Potential Groundwater Resources Research Articles

Evaluation of groundwater hydrogeochemical characteristics and delineation of geothermal potentialities using multi criteria decision analysis: Case of Tozeur region, Tunisia

The use of geothermal energy in Tunisia is limited to its instant use because of the low enthalpy resources, especially in the southern part of the country. The Djerid Basin has remarkable geothermal resources with low to moderate temperatures that have been used only for irrigation of oases and heating greenhouses. In order to evaluate the geothermal potential of groundwater resources of Tozeur region located in the Djerid Basin, a synthetic approach including geological, geophysical, physicochemical, hydrogeological and geothermometric characteristics of groundwater is indispensable. It aims to determine: (1) the evolution of the water chemistry, (2) the origin of thermal waters and their reservoir temperature, (3) the mixing mechanism of geothermal fluid and (4) the mapping of geothermal potentialities with Multi-Criteria-Decision-Analysis (MCDA) using GIS platform.The hydrogeochemical approach revealed that the studied geothermal system is characterized by temperature values ranging between 25 and 75°C and total dissolved solids (TDS) values between 0.7 and 5.8 g/l.Furthermore, the use of silica geothermometers and saturation indices for different solid phases gave estimated geothermal reservoir temperature ranging between 92 and 104 °C and between 100 and 125 °C, respectively.In addition, the equilibrium processes elucidated that the thermal waters are mostly in the oversaturated condition with respect to calcite, aragonite and dolomite, but they are saturated with evaporate minerals.According to the obtained results of the MCDA, the spatial assessment of the potential geothermal areas using Weighted overlay and Boolean logic Models are 37 % and 5 % respectively.The findings in this study contribute to a better understanding of groundwater sustainability for supporting geothermal project on renewable energy and can be used as a synthetic document for realistic management of groundwater resources.

Geochemical evidence for regional and long-term topography-driven groundwater flow in an orogenic crystalline basement (Aar Massif, Switzerland)

Detailed knowledge about the circulation of meteoric water in non-magmatic, orogenic belts is fundamental for assessing the potential of such settings for geothermal power production, as well as their use as potential groundwater resources. To get more general insight into these hydrological processes, we have conducted regional (20 × 10 × 9 km) thermal-hydraulic-chemical (THC) simulations of meteoric water circulation in the orogenic, crystalline basement of the Aar Massif in the Central Alps, Switzerland. Model results were compared to numerous geochemical and isotopic analyses of groundwater discharging into the longest and deepest tunnel of the world, the Gotthard railbase tunnel located within the model domain. Explicitly considering the surface topography in our model was sufficient to reproduce all key characteristics of the tunnel inflows (salinity, temperature, δ18O values, and up- and downward directed flow zones inferred from geochemical constraints). This quantitatively confirms that surface topography operates as the governing control on fluid flow in orogenic crystalline basements with meteoric water infiltration occurring at high altitude and resulting upward directed flow zones along major valleys. Owing to low flow rates below 2 m year−1, computed residence times of the longest flow paths were above 100 k years, confirming that groundwater and/or porewater in orogenic crystalline basements may act as an archive for palaeohydrologic variations. Moreover, simulation results show that down to the lower model boundary at 9 km depth, penetration of meteoric water is not limited by the decrease in permeability with depth that is typically observed in granitic rocks. This suggests that advective fluid transport in orogenic crystalline basements may reach the brittle-ductile transition zone and that infiltrating meteoric water can attain temperatures well above 150 °C. We conclude that orogenic geothermal systems are promising plays for geothermal power production.

