scholarly journals Assessment of Aquifer Vulnerability Using Multi-Criteria Decision Analysis around Akure Industrial Estate, Akure, Southwestern Nigeria

2019 ◽  
pp. 1-13
Author(s):  
A. D. Adebiyi ◽  
S. O. Ilugbo ◽  
O. E. Bamidele ◽  
T. Egunjobi
Keyword(s):  
Hydraulic Conductivity ◽  
Aquifer Vulnerability ◽  
Geophysical Investigation ◽  
Southwestern Nigeria ◽  
Current Electrode ◽  
Longitudinal Conductance ◽  
Industrial Estate ◽  
Vulnerability Map ◽  
Very High ◽  
Vulnerable Zones

This study is aimed at evaluating of aquifer vulnerability in a typical basement complex environment of Akure industrial estate, Akure, Southwestern Nigeria. A multi-criteria model is developed for achieving this aim; the vulnerability model which is based on topsoil resistivity, longitudinal conductance, thickness of layer overlying aquifer, and hydraulic conductivity of each sounding point across the study area is successfully used to evaluate the aquifer vulnerability of the area for future groundwater development programme in the area. Geophysical investigation involving vertical electrical sounding is carried out across the study area. A total of thirty one (31) vertical electrical soundings (VES) data were acquired using Schlumberger array with maximum half-current electrode separation of 100 m. Three to five geoelectric layers were delineated across the study area. The curve types obtained are the A, H, K, KH, HA, AA, QHA and KHA.The map of topsoil resistivity, longitudinal conductance, thickness of layer overlying aquifer, and hydraulic conductivity were generated and synthesized to producing the vulnerability map. The vulnerability map shows that the area is characterized by five zones; very low, low, moderate, high and very high. The mid-western, southeastern and closure at the northern part of the study area are delineated to be very low to low vulnerable zones, followed by the eastern and part of the western and central part of the study area which are categorized as moderate vulnerable zones, and finally the southern and northern part of the study area which are characterized by high and very high vulnerable zone.

scholarly journals Using Geoelectric Soundings for Estimation of Hydraulic Characteristics of Aquifers in the Coastal Area of Lagos, Southwestern Nigeria

2014 ◽  
Vol 11 ◽  
pp. 30-39 ◽  
Author(s):  
J.O. Fatoba ◽  
S.D. Omolayo ◽  
E.O. Adigun
Keyword(s):  
Hydraulic Conductivity ◽  
Saline Water ◽  
Pumping Test ◽  
Shallow Aquifer ◽  
High Porosity ◽  
Hydraulic Characteristics ◽  
Southwestern Nigeria ◽  
Geoelectric Section ◽  
Current Electrode ◽  
Transverse Resistance

Electrical resistivity investigation was carried out at Ibeju Lekki, Southwestern Nigeria. The thrust of this study is to determine the geoelectrical parameters of the shallow aquifer and estimate the hydraulic characteristics of this aquifer unit from the surface geophysics. The area falls within the Dahomey basin of the Nigeria sedimentary terrain. Twenty-one VES were conducted using Shlumberger array with a maximum half current electrode (AB/2) of 100 m giving total spread of 200 m. Data were interpreted using partial curve matching technique and assisted 1-D forward modeling with WINRESIST software. The qualitative interpretation revealed KQ curves (ρ1 < ρ2 > ρ3 > ρ4) and KH curve (ρ1 < ρ2 > ρ3 < ρ4). The geoelectric section generated from the results of the VES revealed a four geo-electric layers; these include topsoil with resistivity ranging from 213-5404 Ωm, dry sand with resistivity values vary from 301to 17178 Ωm, saturated sand with resistivity varying from 110 to1724 Ωm and sand (saline water content) with resistivity values of between 8 and 97 Ωm. The major aquifer in the area occurs at the third geoelectric layer. The depth to this aquifer is of between 0.7m and 6.0m and the layer thickness is between 0.2 m and 19.9 m. The hydraulic characteristics of the aquifer estimated from the geoelectric parameters reveal that the aquifer has porosity values of between 29.4 % and 57.7 %, protective capacities of between 0.00013 and 0.015 mhos, transverse resistance ranges from 345-18502 Ωm2, transmissivity values vary from 13 to 310 m2/day and hydraulic conductivity ranges from 0.8-65 m/day. The results show that the aquifer is characterized by high porosity and low protective capacities of overburden layers indicating that it is highly vulnerable to surface contamination. It has high transverse resistance, high transmissivity, and high hydraulic conductivity indicating that the aquifer can transmit water at higher rate and sustain the need of the community. This study has demonstrated the efficacy of surface geophysics in estimating hydraulic characteristics of an aquifer where pumping test data are not available and also to determine its vulnerability to surface contaminants.

