Mapping Of Groundwater Resources Research Articles

Vulnerability Mapping of Groundwater Resources of Mekelle City and Surroundings, Tigray Region, Ethiopia

The management and monitoring of the quality of water resources in the Mekelle area are challenging, due to both geogenic and anthropogenic impacts. The extent of these impacts and the sources of pollution in this area have not been thoroughly investigated. In this article, a mapping of water resources vulnerability was carried out using the DRASTIC method and a modified DRASTIC vulnerability map was produced. Single-parameter and map-removal sensitivity analyses were performed on the relevant rates and weights. A final DRASTIC vulnerability index, varying from 54 to 140, was divided into four vulnerability classes: low (225.7 km2), medium (302.8 km2), high (307.2 km2), and very high (187.6 km2); the values in the parentheses indicate the corresponding areal coverage of each class. Similarly, a modified DRASTIC vulnerability index, ranging from 91 to 192, was divided into four vulnerability classes: low (166.4 km2), medium (266.8 km2), high (338.0 km2), and very high (252.2 km2) Nitrates were used to validate both models. in which moderate positive correlations (with Pearson’s correlation coefficient, r) of 0.681 and 0.702 were calculated for the DRASTIC and modified DRASTIC indices, respectively. A comparison of the two maps showed that significant sources of pollution are located in areas with high to very high vulnerability. The results of this research work can be used for the protection and monitoring of groundwater resources in the Mekelle area.

IRS-1C Satellite Data Utilization for Groundwater Prospects Mapping for the Entire Country Under National Rural Drinking Water Program (NRDWP): A State of the Art Initiative

Conventional methods of groundwater targeting often result in failures due to improper selection of sites as a result of the lack of scientific database. Satellite-based mapping using geographic information system (GIS) has brought a paradigm shift in the mapping of the natural resources including groundwater. Remote sensing is a cost effective technique to carry out the groundwater prospects mapping which otherwise is difficult to achieve at national scale. A comprehensive database could be created on groundwater resource mapping and assessment using IRS LISS III satellite data from IRS-1C and its follow-on missions like IRS-1D and Resourcesat-1 for the entire India which was first of its kind. A national mission called National Rural Drinking Water Program was launched in the year 1999 to carry out groundwater prospects mapping at 1:50,000 scale for the entire country using 23.5 m resolution IRS LISS III satellite data. The objective of the project was to generate groundwater prospects maps on 1:50,000 scale in GIS format showing (a) different prospective zones in terms of yield and depth of aquifer and (b) tentative sites of different recharge structures suitable in the area. It is imperative that the mammoth task of preparing 4898 groundwater prospects maps on 1:50,000 scale for the entire country has become a reality due to the timely and continuous availability of LISS III satellite images from IRS-1C sensor and its follow-on missions.

An Integrated Study to Delineate the Groundwater Potential Zones Using Geospatial Approach of Sidhi Area, Madhya Pradesh

The surface and groundwater resources are depleting over time, therefore, it becomes essential to monitor and preserve these resources and also to protect their quality. Remote sensing and GIS has become an important tool of hydrological studies in recent times which helps in assessing and mapping of ground-water resources. The remote sensing and GIS approach are well known and widely used techniques to integrate contributing hydrogeological factors namely, geology, geomorphology, lineaments density, drainage density, soil type, slope and land use/land cover. A study was conducted to delineate the groundwater potential zones in a part of Sidhi area, Madhya Pradesh using remote sensing and GIS techniques. Landsat 8 satellite data and Aster DEM is integrated with toposheets for systematic mapping. All thematic layers were integrated, overlaid and analysed using GIS software. Groundwater potential zone is delineated and to interpret thematic layer, appropriate weights assigned to topographical features for assessing the potential zone. The zones are divided into high, moderate and low groundwater potential zones. The study reveals that 21.36% of the area has high potential, 48.12% moderate and 30.51% low potential zone for groundwater occurrence. The result of this study suggests that the favourable potential zones would prove to be very helpful for better planning and management of groundwater resources in the study area.

Groundwater applications of towed TEM in diverse geology at farm scale

SummaryVehicle towed transient TEM systems have opened up possibilities of comprehensive mapping of groundwater resources at farm scale. At this scale airborne TEM usually has too much setup cost and conventional TEM conducted on foot is usually too laborious and rarely economically viable. Interpretation of data requires understanding of diverse geology, from alluvial geomorphology, volcanogenic deposition, weathering and erosion processes and the often complex combination of these. Further, impacts on the data by fences, buried cables and modelling imperfections must be separated from geological impact. Typically, it is the detail of the survey that renders it interpretable rather than system quality alone.

