Assessment Of Groundwater Resources Research Articles

Uncovering the groundwater resource potential of Murchison Region in Western Australia through targeted application of airborne electromagnetics

Access to water is identified a key infrastructure need for mining, energy and industry development. In Western Australia, the scale of planned developments linked to current mineral exploration and mining is set to generate significant economic value for the State, but its realisation is dependent on ensuring access to groundwater. To address these issues, The WA Government Department of Water (DoW) has embarked on a series of groundwater investigations to identify and establish long-term water resources in regional areas where agriculture and mining opportunities have the potential for development. The Murchison in northern WA was identified as one of six key priority areas for this initiative. With numerous known mineral deposits having potential for development, locating and securing an adequate, sustainable long-term water supply is a critical consideration if these mineral resources are to be developed further. While it is known that there are significant groundwater resources in the region, at present these are generally poorly understood. Of particular importance are the palaeovalley aquifers which are known (locally) to contain a significant resource, but which are relatively poorly characterised. To aid an understanding of their extent an airborne electromagnetic (AEM) survey was commissioned and flown in the Murchison extending over an area in excess of ~106 000 km2. Prior studies at a local scale had indicated that airborne EM would be very effective at defining the location and thickness of palaeovalleys in the region. Pilot investigations also determined the most appropriate AEM system to use for acquisition. These studies suggested that the buried palaeovalleys were most likely to be near-coincident with contemporary valley systems developed in a granite/gneiss-greenstone basement. Covering such a large region required a novel approach to survey design to maximize the information relating to their expected spatial variability. Therefore a terrain index (MrVBF) was used with the SRTM 1sec DEM to define the extent of contemporary valleys, and the extent of the AEM survey area. This approach allowed survey acquisition costs to be kept to less than half that of flying a more “traditional” survey over the entire area. It also allowed for the acquisition of data with a closer line spacing than would have been possible otherwise, therefore capturing more of the spatial variability associated with the palaeovalley systems. The results have demonstrated the validity of the strategy adopted and have shown that in the absence of conventional hydrogeological information, geophysical methods are demonstrably a cost and time effective approach to upscaling local hydrogeological information, thereby fast tracking groundwater resource assessments that would otherwise take decades to complete.

Water Quality Assessment of Groundwater Resources in Qaleeh Shahin Plain Based on Cd and HEI

Abstract Aims: The chemical elements in water resources, especially groundwater, can affect the water consumption purposes. The aim of this study was to evaluate the status of the overall pollution level of ground water of Qaleeh Shahin plain with respect to heavy metals by Cd and HEI methods. Instrument & Methods: This cross-sectional semi-experimental study was conducted in Sarpol-e Zahab township in Kermanshah Province, west of Iran. For this purpose, 20 groundwater wells were chosen randomly. The samples were filtered (0.45μm), stored in polyethylene bottles and were acidified at a pH lower than 2 by adding concentrated HNO3 in order to avoid metal adsorption onto the inner bottle walls. Element concentrations were determined using ICP-OES. The correlation between the metals in the different seasons, between the indices values and concentration of metals and between different indices values was assessed by Pearson’s correlation coefficient. Findings: There were no significant correlations between the concentrations of the elements in 2 seasons except between As and Cd in winter (r=0.544; p<0.05). Only the concentration of Pb had significant correlations with Cd (r=0.937; p=0.0001) and HEI (r=0.997; p=0.0001) values in winter and with Cd (r=0.997; p=0.0001) and HEI (r=0.810; p=0.0001) values in summer, which indicated Pb as the main contributory pollutant. The correlation between Cd and HEI was significant in winter (r=0.943; p=0.0001) and was significant in summer (r=0.818; p=0.0001). Conclusion: The water resources of Qaleeh Shahin plain, Kermanshah Province, Iran, are not polluted by heavy metals and are suitable for drinking.

