O.M. Semenova State Hydrological Institute; Gidrotehproekt Ltd, St. Petersburg, Russia

1. Assessment of Runoff Engineering Characteristics in Conditions of the Shortage of Hydrometeorological Data in North-Eastern Russia O.M. Semenova State Hydrological Institute; Gidrotehproekt Ltd, St. Petersburg, Russia L.S. Lebedeva St. Petersburg State University; Nansen Centre, St.Petersburg, Russia I.N. Beldiman "Khotugu Oruster" (the North Rivers), Yakutsk, Russia Hydrograph Model Research Group St. Petersburg, Russia www.hydrograph-model.ru

2. Agenda • Tasks of geotechnical site investigations and construction in rich by natural resources North-East of Russia • Poor hydrometeorological network which was significantly diminished in the last 20 years • Observed environmental changes which impact differently in various permafrost landscapes • Permafrost as the factor governing hydrological processes Statistical approach based on extrapolation of observational data and currently used in design engineering practice is not reliable any more www.hydrograph-model.ru

3. Goal To develop unified approach (modelling tool) for assessment of design flood characteristics in changing environment which may be applied in various permafrost conditions Requirements to the model • Process-oriented deterministic model • Physically observable parameters with the possibility to estimate them a priori and systematize by typical landscapes • Ability to port parameters to ungauged watersheds without calibration www.hydrograph-model.ru

4. Research strategy Historical re-analysis Physically observable parameters Stochastic weather generator Deterministic hydrological model Series of daily meteorological data Series of simulated runoff Numerical evaluation of runoff characteristics in probabilistic mode Ensembles of climate projections www.hydrograph-model.ru

5. Variety of landscapes and complex process interactions Bush tundra Deep active layer, Subsurface runoff Larch forest Shallow active layer, surface runoff Riparian vegetation Bare rocks www.hydrograph-model.ru

6. Common approaches for permafrost hydrology modelling Large scale hydrological models (LSS) integrated into climate modelling systems Development of refined physically-based models of specific processes Crude representation of processes without their specification in different conditions OR Calibration-based, require specific data Applicable in very limited cases The output values for runoff and variable states are averaged by large territories Both not reliable in assessment of runoff characteristics www.hydrograph-model.ru

7. 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

8. Typical landscapes Soil horizons:

9. PhysicalpropertiesofthesoilsdrivingtheprocessesofactivelayerformationPhysicalpropertiesofthesoilsdrivingtheprocessesofactivelayerformation www.hydrograph-model.ru

10. Results of modellingactivelayerdynamics Simulated (pink) and observed (black) thawing depths in the larch forest site, m simulated observed Simulated (green) and observed (black) thawing depths in the bare rock site, m simulated observed

11. Resultsofrunoff modelling attheKolymawater-balance stationwatersheds Yuzhny Creek, 0.27 km2, 1978, m3/s Sparse forest Severny Creek, 0.33 km2, 1979, m3/s Bush tundra Гидрографы на малых водосборах и картинки www.hydrograph-model.ru

12. Results of runoff modelling at the Kolyma water-balance station watersheds Morozova Creek, 0.63 km2, 1977, m3/s Bare rock Kontaktovy Creek, 21.2 km2, 1978, m3/s Landscape distribution: Bare rock – 32 % Bush tundra – 29 % Sparse forest – 21 % Larch forest – 18 %

13. Verification of the modelling results on poorly studied basins www.hydrograph-model.ru

14. Resultsofrunoff modelling atpoorlygaugedbasins The Ayan-Yuryakh river, 9560 км2, 1978-1979. The Tenke river, 1820 км2, 1978-1979. Mountainous relief and absence of meteorological stations. Input data were interpolated from stations located outside the basin www.hydrograph-model.ru

15. Extrapolation of observed runoff series with simulations using historical meteorological data Detrin river, 5630 км2, 1978-1979 Two meteostations within basin The Ayan-Yuryakh river, 9560 км2. Distribution curves of maximum discharges: Observed 1977-1984 Simulated 1957-1984 simulated observed www.hydrograph-model.ru

16. Estimation of maximum runoff distribution curves using stochastic weather generator The Tenke River basin, 2.2 km from the mouth of the Nilkoba River (1820 km2) 1 – observed; 2 – simulated on the basis of available historical data; 3 - the 1000-year-long series obtained on the basis of DS-modeling www.hydrograph-model.ru

17. Conclusions • The Hydrograph Model demonstrates adequate representation of permafrost processes in terms of active layer and runoff dynamics • 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 may be successfully transferred to other basins without specific observations • The Hydrograph model may be applied as a practical tool to estimate runoff characteristics using any source of meteorological data such as historical observations, re-analysis, future climate model projections www.hydrograph-model.ru www.hydrograph-model.ru

18. Acknowledgements The authors acknowledge the support of the TICOP’s organizers, sponsors and PYRN for the provided opportunity to attend the Conference. Thank you for attention! www.hydrograph-model.ru www.hydrograph-model.ru