## For optimal flood routing management on your dam

without any inflow calculations,

following dam safety principles

Play now# Frequently asked questions

## In “Game of Gates”, are there enough parameters to describe my dam and reservoir?

The proposed data set is simplified, easy and quick to implement. It will represent an approximate vision of a dam, broadly sufficient to simulate its reactions during a flood. Nevertheless, some differences may appear compared to the actual behavior observed.

The approximate representation of the reservoir is thus modeled by a polynomial equation, representing a reservoir with regular slopes. Thus, morphological singularities will not be represented. To limit this problem, we advise you to limit the modeling of the reservoir to the upper levels likely to cause manoeuvres in case of flood (minimum modeling level relatively close to the setpoint level).

The approximate representation of the reservoir is thus modeled by a polynomial equation, representing a reservoir with regular slopes. Thus, morphological singularities will not be represented. To limit this problem, we advise you to limit the modeling of the reservoir to the upper levels likely to cause manoeuvres in case of flood (minimum modeling level relatively close to the setpoint level).

## What are the definitions of the parameters to submit for the setup of the dam?

The parameters to enter are as follows:

• Setpoint: the target altitude, for the regulation of the water level

• Maximum level: this level is the maximum allowed during a flood. It must be higher than the setpoint. In case of an overtopping, an alert will be given during the game.

• Height of the dam: this is the physical height of the dam, taken between the maximum level and the toe of the dam. It is given in meters (for example: 742 as maximum level, foot of the dam at 638 => height of the dam will be 104m)

• Minimum modeling level: Defines the minimum water level considered in the model, and therefore the reservoir interval that will be taken into account during a simulation.

• The surface area of the reservoir at the setpoint level: it is expressed in m² and represents the surface area of the reservoir measured at the setpoint.

The verification relates to the form of the function of the surface area of the lake according to the chosen maximum and minimum levels.

• Setpoint: the target altitude, for the regulation of the water level

• Maximum level: this level is the maximum allowed during a flood. It must be higher than the setpoint. In case of an overtopping, an alert will be given during the game.

• Height of the dam: this is the physical height of the dam, taken between the maximum level and the toe of the dam. It is given in meters (for example: 742 as maximum level, foot of the dam at 638 => height of the dam will be 104m)

• Minimum modeling level: Defines the minimum water level considered in the model, and therefore the reservoir interval that will be taken into account during a simulation.

• The surface area of the reservoir at the setpoint level: it is expressed in m² and represents the surface area of the reservoir measured at the setpoint.

The verification relates to the form of the function of the surface area of the lake according to the chosen maximum and minimum levels.

## What are the definitions of the spillway categories?

Gated spillways: gated organs whose opening can be ordered during the flood.

Weirs: weirs or ungauged weirs, the flow rate of which will depend only on the level of retention (without intervention during the flood simulation).

Weirs: weirs or ungauged weirs, the flow rate of which will depend only on the level of retention (without intervention during the flood simulation).

## How are the flow values entered in the tables?

Both tables have two columns: water levels and maximum possible outflows of the evacuation organs of each category (gated spillways and weirs). The sum of possible flows of a group of organs of the same category is therefore considered.

The upper water level must be the maximum water level of the model, the lower water level will be the minimum water level of the model. The choice of intermediate levels is left open. It is advisable to specify the thresholds of the different evacuation organs, in order to delimit their working altitudes.

The upper water level must be the maximum water level of the model, the lower water level will be the minimum water level of the model. The choice of intermediate levels is left open. It is advisable to specify the thresholds of the different evacuation organs, in order to delimit their working altitudes.

## How is the outflow of generating units specified?

This value will be entered when launching a simulation. It will be the maximum possible value, which can be varied during a simulation.

## What is the influence of the shape of a flood hydrograph on dam management?

The faster and shorter a flood, the more it will correspond to a storm event. Its gradient can therefore be very high, but the duration of the flood will be limited. This type of flood will therefore have a significant impact on small surface area reservoirs.

On the other hand, a snow melting flood will have lower gradients, but may bring a larger volume over a longer period.

On the other hand, a snow melting flood will have lower gradients, but may bring a larger volume over a longer period.

## How to choose the manoeuvering period?

The manoeuvering period corresponds to the delay between two manoeuvres on the gated spillways. It will be chosen shorter to ensure more efficient level regulation, especially if the magnitude of the flood is significant relative to the lake surface. On the other hand, too frequent manoeuvres are difficult to achieve on-site, and can cause undesirable oscillations in the outflow. A compromise is therefore to be reached.