Identifications of aquifer group classification by using environmental isotope and hydrogeochemistry method: a case study of Huabei plain, China

Aquifer group classification is a prerequisite for groundwater resources evaluation as well as groundwater utilization, which making an important effect on human being living and production activities. So far, lithology is the primary criteria in aquifer group classification, but the available and specific supporting ideas are still insufficient. Supposing that two aquifers separated by clay had hydraulic connection in multilayer aquifer systems, groundwater flow from top to bottom of aquifer would be impacted by the clay in chemistry and isotope characteristic and presents some kind of regulations. According to these regulations, aquifer group classification would be more reasonability, and groundwater resources assessment and pollution management would be more purposeful. This research analyzed the hydraulic connection of groundwater in different aquifer and salt movement in clay soil by using isotopic and chemical data. The results showed that electrical conductivity of groundwater in clay soil is influenced by the source of the groundwater, having a continuous trend with depth, and clay soil in certain depth presented the feature of impeding salt migration. Because of the semipermeable feature of clay soil, stable isotope composition of groundwater in different depth is affected by clay’s distribution. This pattern of isotope and hydrogeochemical composition would be a valuable reference for groundwater evaluation and aquifer group classification.

Analysis of subsurface temperature data to quantify groundwater recharge rates in a closed Altiplano basin, northern Chile

Quantifying groundwater recharge is a fundamental part of groundwater resource assessment and management, and is requisite to determining the safe yield of an aquifer. Natural groundwater recharge in arid and semi-arid regions comprises several mechanisms: in-place, mountain-front, and mountain-block recharge. A field study was undertaken in a high-plain basin in the Altiplano region of northern Chile to quantify the magnitude of in-place and mountain-front recharge. Water fluxes corresponding to both recharge mechanisms were calculated using heat as a natural tracer. To quantify in-place recharge, time-series temperature data in cased boreholes were collected, and the annual fluctuation at multiple depths analyzed to infer the water flux through the unsaturated zone. To quantify mountain-front recharge, time-series temperature data were collected in perennial and ephemeral stream channels. Streambed thermographs were analyzed to determine the onset and duration of flow in ephemeral channels, and the vertical water fluxes into both perennial and ephemeral channels. The point flux estimates in streambeds and the unsaturated zone were upscaled to channel and basin-floor areas to provide comparative estimates of the range of volumetric recharge rates corresponding to each recharge mechanism. The results of this study show that mountain-front recharge is substantially more important than in-place recharge in this basin. The results further demonstrate the worth of time-series subsurface temperature data to characterize both in-place and mountain-front recharge processes.

Vulnerability evaluation of a coastal aquifer via GALDIT model and comparison with DRASTIC index using quality parameters

ABSTRACTIn recent years, environmental assessments of groundwater resources have resulted in the development of models that help identify the vulnerable zones. An aquifer is investigated using both GALDIT and DRASTIC indices. The GALDIT model is developed to determine the vulnerability of coastal aquifers in terms of saltwater intrusion whereas the DRASTIC model is generally applicable to all aquifers. Having compared the results of both the GALDIT and DRASTIC models with quality parameters, the salinity model proved to be more appropriate in identifying the vulnerability of coastal aquifers. The results show a Pearson correlation coefficient between TDS and the GALDIT vulnerability map of 0.58 while the corresponding value for the DRASTIC index is 0.48.EDITOR D. KoutsoyiannisASSOCIATE EDITOR A. Fiori

A proposed new approach for groundwater resources assessment in India

Assessment of groundwater resources in India is guided by National Water Policy (1987, 2002) which states that groundwater resources can be exploited only up to its recharge limit. The methodology for groundwater resources assessment in India is broadly based on Ground Water Resources Estimation Methodology, 1997 and it involves assessment of annual replenishable groundwater resources (recharge), annual groundwater draft (utilization) and the percentage of utilization with respect to recharge (stage of development). The assessment units (blocks/watersheds) are categorized based on stage of groundwater development (utilization) and the long term water level trend. The present methodology though useful in identification and prioritization of areas for groundwater management, falls short of addressing several critical issues like spatial and temporal variation of groundwater availability within the aquifer, accessibility of groundwater resources and quality of groundwater. This paper introduces a new categorisation scheme considering the above issues. The proposed scheme takes into account four criteria, viz. (i) stage of exploitation, (ii) extractability factor, (iii) temporal availability factor and (iv) quality factor. In comparison to the existing method used for categorisation, the proposed approach is more inclusive. The methodology is also equally suitable for both alluvial and hard rock terrain since it takes into consideration the variable characteristics of different types of aquifers and convergence of quantitative and qualitative assessment. The categorisation proposed here involves GIS based integration of different parameters/ themes. This allows better representation of spatial variability. The proposed methodology is demonstrated in this paper taking a case study from a hard rock terrain in central India.

