scholarly journals An Evaluation of Groundwater Vulnerability Assessment Methods in a Rapidly Urbanizing City: Evidence From Dakar, Senegal

2021 ◽  
Author(s):  
Abdoulaye Pouye ◽  
Seynabou Cissé Faye ◽  
Mathias Diedhiou ◽  
Cheikh Becaye Gaye ◽  
Richard G. Taylor
Keyword(s):  
Land Use ◽  
Groundwater Quality ◽  
Low Income ◽  
Groundwater Vulnerability ◽  
Unconfined Aquifer ◽  
Aquifer Vulnerability ◽  
Near Surface ◽  
Nitrate Concentrations ◽  
Groundwater Vulnerability Assessment ◽  
The Tropics

Abstract In rapidly growing cities in the tropics, unregulated urban development presents a major risk to groundwater quality. Here, we assess the vulnerability of an unconfined aquifer of Quaternary sands in the Thiaroye area of Dakar (Senegal) to contamination using four GIS-based indices (DRASTIC, DRASTIC_N, SINTACS, SI). Our correlation of assessed vulnerability to observed impact is semi-quantitative, relating observed groundwater quality, based on nitrate concentrations and tryptophan-like fluorescence to vulnerability degrees (i.e. coincidence rates). We show that considerably more of the Thiaroye area has a “very high vulnerability” according to SI (36%) relative to DRASTIC (5%) and SINTACS (9%); “high vulnerability” is estimated using DRASTIC_N (100%), DRASTIC (66%) and SINTACS (69%). Single-parameter sensitivity tests show that groundwater depth, soil, topography, land use and redox parameters strongly influence assessments of groundwater vulnerability. Correlation with observed nitrate concentrations reveals aquifer vulnerability is better represented by SI (coincidence rates of 56%) relative to DRASTIC_N (43%), SINTACS (38%) and DRASTIC (34%). The underestimation of groundwater vulnerability in Dakar using DRASTIC, DRASTIC_N and SINTACS is attributed to their reliance on an assumed capacity of the unsaturated zone to attenuate surface or near-surface contaminant loading, which in the low-income (Thiaroye) area of Dakar is thin and affords limited protection. The inclusion of a land-use parameter in SI improves the characterization of groundwater vulnerability in this low-income, rapidly urbanizing area of Dakar.

scholarly journals A review of groundwater vulnerability assessment in Kenya

2018 ◽  
Vol 7 (2) ◽  
Author(s):  
Halake Guyo Rendilicha
Keyword(s):  
Land Use ◽  
Groundwater Quality ◽  
Land Use Planning ◽  
Vulnerability Assessment ◽  
Groundwater Pollution ◽  
High Reliability ◽  
Groundwater Vulnerability ◽  
Preventive Strategy ◽  
Groundwater Availability ◽  
Groundwater Vulnerability Assessment

Groundwater represents 95% of the world’s unfrozen freshwater. The use of groundwater has significantly increased over the past 50 years and is expected to rise in future due to its high reliability during drought seasons, good quality, generally modest development costs and continuous depletion of surface water. Groundwater pollution is becoming a major threat to fresh groundwater availability and sustainability. The deteriorating groundwater quality and increasing contamination poses detrimental risk to human health and ecosystem in many ways, thereby necessitating the need to study the groundwater vulnerability assessment as a preventive strategy to protect the groundwater from surface pollution. The concept of groundwater vulnerability assessment is dated back in 1970s and applied in many developed countries as an environmental tool used for proper land use planning and decision making without jeopardizing groundwater quality.  This paper is a detail review of available literature on the study of groundwater vulnerability assessment in Kenya. The paper revealed that, the vulnerability assessment concept has not been applied as a mechanism to prevent groundwater pollution, hence rarely used in guiding land use planning in Kenya. This review brings to limelight the importance of groundwater vulnerability assessment in management and protection of groundwater resources in Kenya.*Corresponding author; Email:[email protected] Mobile: 0710953283.1. Soil, Water and Environmental Engineering Department Jomo Kenyatta University of Agriculture and Technology, Kenya

scholarly journals Integrating hydrogeological and second-order geo-electric indices in groundwater vulnerability mapping: A case study of alluvial environments

2021 ◽  
Vol 11 (7) ◽  
Author(s):  
Nyakno Jimmy George
Keyword(s):  
Protective Layer ◽  
Groundwater Vulnerability ◽  
Vulnerability Index ◽  
Aquifer Vulnerability ◽  
Second Order ◽  
Depth Range ◽  
Near Surface ◽  
Groundwater Vulnerability Mapping ◽  
Longitudinal Unit Conductance ◽  
S Model

