Geomorphological and geophysical approach for locating favorable groundwater zones in granitic terrain, Andhra Pradesh, India

Dhakate, Ratnakar; Singh, V. S.; Negi, B.C.; Chandra, Subhash; Rao, V. Ananda

doi:10.1016/j.jenvman.2007.07.014

Cited by 41 publications

(10 citation statements)

References 6 publications

(5 reference statements)

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“…Various degrees of fracturing and connection between fracture networks induce strong variations of hydrogeological properties at all scales (e.g., Le Borgne, Bour, & Caudal, ; Le Borgne, Bour, de Dreuzy, Davy, & Touchard, ; Maréchal, Dewandel, & Subrahmanyam, ; Paillet, ). The few available works on upscaling and regionalizing aquifer parameters in crystalline aquifers has mainly focused on transmissivity or hydraulic conductivity mapping, based on hydraulic test data (Chandra, Ahmed, Ram, & Dewandel, ; Razack & Lasm, ), classified transmissivity (indexed) maps, or potential aquifer zone maps (Courtois et al, ; Darko & Krásný, ; Dhakate, Singh, Negi, Chandra, & Ananda, ; Krásný, ; Krásný, ; Lachassagne et al, ; Madrucci, Taioli, & de Araujo, ).…”

Section: Introductionmentioning

confidence: 99%

A methodology for regionalizing 3‐D effective porosity at watershed scale in crystalline aquifers

Dewandel¹,

Caballero²,

Perrin

et al. 2017

Hydrological Processes

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International audience13 An innovative approach for regionalizing the 3-D effective-porosity field is presented and 14 applied to two large, overexploited and deeply weathered crystalline aquifers located in 15 southern India. The method derives from earlier work on regionalizing a 2-D effective-16 porosity field in that part of an aquifer where the water table fluctuates, which is now 17 extended over the entire aquifer using a 3-D approach. A method based on geological and 18 geophysical surveys has also been developed for mapping the weathering profile layers 19 (saprolite and fractured layers). The method for regionalizing 3-D effective porosity 20 combines: water-table fluctuation and groundwater budget techniques at various cell sizes 21 with the use of satellite based data (for groundwater abstraction), the structure of the 22 weathering profile and geostatistical techniques. The approach is presented in detail for the 23 Kudaliar watershed (983 km 2), and tested on the 730 km 2 Anantapur watershed. At watershed 24 scale, the effective porosity of the aquifer ranges from 0.5% to 2% in Kudaliar and between 25 0.3% and 1% in Anantapur, which agrees with earlier works. Results show that: i) depending 26 on the geology and on the structure of the weathering profile, the vertical distribution of 27 effective porosity can be very different, and that the fractured layers in crystalline aquifers are 28 not necessarily characterized by a rapid decrease in effective porosity; and ii) that the lateral 29 variations in effective porosity can be larger than the vertical ones. These variations suggest 30 that within a same weathering profile the density of open fractures and/or degree of 31 weathering in the fractured zone may significantly varies from a place to another. 32 The proposed method provides information on the spatial distribution of effective porosity 33 which is of prime interest in terms of flux and contaminant transport in crystalline aquifers. 34 Implications for mapping groundwater storage and scarcity are also discussed, which should 35 help in improving groundwater resource management strategies. 36 3

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Section: Introductionmentioning

confidence: 99%

A methodology for regionalizing 3‐D effective porosity at watershed scale in crystalline aquifers

Dewandel¹,

Caballero²,

Perrin

et al. 2017

Hydrological Processes

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“…The geoelectrical method provides a wide range of variations in the subsurface electrical resistivity. The variations are often associated with water content and lithology; hence, it is one of the most powerful geophysical methods often used in providing solutions to hydrogeological problems [4][5][6]. Recently, induced polarization method which is based on the chargeability effect of the subsurface has proved to be of significant value in the investigation of lithological variability of unconsolidated sediments especially in the mapping of clay content.…”

Section: Introductionmentioning

confidence: 99%

Investigation of lithological control of iron enrichment in groundwater using geophysical techniques in Yenagoa, Southern Nigeria