Study on availability of groundwater resources in Selangor state of Malaysia for an efficient planning and management of water resources

Abstract Groundwater has become an important source of water to meet the increasing requirement for domestic, industrial, and agricultural needs. The study was formulated to assess the availability of groundwater resources in Selangor State, Malaysia. An integrated MIKE SHE and MIKE 11-based surface water–groundwater interaction model was developed to fulfill the study objectives. Model results illustrated that groundwater flows from the eastern part of the hilly region to the western part and ultimately discharges into the sea. The study also revealed that Sungai Langat, Sungai Klang, and Sungai Selangor receive water from groundwater and do not feed the groundwater. Approximate potential groundwater resources based on water balance study varies from 860–960 million liter per day (MLD), 630–690 MLD, 810–870 MLD to 630–690 MLD for Langat basin, Klang basin, Selangor basin, and Bernam basin, respectively. Impacts due to extreme dry condition showed that groundwater table declined about 0.5–3 m in most of the area. However, groundwater level for the major portion of Selangor State will drop to about 0–1 m for increased abstraction due to changed land-use pattern. Study findings may be used for a holistic and comprehensive management of groundwater resources for sustainable development in Selangor State, Malaysia.

Integrated assessment of groundwater resources in a semi-arid watershed of South India: implications for irrigated agriculture

Groundwater resources play a vital role in the socio-economic development of Andipatti watershed—a semi-arid region situated in Theni district of Tamil Nadu, South India. Due to a short spell of rainfall (40 days in a year) and ephemeral nature of streams, the quantum of surface water in the watershed is not found to cope with the agricultural requirements and as a result, more emphasis is given to the exploitation of groundwater. The haphazard utilization of groundwater for agricultural practices affects the quantum and quality of groundwater severely. The present study is attempted to assess the potential, level, quality, suitability and utilization level of groundwater resources in an integrated manner. Groundwater potential of the study area is assessed using resistivity, well yield and dug well data. The groundwater potential zones exhibit a strong relationship with land use pattern i.e. poor potential zones is marked by fallow lands. The spatial pattern of groundwater level and quality is examined using the data collected from 34 open wells across the study area during pre-monsoon and post-monsoon seasons. The groundwater level of the watershed varies from 0.5 to 47 m with an average fluctuation of 2 to 4 m. The long-term fluctuations of the groundwater level showed that there is a cyclic trend depending upon the rainfall pattern of the watershed. However, the declining trend of groundwater level noticed especially in the upper part of the watershed. The suitability of groundwater for irrigated agriculture is examined using the concentrations and indices of chloride, magnesium ratio, sodium adsorption ratio, residual sodium carbonate, soluble sodium percentage, and permeability index of the collected groundwater samples. A method formulated by the US Salinity Laboratory is also attempted for the classification of groundwater quality zones. In order to ascertain and suggest sustainable planning measures, utilisation pattern of groundwater is assessed on a micro-watershed scale. The spatial distribution of analyzed parameters shows the suitability of groundwater for irrigation and associated impacts in the watershed.

Hydrogeomorphological mapping using geospatial techniques for assessing the groundwater potential of Rambiara river basin, western Himalayas

Integration of geospatial techniques (remote sensing and geographical information system) for the identification of groundwater potential has become an important tool in evaluating, monitoring and conserving groundwater resources. Effective utilization of groundwater resources has become important due to changing climatic scenario. Hence, estimating the zones of potential groundwater recharge is extremely important for the protection and management of water quality of groundwater systems. In this study, Rambiara river basin, southern-eastern part of Kashmir valley, was examined to assess its groundwater resource potential. Geospatial techniques were used to assimilate five causative factors: lithology/geology, land use and land cover, lineaments, drainage, and slope. The factor weight contributing to the groundwater recharge was acquired using satellite image data, lithological/geological maps, and a land use/land cover database followed by field validations. Based on the results obtained, it was observed that the premier recharge potential zones are located down the slope of the river basin due to the dominance of alluvium and agricultural land. Hard rock lithology located towards upstream areas of the basin allows less water to infiltrate.

