The challenges of modelling phosphorus in a headwater catchment: Applying a 'limits of acceptability' uncertainty framework to a water quality model
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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DOI：
10.1016/j.jhydrol.2018.01.063
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发表时间：
2018-03-01
影响因子：
6.4
通讯作者：
Haygarth, P. M.
中科院分区：
文献类型：
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作者：
Hollaway, M. J.;Beven, K. J.;Haygarth, P. M.
需要对磷 (P) 从陆地到水的转移进行建模和预测，但这具有挑战性，因为涉及大量复杂的物理和生物地球化学过程。本研究首次提出了土壤和水评估工具 (SWAT) 的广义似然不确定性估计 (GLUE) 框架的“可接受限度”方法，应用于英国坎布里亚郡纽比贝克流域 (12.5 km(2)) 的水质问题。使用高频出口数据（流量和 P），将单独的评估标准（可接受限度）分配给所有评估时间步骤中观察到的流量和 P 负载，从而确定模型在哪些地方表现良好/较差，并推断哪些过程需要在模型结构中进行改进。为了获得一组行为模拟（5,000,000 次中分别有 1001 次和 1016 次），最初的可接受性限制需要大幅放宽（根据所使用的评估标准，在标准化范围内放宽 5.3 到 6.7 之间的系数）。在测试的 39 个模型参数中，无论选择何种评估指标，地下过程和相关参数的表示始终显示为模型不满足评估标准的关键。因此得出的结论是，SWAT 不是指导该流域磷管理的合适模型。这种方法强调了高频监测数据对于设置稳健模型评估标准的重要性。它还提出了一个问题，即是否有可能有足够的输入数据来驱动这些模型，以便我们可以对它们的预测以及它们为流域管理策略提供信息以解决农业扩散污染问题的能力充满信心。 (C) 2018 作者。由 Elsevier B.V. 出版
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 (12.5 km(2)), 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 6.7 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. (C) 2018 The Authors. Published by Elsevier B.V.