Stoplogs

Stoplogs are hydraulic engineering control elements that are used in floodgates to adjust the water level or flow rate in a river, canal, or reservoir. Stoplogs are sometimes confused with flashboards, as both elements are used in bulkhead or crest gates. Stoplogs are typically long rectangular timber beams or boards that are placed on top of each other and dropped into premade slots inside a weir, gate, or channel. Present day, the process of adding and removing stoplogs is not manual, but done with hydraulic stop log lifters and hoists. Since the height of the barrier can only be adjusted through the addition and removal of stoplogs, finding a lighter and stronger material other than wood or concrete became a more desirable choice. Other materials, including steel and composites, can be used as stoplogs as well. Stoplogs are designed to cut off or stop flow through a conduit.

Stoplogs are modular in nature, giving the operator of a gated structure the ability to control the water level in a channel by adding or removing individual stoplogs. A gate may make use of one or more logs. Each log is lowered horizontally into a space or bay between two grooved piers referred to as a stop log check. In larger gate structures, there will be multiple bays in which stoplogs can be placed to better control the flow rate through the structure.

Stoplogs are frequently used to temporarily block flow through a spillway or canal during routine maintenance. At other times stoplogs can be used over longer periods of times, such as when a field is flooded and stoplogs are being used in smaller gates in order to control the depth of water in fields. The logs may be left in and adjusted during the entire time that the field is submerged.

In most cases, the boards used are subjected to high flow conditions. As individual stoplogs begin to age they are replaced. Typically small amounts of water will leak between individual logs.

Stoplogs are typically used in structures where the removal, installation, and replacement of the logs is expected infreqeuently. When larger flows of water are passing through a stoplog gate, it can be difficult to remove or place individuals logs. Larger logs often require multiple people to position and lift the logs.

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Wikipedia