Simulating cold-region hydrology in an intensively drained agricultural watershed in Manitoba, Canada, using the Cold Regions Hydrological Model
Etrophication and flooding are perennial problems in agricultural watersheds of the northern Great Plains. A high proportion of annual runoff and nutrient transport occurs with snowmelt in this region. Extensive surface drainage modification, frozen soils, and frequent backwater or ice-damming i...
| Main Authors: | , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2017-07-01
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| Series: | Hydrology and Earth System Sciences |
| Online Access: | https://www.hydrol-earth-syst-sci.net/21/3483/2017/hess-21-3483-2017.pdf |
| Summary: | Etrophication and flooding are perennial problems in agricultural watersheds
of the northern Great Plains. A high proportion of annual runoff and nutrient
transport occurs with snowmelt in this region. Extensive surface drainage
modification, frozen soils, and frequent backwater or
ice-damming impacts on flow measurement represent unique challenges to accurately
modelling watershed-scale hydrological processes. A physically based,
non-calibrated model created using the Cold Regions Hydrological Modelling
platform (CRHM) was parameterized to simulate hydrological processes within a
low slope, clay soil, and intensively surface drained agricultural watershed.
These characteristics are common to most tributaries of the Red River of the
north. Analysis of the observed water level records for the study watershed
(La Salle River) indicates that ice cover and backwater issues at time of
peak flow may impact the accuracy of both modelled and measured streamflows,
highlighting the value of evaluating a non-calibrated model in this
environment. Simulations best matched the streamflow record in years when
peak and annual discharges were equal to or above the medians of
6.7 m<sup>3</sup> s<sup>−1</sup> and 1.25 × 10<sup>7</sup> m<sup>3</sup>, respectively, with
an average Nash–Sutcliffe efficiency (NSE) of 0.76. Simulation of low-flow
years (below the medians) was more challenging (average NSE < 0), with
simulated discharge overestimated by 90 % on average. This result
indicates the need for improved understanding of hydrological response in the
watershed under drier conditions. Simulation during dry years was improved
when infiltration was allowed prior to soil thaw, indicating the potential
importance of preferential flow. Representation of in-channel dynamics and
travel time under the flooded or ice-jam conditions should also receive
attention in further model development efforts. Despite the complexities of
the study watershed, simulations of flow for average to high-flow years and
other components of the water balance were robust (snow water equivalency
(SWE) and soil moisture). A sensitivity analysis of the flow routing model
suggests a need for improved understanding of watershed functions under both
dry and flooded conditions due to dynamic routing conditions, but overall
CRHM is appropriate for simulation of hydrological processes in agricultural
watersheds of the Red River. Falsifications of snow sublimation, snow
transport, and infiltration to frozen soil processes in the validated base
model indicate that these processes were very influential in stream discharge
generation. |
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| ISSN: | 1027-5606 1607-7938 |