AbstractAVI (Aquifer vulnerability index), GOD (groundwater occurrence, overlying lithology and depth to the aquifer), GLSI (geo-electric layer susceptibility indexing) and S (longitudinal unit conductance) models were used to assess economically exploitable groundwater resource in the coastal environment of Akwa Ibom State, southern Nigeria. The models were employed in order to delineate groundwater into its category of vulnerability to contamination sources using the first- and second-order geo-electric indices as well as hydrogeological inputs. Vertical electrical sounding technique employing Schlumberger electrode configuration was carried out in 16 locations, close to logged boreholes with known aquifer core samples. Primary or first-order geo-electric indices (resistivity, thickness and depth) measured were used to determine S. The estimated aquifer hydraulic conductivity, K, calculated from grain size diameter and water resistivity values were used to calculate hydraulic resistance (C) used to estimate AVI. With the indices assigned to geo-electric parameters on the basis of their influences, GOD and FSLI were calculated using appropriate equations. The geologic sequence in the study area consists of geo-electric layers ranging from motley topsoil, argillites (clayey to fine sands) and arenites (medium to gravelly sands). Geo-electric parametric indices of aquifer overlying layers across the survey area were utilized to weigh the vulnerability of the underlying water-bearing resource to the contaminations from surface and near-surface, using vulnerability maps created. Geo-electrically derived model maps reflecting AVI, BOD, FLSI and S were compared to assess their conformity to the degree of predictability of groundwater vulnerability. The AVI model map shows range of values of log C ( −3.46—0.07) generally less than unity and hence indicating high vulnerability. GOD model tomographic map displays a range of 0.1–0.3, indicating that the aquifer with depth range of 20.5 to 113.1 m or mean depth of 72. 3 m is lowly susceptible to surface and near-surface impurities. Again, the FLSI map displays a range of FLSI index of 1.25 to 2.75, alluding that the aquifer underlying the protective layer has a low to moderate vulnerability. The S model has values ranging from 0.013 to 0.991S. As the map indicates, a fractional portion of the aquifer at the western (Ikot Abasi) part of the study area has moderate to good protection (moderate vulnerability) while weak to poor aquifer protection (high vulnerability) has poor protection. The S model in this analysis seems to overstate the degree of susceptibility to contamination than the AVI, GOD and GLSI models. From the models, the categorization of severity of aquifer vulnerability to contaminations is relatively location-dependent and can be assessed through the model tomographic maps generated.

Application of a GIS-based DRASTIC model and groundwater quality index method for evaluation of groundwater vulnerability: a case study, Sefid-Dasht

2015 ◽  
Vol 15 (4) ◽  
pp. 784-792 ◽  
Author(s):  
Nastaran Khodabakhshi ◽  
Gholamreza Asadollahfardi ◽  
Nima Heidarzadeh
Keyword(s):  
Groundwater Quality ◽  
Quality Index ◽  
Major Ions ◽  
Groundwater Vulnerability ◽  
Vulnerability Index ◽  
Aquifer Vulnerability ◽  
Index Method ◽  
Drastic Model ◽  
Groundwater Quality Index ◽  
The North

Pollution control and removal of pollutants from groundwater are a challenging and expensive task. The aims of this paper are to determine the aquifer vulnerability of Sefid-Dasht, in Chaharmahal and Bakhtiari province, Iran, using the DRASTIC model. In addition, the groundwater quality index (GQI) technique was applied to assess the groundwater quality and study the spatial variability of major ion concentrations using a geographic information system (GIS). The vulnerability index ranged from 65 to 132, classified into two classes: low and moderate vulnerability. In the southern part of the aquifer, the vulnerability was moderate. Furthermore, the results indicate that the magnitude of the GQI index varies from 92% to 95%. This means the water has a suitable quality. However, from the north to the south and southwest of the aquifer, the water quality has been deteriorating, and the highest concentration of major ions was found in the southwest of the Sefid-Dasht aquifer. A comparison of the vulnerability maps with the GQI index map indicated a poor relation between them. In the DRASTIC method, movement of groundwater is not considered and may be the reason for such inconsistency. However, the movement of groundwater can transport contaminants.

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.

