1. 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

2. Variety of landscapes and complex process interactions
Bare rocks
Bush tundra
Deep active layer
Subsurface runoff
Shallow active layer, surface runoff
Larch forest
Riparian vegetation

3. Motivation Objectives
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

4. Study area: Kolyma water-balance station
Creek
Area, km2
Average (and maximum) elevation, m
Average (and maximum) slope, º
Area occupied by a certain landscape, %
Rocky talus
Mountain tundra
Sparse trees
Forest and bogs
Morozova
0.63
1370 (1700)
33 (50) 98 2
Severny
0.33
1020 (1300)
21 (40) 24 63 13
Yuzhny
0.27
985 (1100)
17 (30) 5 17 56 22
Kontaktovy
21.2
1070 (1700)
25 (50) 34 27 12
Mean air temperature is -11,40С
Mean annual precipitation 320 mm
Elevation ranges m
Variety of landscapes
Continuous permafrost with the thickness up to 400 m
Representative for the vast territories of Upper Kolyma River Basin

5. List of measurements conducted at KWBS

6. Scheme of the typical landscapes
Bare rocks
Bush tundra
Sparse forest
Larch forest

7. initially developed by Prof. Yury Vinogradov
The Hydrograph model
Process-based (explicitly includes 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. Yury Vinogradov

8. Physical ground properties that drive the processes of active layer formation
Moss and
lichen
Peat
Clay with
inclusion of rocks
Bedrock
Density, kg/m3
500
1720
2610
Porosity, % 90 80 55 35
Water holding capacity, % 60
20-40 13 7
Infiltration coefficient,
mm/min 10
0.0005
0.05-1
Heat capacity, J/(kg oC)
1930
840
750
Heat conductivity,
W/(m oC)
0.8
1.2
1.5
Wilting point, % 8
6-8 4
2-3

9. Soil thaw/freeze processes and runoff formation Type 1 – peaty soils and surface flow
Peaty soil is fully saturated with ice during snow melt. It thaws slowly and surface flow occurs.
observed runoff
simulated runoff
snow water equivalent
infiltration into soil
surface flow
observed soil thaw depth
simulated soil thaw depth

10. Soil thaw/freeze processes and runoff formation Type 2 – rocky stratum and subsurface flow
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

11. flow dependence on air temperature
Stages of the soil thawing and spring flow formation (Bantsekina, 2003)
flow dependence on air temperature
Data of ice content in the rocky stratum don’t exist. According to literature each year in freshet period mm ground ice are formed. Modelling results for show mm.

12. Observed and simulated thawing depths in bare rocks, bush tundra and larch forest, 1962

13. Runoff modelling at slope scale
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

14. Runoff modelling at slope and small scale
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

15. Conclusions www.hydrograph-model.ru
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
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: /s

16. Thank you for attention