What needs to be done during the water - storage period of the air - shield gates in Shenyang?

Today, I will introduce in detail the precautions during the water - storage period of the air - shield gates in Shenyang. Friends who are interested can follow me and take a look.

During the water - storage period of the air - shield gates in Shenyang, at the basic cross - section, the water surface widens, the water level rises, the water - surface slope approaches 0, the cross - sectional area of the waterway increases, and the flow velocity decays sharply. The cross - section is basically in a stagnant - water state. However, when storing water, the water level at the basic cross - section keeps rising, and there should be a certain amount of flow passing through, but this part of the flow is very small. When using the 11 - point method with a low - speed current meter for flow measurement, it is shown that there is a weak flow velocity at some points in the upper water flow, and there is a weak flow velocity at very few points in the lower part, which proves that the lower part is stagnant water. In this case, if the conventional flow - measurement scheme (one - point method on the water surface or 0.6 - depth method) is used for measurement, it will surely lead to an over - estimation of the flow. Personally, it is recommended to use the 5 - point method or the 11 - point method for flow measurement. This can objectively ensure the correct vertical distribution of the flow velocity, eliminate the influence of the stagnant - water layer in the lower part, and obtain a more accurate flow rate.

During overflow, based on the principle of water flow continuity, a suitable temporary cross - section is selected for measurement at a specific distance from the basic cross - section where there is no addition of water from tributaries. During the water - storage period, the flow rate is no longer measured directly. Record the start time of water storage and the end time of water release. During this period, the flow passing through the basic cross - section is obtained by referring to the channel storage curve to find the change in water storage for discharge routing. The change in water storage is allocated over the time period from the start of water storage of the Shenyang air - shield gate to the end of water release to calculate the flow rate. This method requires knowledge of the start time of water storage and the end time of water release of the Shenyang air - shield gate, as well as the establishment of a channel storage curve and a water gauge on the dam.

To ensure the accuracy of flow measurement and water volume control, the original hydrological station measurement cross - section can be relocated, and hydrological measurement facilities can be constructed. The cross - section can be moved to an unaffected area upstream of the Shenyang air - shield gate or to a location downstream of the Shenyang air - shield gate for flow measurement. When moving it downstream, attention should be paid to the distance from the Shenyang air - shield gate. If the distance is too close, when the Shenyang air - shield gate releases water, the water flow changes sharply and the flow regime is unstable, which affects flow measurement and the safety of personnel and facilities. It should be set in a place where the water flow is stable.

This is all for the content introduced in this issue. I hope it is helpful to you.