Aquifer Depth Research Articles

Seawater intrusion characterization based on electrical resistivity and hydrogeochemical methods; surrounding Rosetta branch area, Egypt

Seawater intrusion (SWI) is one of the most common environmental issues in recent years, posing a threat to groundwater quality and sustainability, especially in coastal aquifers. The current climate changes linked to rising sea levels as well as the excessive pumping of groundwater, linked to the lack of natural recharge, have exacerbated this environmental problem. As a result, to characterize and detect seawater intrusion in this region. This paper presents a comprehensive combination of geoelectric methods represented by artificial vertical electrical soundings (VES) and hydrogeochemistry of groundwater. Vertical electrical resistivity values are obtained by Schlumberger's array of twenty-six VESes distributed all over the area using the Eleric-T device. However, the electrical resistivity sounding method succeeded to outline the aquifer depth, extension and thickness. The hydrogeochemical techniques outline the ions, cations, water types and water quality based on the chemical analysis of 26 groundwater samples. Both two types are contributed to emphasis the results. The VES results succeeded to describe the Pleistocene aquifer lithology and subdivides it into fresh, brackish and salt zones (freshwater – saltwater interface). The hydrochemical characteristics of groundwater samples through the physiochemical parameters, Chadha diagram, ionic relations and DWQI confirm the influence of SWI on the chemistry of groundwater in the concerned area. Consequently, these results confirm that the integration between the electrical resistivity and hydrochemical methods are effective tools for the characterization of seawater intrusion in this important region in terms of agricultural activity in Egypt.

Hyporheic zone geochemistry of a multi-aquifer system used for managed aquifer recharge in Beijing, China

Hyporheic groundwater geochemistry evolution depends on the interactions of surface water and groundwater (SW–GW). Hydrodynamic variations driven by the long-term managed aquifer recharge (MAR) practice could change hyporheic geochemical processes, which requires a better understanding for groundwater management. In this work, a geochemical survey was conducted in a multi-aquifer MAR system. The results showed great impact of the MAR practice on the hydrodynamics and major ion chemistry of groundwater in the hyporheic zone compared to natural recharge. Besides, related geochemical processes including rock weathering and ion exchange showed increased effect on hyporheic hydrochemistry with aquifer depth, depending on hydrogeological conditions in addition to river water infiltration. Combined with hydrochemical indicators and the end-member mixing model, the relative contribution of precipitation to groundwater was estimated to be 5% for the 30-m aquifer, 16% for the 50-m aquifer, and 64% for the 80-m aquifer. However, precipitation made small contributions (<5%) to the major ions of groundwater regardless of depth. Conversely, the relative contributions of river water infiltration decreased with aquifer depth (95%→84%→36%), and its proportional contributions to major ions showed a similar trend (90%→84%→39%), which suggests reduced SW–GW interaction intensity with depth in the hyporheic zone. The major ion compositions of hyporheic groundwater tend towards river water after the long-term MAR practice, reflecting comprehensive effect of mixing and related geochemical processes. This study demonstrates the relevance of detailed studies at regional scale to understand anthropogenic effects from projects such as MAR on groundwater geochemistry especially in multi-aquifer systems.

Exploration of Shallow Geothermal Energy Aquifers by Using Electrical Resistivity Survey in Laki Range Jamshoro district Sindh, Pakistan

Geothermal water is increasingly used around the world for its exploitation. Bulk electrical resistivity differences can bring significant information on variation of subsurface geothermal aquifer characteristics. The electrical resistivity survey was carried out in Laki range in lower Indus basin in the study area to explore the subsurface geothermal aquifers. The Schlumberger electrode configuration with range from 2 m to 220 m depth was applied. Three prominent locations of hot springs were selected including Laki Shah Saddar, Lalbagh and Kai hot spring near Sehwan city. After processing resistivity image data, two hot water geothermal aquifers were delineated at Laki Shah Sadder hot springs. The depth of first aquifer was 56 m and its thickness 38 m in the limestones. The depth of second aquifer of 190 m and with thickness of 96 m hosted in limestone. In Lalbagh hot springs two geothermal aquifers were delineated on the basis of apparent resistivity contrast, the depth of first aquifer zone in sandstone was in sandstone 15 m and thickness 12 m, while the depth of second aquifer was 61m and thickness was 35m. In Kai hot springs two hot water geothermal aquifers were delineated. The depth of first geothermal aquifer was 21m and thickness was 18 m and the depth of second aquifer was 105 m and thickness was 61m present in sandstone lithology. Present work demonstrates the capability of electrical resistivity images to study the potential of geothermal energy in shallow aquifers. These outcomes could potentially lead to a number of practical applications, such as the monitoring or the design of shallow geothermal systems.

