8. Model validations
The most important property of any model is its ability to predict actual situations.
The most serious shortcomings of most of the spill models to date has been the lack of testing.
Testing the model should be part of the model creation.
In this section, number of comparisons between the calculations and specially conducted experiments and field exersises will be presented.
This section begins with a number of comparisons with reliable laboratory and field measurements of a velocity fields and free surface elevations in two- and three-dimensional sections of open channels and river courses.
The applications for spill exercises for real natural river conditions will follow next.
8.1 Free surface flows in open channels
The number of sub- and super-critical free-surface flows have been calculated. Different bed shapes and plane geometries have been considered. They include :
8.2 Flows and oil slicks in a scaled river sections
The next step in validation program was to compare the measured velocity distributions with calculated profiles for the typical river situations presented by down scaled hydraulic models.
The example which follows next is for the scaled section of River Amur of Russian Far East.
The picture presents the calculated vector velocity field and water currents visualised by stream lines. In most cases the overall agreement has proved to be good.
Water currents in a model of River Amur.
The number of oil slick movement studies have also been carried out for scaled river models.
The photos of oil slicks at different time moments favourably compared with the locations and shapes of predicted slicks.
The example of the comparison will be shown on the next panel.
The scaled model in question is again the River Amur section just presented for velocity fields.
8.3 Water currents in natural rivers
The considerable attention has been given for comparison model velocity fields with data of hydrological field measurements in real river conditions. Two examples illustrate rather typical comparisons.
The simulated contours of velocity vector magnitudes for three cross sections of the reach of the Volga River's branch Volozhka are shown in next panel. The model employed three dimensional BFC option.
The numbers in the contour fields represent the field measurements. Calculated velocity vectors are found to compare favorably with data obtained in the field for the conditions of summer flow in 1993.
Velocity magnitudes in Volozhka.
The two-dimensional shallow water option has been used to calculate the flow currents in the section of the Kiya River of West Siberia, see next panel , for the summer flow disharge of 1994. To simulate the highly varying depth, the coast line geometry, the presence of dams and islands shapes the BFC option is used in all directions.
The agreement between the field measurement of the velocity magnitudes and the predicted profiles is found to be very reasonable.
