干旱区生态环境知识资源中心

The Alto Loica experimental site was established to achieve some understanding of the hydrological characteristics and the effects of afforestation on soil and water conservation in serni-arid regions in Chile. Hydrological measurements were taken in the 16.25-ha catchment for seven years. Because of the high variability of annual rainfall, there was a drought year in which streamflow disappeared throughout the year. As the catchment contains intermittent streams, mean annual baseflow is only 5.9% of mean annual rainfall, while mean annual evapotranspiration is 62.6% of that. The seasonal fluctuations of soil moisture storage Suggest that Moisture conditions during the period of December through March may be the driest ones for the growth of vegetation. While Horton overland flow Occurs over grassy and shrub covered hillside during high rainfall intensities, it contributes largely to sharp hydrograph peaks. During large rainstorms, the mean runoff coefficient was more than 50%. Hence, measures to reduce overland flow are required for afforestation as well as soil and water conservation.