Isotopes (δ18O, δD and 3H) variations in groundwater with emphasis on salinization in the state of Punjab, India

The state of Punjab has a dominant agrarian economy and is considered India's bread basket. However, it is now under the problem of falling agro-economy primarily because of pervasive depletion of groundwater levels and deteriorating groundwater quality in south-west Punjab, but increasing salinity is a major concern. The irrigation requirements of crops are fulfilled by groundwater and canal water but the introduction of canal irrigation has led to waterlogging and subsequent salinization rendering large fertile-land areas becoming unproductive mainly in the south-western part of Punjab. There was an apprehension that excessive withdrawal of groundwater might have caused a reversal of natural groundwater flow pattern that might have caused ingress of saline water into fresh groundwater region of central Punjab. To address the apprehension related to the rise in groundwater salinity and its subsequent ingression in the fresh-water zone and suggest suitable management solutions, a study was undertaken to analyse the data related to salinity, isotopes, land-use and land cover (LULC) along with field and laboratory experimental results. The depth-wise isotope analysis shows that there is a large variation in isotopic signatures of shallow and intermediate aquifers and it decreases with the depth of aquifers (150–250 m). It appears that very deep groundwater (>250 m) is relatively isolated and does not show a large variation or mixing effect. Tritium analysis shows that dynamic groundwater is actively recharged through canal, river, and/or rain. The presence of modern groundwater at deeper depth indicates a good interconnection between shallow and deep groundwater. Interpretations of the results show that the canal is the main source of groundwater recharge in south-west Punjab and the evaporation process is responsible for increasing the salinity hazard. In the central parts of Punjab, groundwater and rain are the main sources of groundwater recharge, while rain is the main source of groundwater recharge in the Kandi area. In the south-west Punjab, some primary salinity has formed as a result of mineral dissolution which has further increased due to evaporative enrichment.

Experimental Design of Physical Unconfined Aquifer for Evaluation of Well Abstraction Effects: Laboratory Approach

In unconfined aquifer water flows in both horizontal and vertical direction when pumping. So its study during pumping action is more complex. Soil type, porosity, hydraulic conductivity and transmissivity are important parameters that control the specific yield, drawdown and radius of influence on aquifer while abstraction. Due to large extraction of water from the aquifer, the water table drops down and may lead to permanent depletion of yield capacity of aquifer. For practical understanding of water being pumped from aquifer and its impacts on water storage the easiest method is experimental approach .So therefore, this study was planned to carry out the well abstraction from unconfined aquifer of homogeneous sandy soil designed as physical model on rainfall simulator at hydraulic laboratory hall of Campus itself. The catchment dimension is 2.2 meter length, 1 meter width and 0.15 meter depth with impermeable base filled with fine sand as per specification. The simulator was adjusted to make horizontal aquifer. The experimental observations were carried out in two conditions, first was well abstraction with no rainfall after saturation and the second is with rainfall even after saturation condition obtained. The two wells were operated for the abstraction of water simultaneously so that the effect of one well to another could be studied. After observation and data collection, for the analysis of hydraulic conductivity Dupit model. Empirical model and relative effective porosity model (REPM) were used for the comparative study. Similarly the radius of influence was estimated by three models (weber,Kusakin and Sichardt). For the estimation of transmissivity of the aquifer Thien model was used. Also the general equation (product of hydraulic conductivity and depth of aquifer) was used. Study showed the suitability of the available theories and governing equations for unconfined aquifer. The most important part of the study was to establish the correlation of drawdown and radius of influence with the time period of well abstraction. From the results the correlation coefficient for time and drawdown was of 90% and for time and radius of influence was 97%.

