Imperial College London

ProfessorAdrianButler

Faculty of EngineeringDepartment of Civil and Environmental Engineering

Professor of Subsurface Hydrology
 
 
 
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Contact

 

+44 (0)20 7594 6122a.butler Website

 
 
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Assistant

 

Miss Judith Barritt +44 (0)20 7594 5967

 
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Location

 

232Skempton BuildingSouth Kensington Campus

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Summary

 

Publications

Publication Type
Year
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135 results found

Muftah H, Rowan TSL, Butler AP, 2021, Towards open-source LOD2 modelling using convolutional neural networks, MODELING EARTH SYSTEMS AND ENVIRONMENT, ISSN: 2363-6203

Journal article

Dobson B, Jovanovic T, Chen Y, Paschalis A, Butler A, Mijic Aet al., 2021, Integrated modelling to support analysis of COVID-19 impacts on London's water system and in-river water quality, Frontiers in Water, Vol: 3, Pages: 1-18, ISSN: 2624-9375

Due to the COVID-19 pandemic, citizens of the United Kingdom were required to stay at home for many months in 2020. In the weeks before and months following lockdown, including when it was not being enforced, citizens were advised to stay at home where possible. As a result, in a megacity such as London, where long-distance commuting is common, spatial and temporal changes to patterns of water demand are inevitable. This, in turn, may change where people’s waste is treated and ultimately impact the in-river quality of effluent receiving waters. To assess large scale impacts, such as COVID-19, at the city scale, an integrated modelling approach that captures everything between households and rivers is needed. A framework to achieve this is presented in this study and used to explore changes in water use and the associated impacts on wastewater treatment and in-river quality as a result of government and societal responses to COVID-19. Our modelling results revealed significant changes to household water consumption under a range of impact scenarios, however, they only showed significant impacts on pollutant concentrations in household wastewater were in central London. Pollutant concentrations in rivers simulated by the model were most sensitive in the tributaries of the River Thames, highlighting the vulnerability of smaller rivers and the important role that they play in diluting pollution. Modelled ammonia and phosphates were found to be the pollutants that rivers were most sensitive to because their main source in urban rivers is domestic wastewater that was significantly altered during the imposed mobility restrictions. A model evaluation showed that we can accurately validate individual model components (i.e., water demand generator) and 30emphasised need for continuous water quality measurements. Ultimately, the work provides a basis for further developments of water systems integration approaches to project changes under never-before seen scenarios.

Journal article

Upton KA, Jackson CR, Butler AP, Jones MAet al., 2020, An integrated modelling approach for assessing the effect of multiscale complexity on groundwater source yields, JOURNAL OF HYDROLOGY, Vol: 588, ISSN: 0022-1694

Journal article

Islam MA, Hoque MA, Ahmed KM, Butler APet al., 2019, Impact of climate change and land use on groundwater salinization in southern Bangladesh-implications for other Asian deltas, Environmental Management (New York): an international journal for decision-makers, scientists and environmental auditors, Vol: 64, Pages: 640-649, ISSN: 0364-152X

Pervasive salinity in soil and water is affecting agricultural yield and the health of millions of delta dwellers in Asia. This is also being exacerbated by climate change through increases in sea level and tropical storm surges. One consequence of this has been a widespread introduction of salt water shrimp farming. Here, we show, using field data and modeling, how changes in climate and land use are likely to result in increased salinization of shallow groundwater in SE Asian mega-deltas. We also explore possible adaptation options. We find that possible future increase of episodic inundation events, combined with salt water shrimp farming, will cause rapid salinization of groundwater in the region making it less suitable for drinking water and irrigation. However, modified land use and water management practices can mitigate the impacts on groundwater, as well as the overlying soil, from future salinization. The study therefore provides guidance for adaptation planning to reduce future salinization in Asian deltas.

Journal article

Weaver KC, Hoque MA, Amin SM, Markússon SH, Butler APet al., 2019, Validation of basaltic glass adsorption capabilities from geothermal arsenic in a basaltic aquifer: A case study from Bjarnarflag power Station, Iceland, Geoscience Frontiers, Vol: 10, Pages: 1743-1753, ISSN: 1674-9871

