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A Monte Carlo approach to the inverse problem of diffuse pollution risk in agricultural catchments

Milledge, David and Lane, Stuart N. and Heathwaite, Louise and Reaney, Sim M. (2012) A Monte Carlo approach to the inverse problem of diffuse pollution risk in agricultural catchments. The Science of The Total Environment, 433. pp. 434-449.

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Abstract

The hydrological and biogeochemical processes that operate in catchments influence the ecological quality of freshwater systems through delivery of fine sediment, nutrients and organic matter. Most models that seek to characterise the delivery of diffuse pollutants from land to water are reductionist. The multitude of processes that are parameterised in such models to ensure generic applicability make them complex and difficult to test on available data. Here, we outline an alternative -­data-driven -­ inverse approach. We apply SCIMAP, a parsimonious risk based model that has an explicit treatment of hydrological connectivity. We take a Bayesian approach to the inverse problem of determining the risk that must be assigned to different land uses in a catchment in order to explain the spatial patterns of measured in-­‐stream nutrient concentrations. We apply the model to identify the key sources of nitrogen (N) and phosphorus (P) diffuse pollution risk in eleven UK catchments covering a range of landscapes. The model results show that: 1) some land use generates a consistently high or low risk of diffuse nutrient pollution; but 2) the risks associated with different land uses vary both between catchments and between P and N delivery; and 3) that the dominant sources of P and N risk in the catchment are often a function of the spatial configuration of land uses. Taken on a case by case basis, this type of inverse approach may be used to help prioritise the focus of interventions to reduce diffuse pollution risk for freshwater ecosystems.

Item Type: Article
Journal or Publication Title: The Science of The Total Environment
Uncontrolled Keywords: Diffuse Pollution ; Hydrological connectivity ; Land cover ; Nutrients ; Nitrogen ; Phosphorus ; Risk ; modelling
Subjects: G Geography. Anthropology. Recreation > GE Environmental Sciences
Departments: Faculty of Science and Technology > Lancaster Environment Centre
ID Code: 54142
Deposited By: ep_importer_pure
Deposited On: 15 May 2012 16:06
Refereed?: Yes
Published?: Published
Last Modified: 07 Sep 2013 00:20
Identification Number:
URI: http://eprints.lancs.ac.uk/id/eprint/54142

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