By , I.; , A. I.; , I.C.; , H.M. and , C.M.

This work was carried out to evaluate the hydrogeological and geophysical properties of Abakaliki and Afikpo environs. Forty-seven (47) Vertical Electrical Sounding data were acquired with electrode spacing (AB/2) of 500m using Schlumberger electrode configuration. Conventional curve matching techniques were used to interpret the data and obtain initial model parameters. Results of the study showed 3-7 electric layers which indicate multiple aquifer system. QQH, QHK, KHK and QQHK models were the Vertical Sounding curves obtained. The aquiferous layers make up the third and fourth layers. The resistivity of the aquifer varies from 10.74Ωm to 13201Ωm with an average of 1013.58 Ωm. Aquifer depth ranges from 6.2m to 92.5m with an average aquifer depth of 27.07m, while the aquifer thickness varies from 2.3m to 55.87m with an average of 15.61m. Transverse resistance varies from 65.34Ωm2to 7079.14 Ωm2 with an average of 9966.29 Ωm2; and the longitudinal conductance varies from 0.00018Ω-1 to 1.65 Ω-1 with an average of 0.026 Ω-1. From the study, 49% of the study area falls under the poor protective rating while 21% falls under the weak rating with 25% and 5% which makes up the moderate and good ratings respectively. Using the average longitudinal conductance, it is observed that the study area is moderately protected.

No Cryosphere‐Confined Aquifer Below InSight on Mars

AbstractThe seismometer deployed by the InSight lander measured the seismic velocity of the Martian crust. We use a rock physics model to interpret those velocities and constrain hydrogeological properties. The seismic velocity of the upper ∼10 km is too low to be ice‐saturated. Hence there is no cryosphere that confines deeper aquifers and possibly no aquifers locally. An increase in seismic velocity at depths of ∼10 km could be explained by a few volume percent of mineral cement (1%–5%) in pore space and may document the past depth of aquifers.

Spatial variation of groundwater vulnerability to nitrate pollution under excessive fertilization using index overlay method in central Tunisia (Sidi Bouzid basin)*

AbstractOne of the major challenges in assessing groundwater vulnerability to pollution is the inadequate factors number and weight. Therefore, to carefully improve the assessment of groundwater vulnerability, a model independent of weight assignment errors was used. Moreover, the specific vulnerability index (SVI) of Sidi Bouzid North's groundwater was assessed in this study. Intrinsic vulnerability index (IVI) assessment was determined in the first step by the arithmetic mean calculation by the index overlay method (IOM) based on the D: Depth of aquifer; P: annual average Precipitation; L: Lithology of the vadose zone and S: percent of Slope (DPLS) model. Then SVI was assessed by linking new factors (LU and NO3−) to IVI. Consequently, 83 samples were analysed for NO3−, showing high values that exceed 50 mg l‾¹. The spatial distribution of IVI shows three vulnerability classes in the study area, namely low (8%), moderate (15%) and high (77%). The evaluation of SVI based on the risks associated with the NO3− and LU factors using GIS indicates that about 95% of the total study area is classified with high SVI levels. It displayed a good correlation with NO3− and provided a high discretization of the groundwater risk from natural and anthropogenic pollution. This alarming situation suggests the necessity to apply water‐saving irrigation action for adequate water management.

An Overview of Aquifer Physiognomies and the δ18O and δ2H Distribution in the South African Groundwaters

A comprehensive assessment of the stable isotope distribution in the groundwater systems of South Africa was conducted in relation to the diversity in the aquifer lithology and corresponding hydraulic characteristics. The stable isotopes of oxygen (18O) and hydrogen (2H) in groundwater show distinct spatial variation owing to the recharge source and possibly mixing effect in the aquifers with the existing water, where aquifers are characterized by diverse hydraulic conductivity and transmissivity values. When the shallow aquifer that receives direct recharge from rainfall shows a similar isotopic signature, it implies less mixing effect, while in the case of deep groundwater interaction between recharging water and the resident water intensifies, which could change the isotope signature. As aquifer depth increases the effect of mixing tends to be minimal. In most cases, the isotopic composition of recharging water shows depletion in the interior areas and western arid zones which is attributed to the depleted isotopic composition of the moisture source. The variations in the stable isotope composition of groundwater in the region are primarily controlled by the isotope composition of the rainfall, which shows variable isotope composition as it was observed from the local meteoric water lines, in addition to the evaporation, recharge and mixing effects.