Arsenic is a carcinogen known for its acute toxicity to organisms. Geothermal waters are commonly high in arsenic, as shown at the Bjarnarflag Power Plant, Iceland (∼224 μg/kg of solvent). Development of geothermal energy requires adequate disposal of arsenic-rich waters into groundwater/geothermal systems. The outcome of arsenic transport models that assess the effect of geothermal effluent on the environment and ecosystems may be influenced by the sensitivity of hydraulic parameters. However, previous such studies in Iceland do not consider the sensitivity of hydraulic parameters and thereby the interpretations remain unreliable. Here we used the Lake Mývatn basaltic aquifer system as a case study to identify the sensitive hydraulic parameters and assess their role in arsenic transport. We develop a one-dimensional reactive transport model (PHREEQC ver. 2.), using geochemical data from Bjarnarflag, Iceland. In our model, arsenite (H 3 AsO 3 ) was predicted to be the dominant species of inorganic arsenic in both groundwater and geothermal water. Dilution reduced arsenic concentration below ∼5 μg/kg. Adsorption reduced the residual contamination below ∼0.4 μg/kg at 250 m along transect. Based on our modelling, we found volumetric input to be the most sensitive parameter in the model. In addition, the adsorption strength of basaltic glass was such that the physical hydrogeological parameters, namely: groundwater velocity and longitudinal dispersivity had little influence on the concentration profile.

Journal article

MacAllister DJ, Graham MT, Vinogradov J, Butler AP, Jackson Met al., 2019, Characterising the self-potential response to concentration gradients in heterogeneous sub-surface environments, Journal of Geophysical Research. Solid Earth, Vol: 124, Pages: 7918-7933, ISSN: 2169-9356

Self‐potential (SP) measurements can be used to characterise and monitor, in real‐time, fluid movement and behaviour in the sub‐surface. The electrochemical exclusion‐diffusion (EED) potential, one component of SP, arises when concentration gradients exist in porous media. Such concentration gradients are of concern in coastal and contaminated aquifers, and oil and gas reservoirs. It is essential that estimates of EED potential are made prior to conducting SP investigations in complex environments with heterogeneous geology and salinity contrasts, such as the UK Chalk coastal aquifer. Here, we report repeatable laboratory estimates of the EED potential of chalk and marls using natural groundwater (GW), seawater (SW), deionised (DI) water and 5 M NaCl. In all cases the EED potential of chalk was positive (using a GW/SW concentration gradient the EED potential was c.14 to 22 mV), with an increased deviation from the diffusion limit at the higher salinity contrast. Despite the relatively small pore size of chalk (c.1 μm), it is dominated by the diffusion potential and has a low exclusion‐efficiency, even at large salinity contrasts. Marl samples have a higher exclusion‐efficiency which is of sufficient magnitude to reverse the polarity of the EED potential (using a GW/SW concentration gradient the EED potential was c.‐7 to ‐12 mV) with respect to the chalk samples. Despite the complexity of the natural samples used, the method produced repeatable results. We also show that first order estimates of the exclusion‐efficiency can be made using SP logs, supporting the parameterisation of the model reported in Graham et al. (2018), and that derived values for marls are consistent with the laboratory experiments, while values derived for hardgrounds based on field data indicate a similarly high exclusion‐efficiency. While this method shows promise in the absence of laboratory measurements, more rigorous estimates should be made where possible and can be conducted following

Journal article

Upton KA, Butler AP, Jackson CR, Mansour Met al., 2019, Modelling boreholes in complex heterogeneous aquifers, Environmental Modelling & Software, Vol: 118, Pages: 48-60, ISSN: 1364-8152

Reliable estimates of the sustainable yield of supply boreholes are critical to ensure that groundwater resources are managed sustainably. Sustainable yields are dependent on the pumped groundwater level in a borehole, how this relates to vertical aquifer heterogeneity, and features of the borehole itself. This paper presents a 3D radial flow model (SPIDERR), based on the Darcy-Forchheimer equation, for simulating the groundwater level response in supply boreholes in unconfined, heterogeneous aquifers. The model provides a tool for investigating the causes of non-linear behaviour in abstraction boreholes, which can have a significant impact on sustainable yields. This is demonstrated by simulating a variable-rate pumping test in a Chalk abstraction borehole. The application suggests the non-linear response to pumping is due to a combination of factors: a reduction in well storage with depth due to changes in the borehole diameter, a reduction in hydraulic conductivity with depth, and non-Darcian flow.

