ADAPTING LOW‐FLOW FREQUENCY ANALYSIS FOR USE WITH SHORT‐PERIOD RECORDS

Abstract

ABSTRACTLow‐flow frequency analysis techniques are robust only where the flow record is relatively long and the flow regime is known to be stationary over time. If applied to short‐period flow records. low‐flow frequency analysis can give poor or misleading results. This paper examines the effectiveness of data‐transfer methods for improving the characterisation of low‐flow frequency relationships for gauged sites with flow records of less than fifteen years.Two transfer methods were considered. In each case the sequence of annual minimum flows from an analogue catchment was used to provide extra information about the sequence of flows at the site of interest. Transposing the standardised probability distribution function of annual minima between analogue sites worked where their flow records were highly correlated. However, better results were obtained where recurrence intervals for observations at the subject site were estimated from recurrence intervals for the same years in the analogue record.