Implications For Groundwater Management Research Articles

Two decades of land subsidence in Kolkata, India revealed by InSAR and GPS measurements: implications for groundwater management and seismic hazard assessment

Two decades of land subsidence in Kolkata, India revealed by InSAR and GPS measurements: implications for groundwater management and seismic hazard assessment

Climate changes and variability in the Great Artesian Basin (Australia), future projections, and implications for groundwater management

The Great Artesian Basin (GAB) in Australia is one of the largest aquifer systems in the world and it supports a range of agriculture, industry, fragile ecosystems, and townships. Climate variability and future projections of climate change will impact on both recharge of the GAB and demands on the resource. Understanding the climate in the GAB region is therefore critical to informing regional groundwater management. Observed decadal climatic variability and trends were assessed for significance with Kendall’s test and investigated in light of future climate scenarios with 40 global climate model (GCM) outputs. Historic climate observations show that the GAB region had become warmer and wetter over the last five to six decades. The annual rainfall increased by 0.95 mm/year2 during the period 1960–2016, although this trend magnitude was neither statistically significant nor uniform geographically across the GAB. The annual means of daily mean, maximum, and minimum temperatures increased during that period by 0.019, 0.019, and 0.020 °C/year, with statistically significant increases in 92.4, 91.4 and 85.1% of the GAB, respectively. Trends of other rainfall statistics associated with recharge indicated an increase of the 95th percentile daily rainfall amount, an increase of average rainfall intensity, and a statistically significant decrease in mean wet-spell length. In contrast with past warm and wet climate, the future climate in the GAB region is projected to be warmer and drier, which would potentially produce serious challenges for groundwater resources management for the region.

Simulating deep drainage and nitrate leaching on a regional scale: implications for groundwater management in an intensively irrigated area

Groundwater management in irrigation areas requires a comprehensive understanding of the interactions between agricultural management practices and the underlying groundwater resource. Unsaturated zone modelling can be used to predict rates of water and solute movement through the soil profile. By incorporating expert knowledge and measured data, it is possible to investigate the relative influence of management vs environmental factors on water and solute movement. The Agricultural Production Systems sIMulator (APSIM) has been applied to simulate the impacts of both environmental factors and agricultural management factors on deep drainage and nitrate leaching in the Lower Burdekin, North Queensland, Australia. Based on the results of this modelling, predicted annual average deep drainage rates were found to be controlled primarily by soil properties, irrigation scheduling, and, to a lesser extent, annual rainfall. The key factors which were found to control nitrate leaching were: irrigation water quality, fertilizer application rates, soil type, crop management, and irrigation scheduling. However, increases in the concentrations of nitrate in irrigation water resulted in a 64-fold increase in predicted nitrate-leaching rates, compared with a 22-fold increase in predicted nitrate-leaching rates associated with increased fertilizer application rates. As significant quantities of nitrate are predicted to be leached below the root zone, the immediate priority should be to increase monitoring of groundwater quality with a focus on quantifying the transport of nutrients to sensitive receptors.

Seasonal and spatio-temporal patterns, evolution and quality of groundwater in Cross River State, Nigeria: implications for groundwater management

A systematic study was carried out to understand the spatial, temporal and seasonal variability of the hydrochemical processes controlling the water chemistry in Cross River State (Nigeria). This is based on the fact that existing aquifers are prone to contamination and no comprehensive study exists in the literature to address this problem. Results of the study showed that the groundwater samples are moderately acidic (pH 4.01–7.57), fresh (TDS Na+ > Mg2+ > K+ and Cl− > HCO3− > SO42− for all the different sampling scenarios. Interpretation of the analytical data showed predominance of water types such as Na+–Cl− > Ca2+–Cl− > Ca2+–HCO3−. Chemical data indicate that irrespective of the scenario considered, the water chemistry is controlled by silicate and carbonate weathering, brine dissolution, ion exchange, biological and human activities. The results also suggest good quality water for drinking and agricultural applications based on national and international indices and standards. The findings of this study will act as a guide against future pollution of groundwater and sustainable development of groundwater resource in Cross River State.

