A hydraulic drop is a term used to describe a quick change that occurs in the depth of a channel of water. When a drop of this type takes place, the depth goes from a relatively high stage to one that is noticeable lower. The change may be due to shifts in the slope of the channel itself or may be artificially created by the use of construction that seeks to control the flow of water through a channel.
The idea of a hydraulic drop is the opposite of what is known as a hydraulic jump. A jump occurs when the depth of the water in the channel goes from a relatively low point or stage to one that is noticeably higher. As with the drop, the jump may be due to a natural change in the slope of the channel, or have to do with manual attempts to impact the water level within the channel.
Along with a natural change in the channel slope, a hydraulic drop may be created by controlling the discharge of water into the channel. This can be managed using a series of locks to cause the water level to lower when needed. The same general process can also be used to create a jump if there is a need to increase that water level. One benefit of this type of system is that it is easier to control the depth of the waterway so that the degree of flooding occurring during a rainy season is kept to a minimum. At the same time, this approach can also be used to release more water into the waterway during dry periods, effectively benefiting anyone who relies on the ongoing flow in the channel as a source of water for crops or even as a means of conveying goods from one location to another.
Assessing the potential within a channel flow for hydraulic drop as well as hydraulic jump is crucial if the goal is to construct locks or other devices to help control that flow. By identifying natural slopes within the channel, it is easier to determine where to place the locks and even how many locks to construct in order to achieve the desired level of control over the hydraulic drop along with the jump. Along with depth, considering the average speed of the current during different seasons will also make it easier to determine the best ways to go about controlling channel flow and making the best possible use of the waterway.