Review: Groundwater resource potential and status of groundwater resource development in Ethiopia

The groundwater resources potential of Ethiopia is estimated to be about 40 billion cubic meters. Groundwater has been used as the main source of water supply since the 1970s for the main cities, towns and dispersed rural communities across the country, where provision of reticulated surface-water schemes is often expensive because of initial project construction costs and poor water quality. The exponential growth of the urban population and agriculture-led industrial development have resulted in greater attention to groundwater as the potentially cost-effective water supply source. As part of the growing focus on the use of groundwater, the Ethiopian government is currently implementing irrigation projects. One plan involves nine irrigation projects covering an estimated area of 8,000 ha, being developed on a pilot scale, with 9,000 test wells, 28,000 monitoring wells and 14,657 spring improvements. If this unprecedented Ethiopian groundwater-centred development plan is implemented successfully at such a scale, it is highly likely that its success will persuade other Sub-Saharan developing nations to put in place the necessary policies, regulations and investment for infrastructure and capacity development for exploring, exploiting and managing their groundwater resources.

Groundwater characterization and potential impacts of agricultural activities in the Sers El Kef plain

Tunisia has very limited potential of surface and groundwater resources which are subject to different quantitative and qualitative forms of degradation. The risk of groundwater pollution results from the interaction between the vulnerability of aquifers to pollution and anthropogenic activities. Our research focuses on the study of the Sers water table water quality (northwest Tunisia) following the inputs used for agricultural activities in the region. Water samples were extracted from 40 wells to analyze the main physicochemical parameter indicators of the groundwater quality. The results obtained show that these waters have two major facies: Na-Cl and Ca-Mg-SO4. The nitrate contents are relatively high suggesting that the agricultural activities are probably the most important anthropogenic source of water contamination. The results of the Standardized Principal Component Analysis (SPCA) confirm the geochemical methods and results and provide further information about the water quality of the Sers El Kef aquifer. In addition, the pollution degree differs from one site to another depending on the spreading rate of nitrogen fertilizers and the distance from the pollution source.

Uncovering the Musgrave Province in South Australia using airborne EM

Two airborne electromagnetic (AEM) surveys were undertaken in the Musgrave Province in South Australia in 2016 with the objective to increase knowledge about cover characteristics, thereby helping reduce exploration risks and to gain an understanding of the groundwater resource potential of the area. The Province is highly prospective for magmatic Ni-Cu-PGE and IOCG deposits, where a transported regolith imposes a significant challenge to exploration. Effective exploration through this region requires an understanding of that cover, its character and its spatial variability. This cover is also a source of groundwater that supports community and environment but our understanding of this resource is compromised by the limited information we have about it. Two different systems, TEMPEST and SkyTEM, were used for the survey, each covering around 8000 line km with a line spacing of 2 km. The line spacing was deliberately chosen to provide a spatially coherent picture of the subsurface conductivity structure, particularly the buried palaeovalleys known to be present in the region. The two datasets were processed and inverted and the results assessed against known information from drill holes. Both systems map the palaeovalley systems in the area well and provide information about the location and geometry of these. Furthermore the results indicate that it is possible to map variability within the cover using AEM, as well as structural controls on the orientation of the palaeovalleys. Airborne electromagnetic surveys used in logistically challenging areas can therefore be a useful mapping tool for areas with varied but unknown cover sequence thickness and thereby reducing exploration risks, as well as increasing the information content about groundwater resources.

