Estimation of real evapotranspiration and its variation in Mediterranean landscapes of central-southern Chile

Evapotranspiration (ET_d) is a key controller in the ecohydrological processes of semi-arid landscapes. This is the case of the dry land in Chile's central-southern zone, where forestry, farming and livestock activities must adapt to precipitation with considerable year-on-year variations. In this study, the spatial distribution of ET_d was estimated in relation to the land use map and physical parameters of the soil. The ET_d was estimated through the Simplified Surface Energy Balance Index (S-SEBI) using data from weather stations and remote data provided by the ASTER and MODIS sensors for November 2004 and 2006, respectively. The spatial variability of ET_d was compared among different plant types, soil textural classes and depths using non-parametric statistical tests. In this comparison, the highest rates of ET_d were obtained in the forest covers with values of 7.3 ± 0.8 and 8.4 ± 0.8 mm d^-1 for 2004 and 2006, respectively. The lowest values were estimated for pastures and shrublands with values of 3.5 ± 1.2 mm d^-1 and for crops with rates of 4.4 ± 1.6 mm d^-1. Comparison of the ET_d of the native forest covers and plantations of exotic species showed statistically significant differences; however, no great variation was noted, at least in the study months. Additionally, the highest rates of ET_d were found in the clay loam textures (6.0 ± 1.8 and 6.4 ± 2.0 mm d^-1) and the lowest rates in the sandy loam soils (3.7 ± 1.6 and 3.9 ± 1.6 mm d^-1) for 2004 and 2006, respectively. The results enable analysis of the spatial patterns of the landscape in terms of the relation between water consumption, ET and the biophysical characteristics of a Mediterranean ecosystem. These results form part of the creation of tools useful in the optimization of decision-making for the management and planning of water resources and soil use in territories with few measuring instruments.