Electro-geohydraulic estimation of shallow aquifers of Owerri and environs, Southeastern Nigeria using multiple empirical resistivity equations

Estimates of the geohydraulic parameters of the aquifers of Owerri and environs were carried out using different empirical resistivity equations with the objective of evaluating the predictive capabilities of the various equations. Forty Vertical Electrical Sounding (VES) data were acquired with a maximum half-current electrode spacing of 500 m using the Schlumberger electrode configuration. Aquifer resistivity across the study area varies from 330 to 78,100 Ωm with a mean value of 9465.8 Ωm. Aquifer depth ranges from 22.5 to 91.8 m with a mean value of 61.79 m while aquifer thickness across the study area ranges from 10.8 to 77.0 m with an average value of 36.72 m. The Dar-Zarrouk parameters revealed that the transverse resistance ranges from 12,276 to 2,297,120 Ωm2 with a mean value of 330,297.01 Ωm2 while the longitudinal conductance ranges between 0.000214 and 0.529231 Ω−1 with a mean value of 0.01323Ω−1. Aquifer hydraulic conductivity values vary from about 2.97–58.55 m/day with a mean value of 15.55 m/day while aquifer transmissivity values vary from about 37.433–7004.61 m2/day with a mean value of 1007.18 m2/day. Aquifer storativity values across the study area vary from 0.0000324 to 0.000231 with a mean value of 0.00011 while aquifer hydraulic diffusivity values ranged between 335,425 and 79,383,443.33 with a mean value of 9,621,354.647. Model ranking using statistical analysis revealed that out of the three different equations used for estimating hydraulic conductivity in the study area, the New Model equation is the best alternative in the absence of pumping test data.

Performance Study of the Direct-Coupled Photovoltaic Water Pumping System for the Rural-Isolated Agricultural Region in Iraq

The rural-isolated agricultural region in Iraq and some developing countries lack access to electricity, and thus the primarily alternative is to use diesel water pumping systems to irrigate their crops. However, due to a rise in the oil's price on the international market, toxic pollution from burning oil, high maintenance costs, and short lifespans have been challenged to create more viable alternatives. Renewable energy can limit the use of fossil fuels, particularly by using the solar-powered water pumping system. This article aimed at finding an optimal design for a direct-coupled photovoltaic water pumping system in Iraq. The article presents the significant design aspect for an optimal system, such as the groundwater aquifer depth, installation aspect, cost, and irrigation efficiency. The design offers a combination of sprinkler and environmentally sustainable and cost-effective photovoltaic technology to reduce electricity and water use. A deep well to the storage system is adopted with, 40m maximum well depth, 90m3 reservoir, 1200W submersible pump, and 1800 Wp, which can supply water to 12 greenhouses for three days. The yearly results show pumping efficiency is increased up to 42.6%, used water need is achieved at 10950 m3, and unused energy is reduced by 48.8%.

Variations of Groundwater Dynamics in Alluvial Aquifers with Reclaimed Water Restoring the Overlying River, Beijing, China

