Informing the Vermilion River Watershed Plan through Application of the Cold Regions Hydrological Model Platform
Date
2012
Authors
Pomeroy, John W.
Fang, Xing
Shook, Kevin
Westbrook, Cherie
Brown, Tom
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Centre for Hydrology, University of Saskatchewan, Saskatoon, Saskatchewan
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Technical Report
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Abstract
The Vermilion River Basin has been identified as one of most altered basins in the North Saskatchewan River Basin by the North Saskatchewan Watershed Alliance. Of all the basin altering activities, wetland drainage is thought to be the most important one in impacting watershed hydrology. The Cold Regions Hydrological Model (CRHM) has had recent developments that make it particularly appropriate to evaluate the impacts of Canadian Prairie wetlands on hydrology. In light of the importance of wetlands in the Vermilion River Basin and the capability of CRHM, this study had five objectives:
1) Setup CRHM for the Vermilion River Basin and conduct preliminary tests using local
meteorological data.
2) Develop an improved wetland module that incorporates the dynamics of drained
wetland complexes in the physically based, modular Prairie Hydrological Model of
CRHM.
3) Refine CRHM results using advances in the improved wetland module, additional
parameter data and other adjustments as necessary.
4) Demonstrate scenarios/sensitivity of landscape components such as wetlands and
uplands to support planning decisions and make recommendations for land and
watershed management.
5) Apply CRHM results to fortify recommendations and support decision making during
initial plan implementation.
The objectives were addressed with the following methodology. Existing data on precipitation,
hydrometeorology, wetland characteristics, stage and extent, drainage pattern and land cover in the Vermilion River Basin were compiled. The existing CRHM Prairie Hydrological Model
formulation was set up on the basin and test runs conducted and compared to streamflow
hydrographs over multiple years. Then, improvements to the Prairie Hydrological Model
formulation of CRHM were made so that CRHM could simulate sequences of many wetlands of
varying sizes. The improved model was evaluated through hydrological simulation and
quantitative analysis of streamflow and then used in sensitivity analysis of the effect of changing wetland drainage/restoration on streamflow for the Vermilion River. The model was then used to evaluate wetland manipulation and climate scenarios to fortify recommendations, explore options and support decision making for the implementation of the Vermilion watershed plan.
The streamflow response of the Vermilion River Basin at its mouth was found to be dominated by channel hydraulics and the control structures in the lower basin and so it is influenced by
wetlands only to the extent that the management regime of these control structures is affected by upstream hydrological behaviour of the tributaries with respect to volume and timing of
streamflow inputs to the structures. Changes in the upper basin streamflows are more likely to be controlled by changes in the basin hydrological processes rather than in-stream water management and/or channel modifications and therefore the upper basin streamflows are more likely to show the effects of the manipulation of wetland storage.
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Keywords
Streamflow, Hydrological modelling, Cold Regions Hydrological Model, Wetland drainage, Land use change, Vermilion River, Alberta
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Centre for Hydrology Report #12