Characterizing and reducing equifinality by constraining a distributed catchment model with regional signatures, local observations, and process understanding

Distributed catchment models are widely used tools for predicting hydrologic behavior. While distributed models require many parameters to describe a system, they are expected to simulate behavior that is more consistent with observed processes. However, obtaining a single set of acceptable paramete...

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Bibliographic Details
Published in:Hydrology and earth system sciences Vol. 21; no. 7; pp. 3325 - 3352
Main Authors: Kelleher, Christa, McGlynn, Brian, Wagener, Thorsten
Format: Journal Article
Language:English
Published: Katlenburg-Lindau Copernicus GmbH 05.07.2017
Copernicus Publications
Subjects:
Behavior
Calibration
Case studies
Catchment models
Catchment scale
Catchments
Coastal inlets
Computer simulation
Constraints
Design and construction
Goodness of fit
Groundwater
Groundwater levels
Groundwater table
Headwater catchments
Headwaters
Hydrologic models
Hydrology
Knowledge bases (artificial intelligence)
Modelling
Parameter estimation
Parameter identification
Parameters
Researchers
Scale (ratio)
Signatures
Simulation
Snow
Snow-water equivalent
Soil
Soil investigations
Stream discharge
Stream flow
Stringers
Studies
Time series
Vegetation
Water cycle
Water table
Watersheds
ISSN:1607-7938, 1027-5606, 1607-7938
Online Access:Get full text
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Summary:Distributed catchment models are widely used tools for predicting hydrologic behavior. While distributed models require many parameters to describe a system, they are expected to simulate behavior that is more consistent with observed processes. However, obtaining a single set of acceptable parameters can be problematic, as parameter equifinality often results in several behavioral sets that fit observations (typically streamflow). In this study, we investigate the extent to which equifinality impacts a typical distributed modeling application. We outline a hierarchical approach to reduce the number of behavioral sets based on regional, observation-driven, and expert-knowledge-based constraints. For our application, we explore how each of these constraint classes reduced the number of behavioral parameter sets and altered distributions of spatiotemporal simulations, simulating a well-studied headwater catchment, Stringer Creek, Montana, using the distributed hydrology–soil–vegetation model (DHSVM). As a demonstrative exercise, we investigated model performance across 10 000 parameter sets. Constraints on regional signatures, the hydrograph, and two internal measurements of snow water equivalent time series reduced the number of behavioral parameter sets but still left a small number with similar goodness of fit. This subset was ultimately further reduced by incorporating pattern expectations of groundwater table depth across the catchment. Our results suggest that utilizing a hierarchical approach based on regional datasets, observations, and expert knowledge to identify behavioral parameter sets can reduce equifinality and bolster more careful application and simulation of spatiotemporal processes via distributed modeling at the catchment scale.
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ISSN:1607-7938
1027-5606
1607-7938
DOI:10.5194/hess-21-3325-2017