A Study of the Breakup Characteristics of the Chena River Basin Using ERTS Imagery: Completion Report

Abstract

Snowmelt and rainfall floodinq is a major water resource problem in Alaska. At the present time, forecastinq of these floods is based on a sparse hydrological and climatological network. Numerous basins with drainage areas of 5,000 km2 and less remain completely ungaged. The lack of data causes uncertainty in the design of transportation schemes such as tile Trans-Alaska oil pipeline. This project studied the utility of using ERTS-l imagery as a source of additional data for the prediction of snowmelt runoff, the most dynamic hydroloqic event in arctic and subarctic basins. Snow distribution as determined from the satellite imagery was compared with values determined from the conventional snow course stations and with the results of a snowmelt energy model. The Chena River Basin was selected because of the availability of ground truth data for comparison. Very good agreement for snow distribution and rates of ablation was found between the ERTS-l imagery, the snowmelt model, and field measurements. Monitoring snowmelt rates for relatively small basins appears to be practical. The main limitation of the ERTS-l imagery is the interval of coverage. More frequent overflights providing coverage are needed for the study of transient hydrologic events. ERTS-l data is most useful when used in conjunction with snowmelt prediction models and existing snow course data. These results should prove very useful in preliminary assessment of hydrologic conditions in ungaged watersheds and will provide a tool for month-to-month volume forecasting.