scholarly journals Regional Aquifer Vulnerability and Pollution Sensitivity Analysis of Drastic Application to Dahomey Basin of Nigeria

2020 ◽  
Vol 17 (7) ◽  
pp. 2609
Author(s):  
Saheed Adeyinka Oke
Keyword(s):  
Sensitivity Analysis ◽  
Vadose Zone ◽  
Shallow Groundwater ◽  
Aquifer Vulnerability ◽  
Single Parameter ◽  
Southwestern Nigeria ◽  
Groundwater Vulnerability Mapping ◽  
Dahomey Basin ◽  
Vulnerability Map ◽  
The Impact

Shallow groundwater vulnerability mapping of the southwestern Nigeria sedimentary basin was assessed in this study with the aim of developing a regional-based vulnerability map for the area based on assessing the intrinsic ability of the aquifer overlying beds to filter and degrade migrating pollutant. The mapping includes using the established seven parameter-based DRASTIC vulnerability methodology. Furthermore, the developed vulnerability map was subjected to sensitivity analysis as a validation approach. This approach includes single-parameter sensitivity, map removal sensitivity, and DRASTIC parameter correlation analysis. Of the Dahomey Basin, 21% was classified as high-vulnerability and at risk of pollution, 61% as moderate vulnerability, and 18% as low vulnerability. Low vulnerability areas of the basin are characterised by thick vadose zones, low precipitation, compacted soils, high slopes, and high depth to groundwater. High-vulnerability areas which are prone to pollution are regions closer to the coast with flat slopes and frequent precipitation. Sensitivity of the vulnerability map show the greatest impact with the removal of topography, soil media, and depth to groundwater and least impact with the removal of the vadose zone. Due to the subjectivity of the DRASTIC method, the most important single parameter affecting the rating system of the Dahomey Basin DRASTIC map is the impact of the vadose zone, followed by the net recharge and hydraulic conductivity. The DRASTIC vulnerability map can be useful in planning and siting activities that generate pollutants (e.g., landfill, soak away, automobile workshops, and petrochemical industries) which pollute the environment, groundwater, and eventually impact the environmental health of the Dahomey Basin’s inhabitants.

scholarly journals Application of Aquifer Vulnerability Index (AVI) method to assess groundwater vulnerability to contamination in Semarang urban area

2018 ◽  
Vol 159 ◽  
pp. 01036 ◽  
Author(s):  
Thomas Triadi Putranto ◽  
Narulita Santi ◽  
Dian Agus Widiarso ◽  
Dimas Pamungkas
Keyword(s):  
Hydraulic Conductivity ◽  
Urban Area ◽  
Unsaturated Zone ◽  
Groundwater Vulnerability ◽  
Vulnerability Index ◽  
Aquifer Vulnerability ◽  
Vulnerability Map ◽  
Two Parameters ◽  
Sediment Layers ◽  
Sedimentary Layer

An approach to assess groundwater to contamination is developing groundwater vulnerability map. Groundwater vulnerability is formulated as an intrinsic relative, the dimensionless property of a groundwater system that depends on its sensitivity to unfavourable human and natural impacts. Thus, to assess groundwater vulnerability to contamination in Semarang urban area is the objective of this research by using Aquifer Vulnerability Index (AVI). This method considered of two parameters related to the unsaturated zone, i.e. thickness (d) of each sedimentary layer in the unsaturated zone and Estimated hydraulic conductivity (K) of these sedimentary layers. There are five levels of groundwater vulnerability by using AVI method, i.e. extremely low, low, moderate/medium, high, and extremely high. The thinner the layer covers the aquifer, and the higher the value of the hydraulic conductivity of sediment layers will be increasingly vulnerable to pollution.

scholarly journals Flood vulnerability mapping using the spatial multi-criteria evaluation (SMCE) method in the Minraleng Watershed, Maros Regency, South Sulawesi

