Abstract:
In Semi-arid Africa, evaporation is the dominant hydrological flux and hence an important
component in water resources management. However, it is a challenge to fairly estimate the
spatial variation of evaporation especially on composite terrains due to heterogeneity of the
landscape. This is further compounded by the uncertainties associated with the various
approaches used for estimating the flux, most of which are based on extrapolating point
observations. In the recent past, there has been progress in developing and validating various
remote sensing algorithms for computing evaporation over large spatial extents.
One such algorithm, the Surface Energy Balance System (SEBS) was applied in the Mkindo
catchment, located in the upper-Wami River basin in Tanzania using the Moderate
Resolution Imaging Spectroradiometer (MODIS) satellite images. Six images covering June
2008 to September 2009 were analyzed together with a land use map of the same area. The
SEBS evaporation estimates were compared with the potential evaporation over the Mkindo
catchment.
SEBS results showed good correlation with the computed Potential evaporation computed
from climatological parameter in the catchment, with different land uses/cover types having
different evaporative water use signature, on both daily and monthly time scale. Forest and
irrigated agriculture land use, located on the lower parts of the catchment, had relatively
higher evaporative water use compared to the other land uses in the catchment.