Some of the rivers in northern China are dried, and reclaimed water (RW) is used to restore these degraded river ecosystems, during which the RW could recharge the aquifer by river bank infiltration. From 2007 to 2018, 2.78 × 108 m3 of RW has been replenished to the dried Chaobai River (Shunyi reach), Beijing, China, which is located on the edge of one depression cone in groundwater caused by groundwater over-pumping. The groundwater hydrodynamic variations and the flow path of the RW were identified by eight-year hydrological, hydrochemical, and stable isotopic data, together with multivariate statistical analysis. The RW infiltration drastically impacts the groundwater dynamics with a spatiotemporal variation. The 30-m depth groundwater levels at Perennial intake reach increased quickly around 3 m after 2007, which indicated that they were dominated by RW infiltration. Other 30-m depth groundwater levels were controlled by precipitation recharge from 2007 to 2011, showing significant seasonal variations. In 2012, with more RW transferred to the river, the hydrodynamic impact of the RW on 30-m depth aquifer expanded downstream. However, the 50-m and 80-m depth groundwater levels showed decreasing trend with seasonal variations, due to groundwater pumping. The 30-m depth aquifer was mainly recharged by RW, being evidenced by the enriched δ2H and δ18O. The depleted δ2H and δ18O of the 50-m and 80-m depth groundwater indicated that they were dominated by regional groundwater with meteoric origin. The heterogenous properties of the multi-layer alluvial aquifer offer the preferential flow path for RW transport in the aquifers. The proportion of the RW in the aquifers decreases with depth that was calculated by the chloride conservative mixing model. The increased lateral hydraulic gradient (0.43%) contributes to the RW transport in the 30-m depth aquifer. RW usage changed 30-m depth groundwater type from Ca·Mg-HCO3 to Na·Ca·Mg-HCO3·Cl. RW preferentially recharged the 50-m and 80-m depth aquifers by vertical leakage.

Estimation of hydrogeological parameters using physically based hydrological modelling and lithology data in ungauged creek catchments of southern Taiwan

ABSTRACT Streamflow recession analysis is widely used for estimating catchment-scale hydrogeological parameters in gauged catchments because of its low cost, ease of use, and efficiency in terms of results. In this work, however, the same methodology was applied to ungauged creek catchments, where low recession flows were simulated using physically based, semi-distributed, continuous hydrological modelling. Moreover, a combination approach was used to reasonably estimate the effective aquifer depth (D) with borehole lithology and digital elevation model data. The estimated hydraulic conductivity (k) values ranged between 10–5 and 10–3 m s–1, and they were comparable with the results of a field test. By contrast, the specific yield (Sy ) values obtained through streamflow recession analysis (10–7 to 10–5) were lower than the results of the field tests at different aquifer depths. However, the Sy values obtained for alluvial catchments (on the order of 10–5) were comparable. Thus, the results of the comparison support the application of the streamflow recession analysis scheme for estimating hydrogeological parameters in ungauged creek catchments.

Identification of Groundwater Potential Using Wenner Configuration 2D Resistivity Method (Kupang, Nusa Tenggara Timur)

Kupang is the capital of the Indonesian province of Nusa Tenggara Timur, and has an estimated population in 2019 of 434,972. It is the biggest city and port on the island of Timor. The needs for groundwater is urgent in Kupang. The geology of Kupang is located on the Batu Gamping Koral Formation which composed by coral limestone, which is physically barren and dry. So that local residents often have some problems with water availability. Therefore, needed the information about potential and depth of groundwater aquifers in the area. Measurement of the Wenner configuration 2D resistivity method has been carried out to identify the subsurface to determine the potential for groundwater. Inversion were performed using the method of Least-Square Smoothness Constraint. The result of the interpretation shows that the subsurface resistivity value in the area ranges from 0.4-13.108 Ω m, and groundwater aquifer potential lies at trajectories KPG 01, 02, 03, 04, 14, 15. In the Batu Gamping Koral Formation there is groundwater potential in depth between 0-85 m with a resistivity value of 25.6-205 Ω m, and its constituent rocks are limestone sand and sand. In the Alluvium Formation, the groundwater potential in depth between 0-20 m with resistivity value of 25.6-410 Ω m, and its constituent rock is sand. Whereas in Bobonoro Formation, there is no groundwater potential.

