Analysis of the impact of hydraulic properties and climate change on estimations of borehole yields

Ascott, Matthew; Mansour, Majdi; Bloomfield, John P.; Upton, Kirsty

doi:10.1016/j.jhydrol.2019.123998

Cited by 10 publications

(8 citation statements)

References 51 publications

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“…associated with intense rainfall such as in dry subtropical locations (Cuthbert et al, 2019) where more complex representation of the climatic control on the simulated abstractions may be needed (e.g., Ascott et al, 2019).…”

Section: Representativity Of the Simulated Wba Profiles And Maximum Amentioning

confidence: 99%

“…The climatic signal was simply simulated as a constant net recharge influx active over the 4 months of a wet season. In reality, the response of recharge to rainfall is likely more complex and nonlinear (Acworth, 2019), as in areas where recharge is 10.1029/2020WR027746 associated with intense rainfall such as in dry subtropical locations (Cuthbert et al, 2019) where more complex representation of the climatic control on the simulated abstractions may be needed (e.g., Ascott et al, 2019).…”

Section: Representativity Of the Simulated Wba Profiles And Maximum Allowable Yieldsmentioning

confidence: 99%

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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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Section: Representativity Of the Simulated Wba Profiles And Maximum Amentioning

confidence: 99%

Section: Representativity Of the Simulated Wba Profiles And Maximum Allowable Yieldsmentioning

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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“…Both water resource system and distributed groundwater models can be subject to long run times, which has limited the extent of uncertainty analysis that has been undertaken. Whilst models have used stochastically derived meteorological data (Harris et al 2014) to explore resource availability under future droughts, limited work has explored the impact of groundwater model structure and parameter uncertainty, which may significantly affect yield estimates in the Chalk (Ascott et al 2019). Integration of water quality has been limited in these models and there can be challenges in accessing models when these are based in proprietary software and contain commercially sensitive information.…”

Section: Improved Integrated Modelling Of Groundwater In the Water Cycle During Droughtsmentioning

confidence: 99%

The effect of seasonality on the application of accumulated degree-days to estimate the early post-mortem interval

Giles

Harrison

Errickson

et al. 2020

Forensic Science International

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Effective management of groundwater resources during drought is essential. How is groundwater currently managed during droughts, and in the face of environmental change, what should be the future priorities? Four themes are explored, from the perspective of groundwater management in England (UK): (1) integration of drought definitions; (2) enhanced fundamental monitoring; (3) integrated modelling of groundwater in the water cycle; and (4) better information sharing. Whilst these themes are considered in the context of England, globally, they are relevant wherever groundwater is affected by drought.

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“…This would be beneficial as it could then be possible to quantify the buffering capacity of groundwater to drought events, which has been shown to be potentially significant in sub‐Saharan Africa (Foster et al, 2012; MacDonald & Calow, 2009; Vouillamoz et al, 2015). Numerous approaches (recently summarized by Ascott et al, 2019) have linked lumped parameter models such as AquiMod to changes in groundwater levels in abstraction boreholes to estimate impacts of climate variability on individual borehole yields. Given suitable abstraction borehole data, this could be undertaken in Burkina Faso.…”

Section: Discussionmentioning

confidence: 99%

In Situ Observations and Lumped Parameter Model Reconstructions Reveal Intra‐Annual to Multidecadal Variability in Groundwater Levels in Sub‐Saharan Africa

Ascott

Macdonald

Black

et al. 2020

Water Resources Research

Self Cite

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Understanding temporal variability in groundwater levels is essential for water resources management. In sub-Saharan Africa, groundwater level dynamics are poorly constrained due to limited long-term observations. Here, we present the first published analysis of temporal variability in groundwater levels at the national scale in sub-Saharan Africa, using 12 multidecadal (ca. 1980s to present) groundwater level hydrographs in Burkina Faso. For each hydrograph, we developed lumped parameter models which achieved acceptable calibrations (NSE = 0.5-0.99). For eight sites not showing significant (p < 0.001) long-term groundwater level declines, we reconstructed groundwater levels to 1902, over 50 years before the earliest observations in the tropics. We standardized and clustered the eight reconstructed hydrographs to compare responses across the sites. Overall, the 12 hydrographs were categorized into three groups, which are dominated by (1) long-term declines (four sites), (2) short-term intra-annual variability (three sites), and (3) long-term multidecadal variability (five sites). We postulate that group 1 is controlled by anthropogenic influences (land use change and abstraction). Correlation of modeled water table depth and groundwater response times with hydrograph autocorrelation suggests that hydrogeological properties and structure control differences between groups 2 and 3. Group 3 shows a small recovery in groundwater levels following the 1970/1980s drought. Differences in intra-annual to multidecadal variability in groundwater levels have implications for water management and highlight the value of long-term monitoring. Reconstructions contextualize current groundwater status, forecasts, and projections. The approach developed is generic and applicable where long-term groundwater level data exist.

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Analysis of the impact of hydraulic properties and climate change on estimations of borehole yields

Abstract: Analysis of the impact of hydraulic properties and climate change on estimations of borehole yields

Cited by 10 publications

References 51 publications

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

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

The effect of seasonality on the application of accumulated degree-days to estimate the early post-mortem interval

In Situ Observations and Lumped Parameter Model Reconstructions Reveal Intra‐Annual to Multidecadal Variability in Groundwater Levels in Sub‐Saharan Africa

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