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THE HYDROLOGIC RESPONSE OF A SMALL CATCHMENT TO CLEAR-CUTTING
Citation:
ABDELNOUR, A., M. STIEGLITZ, F. PAN, R. B. MCKANE, AND B. KWIATKOWSKI. THE HYDROLOGIC RESPONSE OF A SMALL CATCHMENT TO CLEAR-CUTTING. Presented at American Geophysical Union Fall Meeting, San Francisco, CA, December 11 - 15, 2006.
Description:
We simulated how a landscape disturbance (e.g., fire or clear-cutting) alters hillslope and catchment hydrologic processes. Specifically, we simulated how the pattern and magnitude of tree removal in a catchment increases downslope transport of water and alters catchment soil moisture and discharge. The study site is the WS10 catchment of the HJ Andrews LTER, located in the Pacific Northwest, USA. We used a spatially-explicit hydrologic model comprised of connected landscape units. We implicitly modeled biomass removal and the subsequent forest re-growth by manipulating evapotranspiration. We allowed potential evapotranspiration to increase exponentially from zero at the onset of the disturbance to pre-disturbance values within a 40 year period. Simulations show an increase in stormflow and surface runoff from the uplands to the midlands. While soil moisture in the uplands increased in the post-disturbance period, downslope flow increased only minimally. In this catchment, upland soil moisture stayed well below field capacity, and therefore, downslope lateral flow was not initiated. As such, midland and lowland soil moisture, as well as catchment discharge, remained near pre-disturbance values throughout the re-growth period. This behavior in catchment dynamics resulted primarily from the fact that seasonal temperatures and precipitations are out of phase in this region of the US.