An Observatory of Groundwater in Crystalline Rock Aquifers Exposed to a Changing Environment: Hyderabad, India

Core Ideas Long‐term observatories allow the study of global changes to water resources in India. Crystalline rock aquifers are highly heterogeneous. Management of crystalline aquifers necessitates solving several scientific questions. A multidisciplinary approach is necessary for improving water management in India. Multiscale and long‐term work is needed to tackle the scientific challenges found in areas vulnerable to climate change and anthropic pressure. This is the case in the semiarid and drought‐prone regions of southern India where freshwater is scarce and agriculture near fast‐growing cities is triggering high water demand. The Indo‐French Center for Groundwater Research (IFCGR) was established in 1999 between the Indian National Geophysical Research Institute (NGRI) and the French Geological Survey (BRGM) at the NGRI campus in Hyderabad, India. For almost 20 yr, the IFCGR has studied the hydrodynamic properties and associated hydrological processes in crystalline aquifers. To that end, the Center set up two sites for observing groundwater in crystalline rock aquifers: (i) the Maheshwaram basin for the study of groundwater management at catchment scale, and (ii) the Choutuppal experimental site for the detailed study of hydrogeological processes at local scale (between wells). Multiscale approaches allow the characterization of hydrodynamic and transport properties of the shallow weathered part of such crystalline aquifers and the implications for groundwater management under overexploitation conditions. The objective is to provide suitable characterization of aquifer properties for developing modeling and management tools applicable to such heterogeneous aquifers.

The Safe Yield and Climatic Variability: Implications for Groundwater Management.

Methods for calculating the safe yield are evaluated in this paper using a high-quality and long historical data set of groundwater recharge, discharge, extraction, and precipitation in a karst aquifer. Consideration is given to the role that climatic variability has on the determination of a climatically representative period with which to evaluate the safe yield. The methods employed to estimate the safe yield are consistent with its definition as a long-term average extraction rate that avoids adverse impacts on groundwater. The safe yield is a useful baseline for groundwater planning; yet, it is herein shown that it is not an operational rule that works well under all climatic conditions. This paper shows that due to the nature of dynamic groundwater processes it may be most appropriate to use an adaptive groundwater management strategy that links groundwater extraction rates to groundwater discharge rates, thus achieving a safe yield that represents an estimated long-term sustainable yield. An example of the calculation of the safe yield of the Edwards Aquifer (Texas) demonstrates that it is about one-half of the average annual recharge.

Distinct groundwater recharge sources and geochemical evolution of two adjacent sub-basins in the lower Shule River Basin, northwest China

Based on analysis of groundwater hydrogeochemical and isotopic data, this study aims to identify the recharge sources and understand geochemical evolution of groundwater along the downstream section of the Shule River, northwest China, including two sub-basins. Groundwater samples from the Tashi sub-basin show markedly depleted stable isotopes compared to those in the Guazhou sub-basin. This difference suggests that groundwater in the Tashi sub-basin mainly originates from meltwater in the Qilian Mountains, while the groundwater in the Guazhou sub-basin may be recharged by seepage of the Shule River water. During the groundwater flow process in the Tashi sub-basin, minerals within the aquifer material (e.g., halite, calcite, dolomite, gypsum) dissolve in groundwater. Mineral dissolution leads to strongly linear relationships between Na+ and Cl− and between Mg2++ Ca2+ and SO4 2− + HCO3 −, with stoichiometry ratios of approximately 1:1 in both cases. The ion-exchange reaction plays a dominant role in hydrogeochemical evolution of groundwater in the Guazhou sub-basin and causes a good linear relationship between (Mg2++ Ca2+)–(SO4 2− + HCO3 −) and (Na++ K+)–Cl− with a slope of −0.89 and also results in positive chloroalkaline indices CAI 1 and CAI 2. The scientific results have implications for groundwater management in the downstream section of Shule River. As an important irrigation district in Hexi Corridor, groundwater in the Guazhou sub-basin should be used sustainably and rationally because its recharge source is not as abundant as expected. It is recommended that the surface water should be used efficiently and routinely, while groundwater exploitation should be limited as much as possible.

Impacts of a large Sahelian city on groundwater hydrodynamics and quality: example of Niamey (Niger)

The management of groundwater resources is very important in the semiarid Sahel region, which is experiencing rapid urban development. Impacts of urbanization on groundwater resources were investigated in the unconfined aquifer of the Continental Terminal beneath the city of Niamey, Niger, using water level and chemical data. Hydrodynamic and chemical changes are best described by a combination of factors including the historical development of the city, current land use, water-table depth and topography. Seasonal groundwater recharge occurs with high spatial variability, as indicated by water-level monitoring in all wells, but there was no interannual trend over the 5-year study period. Groundwater salinity shows high spatial variability and a minor rising trend. The highest salinity is in the old city centre, with Na–NO3 dominant, and it increases seasonally with recharge. Salinity is much lower and more variable in the suburbs (Ca–HCO3, Ca–NO3, and Na–NO3 dominant). Nitrate is the main ionic contaminant and is seasonally or permanently above the international guidelines for drinking water quality in 36 % of sampled wells, with a peak value of 112 mg L−1 NO3–N (8 meq L−1). Comparison of urban and rural sites indicates a long-term increase in groundwater recharge and nitrate enrichment in the urban area with serious implications for groundwater management in the region.