More frequent manoeuvres will thus be used for small reservoirs, and more inferquent manoeuvres for large ones.

The automatic choice made in the Linear Trajectory algorithm corresponds to this type of compromise.

More frequent manoeuvres will thus be used for small reservoirs, and more inferquent manoeuvres for large ones.

The automatic choice made in the Linear Trajectory algorithm corresponds to this type of compromise.

## How important is the initial water level?

Depending on the initial water level, a certain free volume will be available in the reservoir to store an incoming volume. This will result in a certain attenuation of the flood peak discharge, thanks to a gradual increase in the water level.

## How is the regulation law set up by the computer in the “Linear Trajectory” mode?

It is a standard law, set up automatically. It corresponds to an acceptable efficiency setting, which can in many cases be improved by appropriate studies.

In particular, it is possible to study differing manoeuvre frequencies, according to the value of the outflow. This makes it possible to adopt a slower manoeuvering frequency, better adapted to regular floods. During exceptional floods this frequency can de doubled in order to guarantee more precise management of the water level.

In particular, it is possible to study differing manoeuvre frequencies, according to the value of the outflow. This makes it possible to adopt a slower manoeuvering frequency, better adapted to regular floods. During exceptional floods this frequency can de doubled in order to guarantee more precise management of the water level.

## How are manoeuvres determined in Linear Trajectory mode?

The setup of the Linear Trajectory mode regulation function makes it possible to dispense with the calculation of the inflow to determine manoeuvres to be carried out on-site. The measurements of water level and its variation alone are sufficient.

As a result, the on-site operator can determine his manoeuvres at any time by a simple reading on a double-entry table (water level, variation of water level). This drastic simplification is very significant in insuring the best possible flood routing management, without requiring any special equipment.

In addition, the algorithm used by the Linear Trajectory mode satisfies all stability and robustness criteria for automatic linear systems. This type of regulation function is therefore compatible with full automatic flood routing by PLC.

As a result, the on-site operator can determine his manoeuvres at any time by a simple reading on a double-entry table (water level, variation of water level). This drastic simplification is very significant in insuring the best possible flood routing management, without requiring any special equipment.

In addition, the algorithm used by the Linear Trajectory mode satisfies all stability and robustness criteria for automatic linear systems. This type of regulation function is therefore compatible with full automatic flood routing by PLC.

## How to quit a simulation in progress?

You can select the "Finish Simulation" button. You will be able to visualise the summary of your flood routing management, compared to the computer simulation according to the "Linear trajectory" algorithm. Several comparison criteria will be proposed.

## Case of an imposed initial manoeuvre sequence at the beginning of a flood?

Many dams are subject to regulations requiring the implementation of initial dissuasive manoeuvres, so as to ensure the evacuation of the river bed before opening the spillways.

This option is not shown by "Game of Gates", for simplification purposes. Nevertheless, these manoeuvres could be added in a professional configuration, subject to a specific study.

This option is not shown by "Game of Gates", for simplification purposes. Nevertheless, these manoeuvres could be added in a professional configuration, subject to a specific study.

## How to setup a standby state before operating manoeuvres for flood routing management?

The consideration of standby states for flood management is not included in "Game of Gates", for simplification purposes.

The determination of the criteria to place the dam in standby state, followed by flood state, is nevertheless frequently considered for an industrial project. To this end, the use of special hydrological parameters (gradient coefficients Γ) enables the consideration of the flood's dynamics in order to calculate the various dam operation states.

The determination of the criteria to place the dam in standby state, followed by flood state, is nevertheless frequently considered for an industrial project. To this end, the use of special hydrological parameters (gradient coefficients Γ) enables the consideration of the flood's dynamics in order to calculate the various dam operation states.

## Does the Linear Trajectory flood routing function follow the same methodology throughout the flood?

Yes, the same tables can be used for any phase of the flood (start, peak of flood or recession). It also makes it possible to compensate for sudden variations in the outflow, following the tripping of a generating unit, for example.

## Does the setting of a regulation law in Linear Trajectory mode make it possible to guarantee the respect of the safety objectives during a flood?

The setting of a regulation law indeed makes it possible to respect the main safety objectives during a flood, and to quantify the results. To this end, based on the technical characteristics of the dam and its spillways and taking into account hydrological gradient coefficients, an analytical approach allows the deduction of an optimal parameterisation.

A precise study of these parameters can then guarantee the accuracy of regulation, the ratios of gradients and the water levels reached.

A precise study of these parameters can then guarantee the accuracy of regulation, the ratios of gradients and the water levels reached.