What is runoff?

What Does runoff Mean

Draining is the act and consequence of draining : making something soggy lose the liquid or rushing the final drops of a fluid that remain in a container . The verb to drain comes from the Latin word excurrĕre .

For example: "When it rains so much in such a short time, it is impossible to achieve the runoff of the water found in the streets" , "To promote runoff, the provincial authorities will build a new canal " , "The waste blocked the conduit and therefore that made the runoff difficult ” .
It is also called runoff or runoff to the water that begins to flow when a channel or a reservoir overflows. The water, in this framework, moves along the surface, which can cause various inconveniences.

The characteristics of the runoff, in this sense, are linked to the type of soil , the slope and other factors. This surface runoff is given by the level of precipitation minus infiltration and surface retention.
The runoff begins when both the storage capacity of the surface and the interception power of the flora have been exhausted. From then on, the film of water that runs on the surface arises and erodes the soil, since it flows towards the lower levels.
It is important to mention that river runoff is considered part of the hydrological cycle , which encompasses the entire path that water takes from the moment it falls from the atmosphere until its return due to evaporation. In this cycle, runoff affects circulation. Although runoff is necessary to maintain the flow of lakes and rivers, its excess can be detrimental by erosion .
Delving deeper into the details of this phenomenon that is part of the hydrological cycle , we can say that the most decisive parameters in its appearance are the following: the intensity of precipitation, the infiltration capacity of the area in which it occurs, the characteristics hydraulic conditions and the hydraulic condition of the rock or soil in which it is impacted.
The first of the concepts just mentioned is the intensity of precipitation , which can be defined as the ratio that we obtain by dividing the height of precipitation by unit of time; This is generally calculated in millimeters per hour ( mm / hr ). On the other hand, we have the infiltration capacity , which refers to the maximum speed that the liquid has, in this case water, when it penetrates the surface.
By comparing these parameters, we find information about the processes that may take place depending on the situation. If we talk about the conditions in which the soil is found when precipitation occurs, we can distinguish several possibilities, which considerably affect runoff:

* if the precipitation has an intensity lower than the level of the infiltration capacity and the soil has an amount of humidity that does not reach its field capacity (that is, it does not fulfill the capacity that it can retain once it is saturated), the runoff it is not excessive, since the surface has the possibility of absorbing a large part of the water that precipitates on it;
* If the first condition of the previous point occurs but it usually has an amount of humidity close to or equal to its field capacity, then a percentage of the runoff becomes runoff on the surface, although with volumes of little concern;
* If the precipitation has an intensity greater than the infiltration capacity and the humidity does not reach the field capacity, the soil takes advantage of the humidity and very little water runs off;
* If the first condition of the previous point is met but the soil moisture equals or exceeds its field capacity , almost all the water from the precipitation will be transformed into runoff on the surface.

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