Decline In Groundwater Quality Research Articles

Assessing the sustainability of groundwater quality for irrigation purposes using a fuzzy logic approach

Deterioration of water quality poses significant threats to various aspects of life, particularly affecting agricultural irrigation, the primary source of food production for human consumption. In Iran, unregulated groundwater extraction for agriculture has resulted in a decline in groundwater quality, exemplified by a reduction in permitted wells for water exploitation in the Houmand-Absard aquifer from 47 to 20 over 18 years. Current water quality assessments for agricultural use often employ indicators focusing on specific ions, neglecting a comprehensive evaluation. This study introduces the Fuzzy Groundwater Quality Index (FGWQI), utilizing a fuzzy inference system model to appraise groundwater quality in the Houmand-Absard aquifer, specifically for irrigation in Iran. The FGWQI amalgamates five agriculture-oriented quality indicators: Sodium Adsorption Ratio (SAR), Sodium Percentage (Na%), Magnesium Hazard Ratio (MHR), Kelly's Index (KI), and Potential Salinity (PS). Comparative analyses between FGWQI and the widely used MHR were conducted on water samples collected from twenty stations during the 2021 seasons. Laboratory analyses of the samples determined parameters including Sodium, Calcium, Magnesium, Chloride, and Sulfate. The FGWQI model outperformed traditional indicators, notably MHR, demonstrating more realistic assessments. Despite MHR deeming water quality unsuitable in 47% of cases where FGWQI surpassed 60, FGWQI indicated permissible results (30–70), suggesting that, with proper groundwater management, a greater water resource allocation to agriculture is feasible. By adopting FGWQI over MHR, water wells deemed suitable for irrigation won't be decommissioned, offering farmers increased flexibility in groundwater utilization in the case study region.

Nitrate Contamination of Groundwater in Selected Industrial and Non Industrial Sites, Coimbatore District, Tamil Nadu: Exposure and Health Risk Assessment

Groundwater resources are essential for sustaining human health, agricultural productivity, and industrial growth. In recent years, anthropogenic influences have caused a sharp decline in ground water quality, which is also having an impact on human health in many parts of India. It is crucial to analyze the risk of contamination to human health and the quality of the water supply. Coimbatore is one of the rapidly growing industrial areas in South India. The industrial areas of ground water have a significant impact on ground water quality due to anthropogenic activities such as discharge of Industrial waste, chemicals and pollutants into the ground which make water unsuitable for human and industrial use. Nitrate is the emerging contaminant which can cause a deadly disease methehemoglobinemia. Hence the present study is focused to analyze the ground water of selected industrial and non industrial sites of Coimbatore city. Nitrate concentration ranged from 32.90 to 88.13 mg/l in the samples industrial and non-industrial sites, and over 37% of both the sites had nitrate levels that above the Bureau of Indian Standards’ and WHO’s acceptable limits (45 mg/l and 50 mg/l, respectively). The USEPA human health risk assessment tool was used to examine the potential health hazards of increased nitrate intake for both adults and children.

Assessing the impact of urbanization on groundwater quality of lahore region, Pakistan.

Land use land cover (LULC) dynamics is an important aspect of environmental studies. Lahore is one of the wide-ranging urban cities in the world experiencing rapid development in the form of unplanned urban growth and industrialization, which leads to many adverse consequences. This research focuses on the study of spatio-temporal variability of urbanization and its impact on the water quality index (WQI) in Lahore city using remote sensing (RS) and geographical information systems (GIS). Landsat images (Landsat 7 ETM+, Landsat 8 OLI) between 2005 to 2021 were used to observe the changes in urban growth over seventeen years. GIS is used to create the LULC, normalized difference vegetation index (NDVI), and normalized difference built-up index (NDBI) maps, to study the urbanization impact on the WQI. The results of this study indicate that the groundwater quality of metropolitan Lahore city has significantly dropped within 17years. The extent of the built-up area has been expanded from 22.4% to 953.04% with an increase in the poor WQI area from 1.95% to 37.89%, reveals a general decline in groundwater quality with urbanization. Indeed, the trends observed by the linear regression modelling showed a positive and negative correlation (R2 = 0.67 and -0.74) of WQI with % of urban and vegetation areas respectively. GIS and RS tools have been found effective in assessing spatio-temporal phenomena of urbanization and its impact on groundwater quality. Furthermore, this research would be very helpful in making decisions for managing groundwater resources and illegal urban expansion in Lahore city.

