Wallingford HydroSolutions

Wallingford, United Kingdom

Wallingford HydroSolutions

Wallingford, United Kingdom
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Keller V.D.J.,UK Center for Ecology and Hydrology | Lloyd P.,Wallingford HydroSolutions | Terry J.A.,UK Center for Ecology and Hydrology | Williams R.J.,UK Center for Ecology and Hydrology
Environmental Pollution | Year: 2015

In England and Wales, steroid estrogens: estrone, estradiol and ethinylestradiol have previously been identified as the main chemicals causing endocrine disruption in male fish. A national risk assessment is already available for intersex in fish arising from estrogens under current flow conditions. This study presents, to our knowledge, the first set of national catchment-based risk assessments for steroid estrogen under future scenarios. The river flows and temperatures were perturbed using three climate change scenarios (ranging from relatively dry to wet). The effects of demographic changes on estrogen consumption and human population served by sewage treatment works were also included. Compared to the current situation, the results indicated increased future risk:the percentage of high risk category sites, where endocrine disruption is more likely to occur, increased. These increases were mainly caused by changes in human population. This study provides regulators with valuable information to prepare for this potential increased risk. © 2014 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY license.

Hannaford J.,UK Center for Ecology and Hydrology | Holmes M.G.R.,Wallingford HydroSolutions | Laize C.L.R.,UK Center for Ecology and Hydrology | Marsh T.J.,UK Center for Ecology and Hydrology | Young A.R.,Wallingford HydroSolutions
Hydrology Research | Year: 2013

Flow estimates for ungauged catchments are often derived through regionalisation methods, which enable data transfer from a pool of hydrologically similar catchments with existing gauging stations (i.e., pooling-groups). This paper presents a methodology for indexing the utility of gauged catchments within widely used pooling-group methodologies for high and low flow estimation; this methodology is then used as the basis for a network evaluation strategy. The utility of monitoring stations is assessed using catchment properties and a parallel, but independent, appraisal of the quality of gauging station data, which considers hydrometric performance, anthropogenic disturbances and record length. Results from the application of the method to a national network of over 1,100 gauging stations in England and Wales are presented. First, the method is used to appraise the fitness for purpose of the network for regionalisation. The method is then used to identify gauges which monitor catchments with high potential for regionalisation, but which are deficient in terms of data quality - where upgrades in hydrometric performance would yield the greatest benefits. Finally, gauging stations with limited value for regionalisation, given the poolinggroup criteria employed, are identified. Alongside a wider review of other uses of the network, this analysis could inform a judicious approach to network rationalisation. © Centre for Ecology and Hydrology 2013.

Prudhomme C.,UK Center for Ecology and Hydrology | Haxton T.,Wallingford HydroSolutions | Crooks S.,UK Center for Ecology and Hydrology | Jackson C.,British Geological Survey | And 7 more authors.
Earth System Science Data | Year: 2013

The dataset Future Flows Hydrology was developed as part of the project "Future Flows and Groundwater Levels'' to provide a consistent set of transient daily river flow and monthly groundwater level projections across England, Wales and Scotland to enable the investigation of the role of climate variability on river flow and groundwater levels nationally and how this may change in the future. Future Flows Hydrology is derived from Future Flows Climate, a national ensemble projection derived from the Hadley Centre's ensemble projection HadRM3-PPE to provide a consistent set of climate change projections for the whole of Great Britain at both space and time resolutions appropriate for hydrological applications. Three hydrological models and one groundwater level model were used to derive Future Flows Hydrology, with 30 river sites simulated by two hydrological models to enable assessment of hydrological modelling uncertainty in studying the impact of climate change on the hydrology. Future Flows Hydrology contains an 11-member ensemble of transient projections from January 1951 to December 2098, each associated with a single realisation from a different variant of HadRM3 and a single hydrological model. Daily river flows are provided for 281 river catchments and monthly groundwater levels at 24 boreholes as .csv files containing all 11 ensemble members. When separate simulations are done with two hydrological models, two separate .csv files are provided. Because of potential biases in the climate-hydrology modelling chain, catchment fact sheets are associated with each ensemble. These contain information on the uncertainty associated with the hydrological modelling when driven using observed climate and Future Flows Climate for a period representative of the reference time slice 1961–1990 as described by key hydrological statistics. Graphs of projected changes for selected hydrological indicators are also provided for the 2050s time slice. Limitations associated with the dataset are provided, along with practical recommendation of use. Future Flows Hydrology is freely available for non-commercial use under certain licensing conditions. For each study site, catchment averages of daily precipitation and monthly potential evapotranspiration, used to drive the hydrological models, are made available, so that hydrological modelling uncertainty under climate change conditions can be explored further. © 2013 Author(s).