AusAEM; acquisition of AEM at an unprecedented scale

Exploring for the Future is a four-year programme of the Commonwealth Government that aims to boost Australia’s attractiveness as a destination for investment in resource exploration. A significant component of the data acquisition component of the programme is the AusAEM Airborne Electromagnetic (AEM) Survey. This survey will focus on wide line-spaced acquisition as a regional mapping tool to gather new pre-competitive data and information, on extents never previously attempted. The objectives are to map, at a reconnaissance scale: • trends in regolith thickness, character, and variability • variations in bedrock conductivity • the continuity of key conductive bedrock (lithology-related) conductive units under cover • the groundwater resource potential of the region. The first AEM survey of this programme, when completed, will cover an area of over one million square kilometres (more than the areas of France and Spain together), at a nominal line spacing of 20 km with infill surveys in selected areas for subscription companies. In order to have the greatest impact the survey targets greenfield areas where the resource potential is unknown. The AEM data will contribute to estimating features and character of the cover material. To maximize industry collaboration on the project GA sought, and received, expressions of interest from industry subscribers for infill flying on the regional survey for lines spaced at 200 or 400 meters. Regional AEM surveys improve geological understanding in areas with little or no outcrop. The processed data enables informed interpolations of conductivity between sparse drill-holes and estimates on the depth of the basement-cover interface from geophysical modelling. The modelling results are used to inform follow-up exploration activities thereby reducing exploration risk. The new data will be released to the public domain at regular intervals to promote future activity by the government, exploration and research sectors.

The ‘Exploring For The Future’ Groundwater Programme: A Multi-Physics, Inter-Disciplinary Systems Approach For De-Risking Investment in Agriculture in Northern Australia

The Australian Government has recently provided Aus$100.5M to Geoscience Australia over 4 years (2016-2020) to manage the Exploring for the Future (EFTF) programme designed to increase investment in minerals, energy and groundwater resources, primarily in Northern Australia. The programme includes Aus$30.8M for groundwater-specific investigations, recognizing that there are major gaps in our knowledge of Northern Australia’s groundwater systems and resources. The groundwater component of the EFTF programme is focused on addressing these knowledge gaps, with the aim of underpinning future opportunities for irrigated agriculture, mineral and energy development, and community water supply. The groundwater programme will include identification and assessment of potential groundwater resources and water banking options in priority regional areas, while also analyzing the salinity risk (including seawater intrusion). To rapidly map, characterise and assess regional groundwater systems and resources in the data-poor ‘frontier’ areas of Northern Australia, a multi-physics, inter-disciplinary approach has been developed. The programme involves the initial use of temporal remote sensing ‘data cube’ technologies for surface hydrology and landscape mapping, and acquisition of airborne electromagnetic (AEM) and Ground Magnetic Resonance (GMR) datasets. This provides a framework for targeted investigations including passive seismic, microgravity and GPR; borehole geophysics (Induction, gamma and Nuclear Magnetic Resonance (NMR)); drilling and pump testing; hydrochemistry and geochronology (water, landscapes and geology); as well as soils, regolith and basin/bedrock geological, hydrogeological and structural mapping and modelling. This methodology has enabled rapid identification and assessment of potential groundwater resources, salinity and seawater intrusion hazards, and groundwater dependent ecosystems in several priority regions.

Evaluating the groundwater resource potential of the Dundas buried bedrock valley, southwestern Ontario: an integrated geological and hydrogeological case study

Population growth in the groundwater-dependent municipalities of southwestern Ontario has prompted interest in the exploration for new, previously untapped, groundwater resources. In this study, the groundwater resource potential of the sediments infilling a deeply buried bedrock valley network centred beneath the Region of Waterloo and the counties of Brant and Hamilton–Wentworth are explored. The objectives of this study are to further refine valley location and geometry, understand infilling sediments and their hydrogeological properties, and characterize waters contained within the aquifers to inform future water management decisions. Results of a regional ground gravity survey were instrumental in locating buried bedrock valleys and guided follow-up drilling. Continuous sediment coring and monitoring well installations were completed to target thick and coarse-grained sediment packages that, based on existing borehole data, showed aquifer potential. Hydraulic testing and groundwater sampling results provided valuable insights into groundwater quantity and quality. Highly transmissive aquifers, some worth investigating further, have been identified within portions of the valley network. The aquifers appear to occur at a number of stratigraphic positions and do not necessarily occur as the deepest unit overlying bedrock. Bedrock topography likely played a role, however, in their preferential preservation. They are commonly overlain by thick sequences of relatively impermeable sediments, providing excellent protection from anthropogenic contamination. Information from water chemistry, however, does suggest hydraulic connection to the surface at some locations. Groundwater quality and quantity information combined with a conceptual three-dimensional geologic model aids in the selection of groundwater resource exploration targets within the untapped resources of the deep, Dundas buried valley sediments.

