity and specific capacity of the Dammam aquifer when compared with previous studies in the years 1996 and 2009. Through observation of the monitoring well (W/7), a decrease in groundwater levels of flowing wells in the study area.

Impact of urbanization on groundwater quality and recharge using hydrogeochemical and environmental tracers in the San Salvador Aquifer

Chemical and isotopic characteristics of the urban aquifer of San Salvador, drinking water (SAP) and wastewater systems (SAR), were evaluated in an area of 362 km2 to detect if leakages in both are recharging the aquifer and modifying its natural quality. An amount of 37 sampling sites that includes deep wells and springs, as well as two water import systems of the Metropolitan Area of San Salvador (AMSS) were sampled in 2007, 2009 and 2017. Samples were analyzed for major ions and stable isotopes of d18O and d2H. While the SAR was characterized by chemical tracers of Cl- and NO3-. Results show the existence of four water groups: Groups A (Ca-Mg-HCO3), B (Mg-Ca-HCO3) and D (Na-Ca-HCO3) have meteoric water as their main source of recharge, hence, they do not evidence urban influence in their quality; group C (Na-Ca-HCO3 and Na-Mg-HCO3) is derived from group A, flows under the AMSS and suggests three sources of recharge: Direct natural recharge due to precipitation along urban recharge from SAP and SAR leakages. An expensive “fictitious sustainability” could be perceived due to the quantitative contribution of the SAP recharge, which would be hiding the effects of the extractions and consequently the decrease of groundwater levels in the aquifer. Meanwhile, SAR recharge forewarn of a potential entry of pollutants into the aquifer that must be monitored and treated in a timely manner to avoid contamination. The study highlights the need of an integrated urban water resources management.