Spatiotemporal Analysis of Streamflow Drought in the Mediterranean
Flowing through dry times: Understanding streamflow droughts in the Mediterranean
T.K. Poort (TU Delft - Civil Engineering & Geosciences)
M. Hrachowitz (TU Delft - Water Resources)
More Info
expand_more
Other than for strictly personal use, it is not permitted to download, forward or distribute the text or part of it, without the consent of the author(s) and/or copyright holder(s), unless the work is under an open content license such as Creative Commons.
Abstract
Driven by global temperature increase and changing precipitation patterns, the intensifying hydrological cycle is expected to introduce more frequent and severe streamflow droughts. These changes will have a profound impact on agriculture, ecosystems and water management. This study analysed the spatial and temporal changes in streamflow droughts across 386 Mediterranean river basin from 1970 to 2019, focusing on their drought characteristics: duration, severity, intensity, maximum deficit, inter-arrival time, recovery rate and decline rate. The river basins were categorized into seven climatic regimes, and each was analysed for changes in these drought characteristics. Streamflow droughts were quantified
using the Threshold Level Method, defining drought events as periods in which daily streamflow is below a set threshold. To identify patterns, trends were assessed across four fixed time periods, along with multi-temporal analyses for both annual and seasonal changes. The analysis showed that annual streamflow droughts, although becoming longer, are getting slightly less severe and intense across the majority of river basins. However, distinct seasonal and regional variations were found. Between 1988 and 2019, winter and spring streamflow droughts experienced a decrease in duration and severity (up to -30% for winter) across the entire study area. On the other hand, regional differences were observed for summer and fall. During this same time period, summer and fall streamflow droughts in the Pyrenees, Southern France, Italy and Croatia have become much longer, more severe and more intense (20-40% for summer), whereas Central and Southern Spain experienced decreasing duration and drought deficit volumes. The implications of increasing streamflow drought conditions on the water availability in Mediterranean river basins is severe, which highlights the need for better understanding and water management of streamflow droughts.