Groundwater Vulnerability Mapping in Urbanized Hydrological System Using Modified Drastic Model and Sensitivity Analysis

2018 ◽  
Vol 24 (3) ◽  
pp. 293-304 ◽  
Author(s):  
Ismail Chenini ◽  
Adel Zghibi ◽  
Mohamed Haythem Msaddek ◽  
Mahmoud Dlala
Keyword(s):  
Land Use ◽  
Vadose Zone ◽  
Vulnerability Assessment ◽  
Groundwater Vulnerability ◽  
Vulnerability Index ◽  
Drastic Model ◽  
Groundwater Vulnerability Mapping ◽  
Groundwater Vulnerability Assessment ◽  
Modified Drastic ◽  
The Impact

Abstract The groundwater vulnerability assessment is normally applied to rural watersheds. However, urbanization modifies the hydrogeological processes. A modified DRASTIC model was adopted to establish a groundwater vulnerability map in an urbanized watershed. The modified DRASTIC model incorporated a land-use map, and net recharge was calculated taking into account the specificity of the urban hydrogeological system. The application of the proposed approach to the Mannouba watershed demonstrates that the groundwater vulnerability indexes range from 80 to 165. The study's results shows that 30 percent of the Mannouba watershed area has a high vulnerability index, 45 percent of the area has a medium index, and 25 percent of the study area has a low vulnerability index. To specify the effect of each DRASTIC factor on the calculated vulnerability index, sensitivity analyses were performed. Land use, topography, and soil media have an important theoretical weight greater than the effective weight. The impact of the vadose zone factor has the most important effective weight and affects the vulnerability index. The sensitivity assessment explored the variation in vulnerability after thematic layer removal. In this analysis, the removal of hydraulic conductivity and impact of vadose zone modified the vulnerability index. Groundwater vulnerability assessment in urbanized watersheds is difficult and has to consider the impact of urbanization in the hydrogeological parameters.

scholarly journals GROUNDWATER VULNERABILITY ASSESSMENT TO SEAWATER INTRUSION THROUGH GIS - BASED GALDIT METHOD. CASE STUDY: ATALANTI COASTAL AQUIFER, CENTRAL GREECE

2017 ◽  
Vol 50 (2) ◽  
pp. 798 ◽  
Author(s):  
I. Lappas ◽  
A. Kallioras ◽  
F. Pliakas ◽  
Th. Rondogianni
Keyword(s):  
Seawater Intrusion ◽  
Coastal Aquifer ◽  
Groundwater Resources ◽  
Groundwater Vulnerability ◽  
Aquifer Vulnerability ◽  
Hydrogeological Parameters ◽  
Groundwater Occurrence ◽  
Boundary Parameter ◽  
Groundwater Vulnerability Assessment ◽  
Galdit Method

Groundwater resources assessment has resulted in development of models that help identify the vulnerable zones. This paper presents a GIS-based hydrogeological index, named GALDIT, aiming at the assessment of aquifer vulnerability to seawater intrusion in Atalanti coastal aquifer, Central-Eastern Greece. The above acronym is formed from the most important factors controlling seawater intrusion, that is, four intrinsic hydrogeological parameters, one spatial parameter and one boundary parameter including Groundwater occurrence (aquifer type), Aquifer hydraulic conductivity, depth to groundwater Level above the sea (hydraulic head), Distance from the shore, Impact of seawater intrusion and aquifer’s Thickness. These factors nclude the basic requirements needed to assess the general salinization potential of each hydrogeological setting. Each parameter is evaluated with respect to the other to determine the relative importance of each factor. GALDIT model is described to assess and quantify the significance of vulnerability to seawater intrusion due to excessive groundwater withdrawals. Different thematic maps are prepared for seawater intrusion indicators and overlaid to develop the final vulnerability map. The derived map can be used as a tool for coastal groundwater resources management and areas’ determination of potential saltwater intrusion since the result of GALDIT ndex is classified based on vulnerability rate.

An Agricultural Decision Support System for Optimal Land Use Regarding Groundwater Vulnerability

2010 ◽  
Vol 1 (4) ◽  
pp. 66-79 ◽  
Author(s):  
Konstantinos Voudouris ◽  
Maurizio Polemio ◽  
Nerantzis Kazakis ◽  
Angelo Sifaleras
Keyword(s):  
Land Use ◽  
Decision Support ◽  
Decision Support System ◽  
Support System ◽  
Socioeconomic Development ◽  
Groundwater Resources ◽  
Land Use Changes ◽  
Groundwater Vulnerability ◽  
Alluvial Deposits ◽  
Groundwater Vulnerability Assessment