Using geochemical models to delineate the relationship between the Pleistocene aquifer groundwater and the oxidation ponds at El-Sadat city, Egypt

This study aims to assess the risk of the wastewater plume from the oxidation ponds contaminating the underneath shallow groundwater aquifer. The study area is an industrial city comprised of three main zones: industrial, populated, and agricultural. The study area is bordered on the eastern side by a wastewater pond and the Rosseta Nile river branch. The geochemical investigation is based on the determination of groundwater salinity, major ions, nitrogen compounds (NH4−, NO2−, NO3−), phosphate (PO43−), heavy metals, and the isotopic content (δ18O and δ2H) as well as the geochemical groundwater modeling. The results show most groundwater samples (50%) in the study area are freshwater, 31% are marginal saline water, and 18% are brackish. Higher nitrogen and PO43− compound concentrations are found in the shallow groundwater close to the oxidation ponds and populated zone. The δ18O and δ2H in the Quaternary groundwater is relatively depleted; they range from −2.1 to 2.3‰ and −7 to 21‰, respectively. The integrations of the geochemistry and isotopes show that the Pleistocene aquifer receives considerable recharge percent (14–56%) from the Rosseta Nile river branch and has been polluted due to the seepage from the oxidation ponds (seepage percent range: 0.6–3.6%). The results suggest that excessive fertilizer usage in the agricultural zone, seepage from oxidation ponds into the subsurface aquifer, and the anthropological effects of population size and industrial zones all contribute to the decline in groundwater quality. The highly vulnerable groundwater sites extend from the northeastern areas close to the oxidation ponds and the southwestern areas close to the industrial and populated zones.

Improving the Sustainability of Urban Water Management through Innovative Groundwater Recharge System (GRS)

Negative impacts of groundwater overuse have always been one of the problems of modern cities in arid and semi-arid regions; rapid population growth and climate change have also exacerbated these problems in many areas. One of the best approaches to deal with the impacts of these phenomena (soil subsidence, decline in groundwater quality, and seawater intrusion) is to artificially recharge water into aquifers and raise the groundwater level. In this paper, an innovative solution called Groundwater Recharge Systems (GRS) is proposed with high efficiency, low cost, and fast implementation capability to address these problems. The proposed solution also has the capability of being constructed in urban environments without the need to allocate any spacious land or the need to use any sophisticated technologies. The study of implementing the proposed groundwater recharge systems in the study area showed that the performance of this system, even in worst-case scenarios, will be very significant even considering climate change impacts such as seawater level rise and decline in precipitation.

The application of geographical information system (GIS) approach for assessment of groundwater quality of Zahedan city, Sistan and Baluchestan Province, Iran

The chemical analysis of groundwater samples in 29 well in the Zahedan, Sistan and Baluchestan Province, southeast of Iran was evaluated to determine the hydro-chemical processes and assessment of groundwater quality. In present study the Geographic Information System (GIS) approach was used for Groundwater Quality Index(GQI). The value of this index was reported to be in the average range 48.21% that due to the high amounts of electrical conductivity (EC), total dissolved solids (TDS), total hardness (TH), sulfate ( SO42−), chloride (Cl−) and sodium (Na+)in the water resources. The Gibbs diagram indicated that groundwater chemistry in this area has obtained mainly from evaporation dominance. Assessment of hydrochemical characteristics using Piper trilinear diagram indicates Na–Cl as the predominant hydrochemical facies. Estimates show that water quality in the area has declined. The reasons for the decline in groundwater quality include the lack of rainfall, incomplete feeding of the aquifer and geology of the surrounding area. Finally, solutions were proposed to maintain and improve groundwater quality in the region.

Pollen and diatom evidence of sea water intrusion, east flood canal (Banjir Kanal Timur), Semarang, Indonesia

