Water and Environmental Research Center
Seminars
13 November 2009
An Integrated Multi-Scale Approach to the Study of Evapotranspiration on the Alaskan North Slope: Imnavait Creek Basin
John Mumm
John Mumm
BLS scintillometer transmitter in Imnaviat Creek Basin, North Slope of Alaska. August, 2009
Abstract
Evapotranspiration (ET) plays a significant role in the hydrologic cycle of all basins. Surface-atmosphere exchanges due to ET in the Imnaviat Creek Basin, North Slope of Alaska are estimated from water balance computations to be about 74% of summer precipitation or 50% of annual precipitation. Even though ET is a significant component of the hydrologic cycle in this region, the bulk estimates don't accurately account for spatial and temporal variability due to vegetation type, soil moisture, topography, etc.
Sound methods to compute ET are available (Priestly-Taylor, Thornwaite, and Penman); these methods need to be verified and are often compared against potential ET results from an evaporation pan. HBV is a hydrologic model that uses the estimates of ET to make predictions of the hydrologic response of a watershed; for example, the timing of runoff. The sensitivity of a catchment to changes in ET can also be studied.
Sonic anemometers and scintillometers will be used to collect data on turbulent and heat fluxes to integrate point, spatial, and volumetric measurements, up to satellite scale observations. By having evaporation pans and scintillometers at different locations in the watershed (ridges, mid-slope, valley bottom, etc.) the data collected can quantify the spatial variability of ET in an arctic basin. The ultimate focus of this exercise is to develop a consistent satellite based ET retrieval approach to estimate ET at the regional scale on the North Slope of Alaska.