×J9. Hydrologic non-stationarity and extrapolating models to predict the future

The term ‘hydrologic non-stationarity’ has been used to describe many things, ranging from climate and streamflow variability evident in different periods within a long hydroclimate time series to changes in climate-runoff relationships and dominant hydrological processes over time. Hydrologists have excelled in developing simple to complex models for numerous applications, through analysing and interpreting climate, landscape and hydrologic data to understand hydrologic processes, conceptualising the processes in hydrological models, and calibrating and testing models against multiple observations. These models are particularly good in predicting the streamflow response to changes in the climate inputs and catchment characteristics. However, extrapolating hydrological models to predict further into the future is more challenging as streamflow will be increasingly influenced by higher temperatures and changed ecohydrological processes under higher CO2. Reliably modelling these is difficult because of the complex interactions and feedbacks between many variables and processes in a future environment not seen in the past (i.e., hydrologic non-stationarity that has not been observed).

We invite papers addressing hydrologic non-stationarity and challenges in extrapolating hydrological models to predict the future. This include papers on observed hydrologic non- stationarity, limitations in existing models for modelling through non-stationarity and adapting hydrological models or modelling methods to simulate the future. Modelling methods may range from smart regionalisation, calibration and parameterisation against long or similar hydroclimate records with changing climate-runoff relationship over time, improved conceptualisation of hydrologic processes under extreme conditions (e.g., different surface-groundwater connectivity through long wet and dry spells), to adapting and building models that may adequately simulate surface-atmosphere feedbacks and dominant ecohydrological processes in a significantly warmer and higher CO2 world.

Key topics: Hydrologic nonstationarity, Rainfall-runoff relationship, Surface water-groundwater interaction, Altered response