Semarang City, Indonesia is plagued by a combination of widespread flooding during the wet season and a lack of fresh (potable) water during the dry season, the latter related to saltwater intrusion. The East Flood Canal (Banjir Kanal Timur = BKT) was built to address these problems by improving runoff (drainage) and increasing groundwater recharge. This research was conducted to reconstruct the history of environmental change, including seawater intrusion, along the coast of Semarang using pollen and diatom assemblages from a 190-cm-long, 210Pb-dated sediment core extracted from the estuary at the mouth of the BKT. The age of the sediments within the core ranged over 160 years (the surface dated to 2014). The sediments could be subdivided into three zones on the basis of pollen assemblages and 2 zones on the basis of diatom assemblages. Lower zone assemblages, dominated by Sonneratia alba (mangrove), Acrostichum aureum (Pteridophyte), and Cocconeis pediculus (an epiphytic diatom), indicate that historically, the estuarine ecosystem was relatively open to the Java Sea and characterized by periods of marine and freshwater conditions. Thereafter, an upward increase in saline mangrove species of pollen and diatoms, combined with the loss of freshwater species (e.g., Avicennia and Rhizophora), indicates an increasing prevalence of marine conditions at the mouth of the BKT. Increasing salinity was associated with a landward shift in the mangrove ecosystem, a trend indicated by the progressive increase in mangrove plant diversity as statically manifested by the three pollen zones. This landward shift was associated with a “closing off” of marine flow in response to a significant (order of magnitude) increase in the estuarine sedimentation rates at about 1981. Increased sedimentation was presumably related to land-use changes that enhanced sediment delivery to the coast via the BKT. Inherent in these sediments were allochthonous fragments of Asterionella formosa, a freshwater species found in the upper sediment layers. The results of this study are consistent with the increased saltwater intrusion along the coast and a decline in groundwater quality.

Mapping of Groundwater Vulnerability Index in the Alluvial Plain of Semarang City Using the Susceptibility Index Method

One of the negative impacts of settlements and urbanization is the decline in groundwater quality. In maintaining the sustainability of groundwater for a long period of time, a special study is needed, which can be done by examining groundwater vulnerability. The alluvial plain of Semarang City currently faces environmental problems such as degradation of groundwater quality which is the negative impact of the settlement, The purpose of this study was to examine groundwater vulnerability in the alluvial plain area of Semarang City. The Susceptibility Index method is using a spatial analysis tool based on rating and weighting value of some parameters, i.e. Depth of groundwater, recharge, aquifer media, slope, and land use. The result of this research reveals that about 41.3% area is covered under the high vulnerable zone, 50.3% area under moderately vulnerable zone and 8.4% area under the low vulnerable zone. 7 sub districts namely Tugu, Semarang Barat, Semarang Utara, Semarang Timur, Gayamsari, Pedurungan and Genuk, most of which are in the high vulnerability zone. Whereas the Ngaliyan, Semarang Selatan, Semarang Tengah, Candisari, and Gajah Mungkur, which are mostly in the low to moderate vulnerability zones.

Groundwater Quality Assessment Based on Geographical Information System and Groundwater Quality Index

Iran is located in an arid and semi-arid part of the world. Accordingly, the management of the water resources in the country is a priority. In this regard, determining the quality and pollution of surface water and groundwater is very important, especially in areas where groundwater resources are used for drinking. Groundwater quality index (GQI) checks the components of the available water with various quality levels. To assess the quality of drinking groundwater of Yazd-Ardakan plain according to GQI in geographical information system (GIS) environment, the electrical conductivity, sodium, calcium, magnesium, chlorine, pH, sodium adsorption ratio, bicarbonate, sulfate, potassium, water hardness, and all substances dissolved in the waters of 80 wells were determined. The samples were obtained from Yazd Regional Water Organization from 2005 to 2014. Using this data, the map components were plotted by Kriging geostatistical method. Then, the map of GQI was prepared after normalizing each map component, switching to a rating map, and extracting the weight of each component from the rating map. Based on the GQI index map, the index point which was 87 in 2005 has increased to 81 in 2014. These maps show a decline in groundwater quality from west to the east region. This decline in groundwater quality is due to the existence of Neogene Organizations in the east and geomorphologic unit of the bare epandage pediment in the west. The map removal and single-parameter sensitivity analysis showed that GQI index in Yazd-Ardakan plain is more sensitive to the components of electrical conductivity (EC), total dissolved solids (TDS), and total hardness (TH). Therefore, these components should be monitored more carefully and repeatedly.