Identification model of water inrush source based on statistical analysis in Fengyu minefield, Northwest China

Rapid and effective identification of water inrush source is an important guarantee for mine safety production. Hydrogeochemical theory has been applied in coal mining and water prevention and control, but its application scale and coverage are limited. The main reason is that the existing research is mostly based on conventional hydrochemical indicators, and less applied in trace elements and environmental isotopes. In order to explore the evolution mechanism of water inrush in well field and realize the accurate identification of water inrush source, this paper takes Fengyu well field in Shuozhou City, Shanxi Province, China, as the research object. Based on the test results of conventional hydrochemistry, trace elements, and environmental isotope indexes of each aquifer, the hydrogeochemical distribution and evolution law of each aquifer in a minefield are analyzed. Combined with cluster analysis, principal component analysis, and Bayesian stepwise linear discriminant method, the discrimination model of mine water inrush source is established. The results show that, with the gradual increase of aquifer depth, the total dissolved solids (TDS) of water samples showed a decreasing trend; HCO3− is dominant in all aquifers, which may be the result of mixing after water inrush in each aquifer; the content of trace elements in underground aquifer of minefield can be summarized as three principal components of groundwater overflow, river recharge, and dissolution. The distribution of Shanxi water, Taiyuan water, and Ordovician water conforms to the height effect and temperature effect; the established discrimination model of water inrush source in minefield can effectively discriminate water inrush source. The calculation process is simple and the model structure is stable, which is worthy of promotion and application. The research results can provide a scientific basis for the development of water control measures (draining, depressurization, and plugging) in minefields.

Hydrochemical appraisal of groundwater quality for drinking and irrigation: a case study in parts of southwest coast of Tamil Nadu, India

The quality of groundwater standards in Muttom–Mandaikkadu coastal stretch is the focus of the present study, whose coastal aquifers are particularly at risk due to intrusion of marine water. Thirty groundwater samples were scrutinized for the assessment of physical and chemical parameters during January and June. Hydrochemical characteristics were spatially depicted to understand the spatial variations such as (pH, EC, TDS, Na+, K+, Ca2+ and Mg2+, SO42−, HCO3−, and Cl−). Drinking water quality index based on those 11 parameters and irrigation water quality index based on EC, Na%, sodium adsorption ratio and permeability index was used to assess the water quality for drinking and irrigation, respectively. These results demonstrate that dominant hydrochemical facies for groundwater in both months are Na-K-Cl-SO4 type and Ca-Mg-Cl-SO4 type. The USSL diagram endorses that most of the water samples belong to low-medium salinity with low sodium hazards. Cl−/HCO3− ratio indicates that the majority of the samples show low to moderate seawater intrusion in the study area. Additionally, six vertical electrical sounding measuring points (Schlumberger array) were carried out in order to determine the number of the underlying layers, aquifer depths and their thicknesses as well as its influence by the marine water. The geophysical self-potential measurements suggest that the groundwater in the Manavalakurichi area is prone to contamination by seawater intrusion, confirmed by the use of Schlumberger vertical electrical sounding. For better understanding, the subsurface layers were shown in a 2D model using the constructed geoelectrical cross section.

Hydrogeophysical appraisal of groundwater potential in the fractured basement aquifer of the federal capital territory, Abuja, Nigeria

In this study, eighteen (18) vertical electrical sounding (VES) data points were located in the Federal Capital Territory (FCT), Abuja, Nigeria with ABEM Terrameter using Schlumberger array to delineate potential groundwater development areas. Groundwater flow direction map was produced using the elevation of the water level from sea level with GIS Arc/Info Point coverage. The investigated areas have four geoelectric sections, categorized as topsoil, clay, fractured/weathered basement, and fresh basement. The groundwater is mainly confined in the fractured/weathered basement. It generally flows from NW to SE, but this flow is not steady. It has been obstructed and reoriented towards the south, whereas some portion flows towards the northern parts of the aquifer system peradventure due to the variation in aquifer depth from place to place. Out of the 18 VES points, 9 points located around the NE and SE peripherals of the study area have groundwater development potentials at depths ranging from 40 - 80 m and aquifer thickness of 25 – 65 m, characterized by resistivity values that varied from 80 – 680 Ωm, whilst the other nine in the SW and central parts do not show promising groundwater development potentials because they lack fractured/weathered zones. The northern and SE zones, which comprise areas such as Bwari, Kuje, Idu CITEC, Sherete, and GTSSC are the preferred targets for water well drilling than the southern zone. However, other communities including Gwagwalada and Gugugu in the southern zone also offer promising groundwater potentials.

