Abstract:
The use of modeling techniques in hydrology research is now highly developed. It can be seen from the increasing number of hydrologic modeling that appears along with the development of knowledge and the advancement of computer technology. IFAS is a remote sensing program that was developed by a research institution of the Japanese public works called the International Centre for Water Hazard and Risk Management (ICHARM). the IFAS system has several parameters are initially set to default parameter values based on the data downloads from the satellite. This parameter is then calibrated by using a reference from the local hydrological data observed (measured data). If we do not have measured data then must use the default parameter values. Rain hydrological modeling process is carried out in the watershed flow Lubuk Ambacang with data length for 1 Januari until 31 Desember 2004 and then was validated with data length for 1 January until 31 December 2006. Modeling become optimal after the calibration process with the correlation (R) value of 0,717, volume error (VE) of 3,13%, and the coefficient of efficiency (CE) of 0,89. This showed that the model has a high degree of association with the measured data (0,7 <R <1,0), the difference of volume is still tolerable (VE <5%), and the efficiency of model to the measured discharge is quite efficient (0,36 <CE <0,75).
