Abstract ID: 3.12697 | Accepted as Talk | Talk/Oral | TBA | TBA

Streamflow droughts evolve in space and time. Such spatiotemporal evolution of streamflow drought is not just driven by changing hydrometeorological conditions, but also by the river network: the drought signal from different tributaries interact as these tributaries merge. However, little is known about the exact role the river network plays in shaping such spatiotemporal drought relationships. Here, we use large-scale hydrological model simulations over Europe to study the role of the river network in shaping spatiotemporal drought relationships in different hydroclimates such as mountain and lowland regions. We apply complex network theory to study drought connections between different river branches. In particular, we focus on the spatiotemporal relationships between upstream and downstream rivers, between droughts in snow and rainfall-dominated rivers and between different river basins. We find that the stream order is important for the drought connectivity between different river branches, whereas the hydroclimatic context can determine where in a basin the drought signal emerges first. As the river network influences the temporal characteristics of the drought signal, this can also influence larger-scale spatiotemporal drought connections between different river basins. Finally, as hydroclimatic conditions are changing due to climate change, we show that such changes can also lead to changes in drought connectivity over time. Our results have implications for water management, as a better understanding of the role of the river network in shaping spatiotemporal drought behavior can help with projecting drought impacts and designing drought impact relief strategies.