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The challenges of modelling phosphorus in a headwater catchment: Applying a 'limits of acceptability' uncertainty framework to a water quality model

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The challenges of modelling phosphorus in a headwater catchment: Applying a 'limits of acceptability' uncertainty framework to a water quality model. / Hollaway, Michael John; Beven, Keith John; Benskin, Clare McWilliam Haldane et al.
In: Journal of Hydrology, Vol. 558, 03.2018, p. 607-624.

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Hollaway MJ, Beven KJ, Benskin CMH, Collins A, Evans R, Falloon P et al. The challenges of modelling phosphorus in a headwater catchment: Applying a 'limits of acceptability' uncertainty framework to a water quality model. Journal of Hydrology. 2018 Mar;558:607-624. Epub 2018 Feb 2. doi: 10.1016/j.jhydrol.2018.01.063

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@article{f03f6b58549e41078af3de93488b8bb0,
title = "The challenges of modelling phosphorus in a headwater catchment: Applying a 'limits of acceptability' uncertainty framework to a water quality model",
abstract = "There is a need to model and predict the transfer of phosphorus (P) from land to water, but this is challenging because of the large number of complex physical and biogeochemical processes involved. This study presents, for the first time, a {\textquoteleft}limits of acceptability{\textquoteright} approach of the Generalized Likelihood Uncertainty Estimation (GLUE) framework to the Soil and Water Assessment Tool (SWAT), in an application to a water quality problem in the Newby Beck Catchment (12.5km2), Cumbria, United Kingdom (UK). Using high frequency outlet data (discharge and P), individual evaluation criteria (limits of acceptability) were assigned to observed discharge and P loads for all evaluation time steps, identifying where the model was performing well/poorly and to infer which processes required improvement in the model structure. Initial limits of acceptability were required to be relaxed by a substantial amount (by factors of between 5.3 and 6.72 on a normalized scale depending on the evaluation criteria used) in order to gain a set of behavioral simulations (1001 and 1016, respectively out of 5,000,000). Of the 39 model parameters tested, the representation of subsurface processes and associated parameters, were consistently shown as critical to the model not meeting the evaluation criteria, irrespective of the chosen evaluation metric. It is therefore concluded that SWAT is not an appropriate model to guide P management in this catchment. This approach highlights the importance of high frequency monitoring data for setting robust model evaluation criteria. It also raises the question as to whether it is possible to have sufficient input data available to drive such models so that we can have confidence in their predictions and their ability to inform catchment management strategies to tackle the problem of diffuse pollution from agriculture.",
keywords = "SWAT, GLUE, Phosphorus, Uncertainty analysis, River Eden, High frequency data",
author = "Hollaway, {Michael John} and Beven, {Keith John} and Benskin, {Clare McWilliam Haldane} and Adrian Collins and Robert Evans and Peter Falloon and Forber, {Kirsty Jessica} and Hiscock, {Kevin M} and Ron Kahana and Macleod, {Christopher J.A.} and Mary Ockenden and Martha Villamizar and Wearing, {Catherine Louise} and Withers, {P. J. A.} and Jian Zhou and Nick Barber and Haygarth, {Philip Matthew}",
year = "2018",
month = mar,
doi = "10.1016/j.jhydrol.2018.01.063",
language = "English",
volume = "558",
pages = "607--624",
journal = "Journal of Hydrology",
issn = "0022-1694",
publisher = "Elsevier Science B.V.",

}

RIS

TY - JOUR

T1 - The challenges of modelling phosphorus in a headwater catchment

T2 - Applying a 'limits of acceptability' uncertainty framework to a water quality model

AU - Hollaway, Michael John

AU - Beven, Keith John

AU - Benskin, Clare McWilliam Haldane

AU - Collins, Adrian

AU - Evans, Robert

AU - Falloon, Peter

AU - Forber, Kirsty Jessica

AU - Hiscock, Kevin M

AU - Kahana, Ron

AU - Macleod, Christopher J.A.

AU - Ockenden, Mary

AU - Villamizar, Martha

AU - Wearing, Catherine Louise

AU - Withers, P. J. A.

AU - Zhou, Jian

AU - Barber, Nick

AU - Haygarth, Philip Matthew

PY - 2018/3

Y1 - 2018/3

N2 - There is a need to model and predict the transfer of phosphorus (P) from land to water, but this is challenging because of the large number of complex physical and biogeochemical processes involved. This study presents, for the first time, a ‘limits of acceptability’ approach of the Generalized Likelihood Uncertainty Estimation (GLUE) framework to the Soil and Water Assessment Tool (SWAT), in an application to a water quality problem in the Newby Beck Catchment (12.5km2), Cumbria, United Kingdom (UK). Using high frequency outlet data (discharge and P), individual evaluation criteria (limits of acceptability) were assigned to observed discharge and P loads for all evaluation time steps, identifying where the model was performing well/poorly and to infer which processes required improvement in the model structure. Initial limits of acceptability were required to be relaxed by a substantial amount (by factors of between 5.3 and 6.72 on a normalized scale depending on the evaluation criteria used) in order to gain a set of behavioral simulations (1001 and 1016, respectively out of 5,000,000). Of the 39 model parameters tested, the representation of subsurface processes and associated parameters, were consistently shown as critical to the model not meeting the evaluation criteria, irrespective of the chosen evaluation metric. It is therefore concluded that SWAT is not an appropriate model to guide P management in this catchment. This approach highlights the importance of high frequency monitoring data for setting robust model evaluation criteria. It also raises the question as to whether it is possible to have sufficient input data available to drive such models so that we can have confidence in their predictions and their ability to inform catchment management strategies to tackle the problem of diffuse pollution from agriculture.

AB - There is a need to model and predict the transfer of phosphorus (P) from land to water, but this is challenging because of the large number of complex physical and biogeochemical processes involved. This study presents, for the first time, a ‘limits of acceptability’ approach of the Generalized Likelihood Uncertainty Estimation (GLUE) framework to the Soil and Water Assessment Tool (SWAT), in an application to a water quality problem in the Newby Beck Catchment (12.5km2), Cumbria, United Kingdom (UK). Using high frequency outlet data (discharge and P), individual evaluation criteria (limits of acceptability) were assigned to observed discharge and P loads for all evaluation time steps, identifying where the model was performing well/poorly and to infer which processes required improvement in the model structure. Initial limits of acceptability were required to be relaxed by a substantial amount (by factors of between 5.3 and 6.72 on a normalized scale depending on the evaluation criteria used) in order to gain a set of behavioral simulations (1001 and 1016, respectively out of 5,000,000). Of the 39 model parameters tested, the representation of subsurface processes and associated parameters, were consistently shown as critical to the model not meeting the evaluation criteria, irrespective of the chosen evaluation metric. It is therefore concluded that SWAT is not an appropriate model to guide P management in this catchment. This approach highlights the importance of high frequency monitoring data for setting robust model evaluation criteria. It also raises the question as to whether it is possible to have sufficient input data available to drive such models so that we can have confidence in their predictions and their ability to inform catchment management strategies to tackle the problem of diffuse pollution from agriculture.

KW - SWAT

KW - GLUE

KW - Phosphorus

KW - Uncertainty analysis

KW - River Eden

KW - High frequency data

U2 - 10.1016/j.jhydrol.2018.01.063

DO - 10.1016/j.jhydrol.2018.01.063

M3 - Journal article

VL - 558

SP - 607

EP - 624

JO - Journal of Hydrology

JF - Journal of Hydrology

SN - 0022-1694

ER -