The long range goal of this project will be to develop a broad understanding and the capability to model the interdependence of spatially distributed hydrologic processes and ecological regimes across watershed scales. Our approach will be one of investigating physical inter-relationships among hydrologic, ecological and thermal regimes to enable extrapolation of our understanding to greater and greater areas. In order to develop this holistic understanding of the watershed system, we must proceed methodically from basic process studies through manipulation experiments. Consequently, we must remain mindful of the greater goals as we tackle intermediate objectives and insure that we do collect adequate data to support watershed scale modeling while we investigate smaller scale processes.
Our plan is to investigate the changing hydrologic response across and among ecotones. Our objective is to learn what controls the soil moisture dynamics within a landscape type/vegetation unit. Our hypothesis is that various landscape units (i.e. birch/aspen, alder/willow shrub, black or white spruce) will exhibit differing, but predictable soil moisture dynamics. We further believe that by building an understanding of the moisture dynamics within and among landscape units, it will be possible to predict integrated hydrologic responses on watershed scales. These integrated hydrologic processes include stream discharge rates, stream water chemistry, spatially distributed evapotranspiration rates and groundwater dynamics. Measurements of the driving environmental variables (such as climate, soil properties, vegetation type) will be used as input into a model of moisture dynamics. The model will be verified against measurements of soil moisture, but will also be used to examine consequent effects such as ground water flux, stream discharges and stream chemistry. It is our intention to develop this understanding and simulation vehicle starting from the landscape unit so that we may extend this understanding across similar landscape types in Interior Alaska using mesoscale modeling technology or GIS.
This project will have five distinct objectives:
1) Collect adequate meteorologic data to enable calculation of the surface energy balance at every point in the watershed. 2) Collect adequate discharge measurements to enable calibration and verification of a spatially distributed hydrologic model. 3) Collect accurate and frequent measurements of soil moisture content to enable complete understanding of controls and responses of hydrologic regime. 4) Collect chemistry measurements of soil moisture and stream water and ground-water to build an adequate understanding of the interaction of groundwater and surface water. 5) Develop an integrated model of soil moisture dynamics linked to landscape scale geochemical processes.
The tasks which will be accomplished during the first year will be:
1) Upgrade meteorologic instrumentation at two primary sites (Caribou Peak, the confluence of Caribou and Poker Creeks) and at 5 satellite stations (CT-1600, CT-2100, Helmers Ridge, C-4 and P-6). 2) Collect discharge measurements and basic chemistry sampling throughout the summer at C-4, P-6, CJ, PJ, and PC. 3) Measure soil moisture dynamics hourly at a birch/aspen and spruce sites near C-4 and P-6 and in a riparian zone near PC (5 sites total). 4) Develop a lumped parameter hydrologic model (HBV) of C-2, C-3, C-4 andP-6 to quantify the components and characteristics of basins with varying degrees of permafrost.