Journal article

Malcolm G, Jackson M, MacAllister DJ, Vinogradov J, Butler APet al., 2018, Self-potential as a predictor of seawater intrusion in coastal groundwater boreholes, Water Resources Research, Vol: 54, Pages: 6055-6071, ISSN: 0043-1397

Monitoring of self‐potentials (SP) in the Chalk of England has shown that a consistent electrical potential gradient exists within a coastal groundwater borehole previously affected by seawater intrusion (SI) and that this gradient is absent in boreholes further inland. Furthermore, a small but characteristic reduction in this gradient was observed several days prior to SI occurring. We present results from a combined hydrodynamic and electrodynamic model, which matches the observed phenomena for the first time and sheds light on the source mechanisms for the spatial and temporal distribution of SP. The model predictions are highly sensitive to the relative contribution of electrochemical exclusion and diffusion potentials, the ‘exclusion efficiency’, in different rock strata. Geoelectric heterogeneity, largely due to marls and hardgrounds with a relatively high exclusion efficiency, was the key factor in controlling the magnitude of the modelled SP gradient ahead of the saline front and its evolution prior to breakthrough. The model results suggest that, where sufficient geoelectric heterogeneity exists, borehole SP may be used as an early warning mechanism for SI.

Journal article

Todman LC, Chhang A, Riordan HJ, Brooks D, Butler AP, Templeton MRet al., 2018, Soil osmotic potential and its effect on vapor flow from a pervaporative irrigation membrane, Journal of Environmental Engineering, Vol: 144, ISSN: 0733-9372

Pervaporative irrigation is a membrane technology that can be used for desalination and subsurface irrigation simultaneously. To irrigate, the tube-shaped polymer membrane is buried in soil and filled with water. Because of the membrane transport process, water enters the soil in the vapor phase, drawn across the membrane when the relative humidity in the air-filled pores is low. Soils are typically humid environments; however, the presence of hygroscopic compounds such as fertilizers decreases the humidity. For example, at 20°C the humidity in air in equilibrium above a saturated ammonium nitrate solution is 63%. Here, experiments showed that the presence of fertilizers in sand increased the water flux across the membrane by an order of magnitude. An expression for vapor sorption into sand containing different hygroscopic compounds was developed and combined with a model of vapor and liquid flow in soil. The success of the model in simulating experimental results suggests that the proposed mechanism, adsorption of moisture from the vapor phase by hygroscopic compounds, explains the observed increase in the flux from the irrigation system.

Journal article

Rahman AKMM, Ahmed KM, Butler AP, Hoque MAet al., 2018, Influence of surface geology and micro-scale land use on the shallow subsurface salinity in deltaic coastal areas: a case from southwest Bangladesh, Environmental Earth Sciences, Vol: 77, ISSN: 1866-6280

Salinity, both in soil and water, is a ubiquitous problem in coastal Bangladesh, particularly in the southwest. Salinity varies at the local scale (5–10 m), but the relative roles of land use and surface geology on salinity variation in near-surface (< 5 m) groundwater are not fully understood. Surface geology, land use and salinity in near-surface (ca. 3 m) groundwater at two small sites (each 0.05 km2) were explored in the southwest coastal region of Bangladesh. The sediments in the near-surface at both sites are fine and hydrometer analyses of cored samples indicate the dominance of silty clay (70%) along with very fine sand (5%), sandy clay (15%) and clay (10%) materials. Salinity variation in near-surface groundwater tends to follow land use rather than surface geology at the scale of our investigations. The study provides evidence of the influence of land use on the near-surface salinity variation and indicates the importance of land-use planning in salinity management in coastal areas.

Journal article

Hammoud AS, Leung J, Tripathi S, Butler AP, Sule MN, Templeton MRet al., 2018, The impact of latrine contents and emptying practices on nitrogen contamination of well water in Kathmandu Valley, Nepal, AIMS Environmental Science, Vol: 5, Pages: 143-153, ISSN: 2372-0352

Leaching of nitrogen-containing compounds (e.g., ammonia, nitrate) from pit latrines and seepage tanks into groundwater may pose health risks, given that groundwater is a significant source for drinking water in many low-income countries. In this study, three communities within Kathmandu, Nepal (Manohara, Kupondole, and Lokanthali) were visited to investigate the impact of pit latrines on groundwater quality, with a focus on understanding the fate of nitrogen-containing compounds specifically. Well water samples were analyzed over two seasons (wet and dry) for their nitrogen content, dissolved oxygen (DO), chemical oxidation demand (COD), and oxidation-reduction potential (ORP), and samples collected from within the nearby pits were also analyzed to determine nitrogen content and COD. Hand dug wells were found to be more likely receptors of contamination than tube wells, as expected, with inter-well variations related to the relative redox conditions in the wells. Increased pit-emptying frequency was related to lower levels of nitrogen in the latrines and in the nearest wells, suggesting this may be an effective strategy for reducing the risks of groundwater contamination in such settings, all else being equal.

