NATURAL ZONING OF THE DELTA OF LENA RIVER FOR THE RESEARCH OF THE DYNAMICS OF ITS SEA EDGE
History of the delta of Lena River forming in Last Holocene had been clear investigated by pale geographical methods. Undertaking of modern delta dynamics investigation by multitemporal topographic maps and air photos for 1950-1991 had shown the absence of changes. In this work we have created investigation of delta’s sea edge changes for the next time interval from the end of XX century to recent time by space images, mainly from Landsat satellite. At big prolongation of delta’s sea edge for more than 1500 km and its complex construction, shores have various character and dynamic processes at various sections may be different. To take it in account, for investigation of delta’s sea edge dynamics, we have created the division of delta surface into natural regions at the base of topographic and geomorphologic maps and satellite images, taking attention to morphology of river branches - their wideness and density of network, character of their mouths, relief of delta surface, vegetation cover and landscapes at whole. In connection with this regionalization the delta sea edge was divided into 7 sections, and changes had been investigated for every of them. Because of weather conditions and necessity of images without clouds for the end of summer, time interval for investigations in different sections was various. As result of multitemporal images analyzing at 7 sections for 97 % of delta’s sea edge changes were not discovered, but for 3 % changes were investigated and maps of delta dynamics were compiled. In the Western part of the delta of Lena River, at mouth of Olenyok branch, where small local protruding delta was formed, in 1980-2003 erosion of sea edge took place and shore line retreat with middle year velocity 20-30 m/year. Shallows around this delta also eroded and sediments were moved with alongshore stream. In the Northern part of the delta, near mouths of Tumatskie branches, unstable position of shore line was discovered with alternation of it seaward and landward moving. At the Northern-Eastern part of the delta, at small rectilinear section of shore, its erosion in 2005-2016 was fixed with middle year retreat 15-30 m/year. All discovered changes are connected with mouths of branches, taking the lesser share of the Lena River water runoff. At regions with mouths of branches, taking the most part of water run off, there are no changes, so as at shore of sea terrace, included into delta. Delta protruding was not found anywhere.