×K11. Long term changes in the hydrological cycle under a variable and changing climate

This session focuses on hydrological change related to sustained change in climate forcing. Climate affects many aspects of the catchment environment. Well-known hydrological model performance issues encountered under substantially different climate can be caused by the changes occurring in various parts of the catchment system. The multitude of responses and feedbacks developing in the critical zone need to be disentangled and understood to improve our ability to make hydrological predictions under different and continuously variable climatic conditions.

We are interested in catchment phenomena occurring on multiyear to interdecadal timescale that can influence any component of the hydrological cycle. In relation to streamflow, for example, one set of potential mechanisms can be related to changes in the subsurface storage and transport conditions such as unexpected changes in hydrological connectivity or changing recharge for a given rainfall. Another potential cause is climate-induced vegetation change, including changes in species composition, age distribution, or plants physiology.

We invite data-based, physical modelling-based, and experimental studies looking into detecting, quantifying, and synthesising indirect impacts of climate on the hydrological cycle. Both long-term directional change and prolonged but potentially interrupted change, such as multiyear droughts, can teach us about long-term responses, including potential hysteresis and thresholds behaviour. More specifically, the recent multiyear and recurrent droughts in Australia (e.g. Millennium Drought and recent NSW drought) can be used as relevant case studies. Improving our conceptual understanding of catchment responses is expected to help developing better hydrological models robust under changing climate.

Key topics: Hydrological change, Hydrological cycle, Streamflow, Non-stationarity