The distributed hydrological model WEB-DHM and the rice growth model SIMRIW-rainfed are coupled to grasp the required hydro-meteorological information for rain-fed agriculture. The results of the coupled model are validated by the LAI and soil moisture in the Sangker River Basin in western Cambodia. In this simulation, we targeted the dry season rice production in the rain-fed agricultural land so we assumed that they planted rice on 20 September 2011, referring the change of the LAI by MODIS. The sensitivity analysis showed that planting time has relatively higher sensitivity on crop yield than 10-day dry spell during the growing period. Irrigation or small rainfall (2mm/day) after heading until maturity was shown to increase yield. Thus, rainfall prediction at the beginning of the dry season is very important.
