Numerical modelling of hydro, thermal and ice dynamics with application to Teletskoye Lake, Altai Republic, Russia

04-11-2014, Delft

ПИВ

Erik De Goede Deltares

Delft, the Netherlands

Konstantin Koshelev IWEP SB RAS Barnaul, Russia

Content

1. Teletskoye Lake as a case study 2. Numerical results 3. Resume 4. Conclusion

Introduction

In terms of climate change and increasing human pressure on water bodies and their watersheds urgent task is to improve water and environmental monitoring of the environment.

One of direction of solving the problem is to develop mathematical models of hydrological and physico-chemical processes for assessing and predicting the state of ecosystems in large lakes and reservoirs.

This requires the implementation of the correct setting of simulation (specified description of effective turbulent exchange, the formation of density stratification (thermocline and thermal bar), density flows, seiche fluctuations, etc.

A case study

Телецкое озеро

length – 78 км; maximum width – 5,2 км; average width– 2,9 км; maximum depth- 323 м; average depth – 174 м; volume – 41,1 км3; external water exchange- 5,3 years; 70 permanent and 150 temporary inflows; low water temperature during the year; low salinity water– 57-110 µS/см.

Teletskoye Lake as a case study

For the development of methods for mathematical modeling of deep stratified reservoirs, we experimentally and theoretically studied the thermal and gas regimes in Teletskoye Lake - a unique natural reservoir in the south of Western Siberia.

The Teletskoye Lake ecosystem is complex and has been studied in many major national and international research programs.

In the 90’s Teletskoye Lake was considered as one of the

reservoirs analog of the designed Katun reservoir in the environmental assessment study of the Katun hydroelectric power plants project. A number of 1DV-models for physical and chemical processes in deep stratified reservoirs have been developed in IWEP SB RAS (Zinoviev A.T.).

Visual form of Teletskoye Lake basin DEM

To simulate the physical and chemical processes in Teletskoye Lake, data on the morphometric characteristics of its basin are required

On the basis of the field data

in a GIS project "Teletskoye Lake" the digital elevation model (DEM) of the lake basin was built (Marusin K.V.)

Numerical results A special version of Delft3D

The sea-ice module in Delft3D, which is a flexible integrated modelling suite for hydrothermodynamics, morphology (waves, water quality) and interactions between these processes. (Erik De Goede)

The state equation in which density is a function of temperature, salinity and pressure. TEOS-10 and the Chen-Millero empirical formulas are implemented.

Other important Delft3D parameters

Z-model with 60-80 layers, k-e turbulence model, vertical eddy viscosity/diffusivity

Ocean heat flux model, Secchi depth Weather data Albedo of ice/snow

Typical velocity magnitude

Comparison of calculated and measured* temperature distribution along the vertical direction in the deepest point of the Teletskoye Lake 25.07.2013

* Zinoviev A.T., Dyachenko A.V.

Comparison of calculated and measured* temperature distribution along the vertical direction in the deepest point of the Teletskoye Lake 29.08.2013

* Zinoviev A.T., Dyachenko A.V.

Comparison of calculated and measured* temperature distribution along the vertical direction in the deepest point of the Teletskoye Lake 17.10.2013

* Zinoviev A.T., Dyachenko A.V.

Computed temperature on 13.03.2014

The typical density stratification for the summer

Density stratification for the autumn period

Density stratification for the autumn season. An example of an unstable stratification

Typical density stratification for the winter period

Typical density stratification for the spring period

Comparison of different approximations for effective back radiation

Tsurface=0 C, Relative humidity=50%, Cloud coverage=70%

Computed ice thickness during the coldest period

Computed ice thickness on 13.03.2014

Resume

The calculation results in the summer stable stratification period are in good agreement with the available measured data. The calculation results in the autumn unstable stratification period indicate that further work is needed to improve the model (turbulence?). Simulation of ice processes sets increased demands on the required field data. Most of the model parameters must be space and time varying. Although field data are at the moment not available in the right quantity and with the necessary precision, the implemented computer model has shown its efficiency to predict the growth and melting of ice on a deep lake.

Conclusion

A special version of Delft3D is used for 3D hydrothermodynamic modelling in combination with 2D ice dynamics modelling. Results of calculations for the Teletskoye lake are in satisfactory agreement with the available field data. It is shown that the density stratification has a huge impact on flow parameters and ice thickness on Lake Teletskoye. The work to improve the hydrothermodynamics model should continue, taking into account an integrated ice module. The data collection to refine the specific effects of the formation of density stratification of Teletskoye Lake should continue during different hydrological seasons and different weather conditions. It is important to exchange the experiences of such research on other large lakes in Russia and elsewhere in the world.

Thank you for your attention