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.

scholarly journals Aquifer Vulnerability: Its Protection and Management—A Case Study in Pangkalpinang City, Indonesia

2020 ◽  
Vol 2020 ◽  
pp. 1-23
Author(s):  
Gumilar Utamas Nugraha ◽  
Karit Lumban Gaol ◽  
Priyo Hartanto ◽  
Hendra Bakti
Keyword(s):  
Urban Areas ◽  
Groundwater Resources ◽  
Protective Layer ◽  
Groundwater Vulnerability ◽  
Vulnerability Index ◽  
Aquifer Vulnerability ◽  
Anthropogenic Activity ◽  
Groundwater Extraction ◽  
Industrial Areas ◽  
High Level

Increased anthropogenic activity in urban areas has exacerbated the vulnerability of groundwater resources. The AVI, GOD, SINTACS, and DRASTIC methods were used to analyze groundwater vulnerability in Pangkalpinang City. Schlumberger vertical electrical sounding was used to determine the lithology and aquifer configuration in the study area. There are three vulnerability index areas in the city of Pangkalpinang. Low levels of aquifer vulnerability were generally found in the southeastern and northwestern parts of the study area, whereas high levels of aquifer vulnerability were discovered in the northern and southern parts of the study area. Areas with low aquifer vulnerability levels generally have low hydraulic conductivity values on the protective layer. In these areas, groundwater extraction is possible with a reasonable extraction pattern. Industrial areas can also be built by considering environmental aspects. In an area with high-level aquifer vulnerability, groundwater pollution must be considerably managed. The areas should not be designated for industrial areas and excess groundwater extraction.

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.

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 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 Modified AVI Model for Groundwater Vulnerability Mapping: Case Studies in Southern Italy

Water ◽  
2022 ◽  
Vol 14 (2) ◽  
pp. 248
Author(s):  
Daniela Ducci ◽  
Mariangela Sellerino
Keyword(s):  
Southern Italy ◽  
Groundwater Vulnerability ◽  
Aquifer Vulnerability ◽  
Data Availability ◽  
Physical Parameters ◽  
Time Dimension ◽  
Index Method ◽  
Vulnerability Index Method ◽  
Hydrogeological Characteristics ◽  
Groundwater Vulnerability Mapping

Many methods for evaluating the aquifer’s vulnerability to pollution have been developed in the past four decades by using geographic information system (GIS) tools. However, even if the aquifer vulnerability concept is well defined and the methods have been constantly tested and compared, the problem of the choice of the best “standard” method remains. To meet these objectives, aquifer vulnerability maps are of crucial importance. The choice of method depends on several factors, including the scale of the project, the hydrogeological characteristics of the area, and data availability. Among the many methods, the AVI (Aquifer Vulnerability Index) method has been widely used as it considers only two physical parameters. The AVI Index represents the hydraulic resistance of an aquifer to vertical flow, as a ratio between the thickness of each sedimentary unit above the uppermost aquifer (D, length), and the estimated hydraulic conductivity (K, length/time) of each of these layers. The AVI Index has a time dimension and is divided into five classes. In order to avoid a widespread presence of the higher vulnerability classes, especially in shallow aquifers, the AVI classification has been modified using statistical methods. The study reports the application of the modified AVI method for groundwater pollution vulnerability, in three different areas of southern Italy, highlighting the limitations of the method in alluvial aquifers and the differences with other methods.

scholarly journals Karst groundwater vulnerability mapping to the pollution: Case of Dir springs located between EL KSIBA and Ouaoumana (High Atlas, Morocco)

2018 ◽  
Vol 37 ◽  
pp. 01004 ◽  
Author(s):  
L. Alili ◽  
A. Boukdir ◽  
M. R. Maslouhi ◽  
H. Ikhmerdi
Keyword(s):  
Groundwater Vulnerability ◽  
Vulnerability Index ◽  
Karst Groundwater ◽  
High Atlas ◽  
The North ◽  
Groundwater Vulnerability Mapping ◽  
Protective Cover ◽  
The Subject ◽  
Gis Software ◽  
Hydrographic Network

