Scaling Up Spatially Distributed Hydrologic Models of Semi-Arid WatershedsEPA Grant Number: R824784
Title: Scaling Up Spatially Distributed Hydrologic Models of Semi-Arid Watersheds
Investigators: Tarboton, David G.
Current Investigators: Tarboton, David G. , Cooley, K. , Flerchinger, Gerald N , Hanson, C. L , Neale, C.M. U. , Seyfried, M. , Slaughter, C. W.
Institution: Utah State University
EPA Project Officer: Hiscock, Michael
Project Period: October 1, 1995 through September 1, 1998 (Extended to April 30, 2000)
Project Amount: $330,000
RFA: Water and Watersheds (1995) Recipients Lists
Research Category: Water and Watersheds , Water
Description:The purpose of this project is to understand interacting watershed processes over a range of scales in the Reynolds Creek Experimental Watershed (RCEW) in southwest Idaho, USA. The project is a collaborative hydrologic modeling and measurement project involving faculty and students at Utah State University and researchers at the USDA Agricultural Research Service Northwest Watershed Research Center.
The approach consists of the development of a spatially distributed modeling framework that accounts for spatial variability in topography, vegetation and soils to facilitate physically realistic spatial integration of the complete water balance at a range of scales. The RCEW is a semi-arid mountainous watershed comprising range land and forest. The hydrology is snowmelt driven, with complex terrain resulting in spatially variable snow distribution and snowmelt inputs. Snow distribution variability spans several length scales and involves orographic precipitation effects, snow drifting due to wind and differential melt due to variable energy input at different slopes and aspects. This variability interacts with variability in soil moisture, vegetation distribution and evapotranspiration. The problem of understanding this hydrologic system is being tackled through a combination of modeling, field measurements and remote sensing. High resolution multi spectral airborne and satellite imagery is being used to parameterize certain model inputs as well as test model outputs and investigate the effects of applying the models at different spatial scales and with different levels of detail in the input data. The modeling framework being developed includes components to represent snow drifting and melt, infiltration and runoff generation and evapotranspiration. A key aspect of the approach is the testing of components individually as well as when assembled together against point data, integrated measurements and spatial patterns. At this preliminary stage results only include application at Upper Sheep Creek, a 26 ha watershed within the RCEW. Future work will include application to the Tollgate watershed (67 km2) and the full Reynolds Creek (234 km2). Alternative model components that represent different levels of complexity and parameterization will be evaluated.
It is anticipated that this work will lead to a better understanding of the spatial variability and scale dependence of hydrologic processes in this watershed. These results will be generalizable to other watersheds in the semi-arid mountainous western U.S. where streamflow, a critical water resource, is highly variable and sensitive to climate variability, climate change and spatial variability of precipitation and evapotranspiration.