Understanding hydrological flow paths in conceptual catchment models using uncertainty and sensitivity analysis

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Title: Understanding hydrological flow paths in conceptual catchment models using uncertainty and sensitivity analysis
Authors: Mockler, Eva M.
O'Loughlin, Fiachra
Bruen, Michael
Permanent link: http://hdl.handle.net/10197/7875
Date: May-2016
Abstract: Increasing pressures on water quality due to intensification of agriculture have raised demands for environmental modeling to accurately simulate the movement of diffuse (nonpoint) nutrients in catchments. As hydrological flows drive the movement and attenuation of nutrients, individual hydrological processes in models should be adequately represented for water quality simulations to be meaningful. In particular, the relative contribution of groundwater and surface runoff to rivers is of interest, as increasing nitrate concentrations are linked to higher groundwater discharges. These requirements for hydrological modeling of groundwater contribution to rivers initiated this assessment of internal flow path partitioning in conceptual hydrological models. In this study, a variance based sensitivity analysis method was used to investigate parameter sensitivities and flow partitioning of three conceptual hydrological models simulating 31 Irish catchments. We compared two established conceptual hydrological models (NAM and SMARG) and a new model (SMART), produced especially for water quality modelling. In addition to the criteria that assess streamflow simulations, a ratio of average groundwater contribution to total streamflow was calculated for all simulations over the 16 year study period. As observations time-series of groundwater contributions to streamflow are not available at catchment scale, the groundwater ratios were evaluated against average annual indices of base flow and deep groundwater flow for each catchment. The exploration of sensitivities of internal flow path partitioning was a specific focus to assist in evaluating model performances. Results highlight that model structure has a strong impact on simulated groundwater flow paths. Sensitivity to the internal pathways in the models are not reflected in the performance criteria results. This demonstrates that simulated groundwater contribution should be constrained by independent data to ensure results within realistic bounds if such models are to be used in the broader environmental sustainability decision making context.
Funding Details: Environmental Protection Agency
Type of material: Journal Article
Publisher: Elsevier
Copyright (published version): 2018-05-01
Keywords: Conceptual catchment modelingHydrological processesGroundwaterSensitivity analysisParameter identification
DOI: 10.1016/j.cageo.2015.08.015
Language: en
Status of Item: Peer reviewed
Appears in Collections:Centre for Water Resources Research Collection
Earth Institute Research Collection
Civil Engineering Research Collection

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