Prudhomme C.,UK Center for Ecology and Hydrology | Jackson C.,British Geological Survey | Haxton T.,Wallingford HydroSolutions | Crooks S.,UK Center for Ecology and Hydrology | And 15 more authors.
IAHS-AISH Proceedings and Reports | Year: 2014

Science understanding suggests that anthropogenic greenhouse gas emissions will result in a changed climate that will in turn modify patterns of river flow and groundwater recharge, affecting the availability of water and changing the aquatic environment. While many studies have investigated the impact of climate change on river flows in Great Britain, their coverage is uneven and methods vary, and it is very difficult to compare results from different locations and different sectors and to identify appropriate adaptation responses. Future Flows is a set of nationally consistent projections of climate (1-km gridded daily precipitation and 5-km monthly potential evapotranspiration), river flow (for 282 catchments) and groundwater level (at 24 boreholes) for Great Britain at space and time resolutions for hydrological applications. It is based on the Hadley Centre's 11-member ensemble projections HadRM3-PPE run under the Medium emission scenario SRES A1B. The 11 plausible realisations (all equally likely) of nearly 150 years (from 1951 to 2098), described by Future Flows, enable the role of climate variability on river flow and groundwater levels nationally to be investigated and how this may change in the future. Some climate change uncertainty is accounted for by considering all ensemble members together. In addition to the time series, Future Flows contains information on modelling errors in the river flow and groundwater level projections in the form of catchment fact sheets. These fact sheets contain performance measures for hydrological statistics including monthly flow, flow percentiles and for some catchments flood peaks, and separately the hydro (geo)logical modelling errors from the fuller chain of climate-to-hydrology modelling. This information enables any potential user to have a clear view of the modelling uncertainty before they use the data. Future Flows Climate and Future Flows Hydrology are each associated with a Digital Object Identifier and are available to the research community free of charge for non commercial work. © Copyright 2014 IAHS Press.

Llewellyn N.,UK Center for Ecology and Hydrology | Lloyd P.,Wallingford Hydrosolutions | Jurgens M.D.,UK Center for Ecology and Hydrology | Johnson A.C.,UK Center for Ecology and Hydrology
Journal of Chromatography A | Year: 2011

A reliable and specific method was developed for the determination of the cytotoxic drugs cyclophosphamide and ifosfamide in sewage effluent. The most successful combination was found to be Strata-X solid-phase extraction followed by Florisil ® clean-up with analysis by liquid chromatography-tandem mass spectrometry. Quantification by internal standardisation was achieved using custom synthesised d4-cyclophophosphamide. The mass spectrometer was operated in highly selective reaction monitoring (HSRM) mode, which significantly reduced matrix noise and improved sensitivity. Although it suffered from some ionisation suppression, electrospray ionisation (ESI) was found to give an order of magnitude better sensitivity in terms of limit of detection than atmospheric pressure chemical ionisation (APCI). Using final effluent from two different sewage treatment plants, the method was validated following official European guidelines and shown to be a high performance tool for routine analysis at the sub-nanogram per litre level. Depending on the matrix, the limit of detection for cyclophosphamide was between 0.03ng/L and 0.12ng/L and for ifosfamide between 0.05ng/L and 0.09ng/L. For cyclophosphamide the accuracy and precision, tested at 1.7ng/L, were 98-109% and ≤13%, CV respectively. For ifosfamide the accuracy and precision, tested at 1.1ng/L, were 98-113% and ≤15% CV, respectively. Depending on the sample matrix the absolute recovery of the internal standard was between 57% and 70%. The method was tested by analysis of spot samples taken from the final effluent discharges of two sewage treatment plants; the first using a conventional trickling filter treatment process and second employing activated sludge followed by ultra violet treatment. Cyclophosphamide was detected at 0.19ng/L at the first plant and at the second detected at 3.7ng/L and 3.5ng/L, before and after the UV treatment process; ifosfamide was not detectable at either plant. © 2011 Elsevier B.V.

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