Journal article

MacAllister DJ, Jackson MD, Butler AP, Vinogradov Jet al., 2018, Remote detection of saline intrusion in a coastal aquifer using borehole measurements of self potential, Water Resources Research, Vol: 54, Pages: 1669-1687, ISSN: 0043-1397

Two years of self‐potential (SP) measurements were made in a monitoring borehole in the coastal UK Chalk aquifer. The borehole SP data showed a persistent gradient with depth, and temporal variations with a tidal power spectrum consistent with ocean tides. No gradient with depth was observed at a second coastal monitoring borehole ca. 1 km further inland, and no gradient or tidal power spectrum were observed at an inland site ca. 80 km from the coast. Numerical modeling suggests that the SP gradient recorded in the coastal monitoring borehole is dominated by the exclusion‐diffusion potential, which arises from the concentration gradient across a saline front in close proximity to, but not intersecting, the base of the borehole. No such saline front is present at the two other monitoring sites. Modeling further suggests that the ocean tidal SP response in the borehole, measured prior to breakthrough of saline water, is dominated by the exclusion‐diffusion potential across the saline front, and that the SP fluctuations are due to the tidal movement of the remote front. The electrokinetic potential, caused by changes in hydraulic head across the tide, is one order of magnitude too small to explain the observed SP data. The results suggest that in coastal aquifers, the exclusion‐diffusion potential plays a dominant role in borehole SP when a saline front is nearby. The SP gradient with depth indicates the close proximity of the saline front to the borehole and changes in SP at the borehole reflect changes in the location of the saline front. Thus, SP monitoring can be used to facilitate more proactive management of abstraction and saline intrusion in coastal aquifers.

Journal article

Mathias SA, Sorensen JPR, Butler AP, 2017, Soil moisture data as a constraint for groundwater recharge estimation, Journal of Hydrology, Vol: 552, Pages: 258-266, ISSN: 0022-1694

Estimating groundwater recharge rates is important for water resource management studies. Modeling approaches to forecast groundwater recharge typically require observed historic data to assist calibration. It is generally not possible to observe groundwater recharge rates directly. Therefore, in the past, much effort has been invested to record soil moisture content (SMC) data, which can be used in a water balance calculation to estimate groundwater recharge. In this context, SMC data is measured at different depths and then typically integrated with respect to depth to obtain a single set of aggregated SMC values, which are used as an estimate of the total water stored within a given soil profile. This article seeks to investigate the value of such aggregated SMC data for conditioning groundwater recharge models in this respect. A simple modeling approach is adopted, which utilizes an emulation of Richards’ equation in conjunction with a soil texture pedotransfer function. The only unknown parameters are soil texture. Monte Carlo simulation is performed for four different SMC monitoring sites. The model is used to estimate both aggregated SMC and groundwater recharge. The impact of conditioning the model to the aggregated SMC data is then explored in terms of its ability to reduce the uncertainty associated with recharge estimation. Whilst uncertainty in soil texture can lead to significant uncertainty in groundwater recharge estimation, it is found that aggregated SMC is virtually insensitive to soil texture.

Journal article

Scheelbeek P, Chowdhury MAH, Haines A, Alam D, Hoque MA, Butler AP, Khan AE, Mojumder SK, Blangiardo MAG, Elliott P, Vineis Pet al., 2017, Drinking water salinity and raised blood pressure: evidence from a cohort study in coastal Bangladesh, Environmental Health Perspectives, Vol: 125, Pages: 1-8, ISSN: 0091-6765

BACKGROUND: Millions of coastal inhabitants in Southeast Asia have been experiencing increasing sodium concentrations in their drinking-water sources, likely partially due to climate change. High (dietary) sodium intake has convincingly been proven to increase risk of hypertension; it remains unknown, however, whether consumption of sodium in drinking water could have similar effects on health. OBJECTIVES: We present the results of a cohort study in which we assessed the effects of drinking-water sodium (DWS) on blood pressure (BP) in coastal populations in Bangladesh. METHODS: DWS, BP, and information on personal, lifestyle, and environmental factors were collected from 581 participants. We used generalized linear latent and mixed methods to model the effects of DWS on BP and assessed the associations between changes in DWS and BP when participants experienced changing sodium levels in water, switched from "conventional" ponds or tube wells to alternatives [managed aquifer recharge (MAR) and rainwater harvesting] that aimed to reduce sodium levels, or experienced a combination of these changes. RESULTS: DWS concentrations were highly associated with BP after adjustments for confounding factors. Furthermore, for each 100 mg/L reduction in sodium in drinking water, systolic/diastolic BP was lower on average by 0.95/0.57 mmHg, and odds of hypertension were lower by 14%. However, MAR did not consistently lower sodium levels. CONCLUSIONS: DWS is an important source of daily sodium intake in salinity-affected areas and is a risk factor for hypertension. Considering the likely increasing trend in coastal salinity, prompt action is required. Because MAR showed variable effects, alternative technologies for providing reliable, safe, low-sodium fresh water should be developed alongside improvements in MAR and evaluated in "real-life" salinity-affected settings.