The availability of quality water is a basic condition of socioeconomic development. The agriculture water demand can be damaged by contamination of groundwater resources. This paper proposes a tool to preserve groundwater quality by using groundwater vulnerability assessment methods and a decision support system (DSS). The mapping of intrinsic groundwater vulnerability was based on reliable methods, the DRASTIC and the SINTACS methods. A DSS was developed to assess the groundwater vulnerability and pollution risk due to agricultural activities and land use changes. The proposed DSS software package was designed using the Matlab language and efficiently performs tasks while incorporating new maps to cover new areas. The tool was tested at two study areas located in the Mediterranean that are dominated by different prevalent hydrogeological features, that is, the typical porous features of alluvial deposits in the Greek study area and the typical fissured and karstic features of limestones and dolostones in the Italian study area.

scholarly journals Groundwater Quality and Groundwater Vulnerability Assessment

Environments ◽  
2021 ◽  
Vol 8 (10) ◽  
pp. 100
Author(s):  
Konstantinos Voudouris ◽  
Nerantzis Kazakis
Keyword(s):  
Groundwater Quality ◽  
Vulnerability Assessment ◽  
Groundwater Vulnerability ◽  
Finite Resource ◽  
Groundwater Vulnerability Assessment

Groundwater is a valuable and finite resource covering only 30% of the freshwater (3% of the total volume of water) on Earth [...]

An Agricultural Decision Support System for Optimal Land Use Regarding Groundwater Vulnerability

2012 ◽  
pp. 454-466
Author(s):  
Konstantinos Voudouris ◽  
Maurizio Polemio ◽  
Nerantzis Kazakis ◽  
Angelo Sifaleras
Keyword(s):  
Land Use ◽  
Decision Support ◽  
Decision Support System ◽  
Support System ◽  
Socioeconomic Development ◽  
Groundwater Resources ◽  
Land Use Changes ◽  
Groundwater Vulnerability ◽  
Groundwater Vulnerability Assessment ◽  
Karstic Features

The availability of quality water is a basic condition of socioeconomic development. The agriculture water demand can be damaged by contamination of groundwater resources. This paper proposes a tool to preserve groundwater quality by using groundwater vulnerability assessment methods and a decision support system (DSS). The mapping of intrinsic groundwater vulnerability was based on reliable methods, the DRASTIC and the SINTACS methods. A DSS was developed to assess the groundwater vulnerability and pollution risk due to agricultural activities and land use changes. The proposed DSS software package was designed using the Matlab language and efficiently performs tasks while incorporating new maps to cover new areas. The tool was tested at two study areas located in the Mediterranean that are dominated by different prevalent hydrogeological features, that is, the typical porous features of alluvial deposits in the Greek study area and the typical fissured and karstic features of limestones and dolostones in the Italian study area.

scholarly journals Impacts of Climate Change and Different Crop Rotation Scenarios on Groundwater Nitrate Concentrations in a Sandy Aquifer

2020 ◽  
Vol 12 (3) ◽  
pp. 1153 ◽  
Author(s):  
Shoaib Saleem ◽  
Jana Levison ◽  
Beth Parker ◽  
Ralph Martin ◽  
Elisha Persaud
Keyword(s):  
Climate Change ◽  
Land Use ◽  
Winter Wheat ◽  
Groundwater Quality ◽  
Red Clover ◽  
Reference Period ◽  
Future Period ◽  
Continuous Corn ◽  
Nitrate N ◽  
Nitrate Concentrations

Nitrate in groundwater is a major concern in agricultural sub-watersheds. This study assessed the impacts of future climate and agricultural land use changes on groundwater nitrate concentrations in an agricultural sub-watershed (Norfolk site) in southern Ontario, Canada. A fully integrated hydrologic model (HydroGeoSphere) was used in combination with the root zone water quality model (RZWQM2) (shallow zone) to develop water flow and nitrate transport models. Three climate change models and three crop rotations (corn-soybean rotation, continuous corn, corn-soybean-winter wheat-red clover rotation) were used to evaluate the potential impact on groundwater quality (nine predictive scenarios). The selected climate change scenarios yielded less water availability in the future period than in the reference period (past conditions). The simulated nitrate nitrogen (Nitrate-N) concentrations were lower during the future period than the reference period. The continuous corn land use scenario produced higher Nitrate-N concentrations compared to the base case (corn-soybean rotation). However, the best management practices (BMP) scenario (corn-soybean-winter wheat-red clover rotation) produced significantly lower groundwater nitrate concentrations. BMPs, such as the one examined herein, should be adopted to reduce potential negative impacts of future climate change on groundwater quality, especially in vulnerable settings. These findings are important for water and land managers, to mitigate future impacts of nutrient transport on groundwater quality under a changing climate.

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