Characterization of the Hammamet basin aquifer (North-East of Algeria) through geochemical and geostructural methods and analysis

AbstractMorphostructural, hydrogeological and hydrochemical approaches were applied to Hammamet plain and its surrounding mountains in the eastern part of Algeria to characterize the groundwater system and its potential for exploitation. The Essen and Troubia Mountains form the natural boundaries of Hammamet plain. The objective of this study is to utilize remote sensing techniques combined with structural analysis, hydrogeology and hydrogeochemistry to identify the potential fracture zones for groundwater in the strongly fractured and karstified deep aquifers. The delineated zones of potential groundwater resources are verified by detailed hydrogeological field surveys.From a hydrogeological point of view, these two mountains, constitute a unit limited by faults oriented ENE-WSW, NNW-SSE and NNE-SSW. Specifically, fractures of the latter two directions influence the compartmentalization and the hydrogeological functioning of this unit. According to the degree of fracturing and/or karstification, two basic types of aquiferous behaviour have been distinguished: fissured aquifer (Essen Mountain and Troubia Mountain), and porous aquifer (Hammamet plain).The study of the hydrochemical characteristics of groundwater samples shows that the majority of samples are mainly of HCO3− and Ca2+ water type. The ionic speciation and mineral dissolution/precipitation was calculated with the PHREEQC software. The chemical composition of the water is influenced by the dissolution and/or precipitation processes during the water–rock interaction and by the cationic exchange reactions between groundwater and alluvial sediments. The high content of CO2 in the water samples suggests that they circulate in a geochemical open system. The isotopic analysis of some groundwater samples shows a similarity with the meteoric waters, which reflect their short residence time and a low evaporation of the infiltrated water.

Exploration of potential groundwater resources at Thuwal area, north of Jeddah, Saudi Arabia, using remote sensing data analysis and geophysical survey

The study uses the applications of remote sensing in analyzing the main topographic features of the study area. The digital elevation model derived from the Shuttle Radar Topography Mission (SRTM) satellite is used to devise spillway torrents and their tributaries of the different drainage basins in the study area. The digital rainfall data recorded by the Tropical Rainfall Measuring Mission (TRMM) climate research satellite is used to determine places with the highest rainfall within the different drainage basins in the area. Other satellite data (e.g. Landsat-8) are used in identifying and studying the various geological structures in the study area, which intersect the spillway torrents. Such areas may allow seizure of large quantities of water as potential, close to the surface, groundwater (Quaternary) aquifer. Areas of potential hydrological traps have been identified and marked for further geophysical (geoelectrical) surveys. The geophysical studies helped in identifying the shallow geological structures and the thickness of the subsurface sediments. It also assists in determining the size of the groundwater aquifer and the water quality within these aquifers. The study showed a decline of freshwater aquifer in Quaternary sediments. The Tertiary groundwater aquifer is the most prevalent, where this appears normal saline aquifer. All the aquifers within the study area are being recharged from Quaternary sediments by rainwater. The cumulative annual precipitation rate increases in the South-East of the study area, specifically over Wadi Khulais and significantly drops to lower rainfall rates in the rest of the region. Running water permeates the Quaternary sediments, which in turn infiltrates and recharges the Tertiary aquifer. The salinity of the latter depends mostly on the nature of its constituent rocky material.