Journal article

Habib A, Sorensen JPR, Bloomfield JP, Muchan K, Newell AJ, Butler APet al., 2017, Temporal scaling phenomena in groundwater-floodplain systems using robust detrended fluctuation analysis, Journal of Hydrology, Vol: 549, Pages: 715-730, ISSN: 0022-1694

In order to determine objectively the fractal behaviour of a time series, and to facilitate potential future attempts to assess model performance by incorporating fractal behaviour, a multi-order robust detrended fluctuation analysis (r-DFAn) procedure is developed herein. The r-DFAn procedure allows for robust and automated quantification of mono-fractal behaviour. The fractal behaviour is quantified with three parts: a global scaling exponent, crossovers, and local scaling exponents. The robustness of the r-DFAn procedure is established by the systematic use of robust regression, piecewise linear regression, Analysis of Covariance (ANCOVA) and Multiple Comparison Procedure to determine statistically significant scaling exponents and optimum crossover locations. The MATLAB code implementing the r-DFAn procedure has also been open sourced to enable reproducible results.r-DFAn will be illustrated on a synthetic signal after which is used to analyse high-resolution hydrologic data; although the r-DFAn procedure is not limited to hydrological or geophysical time series. The hydrological data are 4 year-long datasets (January 2012 to January 2016) of 1-min groundwater level, river stage, groundwater and river temperature, and 15-min precipitation and air temperature, at Wallingford, UK. The datasets are analysed in both time and fractal domains. The study area is a shallow riparian aquifer in hydraulic connection to River Thames, which traverses the site. The unusually high resolution datasets, along with the responsive nature of the aquifer, enable detailed examination of the various data and their interconnections in both time- and fractal-domains.

Journal article

Foster T, Brozovic N, Butler AP, 2017, Effects of initial aquifer conditions on economic benefits from groundwater conservation, Water Resources Research, Vol: 53, Pages: 744-762, ISSN: 0043-1397

Worldwide, there is growing recognition of the need to reduce agricultural groundwater use in response to rapid rates of aquifer depletion. To date, however, few studies have evaluated how benefits of conservation vary along an aquifer's depletion pathway. To address this question, we develop an integrated modeling framework that couples an agro-economic model of farmers' field-level irrigation decision-making with a borehole-scale groundwater flow model. Unique to this framework is the explicit consideration of the dynamic reductions in well yields that occur as an aquifer is depleted, and how these changes in intraseasonal groundwater supply affect farmers' ability to manage production risks caused by climate variability and, in particular, drought. For an illustrative case study in the High Plains region of the United States, we apply our model to analyze the value of groundwater conservation activities for different initial aquifer conditions. Our results demonstrate that there is a range of initial conditions for which reducing pumping will have long-term economic benefits for farmers by slowing reductions in well yields and prolonging the usable lifetime of an aquifer for high-value irrigated agriculture. In contrast, restrictions on pumping that are applied too early or too late will provide limited welfare benefits. We suggest, therefore, that there are ‘windows of opportunity’ to implement groundwater conservation, which will depend on complex feedbacks between local hydrology, climate, crop growth, and economics.

Journal article

MacAllister DJ, Jackson MD, Butler AP, Vinogradov Jet al., 2016, Tidal influence on self-potential measurements, Journal of Geophysical Research. Solid Earth, Vol: 121, Pages: 8432-8452, ISSN: 2169-9313

Long-term surface and borehole self-potential (SP) monitoring was conducted in the UK Chalk aquifer at two sites. The coastal site is ~1.7 km from the coast, and the inland site is ~80 km from the coast. At both sites, power spectral density analysis revealed that SP data contain the main ocean tidal periodic components. However, the principal lunar component (M2), the dominant ocean tidal component, was most significant at the coastal site. The M2 signal in surface-referenced SP data at the inland site was partly due to telluric currents caused by the geomagnetic ocean dynamo. Earth and/or atmospheric tides also contributed, as the SP power spectrum was not typical of a telluric electric field. The M2 component in borehole-referenced data at the inland site was below the significance level of the analysis method and was 2 orders of magnitude smaller than the M2 signal in borehole-referenced SP data at the coastal site. The tidal response of the SP data in the coastal borehole is, therefore, primarily driven by ocean tides. These cause changes in fluid pressure and chemical concentration gradients within the coastal aquifer, leading to time varying electrokinetic and exclusion-diffusion potentials. Borehole-referenced SP measurements could be used to characterize and monitor tidal processes in coastal aquifers such as the intrusion of seawater.