Groundwater Resource Mapping through the Integration of Geology, Remote Sensing, Geographical Information Systems and Borehole Data in Arid-Subarid Lands at Turkana South Sub-County, Kenya

The integrated approach of various techniques which historically have been used independently is key to successful exploration, development, exploitation and management of the groundwater resources. The integration of Remote Sensing (RS), Geographical Information Systems (GIS) and Borehole data has been used in the study area to assess their applicability in groundwater investigation. The area of study lies in the arid and semi-arid lands (ASALs) where principally remote sensing data has been used in extraction of various thematic maps (lithology, lineament, drainage density, and Digital Elevation Model Maps) for groundwater assessment. The GIS platform was used in integrating the RS data and data of productive boreholes. The lineaments generated through remote sensing agree well with structural geology of the area, where high density lineament points overlays the points of intense faulting. Lineaments found in the area correlate well with fault zones, fractures, and lithological contrasts as supported by geological map and structural map. Weathering, faulting and fracturing of the rocks mean a possible increase or a reduction in specific capacities as observed in productive boreholes in sedimentary rocks or igneous/basaltic rocks of the area. Similarly, it is noted that the degree of faulting affects the degree of radius of influence of a borehole in a particular area. These analyses show that groundwater potential within the Sub-County varies spatially with high dependency on geological structures in the basement region and more on geology within the volcanic and younger sediments.

Discriminating Weathering Degree by Integrating Optical Sensor and SAR Satellite Images for Potential Mapping of Groundwater Resources in Basement Aquifers of Semiarid Regions

Unlike in coastal and sedimentary basins, regional-scale exploration of groundwater resources using only geophysical methods is costlier in consolidated rocks such as volcanic rocks and crystalline basement complexes in Africa because of the highly heterogeneous structure of aquifers. Therefore, advanced analysis of remotely sensed images and an accurate assessment of groundwater resources are crucial before carrying out a geophysical prospecting survey. This study proposed a joint analysis of satellite images from optical sensors and synthetic aperture radar (SAR) which aimed to enhance potential mapping accuracy of groundwater resources in crystalline rock areas in a semiarid region. The backscattering coefficient of the SAR data analysis effectively detected the zones of relatively high weathering degree and thus having thick permeable regolith. In addition, a modified clay index calculated from the four band reflectances of the optical sensor image—red, near infrared, and two shortwave infrared bands—was applied to discriminate clay-rich zones from high vegetation activity zones. The clay-rich zones detected corresponded with the highly weathered zones estimated from the small SAR backscattering coefficients. The zones also corresponded with a large density of faults and lineaments and furthermore were verified by high potential yields from groundwater wells. The thickness of weathered zones was likely to increase with a decreasing backscattering coefficient and higher modified clay index values. Conversely, large backscattering coefficients in the narrow zones along the major lineaments from large volumetric scattering because of high vegetation activity, as confirmed by the large vegetation index values, suggested that high moisture content was retained in the soils. In fact, the potential yields of the groundwater wells tended to increase near the lineaments. Accordingly, shallow groundwater occurrence is plausible in those zones.

Modeling groundwater potential zones of Puruliya district, West Bengal, India using remote sensing and GIS techniques

ABSTRACTRemote sensing and geographical information system (RS-GIS) have become a leading tool for modeling and mapping of groundwater resources. An attempt has been made to delineate the groundwater potential zones of Puruliya district using the integrated RS-GIS and AHP techniques. All the themes and their features have been assigned weights according to their relative importance and their normalized weights were calculated after the hierarchical ranking by pair-wise comparison matrix of analytical hierarchy process (AHP). Groundwater potential map has been prepared through weighted overlay model in GIS environment after integrating all the thematic layers. The entire district has been classified into three different groundwater potential zones—high, moderate, and low. Greater portion of the study area (60.92%) fall within the moderate potentiality zone, about 22.55% and 16.53% of the total area fall under the high and low potential zone, respectively. Potential zones have been validated with the groundwater yield data, 10 out of 14 validation points (71.43%), matches with the expected yield classes. It shows that the applied method produces significantly reliable results for the present study which can help the decision makers to formulate an effective plan for the study area.

