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Coupled modelling of soil thaw/freeze dynamics and runoff generation in permafrost landscapes, Upper Kolyma, Russia. Lebedeva L . 1, 4 , Semenova O. 2, 3 1 Nansen Environmental and Remote Sensing Centre 2 Gidrotehproekt Ltd 3 St. Petersburg State University 4 State Hydrological Institute
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Coupled modelling of soil thaw/freeze dynamics and runoff generation in permafrost landscapes, Upper Kolyma, Russia Lebedeva L.1,4, Semenova O.2,3 1Nansen Environmental and Remote Sensing Centre 2Gidrotehproekt Ltd 3St. Petersburg State University 4State Hydrological Institute St. Petersburg, Russia The study is partially supported by Russian-German Otto Schmidt Laboratory for Polar and Marine research
Variety of landscapes and complex process interactions Bush tundra Deep active layer Subsurface runoff Shallow active layer, surface runoff Larch forest Riparian vegetation Bare rocks www.hydrograph-model.ru
Motivation • variety of landscapes and dominated flow formation mechanisms • sparse hydrometeorological network in North-Eastern Russia and nearly absence of research stations • observed environmental changes impact differently in diverse landscapes - analysis of active layer formation and flow generation mechanisms in mountainous permafrost landscapes of the Kolyma Water Balance Station (North-Eastern Russia) - simulate thaw/freeze depths and runoff in homogenious landscape typical for North-Eastern Russia using the Hydrograph model - develop and verify unified approach for hydrological modelling in changing permafrost environments of North-East of Russia Objectives
Study area: Kolyma water-balance station • Mean air temperature is -11,40С • Mean annual precipitation 320 mm • Elevation ranges 800-1700 m • Variety of landscapes • Continuous permafrost with the thickness up to 400 m • Representative for the vast territories of Upper Kolyma River Basin
Scheme of the typical landscapes Bare rocks Bush tundra Sparse forest Larch forest
The Hydrograph model • Process-based (explicitlyincludes all processes) • Observable parameters, no calibration (can be obtained apriori) • Common input daily data (air temperature and moisture, precipitation) • Free of scale problem (from soil column to large basin) initially developed by Prof. YuryVinogradov www.hydrograph-model.ru
PhysicalgroundpropertiesthatdrivetheprocessesofactivelayerformationPhysicalgroundpropertiesthatdrivetheprocessesofactivelayerformation www.hydrograph-model.ru
Soilthaw/freezeprocessesandrunoffformationType 1 – peatysoilsandsurfaceflow Peaty soil is fully saturated with ice during snow melt. It thaws slowly and surface flow occurs. infiltration into soil surface flow observed soil thaw depth simulated soil thaw depth observed runoff simulated runoff snow water equivalent
Soilthaw/freezeprocessesandrunoffformationType 2 – rockystratumandsubsurfaceflow Snowmelt water is re-frozen in soil. Only subsurface flow is formed. liquid water content in soil ice content in soil simulated soil thaw depth observed runoff simulated runoff snow water equivalent
Stages of the soil thawing and spring flow formation (Bantsekina, 2003) Data of ice content in the rocky stratum don’t exist. According to literature each year in freshet period 40-60 mm ground ice are formed. Modelling results for 1969-1990 show 21-48 mm. flow dependence on air temperature
Observed and simulated thawing depths in bare rocks, bush tundra and larch forest, 1962 Bare rocks Bush tundra Larch forest
Runoff modelling atslopescale Yuzny Creek, area 0.27 km2 , sparse forest 1980: NS = 0.74 Severny Creek, area 0.33 km2, bush tundra 1978: NS = 0.86 1 – observed runoff, 2 – simulated runoff, 3 - precipitation www.hydrograph-model.ru
Runoffmodellingatslopeandsmallscale Morozova Creek area 0.63 km2, bare rocks 1979: NS = 0.79 Kontaktovy Creek, 21.2 km2, 1978, m3/s 1978: NS = 0.85 Landscape distribution: Bare rock – 32 % Bush tundra – 29 % Sparse forest – 21 % Larch forest – 18 % 1 – observed runoff, 2 – simulated runoff, 3 - precipitation
Conclusions • Hydrograph model proved its capability to successfully describe soil thawing and freezing, water and ice dynamics in rocky stratum in diverse landscapes based on relatively simple algorithms and observable parameters. • Good agreement between observed and simulated active layer depth and runoff is achieved for small watersheds of the KWBS • Developed set of model parameters which are systematized according to main landscapes of the Upper Kolyma River basin might be transferred to other basins without specific observations www.hydrograph-model.ru Semenova O., Lebedeva L., Vinogradov Yu., 2013 Simulation of subsurface heat and water dynamics, and runoff generation in mountainous permafrost conditions, in the Upper Kolyma River basin, Russia. Hydrogeology Journal vol. 21, iss. 1, 107 – 119. DOI:10.1007/s10040-012-0936-1 www.hydrograph-model.ru