RIVER LOW FLOWS IN AUSTRIA

摘要

This paper gives an overview of river low flow processes and low flow estimation methods in Austria. Stream flow data from 325 sub-catchments in Austria, ranging in catchment area from 7 to 963 km~2, are used. The performance of a number of regionalisation methods for Q95 low flows is assessed by leave-one-out cross-validation which emulates the case of ungauged catchments. The best performance yields a regional regression model that is based on a catchment grouping according to the seasonality of low flows. A Q95 low flow map for all of Austria is presented that combines local stream flow data with the regionalisation estimates. The paper demonstrates how these methods can be used for estimating annual and seasonal low flows for 270 hydropower sites in Austria in the context of assessing the potential effect of the European Water Framework Directive on future hydropower production. It is argued that a combination of different sources of information - various types of regionalisation models as well as stream flow records of various lengths -provides a wealth of information for low flow estimation.