Developing and validating an EU drought risk assessment framework. An evaluation for the Netherlands and the Dutch part of the Rhine River basin.

Abstract

Europe is known as one of the recent hotspots of drought occurrence. While Droughts can have an impact on different environmental, economic, and societal sectors, the society also reacts to them. Therefore, droughts are known as complex phenomenon. Due to this complexity risk frameworks can be an effective method to study droughts as the complexity can be broken into indicators affecting and being affected by droughts. Furthermore, the unequal availability of data, scientific knowledge, and technology across EU countries hinders them from independently developing their own drought risk frameworks. Therefore, this thesis project aims to develop a large-scale drought risk assessment framework on an EU scale based on open sources data that could be used for all EU countries. The drought risk maps are generated using gridded meteorological data and NUTS2 regions dataset for the period from 1990 to 2004. These drought risk maps provide initial insights for identifying regions experiencing drought risk and defining drought coping strategies. The results indicate that the Mediterranean and Balkan regions of the EU, along with Italy, Spain, Germany, and southern Netherlands, faced the highest historical drought risk. Furthermore, drought risk values vary between general and sector-specific drought risk maps. Studying the impact of drought on specific sectors, such as agriculture and navigation, leads to higher risk values for EU regions, while the affected regions mostly remain the same as those in the general drought risk maps. In addition, a lack of future drought risk maps is observed in current studies. Thus, future drought risk maps under the SSP5-8.5 scenario until 2050 were generated using future datasets, including the drought index SPEI12, future GDP, and future population density. The results showed that drought risk might have an increase by about three times, affecting new central and eastern EU regions along with the historically drought-affected regions. As a final step, validation is conducted to compare the EU-scale drought risk maps with local-scale drought risk maps. Validation showed a stronger correlation for SPEI12 and precipitation deficit, than the correlation of SDI12 with both discharge deficit and low-flow duration. Overall, this thesis project provides a drought risk framework applicable to large regions. This framework is an effective starting point for identifying the EU regions that need monitoring and actions to prevent them from natural, social, and economic adverse effects caused by droughts.