Actual Evapotranspiration in Clay Soil on Three Slope Zones in Volcanic Slope of Mt. Sumbing, Central Java-Indonesia

Abstract

Background: Soil physical properties have not been widely discussed as the main factor of evapotranspiration. This study aimed to see the relationship between land and soil physical factors on the evapotranspiration rate that occured at each slope position. Methods: Sampling and measurements were carried out on three slope zones in a landscape, i.e. the upper slope (erosion zone), the middle slope (transition zone) and the lower slope (deposition zone). The soil sampling was carried out to analyze the soil physical properties. The evapotranspiration rate was measured using a modified chamber in two measurement periods. It was carried out throughout the day since the sun started shining the land until sunset or until the sunlight were blocked by rain clouds. Result: The average daily evapotranspiration rate was 0.17 mm hr-1 with the lowest value was 0.02 mm hr-1 and the highest 0.62 mm hr-1. Slope position and slope arrangement were the key factors influencing other controlling factors for the rate of evapotranspiration, including vegetation and soil physical properties.