New flood hazard knowledge

Flood hazards in Yakutian rivers – new knowledge from new data

Scientific questions:

• Do flood characteristics change with changing climate?
• How do flood changes interconnect with trends of air temperature, rain, snow and river ice characteristics?
• How do these changes relate to permafrost landscapes?

The flooding at Yakutian rivers are reportedly an increasing problem. The data support for analysing spatio-temporal changes in flooding and for developing and evaluating flood forecast models will be improved by utilizing new and historical sources of information: river gauging stations provide water level and river flow data with time series since many decades back, but the station network is sparse and stations have been closed temporarily or definitely. Satellite altimetry provides a new method to obtain time series of river water level from previously ungauged locations. The large rivers in Yakutia are favourable for these satellite measurements since the river width must be more than 300 m (ESA Sentinel-3), and the satellite track density is increasing at high latitudes. We will increase the data basis for the flooding level analysis using satellite data. These data can also be used in a forecasting situation, to retrieve information on upstream flooding status, and estimate the arrival of flood peaks at downstream locations. The value of satellite data can be further improved by establishing rating curves and cross-correlate with existing gauging stations. For this purpose, drone technology provides opportunities to improve modelled rating curves for river cross sections, based on high resolution elevation models. SMHI is currently participating in the ESA Hydrology-TEP project exploring satellite altimetry for inland waters. In and Arctic case study, SMHI and MPI will evaluate altimetry data at selected locations close to Yakutsk and collect local data for verification. This project will start in autumn 2019, and will contribute to HYPE-ERAS.