2019

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Hydrochemical analysis of water samples from Yenagoa in the Niger Delta shows widespread occurrence of iron (Fe) in the groundwater. The Fe concentration is more than 0.3 mg/L at many places, and the distribution is heterogeneous both vertically and horizontally. In order to identify the cause of the high heterogeneity, we carried out an integrated study consisting of hydrogeochemical, electrical resistivity sounding and induced polarization (IP) chargeability measurements at eleven sites and 2-D electrical resistivity profiling (at 2 sites). Data processing using inversion techniques resulted in 4-layered resistivity and chargeability-depth models. The results show that clean sand and gravel exhibit high resistivity but low chargeability and normalized chargeability values, whereas clay and sandy clay exhibit relatively low resistivity but high chargeability and normalized chargeability values. In sites where the aquifer is overlain by a thick clay layer, Fe concentration is high (Fe > 0.3 mg/L) in the groundwater and redox potential values range between 118 and 133 mV. We interpret that the low-permeability clay layer creates a relatively atmosphere-isolated state in the underlying aquifer, which is responsible for the reductive ambient subsurface groundwater environment. In sites where the aquifer is capped by silt, Fe concentration is low (< 0.3 mg/L) in the groundwater and redox potential values range between 115 and 164 mv indicating a mild oxidation environment. We interpret that the clay acts as a controlling factor to the Fe enrichment in the groundwater regime. Knowledge of the clay layer, which is identified in the present study, will be helpful in selecting suitable sites for boreholes.

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“…Few works describe the spatial heterogeneity of aquifer parameters in crystalline aquifers, and mainly focus on transmissivity or hydraulic-conductivity mapping based on data from hydraulic tests (Razack and Lasm, 2006;Chandra et al, 2008), on classified transmissivity (i.e. indexed) maps, or on potential aquifer-zone maps (Krásný, 1993(Krásný, , 2000Lachassagne et al, 2001;Darko and Krásný, 2007;Madrucci et al, 2008;Dhakate et al, 2008;Courtois et al, 2010).…”

Section: Introductionmentioning

confidence: 99%

Inferring the heterogeneity, transmissivity and hydraulic conductivity of crystalline aquifers from a detailed water-table map

Dewandel

Jeanpert

Ladouche

et al. 2017

Journal of Hydrology

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Estimating the transmissivity or hydraulic conductivity field to characterize the heterogeneity of a crystalline aquifer is particularly difficult because of the wide variations of the parameters. We developed a new approach based on the analysis of a dense network of watertable data. It is based on the concept that large-scale variations in hydraulic head may give information on large-scale aquifer parameters. The method assumes that flux into the aquifer is mainly sub-horizontal and that the water table is mostly controlled by topography, rather than recharge. It is based on an empirical statistical relationship between field data on transmissivity and the inverse slope values of a topography-reduced water-table map. This relationship is used to compute a transmissivity map that must be validated with field measurements. The proposed approach can provide a general pattern of transmissivity, or hydraulic conductivity, but cannot correctly reproduce strong variations at very local scale (less than10 metres), and will face of some uncertainties where vertical flows cannot be neglected. The method was tested on a peridotite (ultramafic rock) aquifer of 3.5 km 2 in area located in New Caledonia. The resulting map shows transmissivity variations over about 5 orders of magnitude (average LogT:-5.2±0.7). Comparison with a map based on measured water-level data (n=475) shows that the comparison between LogT-computed values and LogT data deduced from 28 hydraulic tests is estimated with an error less than 20% in 71% of cases (LogT±0.4), and with an error less than 10% (LogT±0.2 on average) in 39% of cases. From this map a hydraulic-conductivity map has been computed showing values ranging over 8 orders of magnitude. The repeatability of the approach was tested on a second data set of hydraulic-head measurements (n=543); the mean deviation between both LogT maps is about 11%. These encouraging results show that the method can give valuable parameter estimates, and can characterize aquifer heterogeneity. The computed LogT and LogK maps highlight the spatial distribution of parameters that show a pattern clearly controlled by the fault network of this ultramafic massif. However, the faults are mainly characterized by low-permeability zones; this differs from results on other crystalline aquifers and may be due to the fact that weathering products of peridotite are clay-like materials. The resulting transmissivity map can be used as a starting point for modelling or to direct additional fieldwork.

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Geomorphological and geophysical approach for locating favorable groundwater zones in granitic terrain, Andhra Pradesh, India

Cited by 41 publications

References 6 publications

A methodology for regionalizing 3‐D effective porosity at watershed scale in crystalline aquifers

A methodology for regionalizing 3‐D effective porosity at watershed scale in crystalline aquifers

Investigation of lithological control of iron enrichment in groundwater using geophysical techniques in Yenagoa, Southern Nigeria

Inferring the heterogeneity, transmissivity and hydraulic conductivity of crystalline aquifers from a detailed water-table map

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