Groundwater in fractured bedrock environments: managing catchment and subsurface resources – an introduction

Ofterdinger, Ulrich; MacDonald, Alan; Comte, Jean-Christophe; Young, Michael

doi:10.1144/sp479-2018-170

Cited by 33 publications

(26 citation statements)

References 79 publications

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“…Despite limited productivity, crystalline-rock aquifers play an important role in catchment hydrology (Ofterdinger et al 2019), capable of providing domestic water supplies (Chilton and Foster 1992) and larger supplies for irrigation or towns (Maurice et al 2019) as well as sustaining baseflow to rivers and aquatic ecosystems (Comte et al 2019). Crystalline-rock aquifers are particularly important in India, as crystalline rocks underlie two-thirds of the country (Mukherjee et al 2015) and groundwater is widely abstracted from crystalline aquifers for irrigation.…”

Section: Introductionmentioning

confidence: 99%

Groundwater connectivity of a sheared gneiss aquifer in the Cauvery River basin, India

et al. 2020

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Connectivity of groundwater flow within crystalline-rock aquifers controls the sustainability of abstraction and baseflow to rivers, yet is often poorly constrained at a catchment scale. Here groundwater connectivity in a sheared gneiss aquifer is investigated by studying the intensively abstracted Berambadi catchment (84 km 2) in the Cauvery River Basin, southern India, with geological characterisation, aquifer properties testing, hydrograph analysis, hydrochemical tracers and a numerical groundwater flow model. The study indicates a well-connected system, both laterally and vertically, that has evolved with high abstraction from a laterally to a vertically dominated flow system. Likely as a result of shearing, a high degree of lateral connectivity remains at low groundwater levels. Because of their low storage and logarithmic reduction in hydraulic conductivity with depth, crystalline-rock aquifers in environments such as this, with high abstraction and variable seasonal recharge, constitute a highly variable water resource, meaning farmers must adapt to varying water availability. Importantly, this study indicates that abstraction is reducing baseflow to the river, which, if also occurring in other similar catchments, will have implications downstream in the Cauvery River Basin.

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Section: Introductionmentioning

confidence: 99%

Groundwater connectivity of a sheared gneiss aquifer in the Cauvery River basin, India

et al. 2020

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“…The average groundwater source yield (productivity) of WBAs in Africa is generally low (<60 L/min; MacDonald et al, 2012) due to typically low transmissivity and storativity values (Chilton & Foster, 1995; Howard et al, 1992; Ofterdinger et al, 2019; Taylor & Howard, 2000). However, yields from individual boreholes can vary substantially (Courtois et al, 2010; Jones, 1985; Macdonald & Edmunds, 2014; McFarlane et al, 1992), and hydrogeological conditions sustaining high‐intensity abstractions are possible (Maurice et al, 2019).…”

Section: Introductionmentioning

confidence: 99%

Investigating the Productivity and Sustainability of Weathered Basement Aquifers in Tropical Africa Using Numerical Simulation and Global Sensitivity Analysis

Bianchi

MacDonald

Macdonald

et al. 2020

Water Resources Research

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Groundwater stored in weathered basement aquifers (WBAs) is a strategic water resource. In this study, we investigate the productivity of WBAs and sustainability of groundwater abstractions using a novel process-based stochastic modeling approach, which is applied to simulate abstractions in the Precambrian basement aquifer in Ghana. The statistical distribution of the generated synthetic yield data was found in very good agreement with observed yield data from the same Ghanaian aquifer. Further analysis provided robust insights regarding how different hydrogeological parameters of the WBA, and their interplay, control aquifer productivity and sustainability. Results indicate that 97% of the simulated abstractions could sustain the yield of a hand pump (6 L/min), approximately 30% could also sustain yields >60 L/min, while only 1% could sustain yields greater than 300 L/min. The model indicates that an aquifer transmissivity value of approximately 1.4 m 2 /day is required for a successful hand-pumped borehole, while a higher yielding source (60 L/min) requires a transmissivity value of at least 9.5 m 2 /day. A global sensitivity analysis of 13 model input parameters shows that the thickness of the regolith and the maximum hydraulic conductivity developed at the base of the saprolite are the critical factors controlling success and sustainability for low yielding hand-pumped boreholes. For higher yielding supplies, the net recharge, the depth to groundwater, and the aquifer extent become increasingly significant. Results from this work have important implications for the potential for increased development of groundwater from WBAs in tropical Africa. The average groundwater source yield (productivity) of WBAs in Africa is generally low (<60 L/min;

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“…The hydrodynamic behavior of these aquifer systems meets the criteria mentioned in the literature for fractured-rock aquifers over the last four decades (e.g., [104][105][106][107][108][109][110][111][112][113]). The median depth of the boreholes is 121 m in Sector 1, and higher in Sector 2, around 154 m (Figure 4b).…”

Section: Hydrodynamical Assessmentmentioning

confidence: 99%

Urban Groundwater Processes and Anthropogenic Interactions (Porto Region, NW Portugal)

Afonso

Freitas

Marques

et al. 2020

Water

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Groundwater in fissured rocks is one of the most important reserves of available fresh water, and urbanization applies an extremely complex pressure which puts this natural resource at risk. Two-thirds of Portugal is composed of fissured aquifers. In this context, the Porto urban region is the second biggest metropolitan area in mainland Portugal. In this study, a multidisciplinary approach was developed, using hydrogeological GIS-based mapping and modeling, combining hydrogeochemical, isotopic, and hydrodynamical data. In addition, an urban infiltration potential index (IPI-Urban) was outlined with the combination of several thematic layers. Hydrogeochemical signatures are mainly Cl-Na to Cl-SO4-Na, being dependent on the geographic proximity of this region to the ocean, and on anthropogenic and agricultural contamination processes, namely fertilizers, sewage, as well as animal and human wastes. Isotopic signatures characterize a meteoric origin for groundwater, with shallow flow paths and short residence times. Pumping tests revealed a semi- to confined system, with low long-term well capacities (<1 L/s), low transmissivities (<4 m2/day), and low storage coefficients (<10−2). The IPI-Urban index showed a low groundwater infiltration potential, which was enhanced by urban hydraulic and sanitation features. This study assessed the major hydrogeological processes and their dynamics, therefore, contributing to a better knowledge of sustainable urban groundwater systems in fractured media.

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Groundwater in fractured bedrock environments: managing catchment and subsurface resources – an introduction

Cited by 33 publications

References 79 publications

Groundwater connectivity of a sheared gneiss aquifer in the Cauvery River basin, India

Groundwater connectivity of a sheared gneiss aquifer in the Cauvery River basin, India

Investigating the Productivity and Sustainability of Weathered Basement Aquifers in Tropical Africa Using Numerical Simulation and Global Sensitivity Analysis

Urban Groundwater Processes and Anthropogenic Interactions (Porto Region, NW Portugal)

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