“Perhitungan Evapotranspirasi Menggunakan Citra MODIS (Studi Kasus: Das Cimadur, Banten)”

Abstract

Evapotranspiration (ET) is the most important component of water balance after precipitation. Currently, measurement of evapotranspiration can be conducted with the input data based on Remote Sensing data. This research analyzed empiric equation of evapotranspiration, the Blaney-Criddle, using Land Surface Temperature (LST) value, extracted from Moderate Resolution Imaging Spectroradiometer (MODIS), as an temperature input in this equation. In this research validation was made between LST MODIS (day and night) and temperature of climatology station of Darmaga, at various height (5 cm, 100 cm, 120 cm) and times (07.00, 07.10, 13.00, 13.50 WIB). On LST day, temperature estimated by MODIS, closer to the temperature measurement on climatology station at a height 5 cm, with a R2 value 0,362. While the LST night have a fairly strong relationship with the T station at a height 120 cm. However, the highest R2 value obtained on the relationship between LST night with the T station at a height of 100 cm with a R2 value of 0,567. Generally, the evapotranspiration potential value in Cimadur watershed ranged from 4,45-5,65 mm/day (close to actual condition). With remote sensing based, evapotranspiration value can be presented spatially and temporally. However, there are constraints related the availability of data that caused the evapotranspiration value is only available in the dry months. This study shows that if this condition is corrected by combining the best availability of LST within a month, the availability of data in one month can be increased more than 50% from the initial condition 0%. The validation result between evapotranspiration value which is resulted by the Blaney-Criddle (ETm) and evapotranspiration value from evaporation pan A and Lysimeter, was giving the ETm value closer to the evapotranspiration value from pan A with a different value between ETm and pan A ranged from 0,82-1,32 mm (for 1x1 pixel) and 0,62-1,34 mm (for 3x3 pixel).