Sole Source Of Water Supply Research Articles

A Numerical Approach to Evaluating Groundwater Vulnerability to Seawater Intrusion on Jeju Volcanic Island, South Korea

Seawater intrusion (SWI) is a critical issue for coastal aquifers, especially in islands where groundwater is the sole source of water supply. The objective of this study was to develop a straightforward approach to evaluating groundwater vulnerability to SWI, using a statistical method with spatial analyses applied to the four basins of Jeju volcanic island. In this study, five factors were parametrized, including hydraulic conductivity, groundwater level, distance from shoreline to wells, well depth and groundwater use. These parameters were spatially interpolated and correlated with groundwater electrical conductivity as a proxy for groundwater salinization, resulting in three parameters with significant relations: groundwater use, well depth, and groundwater level. Then, a numerical model for the SWI vulnerability assessment was constructed using ratings and weights, and by evaluating the vulnerability as weak, moderate and high with a numerical index. Regional conditions, including major land-use types, industrial activities, population and the degree of urbanisation, could affect parameters differently at each region. Based on the percentage of area with a high vulnerability, regions of Jeju Island followed the order of eastern > northern > western > southern, indicating that preventive measures for SWI and its influencing parameters could be applied more effectively in certain regions.

Geophysical and hydrogeological investigation to study groundwater occurrences in the Taref Formation, south Mut area – Dakhla Oasis - Egypt

Integrated geophysical and hydrogeological techniques can give vital information about groundwater occurrence in the south Mut area, where groundwater is the sole source of water supply in this arid area. Quantitative interpretation of the Vertical Electric Soundings (VES) clarified the geoelectric succession in the study area. Geoelectric parameters (resistivity and thickness) of each geoelectric layer and the available data of the existing wells were used to illustrate the vertical and spatial extensions of the encountered layers, depth to the water-bearing layer, the structures affecting these layers, water level and groundwater flow of the concerned aquifer.Groundwater in the study area occurs under confined and semi-confined conditions in the northern part and it occurs under unconfined conditions in the southern part. Dar Zarrouk (DZ) parameters were calculated to differentiate the areas of confined conditions from those of unconfined conditions. Groundwater salinity ranges between 343 and 654 ppm which is suitable for all purposes and its type is calcium sulfate and sodium sulfate.Petrophysical analyses were carried out on the collected rock samples to evaluate their mineralogical and pore properties, which showed that this aquifer is composed of arenite sandstone with good porosity.The results of the analysis of three constant pumping tests revealed that the hydraulic conductivity and transmissivity have high values, indicating that the aquifer has high potentiality. Combining the geoelectrical and hydrogeological results, the best sites for drilling new productive wells were recommended.

Future groundwater extraction scenarios for an aquifer in a semiarid environment: case study of Guadalupe Valley Aquifer, Baja California, Northwest Mexico.

Semiarid northwestern Mexico presents a growing water demand produced by agricultural and domestic requirements during the last two decades. The community of Guadalupe Valley and the city of Ensenada rely on groundwater pumping from the local aquifer as its sole source of water supply. This dependency has resulted in an imbalance between groundwater pumpage and natural recharge. A two-dimensional groundwater flow model was applied to the Guadalupe Valley Aquifer, which was calibrated and validated for the period 1984-2005. The model analysis verified that groundwater levels in the region are subject to steep declines due to decades of intensive groundwater exploitation for agricultural and domestic purposes. The calibrated model was used to assess the effects of different water management scenarios for the period 2007-2025. If the base case (status quo) scenario continues, groundwater levels are in a continuous drawdown trend. Some wells would run dry by August 2017, and water demand may not be met without incurring in an overdraft. The optimistic scenario implies the achievement of the mean groundwater recharge and discharge. Groundwater level depletion could be stopped and restored. The sustainable scenario implies the reduction of current extraction (up to about 50%), when groundwater level depletion could be stopped. A reduction in current extraction mitigates water stress in the aquifer but cannot solely reverse declining water tables across the region. The combination of reduced current extraction and an implemented alternative solution (such as groundwater artificial recharge), provides the most effective measure to stabilize and reverse declining groundwater levels while meeting water demands in the region.

Metal enrichment in the groundwater of the arid environment in South Africa

This paper presents the enrichment tendency and spatial distribution of metals in the groundwater which is pumped out from the granitic aquifers in South Africa. Groundwater is the sole source of water supply for the local community in the study area (Namaqualand), and hence, it was necessary to understand the controlling geochemical processes and interrelationship of metals in the groundwater. The geochemical association of metals has been assessed based on the geostatistical methods. The results show that geochemical processes such as oxidation, leaching, and evaporation besides water–rock interaction are very important in controlling metal enrichment in the groundwater from highly mineralized rocks. The metal enrichment index for selected toxic metals in groundwater increases in the order of Cd > U > Cr > Pb. The observed enrichment trend could be considered as a result of mineralization of basement rocks which is facilitated by active geochemical process in the arid environment. The lack of aquifer flushing due to negligible recharge helps the metals to concentrate at shallow groundwater zones supported by severe evaporation process.

