Estimación de la evapotranspiración de cultivo de la cuenca del río Paute mediante imágenes satelitales

Abstract

The main objective of this study is to determine the demand for crop water or known as crop evapotranspiration (ETc) at different scales by using two vegetation indices such as the Normalized Difference Vegetation Index (NDVI) and the Soil Adjusted Vegetation (SAVI) through remote sensing satellite. The study was carried out conducted in the Paute river basin where three images of the Landsat 8 satellite and one of Landsat 7 was used to determine the NDVI and SAVI index. Therefore, these indices were used to estimate the crop coefficient (Kc - VI). To calculate the reference evapotranspiration (ETCr), the Penman-Monteith equation proposed by FAO was used with meteorological data for a period of 5 months. A cubic spline interpolation was applied to obtain daily series of vegetation index between pairs of continuous images. With the calculation of these two factors: (i) the crop coefficient (Kc-VI) and (ii) the evapotranspiration reference (ETCr), the crop evapotranspiration (ETCs) was estimated. The results indicate that crop evapotranspiration with the SAVI index has a similar mean value at daily scale when compared to other investigations performed in the same study area and surrounding areas. Further improvement of the results will demand a larger series of satellite images and meteorological data. However, direct measurements of ET and site-specific crop coefficients would be of helpful to validate of the results and to determine correction factors in order to improve ET estimates in the future