Identification of sources and infiltration regimes of nitrate in the semi-arid Kalahari: Regional differences and implications for groundwater management

The Kalahari region of southern Africa offers much potential for nitrogen input into its groundwater. High nitrate concentrations in Kalahari groundwater are therefore quite common and are caused by both anthropogenic and natural sources. Forecasting groundwater nitrate concentrations remains challenging. Source identification of nitrate contamination in groundwater is an important first step for groundwater management and quality prediction, and is aided by isotope analysis of nitrate in the water. Comparative data from 3 groundwater study sites in the Kalahari of Botswana and Namibia with widely different characteristics are presented. Two of the sites (Ghanzi and Gobabis) have shallow water tables in fractured quartzite. These aquifers were affected by pollution from cattle wastes (manure) and septic tank outflows resulting in groundwater nitrate levels exceeding 1 000 mg NO3/. and in ƒÂ15N values of between +7 and +20 n AIR. Short-term increases of groundwater nitrate concentrations were triggered by exceptional rainfall events occurring every 10-20 years. At the third site (Serowe in Botswana) there is similar land use and land cover, yet the aquifers are deeper, groundwater dates to Late-Pleistocene age and borehole levels do not show a response to present-day high-rainfall episodes. Nitrate levels up to 219 mg/. are found, but lower 15N content (ƒÂ15N of +3 to +8 n) indicates a natural origin of the nitrate. In this area pollution nitrate is sufficiently delayed in the vadose zone, reaching the saturated zone much later. The data from all 3 sites suggest that nitrogen management options can only be evaluated once an understanding of sources, processes and flow patterns has been established.

Groundwater Recharge Environments and Hydrogeochemical Evolution in Beijing, China: Multi-Tracer Approach

The groundwater recharge environments and hydrogeochemical characteristics in Beijing were investigated using a combination of chemical indicators, stable isotopes, and radiocarbon dating. There are two distinct zones for those groundwaters: modern water (1000 a) are depleted, which implies that the palaeowaters were recharged in relatively cold climate. The TDS for all groundwater samples range from 312 to 914 mg/L. Groundwaters are supersaturated with respect to calcite and the δ13C value is stable (around -13‰), which suggests dissolution of calcite is limited. Dissolution of halite, sulfate and carbonate and exchange of cations are main processes of water chemistry. The results have important implications for groundwater management in Beijing, where a certain proportion of the unrenewable water has been mined.

Movement of Water Infiltrated from a Recharge Basin to Wells

Local surface water and stormflow were infiltrated intermittently from a 40-ha basin between September 2003 and September 2007 to determine the feasibility of recharging alluvial aquifers pumped for public supply, near Stockton, California. Infiltration of water produced a pressure response that propagated through unconsolidated alluvial-fan deposits to 125 m below land surface (bls) in 5 d and through deeper, more consolidated alluvial deposits to 194 m bls in 25 d, resulting in increased water levels in nearby monitoring wells. The top of the saturated zone near the basin fluctuates seasonally from depths of about 15 to 20 m. Since the start of recharge, water infiltrated from the basin has reached depths as great as 165 m bls. On the basis of sulfur hexafluoride tracer test data, basin water moved downward through the saturated alluvial deposits until reaching more permeable zones about 110 m bls. Once reaching these permeable zones, water moved rapidly to nearby pumping wells at rates as high as 13 m/d. Flow to wells through highly permeable material was confirmed on the basis of flowmeter logging, and simulated numerically using a two-dimensional radial groundwater flow model. Arsenic concentrations increased slightly as a result of recharge from 2 to 6 µg/L immediately below the basin. Although few water-quality issues were identified during sample collection, high groundwater velocities and short travel times to nearby wells may have implications for groundwater management at this and at other sites in heterogeneous alluvial aquifers.

