Isotope-aided assessment and forecasting of hydroclimatic extremes in Scandinavia through stakeholder co-design

Floods and droughts have large consequences for society and economy in Scandinavia. Knowledge about if and how such extreme events are connected to snow on the ground is limited. This lack of knowledge imparts our ability to predict how much water will run through rivers and is stored in dams with computer models. As climate changes rapidly, we do not know for certain what future extremes will look like. Being trained in the present climate, current models to predict the water running through rivers are even less adequate to predict future floods and droughts. Additional knowledge about the connections between different components in the water cycle, including input from rain and snowfall, storage in lakes and dams, and its pathways in rivers and in the ground can be gained from measuring the stable isotope composition, a natural physical property of water. ISOSCAN will make use of this so far underused information source to improve the predictions of water extremes from computer models. A particular new aspect is that ISOSCAN will work together with regular citizens, such as tourists, to participate in the collection of water samples to access isotope information from a large area. The dataset obtained from both working with such citizen scientists, as well as more regular scientific approaches, will be used to improve a prediction model for water extremes in Scandinavia. The expected outcomes from ISOSCAN therefore include both how to work effectively with citizens to collect samples, the capability to better predict water extremes, and the potential to prepare citizens for future climate extremes.

Snow cover extremes are linked to floods and droughts, and thus have major socio-economic impacts. A lack of more solid evidence on the causes and impacts of extreme seasonal snow cover in Scandinavia causes uncertainties related to the water amount, variability of the snowpack, lack of data for calibrating hydrological models, in particular for hydrological extremes. Being tuned to the present, many current models will not be able to adequately represent future extremes. Water isotopes in precipitation and the snowpack have a large, but hitherto barely exploited potential to improve estimates of the water amount and physical processes contributing to runoff. The overall aim of ISOSCAN is to advance forecasts of hydroclimatic extremes across Scandinavia from novel water resource assessment and model constraints, using new water isotope data from non-traditional sources, co-designed with citizen scientists and stakeholders. ISOSCAN pursue 4 specific objectives: (1) by developing a scalable, effective citizen science framework that involves recreational nature users, including tourists and locals, to overcome the lack in spatiotemporal isotope data in Scandinavia; (2) by obtaining spatially and temporally resolved water isotope data obtained from a range of sources, from literature to fieldwork using a citizen science framework during winter and precipitation across Scandinavia; (3) by utilizing the novel stable water isotope dataset to improve estimates of the snowpack, and physical process representations in a hydrological model; and (4) by disseminating co-designed outcomes and the improved hydrological model capability. This work is expected to lead to a better hydrological process understanding to stakeholders, contributing to mutual learning between citizens and scientists, as well as contributing to stewardship and behavioural changes, and contributes to preparedness against hydroclimatic extremes.