Site-specific accentuation of heavy metals in groundwaters from Ankaleshwar industrial estate, India

The seasonal behavior of environmentally sensitive polymetallic contaminants in groundwaters from Ankaleshwar industrial estate (AIE) India was studied. The potentially toxic elements (Co, Cr, Cu, Mn, Fe, Mo and Ni) demonstrated accentuated enrichment signatures during post-monsoon, besides colossal spatial variability on temporal scale. GIS-based accrual factor raster mapping facilitated the spot-specific quantitative and comparative appraisal of metallic distensions during post-monsoon with a decreasing hierarchy of seasonal augmentation Ni > Cu > Mn > Fe > Co > Mo > Cr. High inconsistencies and spot (pixel) strict exceedingly high accrual factors over these maps concur with diverse land use and surface-polluting sources. Inter-annual adiabatic extension of heavy metals in groundwaters implies their widespread availability in soil and atmospheric backgrounds in the region. Dissimilar performance with contrasting accretion patterns of redox-sensitive metals (Fe and Mo) is revealed by three-component color composites. Heavy metal hyper-accrual realms warrant an immediate demand for upgrading the existing waste management methodologies and aquifer remediation, as the region is highly cultivated and groundwater is the sole source of water supply for drinking, agricultural and other purposes.

Optimal Pump and Recharge Management Model for Nitrate Removal in the Warren Groundwater Basin, California

The town of Yucca Valley located in the southwest part of the Mojave Desert in southern California relies on groundwater pumping from the Warren groundwater basin as its sole source of water supply. This significant dependency has resulted in a large imbalance between groundwater pumpage and natural recharge, causing groundwater levels in the basin to decline more than 90 m from the late 1940s to 1994. Consequently, an artificial recharge program proposed by the Hi-Desert Water District, which provides water service to the town of Yucca Valley, was implemented for the purpose of recovering the groundwater levels; however, the rise in groundwater levels has caused nitrate ( NO3 ) concentration to increase simultaneously. The purpose of this study is to develop an optimal pump and recharge strategy for a planned conjunctive-use project to remove the high-nitrate concentration while maintaining groundwater levels at desired elevations at specified locations as well as meeting water demand. An optimization/ma...

The Effects of Urbanization on Groundwater Quantity and Quality in the Zahedan Aquifer, southeast Iran

This paper investigates the impacts of urban growth on groundwater quality and quantity in the Zahedan aquifer, which is the sole source of water supply for the city of Zahedan, Iran. The investigation is based on the collection of available historical data, supplemented by field and laboratory investigations. Groundwater levels in 40 wells were measured in December 2000. In addition, 102 water samples were taken in two periods during November and December 2000. Of these, 43 samples were analyzed for major ions, 32 samples were analyzed for nitrogen and phosphorus and the remainder for bacteriological contamination. The water level data show that there has been a general decline since 1977 due to over-abstraction. The magnitude of this decline has reached about 20 m in some places. However, in one area over the same period, a rise of about 3 m has been observed. This occurs as a result of the local hydrogeological conditions of shallow bedrock and relatively low permeability materials down stream of this area that limits the flow of groundwater towards the northeastern part of the aquifer. The general fall in groundwater levels has been accompanied by a change in the direction of the groundwater flow and an overall reduction of the areal extent of the saturated region of the aquifer. The city now has a serious problem such that even if the abstracted groundwater is rationed, water is not available for long periods because the demand far exceeds the supply. The heavy impact of urbanization on the groundwater quality is shown through the observed high nitrate (up to 295 mg/l as nitrate) and high phosphorus values (about 0.1 mg/l as P). Significant changes in the chloride concentration are also observed in two areas: increasing from 100 mg/l to 1,600 mg/l and from 2,000 mg/l to 4,000 mg/l, respectively. Furthermore, the bacteriological investigations show that 33 percent of the 27 collected groundwater samples are positive for total coliform and 11 percent of the samples contained fecal coliforms indicating that local sources are strongly influencing the observed chemical data. Greater depths to groundwater reduce the observation of coliform contamination. In general, the unplanned urban development in Zahedan has significantly degraded the region's water resources and significant actions such as upgrading the sewage waste disposal system, locating other sources of water supply, and strict groundwater management will all be needed to resolve the problems that have arisen.

Toward optimal waste management policies for a river basin

A mathematical analysis of marginal cost functions, where the total basin-wide treatment cost for a series of users of water in a river basin is to be minimized subject to constraints, is presented. The situation considered is where a series of water-using firms are located along a river; the river being the sole source of water supply and the only place to discharge wastewater. In such a situation, upstream users, if they discharge waste, impose damage costs on those downstream. On the other hand, if the upstream user is restricted in discharging wastes into the river, the costs for withholding or treating of these wastes are imposed on him. This trade-off is the basis for the minimization of the total basin-wide treatment cost. The results of this study show that under most conditions an optimal solution can be found which balances the upstream marginal waste withholding cost with the downstream damage costs. The analysis is concluded with a presentation of conditions which make these marginal cost relationships sufficient as well as necessary for optimally. Although stream-flow, inflow and outflow are treated as deterministic, this model should be valid except during extreme, transient conditions.

Hydrologic studies of the Putah Creek area in the Sacramento Valley, California

does not appear. First page follows. Introduction The deep alluvial fill of Putah Creek forms a storage basin from which much irrigation water is pumped. Continued and expanding demand upon the underground water supply has caused a gradual recession in the water plane. This condition leads many farmers to question the permanency of their water supply. The College of Agriculture at Davis is located within the basin of Putah Creek. In years of low rainfall, the underground basin is its sole source of water supply. Hence, since the early days of the institution, the Division of Irrigation has observed underground water conditions on the University Farm. The deficient rainfall of the winter of 1930-31 emphasized the need for a comprehensive study of the water supply in the Putah Creek area. Although Bryan (2)5 studied the basin in 1912, conditions have changed materially since that date. An informal project, outlining a study to supplement existing information on the water supply and the pumping conditions of the area, was formulated by the divisions of Agricultural Engineering, Chemistry, and Irrigation.