For example, if a rainfall of P1 inches occurs during a time interval of Δt, the total runoff hydrograph is P1 multiplied by the total unit hydrograph, which is the blue curve (PUH_1) in the figure below. If the rainfall stops after Δt , this is the direct runoff hydrograph.
How do you calculate direct runoff?
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.
What is a direct runoff hydrograph?
Direct runoff hydrograph resulting from a unit depth of excess rainfall occurring uniformly on a watershed at a constant rate for a specified duration . Unit pulse response function of a linear hydrologic system. Can be used to derive runoff from any excess rainfall on the watershed.
What is direct runoff?
Water that flows over the ground surface directly into streams, rivers, or lakes . Also called storm runoff.
How do you calculate runoff discharge?
The Rational Formula is expressed as Q = CiA where: Q =Peak rate of runoff in cubic feet per second C =Runoff coefficient
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. ... Glaciers, snow, and rain all contribute to this natural runoff.
How do you calculate hydrograph runoff?
The first step is to compute the total volume of direct runoff. To do this, add all direct runoff values, and multiply the sum of all the direct runoff flows by the time interval (in seconds) of the series as shown below. (convert cubic feet per second to cubic feet of volume).
What are the different types of runoff?
There are three major types of runoff depending on the source: surface flow, interflow, and base flow .
What are the components of runoff?
- Direct rainfall over the stream:-
- Surface runoff or overland flow: –
- Subsurface flow or interflow:–
- Base flow, groundwater flow or Dry weather flow:-
What is total runoff?
Runoff, in hydrology, quantity of water discharged in surface streams . ... The total runoff is equal to the total precipitation less the losses caused by evapotranspiration (loss to the atmosphere from soil surfaces and plant leaves), storage (as in temporary ponds), and other such abstractions.
How do we measure runoff?
Simple, straightforward methods of calculating runoff can tell you the amount of water that storms bring to the earth. 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.
What are the factors affecting runoff?
- Type of precipitation (rain, snow, sleet, etc.)
- Rainfall intensity.
- Rainfall amount.
- Rainfall duration.
- Distribution of rainfall over the drainage basin.
- Direction of storm movement.
- Precipitation that occurred earlier and resulting soil moisture.
What is peak runoff?
One of the key parameters in the design and analysis of soil and water conservation structures is the resulting peak runoff or the variations of runoff with time (hydrograph) at the watershed outlet. ... The maximum flow at outlet thus attained is called peak flow of runoff.
What is interflow runoff?
Interflow, also known as subsurface runoff is relatively rapid flow toward the stream channel that occurs below the surface . It occurs more rapidly than baseflow, but typically more slowly than surface runoff.
What is another word for runoff?
In this page you can discover 18 synonyms, antonyms, idiomatic expressions, and related words for runoff, like: flow , surplus water, surface-water, groundwater, rainfall, spring runoff, snowmelt, aquifer, ground-water, streamflow and run-off.
What do you mean of runoff?
(Entry 1 of 2) 1 : a final race, contest, or election to decide an earlier one that has not resulted in a decision in favor of any one competitor. 2 : the portion of precipitation on land that ultimately reaches streams often with dissolved or suspended material.
