Using hydrodynamic and bathtub water-level models to assess the current and future storm surge flooding in Tuktoyaktuk

Arctic warming is leading to an increased reduction in sea ice, with models for 2100 indicating a reduction in the Arctic sea ice area from 43 to 94% in September and from 8 to 34% in February (IPCC,2014). The increase of the sea-ice free season duration will result in more exposure of the coasts to wave action, with changing climate also modifying the contribution of terrestrial erosion processes. Coastal erosion can also be increased by warmer seawaters and sea-level rise, with more frequent storms and associated surge events leading to the increase in flooding. During the short open water season (June to October) there has been an increase coastal storms (wind speed > 36 km/h andsurge level > 1.5m), this has led to an increment in coastal erosion and flooding (Fritz et al., 2015, Ramage et al 2018, Irrgang et al 2018).
 
This work focuses on the Hamlet of Tuktoyaktuk(Northwest Territories, Canada), where extensive ultra-high-resolution surveys with unmanned aerial vehicles (UAVs) have been conducted, allowing to generate orthophoto mosaics, digital surface models (DSM), derived land use, geomorphological and socio-economic activity maps. DSMs, bathymetry and meteorological data are used as inputs for flood modelling in MOHID Water software. Validation is conducted using tide gauge and DGPS data from 2019,with the boundary conditions obtained from the FES2014 tide model (FiniteElement Solution). Both approaches run on LiDAR data from 2004 and the UAV DSMsfor direct comparison. This research is done in cooperation with the Hamlet,with the results being provided as a tool for strategical spatial planning,culminating in more resilient mitigation and adaptation measures to climate change. This research is funded by the European Commission H2020 project NUNATARYUK and by the Climate Change Preparedness in the North Program (CCPN).