LOW FLOW FORECASTING WITH RECESSION ANALYSIS APPROACHES

摘要

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