The main motivations for the project are to synthesize environmental and societal knowledge to answer the needs of federal, republic, and local stakeholders and enhance resilience of infrastructure, human, social and cultural capital in changing conditions of Eastern Russian Arctic and subarctic region – Republic of Sakha (Yakutia) through collaboration of natural and social scientists from Japan, Russian Federation and Sweden specialized in hydrological modelling and forecasting, permafrost hydrology, permafrost environmental changes and influences on local and regional economy, agriculture, traditional lifestyle and cultural landscapes.

Natural resilience

A growing number of studies presents evidence of climate change impacts on permafrost, hydrological cycle, socio-economic processes and indigenous communities in the Arctic and subarctic. River monitoring shows increase in annual discharge from the largest Arctic rivers (Peterson et al., 2002; Tananaev et al., 2016), spring snow-cover is reduced at a higher rate than estimated by climate projections (Derksen and Brown, 2012), permafrost is warming up (Biskaborn et al., 2019), active layer depth is increasing (Romanovsky et al., 2010) and thermokarst is intensifying (Grosse et al., 2016), socio-economic processes are shifting along with environmental change (Crate, 2017). River discharge is the single largest freshwater source (50%) to the Arctic Ocean (Slater et al., 2007; Barry and Serreze, 2000), which is why changes in arctic hydrological regimes is of highest interest from climate and earth system perspectives. Increasing freshwater inflow to the Arctic Ocean have potential to influence changes in sea-ice area, deep water formation, ocean circulation and biological production with impacts on the climate system at a much larger scale than the Arctic itself. Modifications of river ice regimes will have a profound influence on the behavior and biological response of stream biota (Huusko et al. 2007) and, therefore, will play a central role in their growth, survival and reproduction. Changes in river ice cover can also have a direct impact on fish productivity and mortality (Prowse et al., 2011). Thermokarst lakes are expanding and the permafrost underneath is thawing due to both the warming and shifting hydrological processes (Crate, 2017). It has the potential to amplify global climate change, because when frozen sediments thaw it unlocks soil organic carbon (Biskaborn et al., 2019).

Human, social and cultural resilience

Human populations in Yakutia have historically clustered along the rivers – areas prone to flooding, but rivers are transportation routes and freshwater resources. The six main cities of Yakutia located on the banks of the Lena River are particularly vulnerable to flooding. There were several catastrophic floods at the Lena, Aldan, Amga, Tatta, Suola, Matta, Bayaga and Markhinka rivers during the recent years 1998-2015 regarding both flooded areas and damage. The city of Lensk was partly destroyed by the huge flood in 2001. In May 2010, a historic flood in the region of Yakutsk led to the evacuation of thousands of people (Gautier et al., 2017). Previous studies have also revealed the direct impact of climate change on the local economic and cultural systems of indigenous peoples. The population is concerned about the manifestations of weather and climate changes in the environment and the real threats to production routes, social communications. The current situation is perceived as a challenge to the established production cycle and the mode of rural life (Boyakova et al., 2012).

Societal resilience to floods

Recent studies (Kontar et al., 2018) have investigated the capacity in the Yakutian society for flood hazard prevention and mitigation and revealed that integrating practice. Although responsible stakeholders such as the Lena River basin Water Authority take actions on flood prevention and mitigation that include ice cutting, dusting and blasting, the added value of these measures is questionable. Stakeholders involved in flood management lack any science-based hydrological predictions and have pointed out the need for flood forecasting system for the region.

