Low Flow and Drought in a German Low Mountain Range Basin

Rising temperatures and changes in precipitation patterns in the last decades have led to an increased awareness on low flow and droughts even in temperate climate zones. The scientific community often considers low flow as a consequence of drought. However, when observing low flow, catchment processes play an important role alongside precipitation shortages. Therefore, it is crucial to not neglect the role of catchment characteristics. This paper seeks to investigate low flow and drought in an integrative catchment approach by observing the historical development of low flows and drought in a typical German low mountain range basin in the federal state of Hesse for the period 1980 to 2018. A trend analysis of drought and low flow indices was conducted and the results were analyzed with respect to the characteristics of the Gersprenz catchment and its subbasin, the Fischbach. It was shown that catchments comprising characteristics that are likely to evoke low flow are probably more likely to experience short-term, seasonal low flow events, while catchments incorporating characteristics that are more robust towards fluctuations of water availability will show long-term sensitivities towards meteorological trends. This study emphasizes the importance of small-scale effects when dealing with low flow events.