Thematic issue: groundwater resources management

Groundwater plays a significant role in the overall circulation of water through the hydrologic cycle. Worldwide, groundwater sources constitute about 25% of total freshwater available, and in many areas, groundwater is the sole source of potable water. Groundwater has usually been considered as a readily available and safe source of water for domestic, agricultural and industrial uses. Groundwater supplies are not unlimited. Its use should be properly planned based on an understanding of the local hydrogeologic setting to ensure sustainable resources. In many areas, extraction of excessive quantities of groundwater has resulted in progressive depletion of resources and the decline of the local water table. Usage in excess of sustainable limits can lead to other adverse consequences: land subsidence, deterioration of groundwater quality, sea water intrusion, degradation of associated surface water streams, ecological damage, and negative impacts on human and animal health. With growing industrialization and other changes in land use, coupled with increased effluent from domestic, agricultural, and industrial growth, a gradual decline in groundwater quality is the common result. Expert, wellorganized water resources planning is the key to preserving water quality. Regional and local policies and strategies for groundwater development and management must be realistic and flexible to be effective for ensuring long-term use of this valuable resource. In this thematic issue, invited research from attendees of the international symposium on ‘‘Efficient Groundwater Resources Management’’, held in Bangkok, Thailand, February 16–18, 2009 are presented, as well as some other manuscripts on the subject. The theme of this important meeting, which was organized by the Department of Groundwater Resources under the Ministry of Natural Resources and Environment, Thailand was ‘‘Groundwater – The Challenge of Quantity and Quality for a Sustainable Future.’’ Co-Organizers were the Thai Hydrogeology Association and the Geological Society of Thailand. CoSponsors were the International Association of Hydrogeologists; UNESCO-International Hydrological Program; Coordinating Committee for Geosciences Programs in East and Southeast Asia; World Bank GW-MATE; and HydroGeoLogic Inc., USA. Manuscripts presented in this thematic issue focus on areas including effective assessment of groundwater opportunities and hazards; efficient groundwater management for urban and rural areas; emerging threats to groundwater quantity and quality; protecting groundwater resources; and groundwater regulation and governance, among other topics. Special thanks are extended to Ashim das Gupta, Oranuj Lorphrensri, and Sucharit Koontanakulvong for their service in helping coordinate this thematic issue.

Hydrochemical Study of Groundwater in Sidoarjo Mud Volcano Area, East Java Indonesia

Mudflow phenomena that was occured in the Porong, Sidoarjo since May 29, 2006 has resulted in environmenta l impacts. One of the impact is the decline in groundwater quality and the presence of gas bubbles in the wells of the population Hydrochemicha l analysis is used to evaluate the quality of groundwater, to know the genesis systems and groundwater aquifers. Hydrochemichalanalysis by Piper diagram show there are three groups of groundwater facies first is bicarbonate chloride facies, chloride bicarbonate facies and chloride facies. Analysis of isotope deuterium (δ2H) and oxygen-18 isotope (δ18O) showed that the water coming from the bubble is related to the hydrological cycle or meteoric water and groundwater around the center of the water spray is included in formation water. Multivariate analysis resulted in two groups: the groundwater in the area of wate r bursts originate from magmatic hydrothermal process while groundwater in wells comes from surface water. Compilation parameters total dissolved solids and dissolved ion of groundwater contamination is divided into three zones, namely a low polluted zone, middle polluted zone and high polluted zone with groundwater pollution spread pattern trending east/northeast in the direction of unconfined groundwater flow. The water that comes out with mud from the center bursts are thought to origina tefrom the volcanic sandstone confined aquifer lithology, the Upper Kalibengformation,Pliocene age.

Hydrogeochemical considerations about the origin of groundwater salinization in some coastal plains of Elba Island (Tuscany, Italy)

Several coastal plains of the Elba Island (Marina di Campo, Portoferraio, Schiopparello, Mola, Porto Azzurro and Barbarossa plains) in Tuscany (Italy) were studied to determine the causes of decline in groundwater quality, using major ion chemistry to establish the causes of groundwater salinization. The study demonstrates that salinization of coastal plain alluvial aquifers is not simply linked to seawater intrusion but is also intimately related to inflows from adjacent aquifers. Ionic ratios, correlation graphs and distribution value maps were employed as the means to understand the hydrochemistry of the study areas. The Mg/Cl ratio in particular can be considered a good tracer to distinguish the main salinization processes that control groundwater chemistry. Seawater intrusion only partly determines the chemistry of some groundwaters, which generally belong to a chloride facies where the salinity is derived principally from freshwater-seawater mixing and the participation of cation exchange. Proceeding inland groundwater quality seems to be principally determined by the inflow of Mg, Ca-HCO(3) or Ca, Na-HCO(3) waters formed from the weathering of silicate minerals in adjoining aquifers. Hydrolysis of these minerals is of prime importance in controlling groundwater chemistry in adjacent alluvial plains. The lateral recharge flows introduce water with a different chemical composition and this variable of freshwater recharge changes the hydrochemistry as a result of mixing between two or more waters types. This situation is further complicated when seawater and base exchange reactions participate, due to seawater intrusion.

