Acceso usuarios
Malika Wimalasuriya, Lalith Chandrapala
Ten day estimates of actual evaporation in Sri Lanka have been made for the period June 1999¿2000, using AVHRR radiances from day-time ascending mode passes of the NOAA 14 meteorological satellite, supplemented with meteorological data measured simultaneously at ground level. During the 12-month period of the study, a total of 88 images have been processed using a residual energy budget and temporally constant evaporative fraction approach to yield 36 estimates of 10-day evaporation for the entire land area of Sri Lanka at 1 km2 resolution. The evaporation estimates, when compared with data from a large aperture scintillometer, showed errors of 17 and 1% in the case of 10-day and monthly evaporation respectively. The comparison with available independent evaporation estimates for specific catchments showed errors ranging from 2 to 8%. These estimates together with images of soil moisture status estimated using remote sensing techniques and rainfall from rain gauge network data were incorporated in a geographic information system (GIS). This provides a solid basis for understanding water consumed by agriculture and environment, in addition to providing a solid foundation for understanding the efficiency of major irrigation systems. The availability of data for the whole country and in a GIS environment with the facility for conducting studies at various spatial scales increases their usefulness for hydrological research in Sri Lanka.
Author Keywords: Actual evaporation; AVHRR; Ten-day averaging; Sri Lanka
