Abstract
Since hydrologic drought is a slowly developing phenomenon, it may be possible to forecast low flow conditions, especially in areas with long dry seasons. This study proposes hydrological drought forecasting methods based on two stream flow recession analyses. The first one is based on a recursive digital filters for baseflow separation and recession characterization for the baseflow forecasting. The second one is based on the theory of “simple dynamical systems of catchments”. The applications of the two methods were demonstrated in Lombok Island in Indonesia and showed that the latter method, which reflects more flexible recession characteristics showed better accuracy in the estimations of the low flows. Nevertheless, both of the presented applications showed underestimations in low flow forecastings compared to the observed ones. The underestimations were mainly associated with the ignorance of the rainfall, especially for long lead time cases.
