Features of alas depression wateriness in Central Yakutia
Roman V. Desyatkin (1)
(1) Institute of Biological Problems of Cryolithozone SB RAS
On the flat territories of cryolithozone the alas landscapes are wide-spread. The quantity of alases reaches16 000 on the area 4 400 square kilometers just in the Central Yakutia. 20-30% of the territory is occupied by alases there. Alas depressions being negative forms of relief are the local accumulation centers. In alas wateriness dynamics main role plays the capacity of closed alas system, which summed up from capacity of alas active layer and alas depression capacity. Alas active layer is a blanket part of alas depression, exposed to periodical thawing and freezing. This layer is heaped up from seasonal thawing soils, alas lake volume and under lake talik. The capacity of alas depression determined by alas area parameters but it is closely limited. Therefore inappreciable fluctuations of exogenous factors (precipitation quantity, temperature conditions and etc.) find out almost mirror reflection in the wateriness of closed geochemical alas systems.
The alas wateriness cycle issues were examined previously by hydrologist „@.G. Nemchinov (1958) and permafrost scientist N.P. Bosikov (1985, 1991). Archival data of alases lake wateriness fluctuation was collected and generalized by philosopher D.S. Makarov (1983). All authors noted the wateriness cycle of alas lake, but clear causes and wateriness rhythm logic are still disclosed. Such condition of the issue is explained by an absence of alas depression hydrology systematic investigation. We tried to generalize the collected data on the alas wateriness and conducted field measurements of a model alas lake for a 1987-2000 period. As the results, the alas lake level has both interseasonal and intraseasonal fluctuations. With the interseasonal fluctuations alas lakes mainly reach the highest level in the first half of summer which is associated with water income as the snowmelt result. Water level rise in the mid of summer is associated with melting of ice impregnated seasonal permafrost and incoming of additional water into the lake. Autumn lake level rise occurs as a result of abundant atmosphere precipitation and finally December - January increase of alas lake level is associated with freezing of shallow parts of lake and water press to the deepest parts of the lake. Existence of 11 years solar and secular (90-years) cycles are developed in multiyear path of alas wateriness fluctuations.
Submittal Information
Name :
Date :
Dr. Roman V. Desyatkin
29-May-01-16:37:43
Organization :
Theme :
Institute of Biological Problems of Cryolithozone SB RAS