Journal article

Foster T, Brozović N, Butler AP, Neale CMU, Raes D, Steduto P, Fereres E, Hsiao TCet al., 2016, AquaCrop-OS: an open source version of FAO's crop water productivity model, Agricultural Water Management, Vol: 181, Pages: 18-22, ISSN: 1873-2283

Crop simulation models are valuable tools for quantifying crop yield response to water, and for devising strategies to improve agricultural water management. However, applicability of the majority of crop models is limited greatly by a failure to provide open-access to model source code. In this study, we present an open-source version of the FAO AquaCrop model, which simulates efficiently water-limited crop production across diverse environmental and agronomic conditions. Our model, called AquaCrop-OpenSource (AquaCrop-OS), can be run in multiple programming languages and operating systems. Support for parallel execution reduces significantly simulation times when applying the model in large geospatial frameworks, for long-run policy analysis, or for uncertainty assessment. Furthermore, AquaCrop-OS is compliant with the Open Modelling Interface standard facilitating linkage to other disciplinary models, for example to guide integrated water resources planning.

Journal article

Scheelbeek PFD, Chowdhury MAH, Haines A, Alam A, Hoque MA, Butler AP, Khan AE, Mojumder SK, Blangiardo MAG, Elliott P, Vineis Pet al., 2016, High concentrations of sodium in drinking water and raised blood pressure in coastal deltas affected by episodic seawater inundations, Lancet Global Health, Vol: 4, ISSN: 2214-109X

Background In times of seawater inundation in coastal deltas, unprotected drinking water sources, such as ponds andshallow tube wells, take on salt water with each inundation. Daily consumption of these saline sources contributes tooverall sodium intake. Although there is evidence that a high dietary salt intake is an important risk factor forhypertension, little is known about the eff ect of high concentrations of sodium in drinking water on populationhealth. In this longitudinal study, we aimed to measure the eff ect of high concentrations of sodium in drinking wateron blood pressure and to assess the reversibility of raised blood pressure when conventional drinking water sourceswere replaced by low-saline water.Methods We used a multistage sampling process to recruit participants aged 18 years or older from the salinityaffectedsub-districts of Dacope, Batiagatha, and Paikgatchha in coastal Bangladesh. Most participants consumeddrinking water from highly saline sources, such as ponds and tube-wells, while a small percentage had access torainwater. In March, 2013, we recorded: baseline concentrations of sodium in drinking water; participants’ bloodpressure; and personal, lifestyle, and environmental characteristics. During the study period, some study participantsgained access to low-saline drinking water alternatives that were installed for use in the dry season, when water fromponds becomes more saline. In March, 2014, and May, 2014, we made follow-up assessments of drinking watersodium, blood pressure, and repeated the questionnaire about personal, lifestyle, and environmental characteristics.We used generalised linear mixed methods to model the eff ect of drinking water sodium on blood pressure andassess reversibility of raised blood pressure when participants switched from conventional drinking water sources tolow-saline alternatives.Findings We included data from 581 participants in analysis, of which 277 (48%) were male. Median age was 38 years(IQR 30&

Journal article

Hoque MA, Scheelbeek PFD, Vineis P, Khan AE, Ahmed KM, Butler APet al., 2016, Drinking water vulnerability to climate change and alternatives for adaptation in coastal South and South East Asia, Climatic Change, Vol: 136, Pages: 247-236, ISSN: 0165-0009

Drinking water in much of Asia, particularly in coastal and rural settings, isprovided by a variety of sources, which are widely distributed and frequently managed atan individual or local community level. Coastal and near-inland drinking water sources inSouth and South East (SSE) Asia are vulnerable to contamination by seawater, mostdramatically from tropical cyclone induced storm surges. This paper assesses spatialvulnerabilities to salinisation of drinking water sources due to meteorological variabilityand climate change along the (ca. 6000 km) coastline of SSE Asia. The risks of increasingclimatic stresses are first considered, and then maps of relative vulnerability along theentire coastline are developed, using data from global scale land surface models, alongwith an overall vulnerability index. The results show that surface and near-surfacedrinking water in the coastal areas of the mega-deltas in Vietnam and Bangladesh-Indiaare most vulnerable, putting more than 25 million people at risk of drinking ‘saline’ water.Climate change is likely to exacerbate this problem, with adverse consequences for health,such as prevalence of hypertension and cardiovascular diseases. There is a need foridentifying locations that are most at risk of salinisation in order for policy makers andlocal officials to implement strategies for reducing these health impacts. To counter therisks associated with these vulnerabilities, possible adaptation measures are also outlined.

