Recent dynamics of hydro-ecosystems in thermokarst depressions in Central Siberia from satellite and in situ observations: Importance for agriculture and human life

Alases, which are thermokarst depressions that are occupied by grasslands and lakes, are an important element of the Central Yakutian periglacial landscape. In recent decades, climatic changes in Central Yakutia have resulted in important changes in environmental conditions. We use different remote-sensing instruments (Landsat 8, TerraSAR-X, ENVISAT-RA2, and Jason-2) alongside in situ observations to investigate 1) the spatial distribution and water regime of alas lakes and their relationships with climatic and geomorphologic factors, 2) the relationship of the alas' grassland productivity with the water regime and 3) the potential of alas grasslands for local agriculture. During the 2002–2010 period, the lake water level rose by 1.3m on average, resulting in lake expansion throughout the region. Since 2011, the lake area decreased and the water level declined by 70cm on the middle terraces (low ground-ice content), while the wetting trend continued until 2016 at higher elevations. Small thermokarst lakes (