The study area is located in the north of the province of Beni Mellal, it covers the Piedmont of the high Atlas between El Ksiba and Ouaoumana. It is characterized by a poorly developed hydrographic network and the presence of very important karstic forms. These forms condition the rapid infiltration to the karstic springs are the subject of this study. In this work we presented a method of mapping the vulnerability to pollution of Karstic springs located between El Ksiba and Ouaoumana. To do this, we have introduced a vulnerability index called F which takes into account four parameters (EPIK): Development of the Epikarst, importance of the protective cover, infiltration conditions and development of the Karst network. The overlay of the thematic maps of these parameters through a GIS software (ArcGIS) gave us a map of the vulnerability to contamination on the whole hydrogeological basin of the springs.

scholarly journals GIS-based assessment of aquifer vulnerability using DRASTIC Model: A case study on Kodaganar basin

2016 ◽  
Vol 20 (1) ◽  
pp. 1-8 ◽  
Author(s):  
Johnny Colins ◽  
M. C. Sashikkumar ◽  
P. A. Anas ◽  
M. Kirubakaran
Keyword(s):  
Groundwater Vulnerability ◽  
Vulnerability Index ◽  
Aquifer Vulnerability ◽  
Sensitivity Analyses ◽  
Drastic Model ◽  
El Sistema ◽  
Soil Media ◽  
Gis Environment ◽  
Para Determinar ◽  
The Impact

<p>Groundwater is vulnerable and more susceptible to contamination from various anthropogenic elements. Various steps are taken to measure the groundwater vulnerability for a sustainable groundwater development. The present study estimates the aquifer vulnerability by applying DRASTIC model in the Geographic Information System (GIS) environment. The DRASTIC model uses seven hydrological parameters which include depth to water level, net recharge, aquifer media, soil media, topography, the impact of vadose zone and hydraulic conductivity. DRASTIC index was calculated from DRASTIC model that ranged from 31 to 154. All these parameters characterize the hydrological setting for evaluating aquifer vulnerability. Sensitivity analyses have also been performed to determine the sensitivity of every individual DRASTIC parameter towards the aquifer vulnerability. Sensitivity analysis indicated that all the parameters have an almost similar influence on vulnerability index. Depth to water parameter inflicts larger impact on aquifer vulnerability followed by recharge, topography and soil Media. The whole of Kodaganar basin is classified into very low, low, moderate and high vulnerable zones. Nearly three- fourth of the basin has very low and low vulnerability. Incorporating DRASTIC model in the GIS environment has proved efficient in handling large volumes of data and in determining the groundwater vulnerability. </p><p> </p><div class="page" title="Page 1"><div class="section"><div class="layoutArea"><div class="column"><p><strong>Evaluación basada en el Sistema de Información Geográ ca a la vulnerabilidad de un acuífero a partir del método DRASTIC: caso de estudio en la cuenca Kodaganar </strong></p><p><strong><br /></strong></p><p><strong>Resumen</strong></p><p>El agua subterránea es vulnerable y más susceptible a la contaminación de varios elementos antropogénicos. Se midió la vulnerabilidad del agua subterránea en varias etapas para establecer el desarrollo sustentable de la fuente acuífera. Este trabajo estima la vulnerabilidad del agua subterránea por la aplicación del método DRASTIC en el entorno del Sistema de Información Geográfica (GIS, en inglés). El método DRASTIC utiliza siete parámetros hidrológicos: profundidad del agua subterránea, recarga neta, litología del acuífero, tipo de suelo, topografía naturaleza de la zona no saturada y conductividad hidráulica del acuífero. El índice DRASTIC fue calculado a través de este método y que oscila entre 31 y 154 unidades. Estos parámetros caracterizan la configuración hidrológica para la evaluación de vulnerabilidad del acuífero. También se realizaron los análisis de susceptibilidad para determinar la respuesta de cada parámetro DRASTIC frente a la vulnerabilidad del agua subterránea. El análisis de susceptibilidad indicó que todos los parámetros tienen una influencia similar en el índice de vulnerabilidad. El parámetro de profundidad ocasiona un mayor impacto en el índice de vulnerabilidad, seguido por la recarga, la topografía y el tipo de suelo. Toda la cuenca de Kodaganar se clasifica en zonas de vulnerabilidad muy baja, baja, moderada y alta. La incorporación del método DRASTIC en el entorno GIS prueba la e ciencia en el manejo de grandes volúmenes de información y en la evaluación de vulnerabilidad de aguas subterráneas.</p>

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.

Sign in / Sign up

Export Citation Format

Share Document