Journal article

Le Vine N, Butler A, McIntyre N, Jackson Cet al., 2016, Diagnosing hydrological limitations of a land surface model: application of JULES to a deep-groundwater chalk basin, Hydrology and Earth System Sciences, Vol: 20, Pages: 143-159, ISSN: 1027-5606

Land surface models (LSMs) are prospective starting points to develop a global hyper-resolution model of the terrestrial water, energy, and biogeochemical cycles. However, there are some fundamental limitations of LSMs related to how meaningfully hydrological fluxes and stores are represented. A diagnostic approach to model evaluation and improvement is taken here that exploits hydrological expert knowledge to detect LSM inadequacies through consideration of the major behavioural functions of a hydrological system: overall water balance, vertical water redistribution in the unsaturated zone, temporal water redistribution, and spatial water redistribution over the catchment's groundwater and surface-water systems. Three types of information are utilized to improve the model's hydrology: (a) observations, (b) information about expected response from regionalized data, and (c) information from an independent physics-based model. The study considers the JULES (Joint UK Land Environmental Simulator) LSM applied to a deep-groundwater chalk catchment in the UK. The diagnosed hydrological limitations and the proposed ways to address them are indicative of the challenges faced while transitioning to a global high resolution model of the water cycle.

Journal article

Parker SJ, Butler AP, Jackson CR, 2016, Seasonal and interannual behaviour of groundwater catchment boundaries in a Chalk aquifer, Hydrological Processes, Vol: 30, Pages: 3-11, ISSN: 1099-1085

Groundwater catchment boundaries and their associated groundwater catchment areas are typically assumed to be fixed on a seasonal basis. We investigated whether this was true for a highly permeable carbonate aquifer in England, the Berkshire and Marlborough Downs Chalk aquifer, using both borehole hydrograph data and a physics-based distributed regional groundwater model. Borehole hydrograph data time series were used to construct a monthly interpolated water table surface, from which was then derived a monthly groundwater catchment boundary. Results from field data showed that the mean annual variation in groundwater catchment area was about 20% of the mean groundwater catchment area, but interannual variation can be very large, with the largest estimated catchment size being approximately 80% greater than the smallest. The flow in the river was also dependent on the groundwater catchment area. Model results corroborated those based on field data. These findings have significant implications for issues such as definition of source protection zones, recharge estimates based on water balance calculations and integrated conceptual modelling of surface water and groundwater systems.

Journal article

Hoque MA, Butler AP, 2016, Mineral nutrients and toxicants in Bangladesh groundwater—do we need a holistic approach to water quality?, Pages: 416-418

Groundwater, a drinking water source for > 95% of inhabitants living in Bangladesh, has received much attention because of its naturally occurring Arsenic (As), but the coupling or decou-pling of As toxicity by other water constituents remains unexplored. Although food provides nutrients, in rural settings, where people subsist on a low nutrient diet, drinking-water-nutrients may supply quantities significant for human health thereby preventing diseases. Here, we show, using augmented datasets from Bangladesh, that the content of groundwater is such that in some areas individuals obtain up to 50% or more of the Recommended Daily Intake (RDI) of some nutrients (e.g., calcium, magnesium, iron) from just 2 litres of drinking water. We also show the spatial association of groundwater nutrients and health outcomes in Bangladesh. We suggest, therefore, that a holistic approach, i.e., considering the entire range of groundwater constituents, should be considered when undertaking health impact studies of groundwater.

