Meso-Scale Hydrological Modeling Using Small Scale Parameterizations in a Discontinuous Permafrost Watershed in the Boreal Forest Ecosystem
Monday, 15 December 2014
The sub-Arctic region lies in the transition zone between the warm temperate region to the south and the cold arctic region to the north. The sub-Arctic hosts sharply contrasting ecosystems that vary over short horizontal spatial scales due to the presence or absence of permafrost. In the discontinuous permafrost zone, the presence or absence of permafrost plays a dominant role to many hydrological processes including stream flow, soil moisture, and water storage dynamics. The distribution of permafrost also has a strong influence on ecosystem composition and function. The land cover and vegetation distribution is also an important parameter affecting the stream flow responses due to the large differences in the transpiration rates between coniferous and deciduous vegetation. As a result, accurate simulation of the hydrology in this region is challenging. The objectives of this study are to improve the parameterization of meso-scale hydrologic simulations in the discontinuous permafrost zone through fine-scale observation and modeling. Slope and aspect, derived from 30m Digital Elevation Model (DEM), are used as a proxy for permafrost distribution and vegetation composition. Small-scale parameterizations were conducted at the two sub-basins (area ~11km2 ) of the Caribou-Poker Creeks Research Watershed (CPCRW) using the Variable Infiltration Capacity (VIC) meso-scale hydrological model. The small scale parameterization simulation results indicate that slope and aspect based vegetation cover and soil parameter parameterization improve meso-scale hydrological modeling in these regions. In order to test the extent to which these small-scale parameterizations are valid, the Chena River Basin (area ~5,478 km2), located in Interior Alaska, is being simulated using these small-scale parameterizations. Aspect will be used as the proxy for the parameterization of vegetation cover and soil property. Results from the VIC simulation using the small scale parameterization will be compared with the results of a simulation using a meso-scale parameterization to evaluate the improvement that may be obtained from higher resolution analyses.