Hydroclimatic variability is an emerging challenge with increasing implications on water resources management, planning, and the mitigation of water-related natural hazards. This variability, along with the continuous development of water demands, and aging water supply system infrastructure make the sustainability of water use a high priority for modern society. In fact, the Global Risk 2015 Report of the World Economic Forum highlights global water crises as being the biggest threat facing the planet over the next decade.

To mitigate the above concerns we need to shed light on hydroclimatic variability and change. Several questions and mysteries are still unresolved regarding natural fluctuations of climate, anthropogenic climate change and associated variability, and changes in water resources. What is a hydroclimatic trend? What is a (long term) cycle? How can we distinguish between a trend and a cycle? Is such discrimination technically useful? How do human activities affect rainfall, hydrological change and water resources availability? How to set priorities and take action to ensure sustainability in light of variability and change?

The objective of this session is to explore hydrological and climatic temporal variability and their connections and feedbacks. More specifically, the session aims to:

1. investigate the hydrological cycle and climatic variability and change, both at regional and global scales;

2. explore the interplay between change and variability and its effect on sustainability of water uses;

3. advance our understanding of the hydrological cycle, benefiting from hydrological records and innovative techniques; and

4. improve the efficiency, simplicity, and accurate characterization of data-driven modeling techniques to quantify the impacts of past, present and future hydroclimatic change on human societies.

This session is sponsored by the International Association of Hydrological Sciences (IAHS) and the World Meteorological Organization – Commission for Hydrology (WMO CHy) and it is also related to the scientific decade 2013–2022 of IAHS, entitled “Panta Rhei - Everything Flows”.