Seasonal variability of the Western Siberia wetlands from satellite radar altimetry
Résumé
Boreal wetlands play an important role in the global water and carbon cycle but their water regime is far from being well understood. The aim of this paper is to study wetland hydrological regime over the 21 mid-size watersheds of the Western Siberia - one of the most bogged regions of the world. By using ENVISAT RA-2 radar altimetry data we analyze seasonal variability of wet zones extent, water level and storage in wetlands. We have identified three main types of wetland water regime characterized by: (1) spring inundation and following deep drainage with/without secondary peak in autumn; (2) spring inundation and low summer variation; (3) spring inundation with medium summer drainage and second autumnal peak. Our estimates show that the floodplain inundation contributes less than 8% to the total wet zones extent. Analysis of the timing of melt and freeze onset and other specific phases of hydrological regime has been done. It was found that the spring inundation lasts for almost 2 months with a latitudinal gradient of melt onset of 8 days/2. No considerable latitudinal gradient has been found for dates of full freeze onset. Our results show that seasonal amplitude of water level variation for northern part of Western Siberia from altimetry is 0.7-1.5 m for lakes and 0.2-0.5 m for bogs. This represents seasonal variation of wetland water storage of 480 mm for non-permafrost and 130 mm for permafrost-affected zones. (c) 2014 Elsevier B.V. All rights reserved.