Conference paper

Hoque MA, Butler AP, 2016, Medical Hydrogeology of Asian Deltas: Status of Groundwater Toxicants and Nutrients, and Implications for Human Health, International Journal of Environmental Research and Public Health, Vol: 13, ISSN: 1660-4601

Drinking water, a fluid primarily for human hydration, is also a source of mineral nutrients. Groundwater, a drinking water source for more than 70% of inhabitants living in Asian deltas, has received much attention because of its naturally occurring arsenic, but the linkage of arsenic toxicity with other water constituents has not been studied. In addition, although nutrients are generally provided by food, in under developed rural settings, where people subsist on low nutrient diets, drinking-water-nutrients may supply quantities critical to human health thereby preventing diseases. Here, we show, using augmented datasets from three Asian deltas (Bengal, Mekong, and Red River), that the chemical content of groundwater is so substantial that in some areas individuals obtain up to 50% or more of the recommended daily intake (RDI) of some nutrients (e.g. calcium, magnesium, iron) from just 2 litres of drinking water. We also show some indications of a spatial association of groundwater nutrients and health outcome using demographic health data from Bangladesh. We therefore suggest that an understanding of the association of non-communicable disease and poor nutrition cannot be developed, particularly in areas with high levels of dissolved solids in water sources, without considering the contribution of drinking water to nutrient and mineral supply.

Journal article

Le Vine N, Butler A, McIntyre N, Jackson Cet al., 2015, Diagnosing hydrological limitations of a Land Surface Model: Application of JULES to a deep-groundwater chalk basin, Hydrology and Earth System Sciences Discussions, Vol: 12, Pages: 7541-7582, ISSN: 1812-2116

Land Surface Models (LSMs) are prospective starting points to develop a global hyper-resolution model of the terrestrial water, energy and biogeochemical cycles. However, there are some fundamental limitations of LSMs related to how meaningfully hydrological fluxes and stores are represented. A diagnostic approach to model evaluation is taken here that exploits hydrological expert knowledge to detect LSM inadequacies through consideration of the major behavioural functions of a hydrological system: overall water balance, vertical water redistribution in the unsaturated zone, temporal water redistribution and spatial water redistribution over the catchment's groundwater and surface water systems. Three types of information are utilised to improve the model's hydrology: (a) observations, (b) information about expected response from regionalised data, and (c) information from an independent physics-based model. The study considers the JULES (Joint UK Land Environmental Simulator) LSM applied to a deep-groundwater chalk catchment in the UK. The diagnosed hydrological limitations and the proposed ways to address them are indicative of the challenges faced while transitioning to a global high resolution model of the water cycle.

Journal article

Foster T, Brozović N, Butler AP, 2015, Why well yield matters for managing agricultural drought risk, Weather and Climate Extremes, Vol: 10, Pages: 11-19, ISSN: 2212-0947

Groundwater-fed irrigation has supported growth in agricultural production around the world by allowing farmers to buffer production against the risks associated with variable and uncertain climatic conditions. However, uncontrolled exploitation has also led to rapid rates of groundwater depletion in many semi-arid and arid regions that threaten farmers' long-term capacity to adapt to future climate change and extreme events. Declining well yields, which control the potential rate and feasibility of groundwater abstraction, are likely to restrict adaptation to drought, but this interaction has largely been neglected in previous research. In this study, we present a set of numerical hydro-economic simulations that assess the joint biophysical and economic effects of climate variability and well yield on irrigated agriculture through a case study in the Texas High Plains region of the United States. Our results demonstrate that reductions in well yield will constrain farmers' ability to use irrigation as an adaptive tool, and may have large negative economic impacts on production. Significantly, economic impacts will be greatest during drought events that are projected to increase in frequency and intensity as a result of climate change. We suggest therefore that management of well yields should be a key consideration when evaluating agricultural drought risk adaptation.

Journal article

Foster T, Brozovic N, Butler AP, 2015, Analysis of the impacts of well yield and groundwater depth on irrigated agriculture, JOURNAL OF HYDROLOGY, Vol: 523, Pages: 86-96, ISSN: 0022-1694

Journal article

Templeton MR, Hammoud AS, Butler AP, Braun L, Foucher JA, Grossmann J, Boukari M, Faye S, Jourda JPet al., 2015, Nitrate pollution of groundwater by pit latrines in developing countries, AIMS Environmental Science, Vol: 2, Pages: 302-313

Journal article

Foster T, Brozovic N, Butler AP, 2014, Modeling irrigation behavior in groundwater systems, WATER RESOURCES RESEARCH, Vol: 50, Pages: 6370-6389, ISSN: 0043-1397

Journal article

Chong YJ, Khan A, Scheelbeek P, Butler A, Bowers D, Vineis Pet al., 2014, Climate change and salinity in drinking water as a global problem: using remote-sensing methods to monitor surface water salinity, INTERNATIONAL JOURNAL OF REMOTE SENSING, Vol: 35, Pages: 1585-1599, ISSN: 0143-1161

Journal article

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