Author(s): Athanasios Loukas; Lampros Vasiliades
Linked Author(s):
Keywords: Ctual evapotranspiration; Hydrological modelling; NDVI; Remote sensing; Runoff simulation
Abstract: The use of actual evapotranspiration derived by satellite data at watershed scale is studied in water balance modelling of forested and rural watersheds in the mountainous region of central Greece. Basin-wide actual evapotranspiration (AET) was estimated through a conceptual physically based six-parameter monthly water balance model. The model uses as input data of monthly temperature, precipitation and potential evapotranspiration, and calculates surface runoff, soil moisture, groundwater recharge and AET. Monthly composites of the Normalized Difference Vegetation Index (NDVI), derived from the National Oceanic and Atmospheric Administration’s (NOAA) / Advanced Very High Resolution Radiometer (AVHRR) were related with the computed monthly AET estimates using multiple linear regression. The developed relationships between NDVI and AET were, then, validated temporally to the four study watersheds. The NDVI-derived actual evapotranspiration agrees satisfactorily with the actual evapotranspiration calculated from the water balance method for both wet and water-limiting conditions. The NDVI derived AET estimates used in the sixparameter water balance model resulted in equally accurate simulations of monthly runoff, when compared with the simulations acquired from the classical application of the calibrated water balance model. The similarity, stability and the robustness of the derived relationships between NDVI and AET led to regional application of the developed relationships in two watersheds which have similar hydroclimatic and geophysical characteristics. The validation results show that the developed AET-NDVI relationships could be possibly applied to other watersheds for accurate AET estimation and runoff simulation.
Year: 2007