Statistical analyses of groundwater chemistry in the Qingdong coalmine, northern Anhui province, China: implications for water\u2013rock interaction and water source identification

Hydrochemistry of groundwater is important in coal mines because it can be used for understanding water–rock interaction and inrush water source identification. In this study, major ion concentrations of groundwater samples from the loose layer aquifer (LA), coal-bearing aquifer (CA) and Taiyuan Formation limestone aquifer (TA) in the Qingdong coal mine, northern Anhui province, China, have been analyzed by a series of statistical methods for identifying the source of chemical constituents in groundwater and the source of inrush water. The results indicate that the mean concentration of the major ions in the LA were ordered as follows: HCO3− > SO42− > Na+ + K+ > Cl− > Ca2+ > Mg2+ > CO32−, whereas average values of the CA in decreasing order are SO42−, Na+ + K+, HCO3−, Cl−, Ca2+, Mg2+ and CO32−, and the major ion concentrations of the TA have the following order: SO42− > Na+ + K+ > Ca2+ > HCO3− > Cl− > Mg2+ > CO32−, and most of the samples are Na-SO4 and Ca-SO4 types. TDS content in water increases with aquifer depth, whereas the pH values ranged from 7.1 to 8.9, indicating a weak alkaline environment. Two sources (weathering of silicate minerals and dissolution of evaporate minerals) have been identified by principal component analysis responsible for the chemical variations of the groundwater, and their contribution ratios have been quantified by Unmix model. Moreover, based on the Q-mode cluster and discriminant analyses, the samples with known sources have been identified correctly to be 95.7% and 97.6%, respectively, and the samples with unknown sources have been determined with high probability (78–100%).

Groundwater level in the southern part of surakarta city depicted from vertical electrical sounding

In the last two decades, the city of Surakarta has shown significant population development, as well as in industry and tourism. This development must be accompanied by the provision of water resources for the lives of the population. As we know that in 2015 and 2019, there was a long dry season that resulted in a lack of water for residents and for the hotel industry, where most residents of Surakarta and the hotel industry are located in the southern part of the city of Surakarta. Therefore, the purpose of this study was to determine the level of groundwater aquifers in the south part of the city of Surakarta. We used the vertical electrical sounding (VES) method with the Schlumberger configuration at 10 survey locations. The current electrode interval in the Schlumberger configuration is from 1.5 meters up to 300 meters. With this stretch of electrode current, it is expected to reach target depth of up to 150 meters. Data processing uses the principle of non-linear optimization method which is to minimize errors from measurement data and models. We found that the depth of the groundwater aquifer was at 40 meters at S9 (shallowest), and at 80 meters at S5 (deepest). Then we compared this result with the survey in 2010 in the same location and same method. We found the lowering of the water table in some site surveys around 3 to 10 meters.

IRS-1C Satellite Data Utilization for Groundwater Prospects Mapping for the Entire Country Under National Rural Drinking Water Program (NRDWP): A State of the Art Initiative

Conventional methods of groundwater targeting often result in failures due to improper selection of sites as a result of the lack of scientific database. Satellite-based mapping using geographic information system (GIS) has brought a paradigm shift in the mapping of the natural resources including groundwater. Remote sensing is a cost effective technique to carry out the groundwater prospects mapping which otherwise is difficult to achieve at national scale. A comprehensive database could be created on groundwater resource mapping and assessment using IRS LISS III satellite data from IRS-1C and its follow-on missions like IRS-1D and Resourcesat-1 for the entire India which was first of its kind. A national mission called National Rural Drinking Water Program was launched in the year 1999 to carry out groundwater prospects mapping at 1:50,000 scale for the entire country using 23.5 m resolution IRS LISS III satellite data. The objective of the project was to generate groundwater prospects maps on 1:50,000 scale in GIS format showing (a) different prospective zones in terms of yield and depth of aquifer and (b) tentative sites of different recharge structures suitable in the area. It is imperative that the mammoth task of preparing 4898 groundwater prospects maps on 1:50,000 scale for the entire country has become a reality due to the timely and continuous availability of LISS III satellite images from IRS-1C sensor and its follow-on missions.