Hydrological droughts are major natural hazards. They are caused by persistent dry weather or freezing, leading to a deficit in soil moisture and reduced groundwater recharge and levels, and to low streamflows or dried-up rivers. All of these facets of hydrological drought may have major impacts on nature, the economy and society, and are therefore the subject of a number of current research initiatives.

The topic of this special issue, HYPER Droughts, originates from the title of the 6th EGU Leonardo Conference (Prague, 2014), which was not only chosen to reflect the importance of drought research. The acronym HYPER Droughts stands for HYdrological Precipitation – Evaporation – Runoff Droughts: droughts in the various, connected components of the water cycle. The related scientific questions are rooted in the concepts of hydrology and climatology but also focus on society and environmental management. This means that a range of disciplines, including surface and groundwater hydrology, climatology and meteorology, (hydro-)ecology and water quality research, geography and history, wood science, water monitoring, modelling and management, environmental statistics, and many other disciplines may contribute to the the topic of HYPER Droughts.

The objective of this special issue is to bring together contributions from a broad range of disciplines with a main focus on the hydrological aspects of droughts. Contributions are solicited that address the following topics:

1. drought governing processes including climate and catchment drivers;

2. indices and tools for monitoring and prediction of droughts;

3. regional modelling of low flows and droughts;

4. reconstruction of historic and prehistoric droughts (from modelling, documentary sources and other proxies, such as tree rings);

5. droughts under hydrological change (climate change and human impacts);

6. drought forecasting (meteorological, hydrological and agricultural perspectives);

7. drought impacts, risk (ecological and economic) and vulnerability;

8. implications for water management.