AWRA Alaska Northern-Region Meetings
December 9, 2009 Bob Bolton, Simulation of streamflow in a discontinuous permafrost environment using a modified first-order, non-linear rainfall-runoff model., International Arctic Research Center, University of Alaska Fairbanks Simulation of streamflow in a discontinuous permafrost environment using a modified first-order, non-linear rainfall-runoff model. Bob Bolton Simulation of stream flow in this region is challenging due to the rapidly changing thermal (permafrost versus non-permafrost, active layer development) and hydraulic (hydraulic conductivity and soil storage capacity) conditions in both time and space (x, y, and z-dimensions). Many of the factors that have a control on both permafrost distribution and the thawing/freezing of active layer (such as soil material, soil moisture, and ice content) are not easily quantified at scales beyond the point measurement. In this study, these issues are addressed through streamflow analysis – the only hydrologic process that is easily measured at the basin scale. Following the general procedure outlined in Kirchner (2008), a simple rainfall-runoff model was applied to three small head-water basins of varying permafrost coverage. A simple, first-order, non-linear differential equation that describes the storage-discharge relationship were derived from three years of stream flow data. The storage-discharge relationship is developed for each month of the summer thaw period (June-September). The monthly relationships are then combined to form a single storage-discharge relationship that changes smoothly throughout the summer period. By allowing the monthly storage-discharge equations to vary through time, the variation in runoff due to changes in the active layer thaw are represented. This simple, nonlinear equation describing the storage-discharge relationship is used to simulate streamflow from evapotranspiration and precipitation data. Simulation results from in the Caribou-Poker Creeks Research Basin, located about 50 km north-east of Fairbanks, Alaska will be presented. |