Climate Variability and Change—Hydrological Impacts (Proceedings of the Fifth FRIEND World
Conference held at Havana, Cuba, November 2006), IAHS Publ. 308, 2006, 117–121.
Low flow estimation in Austria
GREGOR LAAHA1 & GÜNTER BLÖSCHL2
1 Institute of Applied Statistics and Computing, University of Natural Resources and Applied Life Sciences, BOKU Vienna, Gregor Mendel Str. 33, A-1180 Vienna, Austria
gregor.laaha@boku.ac.at
2 Institute for Hydraulic and Water Resources Engineering, Vienna University of Technology, Karlsplatz 13, A-1040 Vienna, Austria
Abstract This paper gives an overview
of river low flow processes and low flow estimation methods in Austria.
Streamflow data from 325 sub-catchments in Austria, ranging in catchment area from
7 to 963 km2, are used for the analyses. The performance of a number of
regionalization methods for q95 low flows is assessed by leave-one-out
cross-validation which emulates the case of ungauged catchments. A regional
regression model based on a catchment grouping according to low flow
seasonality performs best, but low flow estimates from short (one year)
streamflow records outperform the best regionalization method when using an
appropriate climate adjustment method. A q95 low flow map for all of Austria is
compiled that combines local stream flow data with the regionalization
estimates. It is argued that a combination of different sources of
information—various types of regionalization models and streamflow records of
various lengths—provides a wealth of information that should be exploited for
low flow estimation.
Key words catchment grouping; cross validation; low flow;
prediction at ungauged sites; PUB; regionalization; regional regression;
seasonality