Regional Mapping of Groundwater Resources in Data-Scarce Regions: The Case of Laos

This study focuses on Laos, a landlocked nation located in South-East Asia with sub-tropical climate and highly seasonal rainfall distribution. Laos is one of the world’s least developed countries, and currently witnesses an unprecedented level of development that is highly reliant on its natural resources, including groundwater. There is currently very limited data and no nationwide assessment of shallow (<30 m) groundwater resources to support sustainable management. This study provides a first step towards addressing this issue by (i) identifying the major aquifer units of the country; (ii) integrating localized data and regional maps into an assessment of the groundwater potential; and (iii) producing quantitative maps of key hydrogeological indicators. Eight aquifer units have been described and evaluated: (i) Basement aquifers, (ii) Volcanic aquifers, (iii) Schists, (iv) Paleozoic sedimentary, (v) Karsts, (vi) Limestones, (vii) Mesozoic sedimentary and (viii) Alluvial sediments. The Mesozoic sandstones and the Alluvial aquifers are the most extensive and productive hydrogeological systems in the country. The Volcanic and Karstic aquifers, although poorly known, might also have important potential. This assessment, along with the maps of quantitative aquifer indicators, provide a significant improvement in both spatial resolution and accuracy compared to previously available information. It will likely support improved management plans and the identification of areas with higher potential for groundwater development.

Progress on the mapping of groundwater resources and environment in Asia

Progress on the mapping of groundwater resources and environment in Asia

Geoinformatic Modeling of Groundwater Resource Mapping of Shear Zone Regions- A Case Study on Attur Valley, Tamil Nadu, India

The general tendency of mapping groundwater resource using remote sensing and Geographic Information System (GIS) techniques involve assigning higher weightage to geomorphology. But this cannot be used as a thumb rule everywhere, especially an area where many ductile and brittle zones are prevalent. The influence of texture and structure of sheared rocks might play a control over retaining and permitting groundwater to flow. Attur valley is characterized by the presence of many shear zones and faults and hence the rocks are highly fissile within the shear zones. The present study tries to establish a new ranking and weightage scheme and hence a new spatial model for groundwater resource mapping in shear zone area like Attur Valley. This spatial model can be verified with field data such as water level data, pump test and resistivity data.

The Impact on Geological and Hydrogeological Mapping Results of Moving from Ground to Airborne TEM

In the past three decades, airborne electromagnetic (AEM) systems have been used for many groundwater exploration purposes. This contribution of airborne geophysics for both groundwater resource mapping and water quality evaluations and management has increased dramatically over the past ten years, proving how these systems are appropriate for large-scale and efficient groundwater surveying. One of the major reasons for its popularity is the time and cost efficiency in producing spatially extensive datasets that can be applied to multiple purposes. In this paper, we carry out a simple, yet rigorous, simulation showing the impact of an AEM dataset towards hydrogeological mapping, comparing it to having only a ground-based transient electromagnetic (TEM) dataset (even if large and dense), and to having only boreholes. We start from an AEM survey and then simulate two different ground TEM datasets: a high resolution survey and a reconnaissance survey. The electrical resistivity model, which is the final geophysical product after data processing and inversion, changes with different levels of data density. We then extend the study to describe the impact on the geological and hydrogeological output models, which can be derived from these different geophysical results, and the potential consequences for groundwater management. Different data density results in significant differences not only in the spatial resolution of the output resistivity model, but also in the model uncertainty, the accuracy of geological interpretations and, in turn, the appropriateness of groundwater management decisions. The AEM dataset provides high resolution results and well-connected geological interpretations, which result in a more detailed and confident description of all of the existing geological structures. In contrast, a low density dataset from a ground-based TEM survey yields low resolution resistivity models, and an uncertain description of the geological setting.

Hydrochemistry deducing basaltic trap thickness for groundwater resource mapping along the Deccan Volcanic Province (DVP) margin in India

It is hypothesized that hydrochemical parameters can be employed to deduce the basaltic trap thickness and that there exist diverse hydrochemical processes within the existing host rocks along the Deccan Volcanic Province (DVP) margin. Chemical imprints of aquifers, in various flows of flood basalt and fissured zones of granites, had been appraised using major ion chemistry of groundwater in a test site of 623 km2 at the southern margin of the DVP in India. The wide ranging hydrochemical processes, obtained from empirical data, describe the predominance of carbonate, dolomite, calcite and anorthite weathering in basalts, and alkali feldspar (albite and orthoclase) in granites. Results showed that the elevated concentrations of alkaline earth elements in basaltic aquifers and alkali rich elements in granitic aquifers were useful in tracing the sources of host rock for dissolved mineral reactants. Further, a digital elevation model using Shuttle Radar Topography Mission (90 m) elevation satellite data aided in deciphering trap thickness, vertical transition zone of trap and granitic basement comprising the well depths and hydrochemistry. The mapping of trap thickness is useful to explore the groundwater resources at the vertical transition zone between the basaltic trap and granitic base. The estimated thickness of the basaltic trap is varied from 4 to 98 m at the DVP southern margin, which is further verified with the help of exploratory well lithologs matched closely.