2020 ◽  
Vol 153 ◽  
pp. 01004
Author(s):  
Muhammad Fadhil ◽  
Yoanna Ristya ◽  
Nahra Oktaviani ◽  
Eko Kusratmoko
Keyword(s):  
Information System ◽  
Rainfall Intensity ◽  
Physical Factors ◽  
Relative Importance ◽  
Flood Vulnerability ◽  
South Sulawesi ◽  
Multi Criteria Evaluation ◽  
Gis Environment ◽  
Very High ◽  
Vulnerable Zones

This study focuses on the assessment of flood-vulnerable areas in the Minraleng watershed, Maros Regency, where the area experiences floods every year. Spatial analysis in the Geographic Information System (GIS) environment has been applied to estimate flood-vulnerable zones using six relevant physical factors, such as rainfall intensity, slope, Elevation, distance from the rivers, land use and soil type. The relative importance of physical factors has been compared in paired matrices to obtain weight values using the Spatial Multi-Criteria Evaluation (SMCE) method. The result showed that the areas located in Camba sub-district had the high vulnerability. The region with a high and very high vulnerability to flood were spread with an area of 436 ha (0,84 %) and 6.168 ha (11.8%).

scholarly journals Groundwater vulnerability assessment and mapping in shallow groundwater

2021 ◽  
Vol 926 (1) ◽  
pp. 012047
Author(s):  
K Aribowo ◽  
W Wilopo ◽  
D H Barianto
Keyword(s):  
Land Use Planning ◽  
Unsaturated Zone ◽  
Shallow Groundwater ◽  
Primary Source ◽  
Groundwater Vulnerability ◽  
Research Area ◽  
A Value ◽  
Groundwater Vulnerability Assessment ◽  
Vulnerability Map ◽  
Very High

Abstract The increasing population density can contaminate groundwater. So far, groundwater is still the primary source to fulfill clean water and drinking water in Muntilan, Salam, and Ngluwar Sub-District. Studies on groundwater vulnerability are essential to minimize the contamination risks as a piece of basic information for land use planning. This research aims to assess groundwater vulnerability in Muntilan, Salam, and Ngluwar Sub-District. The simple vertical vulnerability (SVV) method with GIS was selected to develop a groundwater vulnerability map. The parameters of this method consist of the type of soil/rock, the thickness of the water-unsaturated zone, and the recharge value. The results show that the research area can be divided into three vulnerability classes: very low, moderate, and high groundwater vulnerability. Very low groundwater vulnerability has a value of more than 70 with very high protection effectiveness. The class is distributed in Muntilan and Salam Sub-Districts. Moderate groundwater vulnerability has a value less than 35 to 65 with moderate protection effectiveness, and high groundwater vulnerability has a value ranging from 24 to 35 with low protection effectiveness. Both of the class is evenly distributed in Muntilan, Ngluwar and Salam Sub-Districts.

scholarly journals GROUNDWATER VULNERABILITY ASSESSMENT USING DRASTIC MODEL OF UP AL-KHASSA DAM SUB-BASIN, KIRKUK, NE IRAQ

2020 ◽  
Vol 53 (2E) ◽  
pp. 12-24
Author(s):  
Madyan Al-Gburi
Keyword(s):  
Vulnerability Assessment ◽  
Groundwater Vulnerability ◽  
Aquifer Vulnerability ◽  
Drastic Model ◽  
Drastic Method ◽  
Groundwater Vulnerability Assessment ◽  
Arc Gis ◽  
Vulnerability Map ◽  
Gis Software ◽  
Program Version

Several studies and assessments have been conducted of areas exposed to pollution, especially areas that contain aquifer. The final extraction of the vulnerability map of the groundwater was constructed through the use of the DRASTIC method by applying the linear equation of the seven coefficients in the Arc GIS software program (Version 10.4). The aim of the study to assess aquifer vulnerability to pollution. Results, vulnerability map range between 75-126 (very low, low, and medium), the study area consists of very low and low vulnerability, except some areas medium vulnerability close to the center of the sub-basin in the standard vulnerability map (s) and 91-149 (very low, low, and medium) for the agriculture or pesticide vulnerability map (p), the medium vulnerability occupies a greater area the center of the sub-basin.

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