Groundwater Resource Assessment: in the Context of Bhawaniganj Pourashava

Groundwater Resource Assessment: in the Context of Bhawaniganj Pourashava

Ecology-oriented groundwater resource assessment in the Tuwei River watershed, Shaanxi Province, China

In arid and semi-arid regions, a close relationship exists between groundwater and supergene eco-environmental issues such as swampiness, soil salinization, desertification, vegetation degradation, reduction of stream base flow, and disappearance of lakes and wetlands. When the maximum allowable withdrawal of groundwater (AWG) is assessed, an ecology-oriented regional groundwater resource assessment (RGRA) method should be used. In this study, a hierarchical assessment index system of the supergene eco-environment was established based on field survey data and analysis of the supergene eco-environment factors influenced by groundwater in the Tuwei River watershed, Shaanxi Province, China. The assessment system comprised 11 indices, including geomorphological type, lithology and structure of the vadose zone, depth of the water table (DWT), total dissolved solids content of groundwater, etc. Weights for all indices were calculated using an analytical hierarchy process. Then, the current eco-environmental conditions were assessed using fuzzy comprehensive evaluation (FCE). Under the imposed constraints, and using both the assessment results on the current eco-environment situation and the ecological constraint of DWT (1.5–5.0 m), the maximum AWG (0.408 × 108 m3/a or 24.29 % of the river base flow) was determined. This was achieved by combining the groundwater resource assessment with the supergene eco-environmental assessment based on FCE. If the maximum AWG is exceeded in a watershed, the eco-environment will gradually deteriorate and produce negative environmental effects. The ecology-oriented maximum AWG can be determined by the ecology-oriented RGRA method, and thus sustainable groundwater use in similar watersheds in other arid and semi-arid regions can be achieved.

Redox controls on methane formation, migration and fate in shallow aquifers

Abstract. Development of unconventional energy resources such as shale gas and coalbed methane has generated some public concern with regard to the protection of groundwater and surface water resources from leakage of stray gas from the deep subsurface. In terms of environmental impact to and risk assessment of shallow groundwater resources, the ultimate challenge is to distinguish (a) natural in situ production of biogenic methane, (b) biogenic or thermogenic methane migration into shallow aquifers due to natural causes, and (c) thermogenic methane migration from deep sources due to human activities associated with the exploitation of conventional or unconventional oil and gas resources. This study combines aqueous and gas (dissolved and free) geochemical and isotope data from 372 groundwater samples obtained from 186 monitoring wells of the provincial Groundwater Observation Well Network (GOWN) in Alberta (Canada), a province with a long record of conventional and unconventional hydrocarbon exploration. We investigated whether methane occurring in shallow groundwater formed in situ, or whether it migrated into the shallow aquifers from elsewhere in the stratigraphic column. It was found that methane is ubiquitous in groundwater in Alberta and is predominantly of biogenic origin. The highest concentrations of biogenic methane (&gt; 0.01 mM or &gt; 0.2 mgL−1), characterized by δ13CCH4 values &lt; −55 ‰, occurred in anoxic Na-Cl, Na-HCO3, and Na-HCO3-Cl type groundwaters with negligible concentrations of nitrate and sulfate suggesting that methane was formed in situ under methanogenic conditions for 39.1 % of the samples. In only a few cases (3.7 %) was methane of biogenic origin found in more oxidizing shallow aquifer portions suggesting limited upward migration from deeper methanogenic aquifers. Of the samples, 14.1 % contained methane with δ13CCH4 values &gt; −54 ‰, potentially suggesting a thermogenic origin, but aqueous and isotope geochemistry data revealed that the elevated δ13CCH4 values were caused by microbial oxidation of biogenic methane or post-sampling degradation of low CH4 content samples rather than migration of deep thermogenic gas. A significant number of samples (39.2 %) contained methane with predominantly biogenic C isotope ratios (δ13CCH4 &lt; −55 ‰) accompanied by elevated concentrations of ethane and sometimes trace concentrations of propane. These gases, observed in 28.1 % of the samples, bearing both biogenic (δ13C) and thermogenic (presence of C3) characteristics, are most likely derived from shallow coal seams that are prevalent in the Cretaceous Horseshoe Canyon and neighboring formations in which some of the groundwater wells are completed. The remaining 3.7 % of samples were not assigned because of conflicting parameters in the data sets or between replicates samples. Hence, despite quite variable gas concentrations and a wide range of δ13CCH4 values in baseline groundwater samples, we found no conclusive evidence for deep thermogenic gas migration into shallow aquifers either naturally or via anthropogenically induced pathways in this baseline groundwater survey. This study shows that the combined interpretation of aqueous geochemistry data in concert with chemical and isotopic compositions of dissolved and/or free gas can yield unprecedented insights into formation and potential migration of methane in shallow groundwater. This enables the assessment of cross-formational methane migration and provides an understanding of alkane gas sources and pathways necessary for a stringent baseline definition in the context of current and future unconventional hydrocarbon exploration and exploitation.