Impact of recharge variations on water quality as indicated by excess air in groundwater of the Kalahari, Botswana

Groundwater is an important and often exclusive water resource in arid and semi-arid regions. The aim of the present paper was to gain insight into the processes and conditions that control the deterioration of groundwater quality in the semi-arid Kalahari of Botswana. Measurements of 3He, 4He, 20Ne, 22Ne, and of 14C of dissolved inorganic carbon (DIC) were combined with existing isotopic and hydrochemical data to investigate groundwater from the Ntane Sandstone Aquifer, which is affected by high nitrate concentrations of non-anthropogenic origin. All groundwater samples revealed neon concentrations in excess to air-saturated water, which we attributed to the addition of excess air during recharge. Neon concentrations ranged from values close to air saturation for 14C DIC rich samples (up to 80.5%MC) up to values of 90% in excess to air-saturated water for lower 14C DIC contents (2.6–61.3%MC). A strong linear correlation of excess Ne with nitrate concentrations suggests an intimate connection between groundwater quality and the processes and conditions during groundwater recharge. Low groundwater recharge rates under present-day semi-arid conditions are associated with low amounts of excess Ne and elevated nitrate concentrations. In contrast to this, higher excess Ne values in groundwater of lower 14C DIC and nitrate contents indicate that the high quality groundwater end-member presumably is related to higher groundwater table fluctuations during wetter climatic conditions in the past. We attribute the decline in groundwater quality with respect to nitrate to a decreasing rate and temporal variability of groundwater recharge, and to concurrent changes in biogeochemical activities following a transition to a drier climate during the Holocene. Under such conditions, a much stronger decrease in groundwater recharge compared to the release of nitrate from soil organic matter may result in elevated nitrate concentrations in the vadose zone and groundwater. This implies a strong impact of climate change on the transport of solutes like nitrate through the vadose zone which needs to be considered in predictions of future groundwater quality.

Methods and technologies for handling mortality losses

Poultry carcasses resulting from death by natural occurrences at high levels of production represents a tremendous amount of organic matter that requires environmentally and biologically safe disposal or utilization. Methods for disposal of poultry carcasses include burial, incineration, composting, and rendering. Burial pits used for carcass disposal pose concerns that include the decline in ground water quality where pits are located and residue remaining in pits after years of use. Burial is no longer permitted in some poultry producing areas of the United States except in the case of catastrophic loss. Incineration is a biologically safe method of disposal; however, it tends to be slow and expensive even when highly efficient incinerators are used. Burial and incineration impose environmental concerns that are becoming less acceptable. Research has been conducted during the past decade in support of composting for carcass disposal. When poultry carcass composting is properly conducted, disease-causing microorganisms do not survive the process and the composted material can be used as a soil amendment. Composting is environmentally sound, relatively inexpensive, and has gained widespread acceptance. Rendering carcasses into a protein by-product meal is an alternative in the United States, but is not permitted in the European Union. Poultry carcasses can be removed from the farm, but the spread of pathogenic microorganisms during routine pickup and transportation to a rendering facility may present a substantial threat. Refrigeration, principally freezing, has potential for short-term storage prior to rendering, but costs of operation and transportation need careful consideration. Lactic acid fermentation of poultry carcasses prior to transportation stabilizes carcass deterioration and minimizes pathogen threat. Fermentation allows for long-term on-farm storage of poultry carcasses, reduced transportation costs and results in a usable feed ingredient. When coupled with rendering, fermentation is an excellent alternative for storing and transporting pathogen-free poultry carcasses. All methods that allow for the environmentally safe and bio-secure disposal of poultry carcasses should be considered. No single method will completely solve the problem.

Groundwater Resource Use Practices and Implications for Sustainable Agricultural Development in the North China Plain: A Case Study in Ningjin County of Shandong Province, PR China

This paper addresses the critical situation of water resource exploitation for agriculture and environmental effects in Ningjin County in the North China Plain. Several negative environmental effects such as declining groundwater table levels, decline in groundwater quality, increased irrigation cost, increased soil salinity, compaction of soil, increased land subsidence and increased incidence of waterlogging have been experienced in the area, as perceived by the local farmers. This is due to overpumping of groundwater by a large number of wells clustered in small areas. The study indicates that if the current pattern of groundwater use, existing attitudes of farmers and improper implementation of policies and regulations is continued, the agricultural activities will face severe consequences and tend to be unsustainable. This warrants new strategies to improve the present situation.

