|Paper title||The thaw lakes and drained thaw lakes in the Yamal peninsula 1961 – 2018, impacts on land cover change and reindeer herding|
|Form of presentation||Poster|
The thaw lakes and drained thaw lake basins are a prominent feature in the Arctic and cover large areas of the landscapes in the high latitudes. Thaw lakes as well as drained thaw lake basins have major impacts on a region’s hydrology, landscape morphology and flora and fauna. Drained lake basins have been studied across regions in the Arctic and differences in abundance and distribution exist between regions in the circumpolar Arctic. Thawing permafrost and drainage lakes can also affect human activities. Our research area is the Yamal peninsula in the Western Siberia, Russia. Yamal Peninsula is about 700 km long and about 150 km wide, extends from 66° to 72° degrees North. In Yamal petroleum industry with related infrastructure networks can be affected by changes in lake and stream hydrology. Nenets reindeer herding is the traditional land use form in the Yamal. Reindeer herding is based on natural pastures and resources, and lakes and streams serve as important fishing resource for own use and sale. Thawing and drained lakes are part of climate change driven landscape changes in the area.
Landsat has been used in multiple studies for the analysis of lake area, extent and drainage or shrinkage events in the circumpolar Arctic. To analyze lake drainage, lake shrinkage and changes in lake extent consistent satellite data with adequate temporal and spatial resolution is needed. Frequent cloud cover in arctic regions during the summer months limits the number of suitable acquisitions of multispectral sensors and hinders the implementation of large-scale time series analysis efforts. Landsat data enables time span from 1972, although Landsat MSS images were rather coarse and good quality images are sparse. Good quality data have only been available since the mid-1980s when Thematic Mapper was launched. Old archival aerial photographs allows looking further back in time, in some cases even to 1940’s, but their limited spatial coverage and availability does enable large scale investigations. Cold war era spy satellite missions like Corona and KH are the only options to expand time span to late 1950’s and early 1960’s.
Our remote sensing datasets cover a period from 1961-2019. Corona data represents the oldest data source and mosaic was compiled from 38 original Corona images. Corona mosaics resolution is about 7 meters. Landsat mosaics are derived from 1980’s and 2010’s data. In addition we use several very high resolution satellite data (Quickbird-2, Worldview-2/3) and drone data to demonstrate lake changes in detail. Field data for verification of drained lakes have been collected from several parts of Yamal. Field data includes observations of changes and vegetation sampling. We have also interviewed several reindeer herders to understand the implications of lake changes for reindeer husbandry.
The changes were observed in the following periods 1961-1988 and 1988-2018. The results show that the disappearance of the lakes occurs throughout the period, but in the latter period the process accelerated. In terms of reindeer husbandry, the issue is multidimensional, as lakes that are quite important for fishing have disappeared in some places. Drained Lake, on the other hand, will soon turn into a good quality pasture land where nutritious grasses and forbs grow, but if drained lake is located in a winter grazing area, it is only a lost fish resource.
Figure: On the left, a partially drained lake, about 10 years ago. Old lake bottom grows with dense grass, sedge and forb carpet. On the right about 2-3 years ago partially drained lake, the revegetation is much slower which is also due to the sandy soil.