Question: What Is Runoff Coefficient?

How do you calculate runoff volume?

For a given surface area such as a roof or yard, multiply the area by the inches of rainfall and divide by 231 to obtain the runoff in gallons.

The factor 231 comes from the fact that the volume of 1 gallon equals 231 cubic inches..

How is peak runoff calculated?

The Rational method predicts the peak runoff according to the formula: Q=CiA, where C is a runoff coefficient, i is the rainfall intensity, and A is the subcatchment area. This formula is applicable to US or metric evaluation, as long as consistent units are employed.

What is the process of runoff?

Runoff occurs when there is more water than land can absorb. The excess liquid flows across the surface of the land and into nearby creeks, streams, or ponds. Runoff can come from both natural processes and human activity. … Runoff also occurs naturally as soil is eroded and carried to various bodies of water.

What is runoff depth?

The volume of water that flows through a certain channel cross-section per unit of time is referred to as discharge. … The mean runoff depth at the measuring point in the receiving water results in the arithmetical mean of the values of the total runoff depth of all area units in the related catchment area.

What is runoff coefficient in hydrology?

Definition. Runoff coefficient is a dimensionless factor that is used to convert the rainfall amounts to runoff. It represents the integrated effect of catchment losses and hence depends upon the nature of land surface, slope, degree of saturation, and rainfall intensity.

What is runoff short answer?

Runoff can be described as the part of the water cycle that flows over land as surface water instead of being absorbed into groundwater or evaporating. Runoff is that part of the precipitation, snow melt, or irrigation water that appears in uncontrolled surface streams, rivers, drains, or sewers.

What are the types of runoff?

Types of Runoff There are three major types of runoff depending on the source: surface flow, interflow, and base flow. These were discussed in Module 101 and are ex- panded upon here. Surface Flow Surface flow is water that has remained on the surface and moves as overland or channel flow.

What is river runoff?

River runoff refers to all water that comes into a river water system from sources such as rainfall, snowmelt and groundwater.

What are the 2 types of runoff?

Runoff may be classified according to speed of appearance after rainfall or melting snow as direct runoff or base runoff, and according to source as surface runoff, storm interflow, or groundwater runoff. 2. The sum of total discharges described in (1), above, during a specified period of time.

How do you calculate the rainfall runoff coefficient?

As explained above, the runoff coefficient from an individual rainstorm is defined as runoff divided by the corresponding rainfall both expressed as depth over catchment area (mm): Actual measurements should be carried out until a representative range is obtained.

What is another word for runoff?

In this page you can discover 18 synonyms, antonyms, idiomatic expressions, and related words for runoff, like: flow, groundwater, rainfall, surplus water, spring runoff, snowmelt, siltation, aquifer, ground-water, surface-water and streamflow.

How do you calculate the runoff coefficient?

How to Calculate Runoff CoefficientThe Rational Method is used for areas less than 50 acres. … Find the appropriate values for each variable. … Calculate the value for “i.” This is a measurement of rainfall intensity. … Isolate and solve for “C.” Your altered equation should look like this: … Find a reputable runoff coefficient table (see Resources).More items…

What is rainfall runoff relationship?

the rainfall-runoff relationship for any rainstorm depends on the dynamic interaction between rain intensity, soil infiltration and surface storage. Runoff occurs whenever rain intensity exceeds the infiltration capacity of the soil, providing there are no physical obstructions to surface flow.

What is direct runoff?

Water that flows over the ground surface directly into streams, rivers, or lakes. Also called storm runoff.