Recognizing and forecasting the hydrologic drought in the upper of Weihe basin

Yearly natural streamflow data of five hydrologic stations over the upper of Weihe basin for 1945-2000 were utilized to analyze the drought characteristics by using Run-theory and Grey system. Based on the theory of run and intercept method, the hydrologic drought duration, drought severity and the value of conditional probability were calculated to evaluate the regional hydrological drought characteristics. The hydro-drought forecasting model was established by using the Grey system theory in order to provide the time span of forecast. The model had the traits of high accuracy and convenience, so it could be used in hydrogical drought analysis.