A Novel Apparatus for Obtaining In Situ Estimates of Anisotropism Hydraulic Conductivity in Fractured Rocks

Abstract The transmissivity of fractured rocks is the essential data of groundwater resource assessment, groundwater pollution prediction, and the seepage controlling underground project in the consolidated rock regions. However, most of the current experimental methods only provide the macroscopic hydraulic conductivity and the cost is very high. In this paper, a new apparatus is developed to detect the anisotropy of hydraulic conductivity in fractured rocks, which is called the Fractured Rocks Slug Testing (FRST) system. The FRST system consists of image orientation recognition equipment, the slug testing equipment, and a computer and data-acquisition console. The inside view of the testing well/borehole can be obtained by the imaging equipment. The occurrence of the fractures can be detected by the electronic compass. The other parameters like the water level displacement and pressure can also be collected during testing. Moreover, an example test was conducted in the fractured consolidated rock region to verify the effectiveness of the FRST apparatus.

Recent developments on field gas extraction and sample preparation methods for radiokrypton dating of groundwater

Summary Current and foreseen population growths will lead to an increased demand in freshwater, large quantities of which is stored as groundwater. The ventilation age is crucial to the assessment of groundwater resources, complementing the hydrological model approach based on hydrogeological parameters. Ultra-trace radioactive isotopes of Kr ( 81 Kr and 85 Kr) possess the ideal physical and chemical properties for groundwater dating. The recent advent of atom trap trace analyses (ATTA) has enabled determination of ultra-trace noble gas radioisotope abundances using 5–10 μ L of pure Kr. Anticipated developments will enable ATTA to analyze radiokrypton isotope abundances at high sample throughput, which necessitates simple and efficient sample preparation techniques that are adaptable to various sample chemistries. Recent developments of field gas extraction devices and simple and rapid Kr separation method at the University of Chicago are presented herein. Two field gas extraction devices optimized for different sampling conditions were recently designed and constructed, aiming at operational simplicity and portability. A newly developed Kr purification system enriches Kr by flowing a sample gas through a moderately cooled (138 K) activated charcoal column, followed by a gentle fractionating desorption. This simple process uses a single adsorbent and separates 99% of the bulk atmospheric gases from Kr without significant loss. The subsequent two stages of gas chromatographic separation and a hot Ti sponge getter further purify the Kr-enriched gas. Abundant CH4 necessitates multiple passages through one of the gas chromatographic separation columns. The presented Kr separation system has a demonstrated capability of extracting Kr with > 90% yield and 99% purity within 75 min from 1.2 to 26.8 L STP of atmospheric air with various concentrations of CH4. The apparatuses have successfully been deployed for sampling in the field and purification of groundwater samples.

Evolution of chemical and isotopic composition of inorganic carbon in a complex semi-arid zone environment: Consequences for groundwater dating using radiocarbon