Geo-spatial technology based study on climate change impact and stewardship for rural India: A pragmatic approach for comprehensive groundwater resource mapping and management

Climate change may influence hydrogeological processes and groundwater resources directly and indirectly in various modes. Therefore, a systematic planning, management and adaption are challenging task. Considering the importance of climate change impact, the study was to identify the sustainable Groundwater (GW) / Drinking Water (DW) resources potential zones, suitable locations for GW harvesting structures, recommendation for GW quality management and GW extraction methods for Dhubri District of Assam, India and also with emphasis on Non-Covered (NC) and Partially-Covered (PC) habitations in the rural area of Dhubri District. The quality and quantity of GW/DW resources potential of the region is under extreme threat due to frequent flood, drought and population pressure. geographic information system (GIS) and Remote sensing (RS) technology along with on-field investigations were used to achieve the goal. GW availability is controlled by the local hydrogeomorphology, geology and geological structures of the area. Based on these controlling factors the GW resource Potential Zone Maps of the study area were prepared. Well inventorisation was also carried out including depth to water level, water level fluctuation, yield range and well-type, etc. It was found that more than half of the area falls under shallow GW table zone. The GW resource potential zones were successfully delineated based on Weightage Value (WV). The entire study area has been classified into various classes that is, excellent, very good, good, moderate and poor. To enhance and manage the GW resources in this area, GW recharge structures such as check-dams, percolation tanks and recharge-pits were suggested. Various types of GW extraction methods such as, Ring Well (RW), Tube Well(TW), Bore Well(BW) were recommended for this region.

Geophysical borehole logging for control of driller’s records: hydrogeological case study from Voltaian sedimentary rocks in northern Ghana

The low borehole yielding potential and the high drilling failure rate of the Voltaian sedimentary rocks of Northern Ghana have been of concern to many local hydrogeologists and international donors. Consequently, several donor-supported projects have been instituted within the last few years with the view to study the hydrogeological characteristics of this ‘difficult’ rock system. One such project is the geophysical borehole logging of 13 boreholes drilled into the Voltaian sedimentary rocks of Northern Ghana to enhance detailed hydrogeological assessment. Natural gamma detectors embedded in the five exploratory logging tools employed for the study ensured depth control by comparing their individual gamma log signatures. The combined gamma and formation resistivity/conductivity response logs provided more detailed lithological information than were shown in the driller’s/geologist’s logs. Significant discrepancies between the logging results and the reported drilled depths, construction depths, and screen settings were observed in seven of the thirteen investigated boreholes. Thus, the reliability of driller’s borehole records seems questionable, which will hamper hydrogeological studies and the mapping of groundwater resources. Further, it may be supposed that the productivity of most wells in Ghana is compromised by poor depth control of screen placement.

Quantitative maps of groundwater resources in Africa

In Africa, groundwater is the major source of drinking water and its use for irrigation is forecast to increase substantially to combat growing food insecurity. Despite this, there is little quantitative information on groundwater resources in Africa, and groundwater storage is consequently omitted from assessments of freshwater availability. Here we present the first quantitative continent-wide maps of aquifer storage and potential borehole yields in Africa based on an extensive review of available maps, publications and data. We estimate total groundwater storage in Africa to be 0.66 million km3 (0.36–1.75 million km3). Not all of this groundwater storage is available for abstraction, but the estimated volume is more than 100 times estimates of annual renewable freshwater resources on Africa. Groundwater resources are unevenly distributed: the largest groundwater volumes are found in the large sedimentary aquifers in the North African countries Libya, Algeria, Egypt and Sudan. Nevertheless, for many African countries appropriately sited and constructed boreholes can support handpump abstraction (yields of 0.1–0.3 l s−1), and contain sufficient storage to sustain abstraction through inter-annual variations in recharge. The maps show further that the potential for higher yielding boreholes ( > 5 l s−1) is much more limited. Therefore, strategies for increasing irrigation or supplying water to rapidly urbanizing cities that are predicated on the widespread drilling of high yielding boreholes are likely to be unsuccessful. As groundwater is the largest and most widely distributed store of freshwater in Africa, the quantitative maps are intended to lead to more realistic assessments of water security and water stress, and to promote a more quantitative approach to mapping of groundwater resources at national and regional level.

Application of a holistic inversion method in salinity risk and groundwater resource mapping in the River Murray corridor, SE Australia

The past decade has witnessed increasing policy demands to demonstrate cost-effective outcomes in environmental management. This has brought focus on the need to understand and map the complexity of biophysical systems in order to maximise the effectiveness of targeted management investments. A rise in demand for more accurate hydrogeological predictions for salinity and groundwater management, has seen increasing emphasis on multi-disciplinary geoscience systems approaches and the use of new or improved geospatial mapping technologies that enable specific gaps in the biophysical knowledge framework to be mapped and characterised with greater certainty.