Delineation of groundwater potential zones using remote sensing, GIS, and AHP technique in Tehran–Karaj plain, Iran

Evaluation of groundwater resources in dry areas without enough data is a challenging task in many parts of the world, including Tehran–Karaj plain in Iran, which includes Tehran, the capital city of Iran and Karaj, one of Iran’s biggest cities. Water demand due to increasing agricultural and industrial activities caused many problems in the field of water resources management. In this study, the potential of groundwater resources was evaluated using remote sensing, geographic information system (GIS), and analytic hierarchy process (AHP) for the first time. Digital Elevation Model from Shuttle Radar Topography Mission was used to generate a slope map and drainage density map. Three Landsat-8 satellite images were utilized to provide lineament density and land cover/land use maps. Geological and soil type maps were provided from the Geological Survey and Mineral Explorations of Iran (GSI). Tropical Rainfall Measuring Mission data were used to prepare average annual precipitation map. Discharge values from 102 pumping wells in the time period of 2002–2014 were used to evaluate the results. Seven data layers were prepared, and the geodatabase was made in GIS. The layers and their classes were assigned weights using AHP method. Finally, the layers were overlaid based on their weights, and the potential map of groundwater resources was generated. The area was classified into five zones with very high, high, moderate, low, and very low potentials. The zones covered 5.95, 32.90, 22.70, 10.20, and 28.25% of the study area, respectively. The results showed good agreement with the field data obtained from discharge wells.

Groundwater potential of the eastern Kalahari region of South Africa

Abstract An integrated approach involving geological, borehole data, hydrogeochemical and environmental isotope analyses was used to determine the groundwater potential of the eastern Kalahari region of South Africa, an area to the west of Mahikeng that stretches northward from the Orange River into Botswana. The total groundwater resource potential for the eastern Kalahari region of South Africa is estimated at 10127 Mm3/a, with the Kalahari Group aquifer showing the greatest potential, comprising 51% of the total resource. The storage capacity of the Kalahari Group aquifer (7130 Mm3) is also impressive, estimated to be more than twice that of the dolomite aquifer (2728 Mm3). Despite having such great potential, the aquifer is not actively recharged and is often associated with very saline water that is not suitable for human and livestock consumption. The limestone and dolomite aquifers of the Campbell Rand Subgroup, as well as the weathered granitic rocks of the Archaean basement, are considered as the most prospective water bearing formations, with a groundwater resource potential estimate of 1981 Mm3/a and 1845 Mm3/a, respectively. Aquifers with the least potential in the project area comprise the fractured basement rocks of the Kraaipan - Amalia greenstone belt, with a groundwater resource potential of 26 Mm3/a, and the fractured sedimentary rocks of the Asbestos Hills Subgroup, with a groundwater resource potential of 108 Mm3/a. The calculated groundwater storage and resource potential in the eastern Kalahari region of South Africa satisfies a large proportion of the water demand in the region.

Planning of Sectoral Water Allocation: A case study of Seyhan River Basin

In this study water allocation plan for Seyhan Basin that is the second largest after the Nile basin located in the eastern Mediterranean was prepared. The purpose of the study is that a plan for water allocation among groups of water use, or sector is developed by considering environmental and socio-economic conditions as well as the potential of surface and groundwater resources. Current (the year 2016) and future conditions (2017, 2022, 2027 and 2037) have been analyzed in terms of economic and environmental aspects. Scenarios on water allocation were created to determine the most suitable water use pattern. The major finding is that water potential is expected to drop to 6.6 billion m 3 in mild drought conditions and 6.3 billion m 3 in severe drought conditions due to the impacts of climate change. Consequently, agricultural water needs are met in the range of 90% level (the year 2037) to 94% level (the year 2017), and environmental flow need s are met in C level of environmental management class in the context of applied method (GEFC) .

GROUNDWATER RESOURCES ASSESSMENT OF GRANULAR AQUIFERS IN GREECE

Sound groundwater resources management is a matter of paramount importance in Circum-Mediterranean, for the ecologic status of the underlying aquifer systems. Freshwater resources in Greece are identified within all types of aquifer formations, however two distinct types are the ones that draw the attention of the scientific and the engineering community; the granular as well as the karst aquifers. This paper describes the groundwater resources potential that are found within granular aquifer formations, in combination with the major environmental threats associated with their exploitation and management.