Estimating groundwater age is important for any groundwater resource assessment and radiocarbon (14C) dating of dissolved inorganic carbon (DIC) can provide this information. In semi-arid zone (i.e. water-limited environments), there are a multitude of reasons why 14C dating of groundwater and traditional correction models may not be directly transferable. Some include; (1) the complex hydrological responses of these systems that lead to a mixture of different ages in the aquifer(s), (2) the varied sources, origins and ages of organic matter in the unsaturated zone and (3) high evaporation rates. These all influence the evolution of DIC and are not easily accounted for in traditional correction models. In this study, we determined carbon isotope data for; DIC in water, carbonate minerals in the sediments, sediment organic matter, soil gas CO2 from the unsaturated zone, and vegetation samples. The samples were collected after an extended drought, and again after a flood event, to capture the evolution of DIC after varying hydrological regimes. A graphical method (Han et al., 2012) was applied for interpretation of the carbon geochemical and isotopic data. Simple forward mass-balance modelling was carried out on key geochemical processes involving carbon and agreed well with observed data. High values of DIC and δ13CDIC, and low 14CDIC could not be explained by a simple carbonate mineral–CO2 gas dissolution process. Instead it is suggested that during extended drought, water–sediment interaction leads to ion exchange processes within the top ∼10–20m of the aquifer which promotes greater calcite dissolution in saline groundwater. This process was found to contribute more than half of the DIC, which is from a mostly ‘dead’ carbon source. DIC is also influenced by carbon exchange between DIC in water and carbonate minerals found in the top 2m of the unsaturated zone. This process occurs because of repeated dissolution/precipitation of carbonate that is dependent on the water salinity driven by drought and periodic flooding conditions. This study shows that although 14C cannot be directly applied as a dating tool in some circumstances, carbon geochemical/isotopic data can be useful in hydrological investigations related to identifying groundwater sources, mixing relations, recharge processes, geochemical evolution, and interaction with surface water.

APPLICATION OF GIS AND GROUNDWATER MODELLING TECHNIQUES TO IDENTIFY THE PERCHED AQUIFERS TO DEMARKATE WATER LOGGING CONDITIONS IN PARTS OF MEHSANA

Groundwater is very important component of the hydrological cycle. It is an important source of water for drinking, domestic, industrial and agricultural uses. It plays a key role in meeting the water needs of various users sectors in India. Ground water resource is contributed by two major sources – rainfall and the other seepage from irrigation of the crops. A man-made effort through artificial recharge for water conservation structures adds to the ground water. The ground water behaviour in Indian sub-continent is highly complicated due to the occurrence of diversified geological formations with considerable lithological and chronological variations, complex tectonic framework, climatological dissimilarities and various hydro-chemical conditions. Assessment of ground water resources of an area requires proper identification and mapping of geological structures, geomorphic features along with sound information regarding slope, drainage, lithology, soil as well as thickness of the weathered zones. &amp;lt;br&amp;gt; This study is to understand the ground water scenario in the water logged areas of Dharoi command while the surrounding areas showing continuous decline of water levels. The area falls in the command area of Dhorai dam and is in Mehsana District of Gujarat State. A part of northern command of Dharoi Command area falls in hard rock areas while the lower and southern portion fall in alluvial areas in the Dharoi Command (RBC) area in Mahsana Mehsana District of the Gujarat State.&amp;lt;br&amp;gt;&amp;lt;br&amp;gt; The study highlights the application of GIS in establishing the basic parameters of soil, land use and the distribution of water logging over a period of time and the groundwater modelling identifies the groundwater regime of the area and estimates the total recharge to the area due to surface water irrigation and rainfall and suggests suitable method to control water logging in the area.

APPLICATION OF GIS AND GROUNDWATER MODELLING TECHNIQUES TO IDENTIFY THE PERCHED AQUIFERS TO DEMARKATE WATER LOGGING CONDITIONS IN PARTS OF MEHSANA

Abstract. Groundwater is very important component of the hydrological cycle. It is an important source of water for drinking, domestic, industrial and agricultural uses. It plays a key role in meeting the water needs of various users sectors in India. Ground water resource is contributed by two major sources – rainfall and the other seepage from irrigation of the crops. A man-made effort through artificial recharge for water conservation structures adds to the ground water. The ground water behaviour in Indian sub-continent is highly complicated due to the occurrence of diversified geological formations with considerable lithological and chronological variations, complex tectonic framework, climatological dissimilarities and various hydro-chemical conditions. Assessment of ground water resources of an area requires proper identification and mapping of geological structures, geomorphic features along with sound information regarding slope, drainage, lithology, soil as well as thickness of the weathered zones. This study is to understand the ground water scenario in the water logged areas of Dharoi command while the surrounding areas showing continuous decline of water levels. The area falls in the command area of Dhorai dam and is in Mehsana District of Gujarat State. A part of northern command of Dharoi Command area falls in hard rock areas while the lower and southern portion fall in alluvial areas in the Dharoi Command (RBC) area in Mahsana Mehsana District of the Gujarat State. The study highlights the application of GIS in establishing the basic parameters of soil, land use and the distribution of water logging over a period of time and the groundwater modelling identifies the groundwater regime of the area and estimates the total recharge to the area due to surface water irrigation and rainfall and suggests suitable method to control water logging in the area.