Stratigraphic controls on seawater intrusion and implications for groundwater management, Dominguez Gap area of Los Angeles, California, USA

Groundwater pumping has led to extensive water-level declines and seawater intrusion in coastal Los Angeles, California (USA). A SUTRA-based solute-transport model was developed to test the hydraulic implications of a sequence-stratigraphic model of the Dominguez Gap area and to assess the effects of water-management scenarios. The model is two-dimensional, vertical and follows an approximate flow line extending from the Pacific Ocean through the Dominguez Gap area. Results indicate that a newly identified fault system can provide a pathway for transport of seawater and that a stratigraphic boundary located between the Bent Spring and Upper Wilmington sequences may control the vertical movement of seawater. Three 50-year water-management scenarios were considered: (1) no change in water-management practices; (2) installation of a slurry wall; and (3) raising inland water levels to 7.6 m above sea level. Scenario 3 was the most effective by reversing seawater intrusion. The effects of an instantaneous 1-m sea-level rise were also tested using water-management scenarios 1 and 3. Results from two 100-year simulations indicate that a 1-m sea-level rise may accelerate seawater intrusion for scenario 1; however, scenario 3 remains effective for controlling seawater intrusion.

Hydrogeology and groundwater ecology: Does each inform the other?

The known, perceived and potential relationships between hydrogeology and groundwater ecology are explored, along with the spatial and temporal scale of these relations, the limit of knowledge and areas in need of research. Issues concerned with the subterranean part of the water cycle are considered from the perspective of the biology of those invertebrate animals that live, of necessity, in groundwater and the microbiological milieu essential for their survival. Groundwater ecosystems are placed in a hydrogeological context including the groundwater evolution along a flowpath, the significance of the biodiversity and of the ecosystem services potentially provided. This is considered against a background of three major components essential to the functioning of groundwater ecosystems, each of which can be affected by activities over which hydrogeologists often have control, and each, in turn, may have implications for groundwater management; these are, a place to live, oxygen and food (energy). New techniques and increasing awareness amongst hydrogeologists of the diversity and broad distribution of groundwater ecosystems offer new opportunities to develop cross disciplinary work between hydrogeologists and groundwater ecologists, already demonstrated to be a field for collaboration with broad benefits.

Groundwater geochemistry of the Chihuahua City region in the Rio Conchos Basin (northern Mexico) and implications for water resources management

AbstractThe Chihuahua City region, located in the semiarid‐arid northern highlands of Mexico, has experienced intensive groundwater abstraction during the last 40 years to meet water demands in the region. A geochemical survey was carried out to investigate the evolution from baseline to modern conditions of a 130‐km flow path including the El Sauz–Chihuahua–Aldama–San Diego de Alcalá regions. The research approach included the use of major chemical elements, chlorofluorocarbons and environmental isotope (18O, 2H, 13C and 14C) tracers. Stable isotopes indicate that groundwater evolves from the evaporation of local rainfall and surface water. Groundwater located at the lower end of the flow section is up to 6000 years old and older groundwater in the order of 9000 years BP was found in a deep well located in the upper part of the flow system, implying contribution from a neighbour basin. The background groundwater chemistry upstream of Chihuahua City results from feldspar weathering. Beyond Chihuahua City the chemical conditions are strongly modified owing to disposal of sewage from public and industrial water supplies into the Rio Chuviscar, subsequent allocation of this water to agricultural irrigation areas and direct infiltration under the river bed. As a consequence, anions like chloride and sulphate are mainly related to surface sources. Nitrate is controlled in part by sewage from public supply and industry and in part by agricultural practices. Arsenic and fluoride are related to weathering of rock formations of local mineralized ranges and subsequent enrichment of the basin‐fill by magmatic processes. The results of this study have implications for groundwater management in an arid region that depends entirely on groundwater for domestic, industrial and agricultural water consumption. Copyright © 2008 John Wiley & Sons, Ltd.

Remotely sensed actual evapotranspiration: implications for groundwater management in Botswana.

In order to determine evapotranspiration losses from the groundwater of an aquifer in Botswana during the dry season, the multi-step Surface Energy Balance Algorithm for Land (SEBAL) was applied using sequential Landsat TM and NOAA-AVHRR data. During satellite overpasses, continuous data on surface temperatures and soil moisture were available from a meteorological tower and field observations for calibration and partial validation of the results. The SEBAL method yielded high actual evapotranspiration (Ea) rates (1.5 – 3 mm/d), if relatively dense savannah vegetation was present, even when the water-table was over 30 m deep, as is the case in the upper part of the aquifer. No relationship between Ea and depth to water-table was found, except in the valleys, where riverine forests are fed by a system of discharging groundwater flow. The patterns on a vegetation map, based on a supervised classification using TM data, including thermal bands, showed similarity with the Ea patterns. The spatial distributions of vegetation types and of Ea have been interpreted as important uptake of water by deep roots; this is supported by increasing evidence from other parts of the world. Sap flow was measured in tall bushes near the tower site. The upper part (2 m) of the soil was dry. The results have implications for the groundwater recharge mechanism and the management of groundwater. Further validation studies have been initiated.