Quantitative assessment of groundwater resource potential in a coalfield of Damodar River Basin India

The present study was carried out for the quantitative assessment of groundwater resource potentials in East Bokaro Coalfield of Damodar River Basin. The rise and fall of groundwater table is closely related to the hydro-meteorological conditions, water level, landform, geology and morphological factors. Average annual rainfall for the entire period of 35 years is 1366 mm in which annual maximum rainfall was 2544 mm in the year 2001 and minimum was 733 mm in the year 2004. The fluctuation of groundwater level ranged between 0.15 and 2.87 mbgl in the study area. Rainfall is the main source to replenish the groundwater by percolation through deep soil zones. Besides rainfall, the mine water discharges from the local mining areas and existing water bodies including water logged in abundant mine quarries. Mine water also contributed to the groundwater recharge as return flow. The study area is highly disturbed and the permeabilities of individual geological units are spatially variable and depend on lithology, fracturing and attenuation with depth. The total annual replenishable recharge was calculated to be 48.5 million m3/year and net annual groundwater availability was estimated to be 13.7 million m3 by rainfall infiltration method. The stage of groundwater development was calculated as per GEC-1997 guideline, which falls under the safe category (i.e., 67%). But water resource conservation for sustainable water management is urgently required in the study area.

Assessment of corrosion and scaling potential in groundwater resources; a case study of Yazd-Ardakan Plain, Iran

The quality of water entering into water distribution network often provides requirements for corrosion and scaling in areas lacking adequate treatment methods, which can cause serious problems. The most commonly used corrosion indices are Langelier saturation index (LSI), Ryznar stability index (RSI), Puckorius scaling index (PSI), and aggressiveness index (AI). This study aimed to evaluate the corrosion and scaling potential of water resources in Yazd-Ardakan Plain, Iran. Therefore, the corrosion and scaling potential of groundwater resources were investigated according to LSI, RSI, PSI, and AI. Spearman rank correlation and spatial autocorrelation (Moran's Index) were incorporated to assess the correlations and source identification of the variables. The Inverse Distance Weighing (IDW) and Contour interpolation techniques were also employed to describe the spatial variability and interpolate the water quality.Results showed that the mean values of LSI, RSI, PSI, and AI were as 0.30±0.31, 7.12±0.57, 9.50±0.69, and 12.74±0.38, respectively. The positive spatial autocorrelation found for all parameters showed that all parameters had a clear and cluster spatial pattern. Moreover, the Spearman correlation indicated that the source of pollution was the same for all water resources.In this study, most of the water resources had low to moderate corrosivity. Although each of corrosion indices depending on the circumstances can be used to describe the water quality, however, the accordance between the analyses of chemical water quality and corrosion indices can give more reliable results.

Application of multi-criteria decision analysis in prediction of groundwater resources potential: A case of Oke-Ana, Ilesa Area Southwestern, Nigeria

Groundwater Potential of Oke-Ana area southwestern Nigeria have been evaluated using the integration of electrical resistivity method, remote sensing and geographic information systems. The effect of five hydrogeological indices, namely lineament density, drainage density, lithology, overburden thickness and aquifer layer resistivity on groundwater occurrence was established. Multi-criteria decision analysis technique was employed to assign weight to each of the index using the concept of analytical hierarchy process. The assigned weight was normalized and consistency ratio was established. In order to evaluate the groundwater potential of Oke-Ana, sixty-seven (67) vertical electrical sounding points were occupied. Ten curve types were delineated in the study area. The curve types vary from simple three layer A and H-type curves to the more complex four, five and six layer AA, HA, KH, QH, AKH, HKH, KHA and KHKH curves. Four subsurface geo-electric sequences of top soil, weathered layer, partially weathered/fractured basement and the fresh basement were delineated in the area. The analytical process assisted in classifying Oke-Ana into, low, medium and high groundwater potential zones. Validation of the model from well information and two aborted boreholes suggest 70% agreement.