Remote Sensing and GIS Based Groundwater Potential Mapping for Sustainable Water Resource Management of Lidder Catchment in Kashmir Valley, India

Abstract: The valley of Kashmir is blessed with abundant water resources. However, high population growth and concentration of population at favorable locations have resulted in increased demand for water. The problem is further aggravated in Lidder catchment where unplanned tourism development has resulted in deterioration of water quality. Multi-Criteria Evaluation (MCE) approach is adopted using IRS P6 LISS III satellite data 2010, geological map published by Geological Survey of India, toposheets prepared by Survey of India, 1961 and field observation. Seven thematic layers (slope, lineament density, drainage density, soil, geology, geomorphology and land use land cover) are generated in GIS environment and weighted according to their relative relevance to groundwater occurrence. Knowledge-based weights and ranks are normalized, and a weighted linear combination technique is adopted to determine the groundwater potential (GWP). The catchment is divided into five zones of very high, high, medium, low and very low GWP. The results show that 50.22% of the total catchment area, which is uninhabited, has very low GWP. However, the densely populated southern part of the catchment has moderate to very high GWP. The study demonstrates that MCE using remote sensing and GIS technology could be efficiently employed as a very useful tool for the assessment and management of groundwater resources especially in regions where data is poor.

3D geological modeling of the Kasserine Aquifer System, Central Tunisia: New insights into aquifer-geometry and interconnections for a better assessment of groundwater resources

Summary The challenge of this study was to create a 3D geological and structural model of the Kasserine Aquifer System (KAS) in central Tunisia and its natural extension into north-east Algeria. This was achieved using an implicit 3D method, which honors prior geological data for both formation boundaries and faults. A current model is presented which provides defendable predictions for the spatial distribution of geology and water resources in aquifers throughout the model-domain. This work has allowed validation of regional scale geology and fault networks in the KAS, and has facilitated the first-ever estimations of groundwater resources in this region by a 3D method. The model enables a preliminary assessment of the hydraulic significance of the major faults by evaluating their influence and role on groundwater flow within and between four compartments of the multi-layered, KAS hydrogeological system. Thus a representative hydrogeological model of the study area is constructed. The possible dual nature of faults in the KAS is discussed in the context that some faults appear to be acting both as barriers to horizontal groundwater flow, and simultaneously as conduits for vertical flow. Also discussed is the possibility that two flow directions occur within the KAS, at a small syncline area of near Feriana. In summary, this work evaluates the influence of aquifer connectivity and the role of faults and geology in groundwater flow within the KAS aquifer system. The current KAS geological model can now be used to guide groundwater managers on the best placement for drilling to test and further refine the understanding of the groundwater system, including the faults connectivity. As more geological data become available, the current model can be easily edited and re-computed to provide an updated model ready for the next stage of investigation by numerical flow modeling.

Water resources assessment in the region of Ben Azzouz (Hadjar Soud, North East Algeria)

Purpose – The purpose of this paper is to give a better knowledge of water resources in the region of Ben Azzouz, and to improve the actual water management through harmonization between the various human communities needs. Design/methodology/approach – After an overview of the geology and hydroclimatology of the study area, the work will be to identify the factors involved in the water balance in the quantitative assessment of groundwater resources, to define areas of use and to estimate water needs for different uses. Findings – The study of the area shows two distinct water reservoirs: the deep aquifer composed of fractured limestone, sands and gravels, and surface massive dune sand aquifer. The impermeable formations are the metamorphic basement and overlying flyschs nappes. Because the average rainfall is relatively high (∼708 mm/year), the region is known by its agricultural vocation and, therefore, most of surface water is assigned to irrigation. The second potential water consumer is population with 2.660 Hm3/year, then industrial needs are 1.793 Hm3/year. Although there was no marked water deficit in the region in the period 2007-2013, it is now time to apply concepts of integrated and sustainable management of water resources in this region because of the growing agricultural practice and population needs. Originality/value – A quantitative diagnosis of water potential of the study area was evaluated for a better rational use of water resources.

