The Use of the Recession Index as an Indicator for Streamflow Recovery After a Multi-Year Drought

Abstract

A procedure is proposed that enables the estimation of natural baseflow in a gauged watershed through analyses of recession curves and stream hydrographs. The analysis results in a surrogate for the recovery level of a watershed after a prolonged drought and allows the medium term prediction of runoff behaviour for water resources management. The method has been applied for the Upper Battle River Watershed in the northern Prairies of Alberta, Canada. Results show that baseflow is extremely low after a multi-year drought (2001 to 2003). The recession index indicates that one year after the climatological end of the drought the integrated watershed storage that usually sustains the baseflow is abnormally low, with associated negative impacts on available water resources. This paper describes the derivation, classification and application of a watershed specific recession index. Results show that the described procedure is relatively simple, reliable and efficient.