Numerous models have been used for simulation of river discharge in Arctic and permafrost dominated regions (e.g. Lebedeva et al, Semenova et al, Pomeroy et al, Andersson et al, Gelfan et al, Macdonald et al), but up to now none of them was tested as a forecasting tool in Yakutia. Representation of key water storages and processes (water in frozen and unfrozen form in snow, soil/permafrost, river and river ice, glaciers) and their spatial variability across a hierarchy of spatial and temporal scales remains a challenge which limits the ability of currently available flood forecasting models (such as the Arctic-HYPE model provided by SMHI). On one hand there is a need to improve our understanding of the role of permafrost thawing, snowmelt, rain, evapotranspiration, lake and reservoir management for the changes in river flow in order to improve the hydrological models. On the other hand, improved access to climate services, meteorological forecasts, new observational data from satellite and drone based remote sensing and developments in hydrological data assimilation provides new opportunities to improve both fundamental understanding as well as forecasting flood capacity.

River ice road infrastructure resilience

Although rivers become dangerous during the springflood they are the most important transportation routes in summer and winter in Yakutia due to the absence of railway, bridges and the limited number of roads on land. Many remote settlements and industrial facilities critically depend on delivery by winter and ice roads that exist only for a limited period from December-January to April. Up to 90% of goods are brought in by trucks during that short winter time. Extraction of gold, diamond, uranium, oil, gas and coal is an important sector of economy in Yakutia which often relies on both navigation and winter ice roads. Moreover, river ice roads link northern communities, thereby providing a ready access for supporting traditional and subsistence lifestyles (Prowse and Brown 2010). Due to global warming, mean annual air temperature in Yakutsk has increased from -10.4 °C (1951-1978) to -8.7 °C (1979-2012). Reduced winter ice road access has numerous negative consequences for communities and the industry sector. In a recent study, Lebedeva et al (2019) found that historical observations show significant trends of ice thickness reduction and shortening of ice cover period lengths due to earlier breakup in spring (as a consequence of the reduced maximum ice thickness). Changes to ice regimes will also make the practice of some traditional subsistence-based lifestyles potentially hazardous and may reduce the ability to undertake some traditional harvesting methods (Prowse et al., 2011). Model simulations for the future suggests that the river ice cover periods may shorten by up to 40 to 50 days under RCP8.5 towards the end of the century, but only up to 10-20 days in the near future and under RCP4.5. These results are important for developing long-term strategies of adaptation and mitigation to climate change on a regional scale, as State Assembly of the Republic of Sakha (Yakutia) pointed out. On the other hand, local stakeholders that deal with design, construction and maintenance of climate-dependent river ice crossings such as Management of Highways of Republic of Sakha (Yakutia) require predictions of river ice on seasonal and sub-seasonal timescales, adapted to local conditions at a higher spatial resolution as currently available model tools.

Permafrost landscape resilience

Large areas of permafrost are subject to degradation. Over the past 30-40 years, the areas of thawing lakes have been steadily increasing (Walter et al., 2006; Jones et al., 2011; Kravtsova, Rodionova, 2011; Ulrich et al., 2017). The formation of a thermokarst high-centered polygons as an indicator of the initial form of degradation of the ice complex has become widespread (Fedorov et al., 2014; Liljedahl et al., 2016 et al.). Spatial pattern of ground subsidence, expansion of incipient thermokarst forms and losses of land on a regional scale is lacking and will be addressed in the project. Identification of tipping points – critical combination of air temperature, precipitation and snow cover that initiate ground ice melt, will be performed. The activation of thermokarst causes the degradation of ice-rich permafrost, ground subsidence and loss of land that was previously used for construction and agriculture including traditional for indigenous communities horse and cattle breeding. Land management is often done without accounting for potentially hazardous permafrost degradation. Local stakeholders in land use planning could erroneously allocate pieces of land prone to subsidence and thermokarst for agriculture and construction. To avoid that a holistic understanding between environmental, societal researchers and stakeholder communities is needed. State Assembly of the Republic of Sakha (Yakutia) together with a group of scientists led by A.N. Fedorov developed the bill about protection and preservation of permafrost that was enacted on 22nd of May 2018. The bill discusses risks of permafrost thaw and related damages of infrastructure in Yakutia. To bring the bill into the action on the local scale guiding documents for sustainable land management and landscape optimization are needed.