Regional frekvensanalyse av hydrologisk tørke og lavvann

Abstract

An assessment of extreme hydrological low flow and drought events is of vital importance to water resources management. One way to reduce the uncertainty in the estimate of the extreme events is to use a regional dataset with observations from several sites. This procedure is commonly applied for floods, and is therefore often referred to as the ‘index flood’ method. This method is also applicable to drought. In this study the index method is applied for the characteristics of drought duration and deficit volume. Because the region under study is affected of water being stored as snow during winter, a distinction between the summer and winter low flow has to be made. L-moments are used to test the regional homogeneity and for determination of the regional distribution. Homogeneous regions is defined based on a split sample procedure.