Dispersion of groundwater age in an alluvial aquifer system

Interpretation of groundwater ages typically rests on assumptions of minimal mixing of different water ages in the water samples. The effects of three‐dimensional, geologic heterogeneity on groundwater mixing and tracer concentrations, however, have not been evaluated. In this study, we use a series of 10 detailed geostatistical realizations along with high‐resolution numerical groundwater flow and contaminant transport simulation to model distributions of groundwater ages and chlorofluorocarbon (CFC) ages at wells within a heterogeneous stream‐dominated alluvial fan aquifer system. Results show that groundwater reaching a well in the heterogeneous aquifer system typically consists of a wide distribution of groundwater ages (often spanning >50 years), even over short (<1.5 m) screened intervals. Additionally, simulated arithmetic mean groundwater ages do not correspond to mean ages estimated from simulated CFC concentrations. Results emphasize the potential ambiguity of “mean” groundwater ages estimated from environmental tracer concentrations in typically heterogeneous geologic systems. The significant dispersion of groundwater ages also implies that ultimate, maximum effects of nonpoint source, anthropogenic contamination of groundwater may not be reached until after many decades or centuries of gradual decline in groundwater quality.

Reaction of subsurface coastal aquifers to climate and land use changes in Greece: modelling of groundwater refreshening patterns under natural recharge conditions

This paper studies the multicomponent ion exchange process and freshening time under natural recharge conditions for three coastal aquifers in Greece. Due to over-pumping and the dry years of 1980–1990 decline in groundwater quality has been observed in most of the Greek coastal aquifers. This decline is caused by a lack of reliable water resource management, water abstraction from great depths, and seawater intrusion resulting in a rise of the fresh/salt water interface (salinisation process) due to a negative water balance. The reverse phenomenon, which should lead to groundwater freshening, is a long process. The freshening process shows chromatographic patterns that are due to chemical reactions such as calcite dissolution and cation exchange, and simultaneously occurring transport and dispersion processes. Using the geochemical simulation codes PHREEQE and PHREEQM (Parkhurst et al., US Geol. Surv. Water Resour. Invest., 80–96 (1980) 210; Appelo and Postma, Geochemistry, Groundwater and Pollution (1994)), these patterns were analysed and the above-mentioned processes were simulated for carefully selected aquifers in Peloponnesus and Crete (Greece). Aquifers of the Quaternary basin of Glafkos in Peloponnesus, the Neogene formations in Gouves, Crete, and the carbonate aquifer of Malia, Crete, were examined as representative examples of Greek coastal aquifer salinisation. The results show that when pumping was discontinued, the time required for freshening under natural conditions of the former two aquifers is long and varies between 8000 and 10,000 years. The Malia aquifer on the other hand, has a freshening time of 15 years. Freshening time was shown to depend mainly on cation exchange capacities and the recharge rate of the aquifers.

Determination of aquifer properties in northern Qatar for application to artificial recharge

Abstract The aquifer system in Qatar has been heavily exploited for agricultural purposes for over 20 years, leading to a decline in groundwater quality. In 1992 the Ministry of Municipal Affairs and Agriculture appointed Entec to carry out a two-year study into the feasibility of using artificial recharge to restore the aquifer system. This study involved field testing and modelling of the Rus and Umm Er Radhuma (UER) aquifers at four sites. Step, constant rate and tracer injection/reabstraction tests were carried out on each aquifer at each site. The step tests on boreholes in the UER indicated that non-Darcian behaviour occurred in the aquifer and extended a significant distance from the pumping boreholes. This was not observed during the step tests on boreholes in the Rus. A variety of techniques were used to analyse data from the constant rate tests and these provided a range of values for standard aquifer parameters as well as allowing a conceptual model of flow processes in the aquifer to be developed. This understanding was used in developing finite difference solute transport models to replicate the results from the tracer tests. Values of dispersivity of 0.5–5 m were derived for the Rus aquifer whilst values in the range 10–150 m were derived for the UER. Effective porosities were high at around 0.2 for both aquifers.