Spatial-Temporal Dynamics of Evapotranspiration in the Podkamennaya Tunguska River Basin

The hydrological role of forest communities dominating in the Podkamennaya Tunguska basin has been assessed by their contribution to the total evaporation in the watershed area based on the landscape differentiation of the region. We have used evapotranspiration parameters obtained by remote sensing data from MODIS Global Evapotranspiration Project (MOD16 ET), which takes into account the climatic data of the studied area, the types of the terrestrial surface, and the diversity of the landcover. The studies show that the evapotranspiration of the specified classes of forest vegetation is characterized by significant variability both in space and with time. The variability of evapotranspiration from year to year is primarily related to changes in meteorological parameters and the leaf index. The evaporation variability in space is determined by general climatic characteristics of the research area and different species composition of forest stands. The analysis of data reveals the tendency to a decrease in the annual evapotranspiration in the Podkamennaya Tunguska basin from 2000 to 2014. A comparative analysis of evapotranspiration trends with those in air temperature and precipitation confirms that the evapotranspiration decrease is related to changes in climatic conditions in the studied area. It is revealed that the landscape structure of watersheds may be used to indicate the processes forming evapotranspiration as an important component of the water balance, as well as to determine the hydrologically significant boundaries of landscapes. The assessment of evaporation from the land surface based on remote sensing data (product MOD16 ET) may be used for water balance calculations in watersheds of various sizes, particularly in the absence of a runoff database.