Integrated Assessment of Groundwater for Agricultural Use in Mewat District of Haryana, India Using Geographical Information System (GIS)

Groundwater is the primary source of irrigation in the Mewat District of Haryana, India. Thus the population of Mewat is considerably reliant on groundwater for meeting their livelihood and domestic needs. An integrated framework was developed using Geographical Information Systems (GIS) for the assessment of groundwater resources for agricultural use. Groundwater quality was assessed using weighted index method and classified into good (36 %), moderate (47 %) and poor (17 %) zones. Groundwater potential on the other hand was analysed using the weighted overlay approach using eight independent variables. The groundwater potential was further classified into good, moderate and poor zones which occupied 29, 61, and 10 % of the study area respectively. Groundwater vulnerability was assessed using DRASTIC method and was found low, moderate and high in 46, 23 and 31 % of the region respectively. A positive correlation value of 0.23 was observed between groundwater quality and potential. Correlation between groundwater quality and vulnerability was found −0.31. Multivariate clustering method was used to integrate the results of groundwater quality, potential and vulnerability in the study area. The integrated groundwater map was classified into five zones in the study area. The result was validated with the soil fertility, irrigation source, and crop yield. Integrated assessment of groundwater resources in the study area; thus provides useful information to decision makers for undertaking measures for sustainable groundwater resource management in the study area.

Recharge variability and sensitivity to climate: The example of Gidabo River Basin, Main Ethiopian Rift

Gidabo River Basin, located in the south eastern Main Ethiopian Rift (MER). The focus is to characterize the spatial and temporal variability of groundwater recharge, identify the drivers that govern its distribution, and to improve the understanding of its sensitivity to precipitation and temperature in the MER by applying the semi-distributed hydrological model, Soil and Water Assessment Tool (SWAT). The average annual recharge for 1998–2010 reveals a remarkable decrease from the highland (410 mm/year) towards the rift floor (25 mm/year). Both the spatial and temporal recharge variability is mainly controlled by the climate. In the rift floor, recharge is found to occur only when annual precipitation exceeds a threshold of approximately 800 mm. A sensitivity analysis reveals that annual recharge is very sensitive to variations in precipitation and moderately sensitive to temperature changes. The relative sensitivity increases from the highland to the rift floor across the watershed. Increases in both precipitation and temperature, as suggested by climate change projections for Ethiopia, appear to have an overall positive impact on recharge in the majority of the catchment. These findings have implications also for other catchments where recharge is spatially nonuniform and provide a basis for further investigations into the assessment of groundwater resources and their vulnerability to climate change at the watershed and sub-watershed scale.

Chemical Considerations for an Updated National Assessment of Brackish Groundwater Resources.

Brackish groundwater (BGW) is increasingly used for water supplies where fresh water is scarce, but the distribution and availability of such resources have not been characterized at the national scale in the United States since the 1960s. Apart from its distribution and accessibility, BGW usability is a function of the chemical requirements of the intended use, chemical characteristics of the resource, and treatment options to make the resource compatible with the use. Here, we discuss relations between these three chemical factors using national-scale examples and local case studies. In a preliminary compilation of BGW data in the United States, five water types accounted for the major-ion composition of 70% of samples. PHREEQC calculations indicate that 57-77% of samples were oversaturated with respect to barite, calcite, or chalcedony. In the study, 5-14% of samples had concentrations of arsenic, fluoride, nitrate, or uranium that exceeded drinking-water standards. In case studies of the potential use of BGW for drinking water, irrigation, and hydraulic fracturing, PHREEQC simulations of a hypothetical treatment process resembling reverse osmosis (RO) showed that BGW had the potential to form various assemblages of mineral deposits (scale) during treatment that could adversely affect RO membranes. Speciation calculations showed that most boron in the irrigation example occurred as boric acid, which has relatively low removal efficiency by RO. Results of this preliminary study indicate that effective national or regional assessments of BGW resources should include geochemical characterizations that are guided in part by specific use and treatment requirements.