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).
How do you calculate runoff volume?
- Take the dimensions of the footprint of your roof and convert them to inches. (So, a 50′ x 20′ roof is 600′′ x 240′′.)
- Multiply the roof dimensions by the number of inches of rainfall. (In this example, 600′′ x 240′′ x 1′′ = 144,000 cubic inches of water.)
How do you find the direct runoff of a hydrograph?
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 rainfall runoff volume?
- Take the dimensions of the footprint of your roof and convert them to inches. (So, a 50′ x 20′ roof is 600′′ x 240′′.)
- Multiply the roof dimensions by the number of inches of rainfall. (In this example, 600′′ x 240′′ x 1′′ = 144,000 cubic inches of water.)
What is a runoff hydrograph?
A runoff hydrograph represents the cumulative runoff resulted from surface and sub-surface (base flow) runoff . The surface runoff or direct runoff hydrograph is obtained from the total storm hydrograph by separating the base flow. ... Due to this reason the errors made in the base flow separation are taken as negligible.
What is mean by direct runoff?
Water that flows over the ground surface directly into streams, rivers, or lakes . Also called storm runoff.
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.
What is a runoff ratio?
Runoff ratio is the runoff for each watershed divided by the precipitation for that watershed . It is the proportion of rainfall that does not infiltrate and is not taken up by evapotranspiration, and thus ends up as runoff. ... These areas will have high runoff ratios.
What is the volume of runoff?
Runoff volume means the volume of water that runs off the site of a land-disturbing activity from a prescribed design storm . ... Runoff volume means the amount or quantity of stormwater that flows on the surface of the ground, as a result of precipitation, and expressed In cubic feet, acre feet or gallons.
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.
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:-
How do you make a runoff hydrograph?
- Step 1: Select Appropriate Precipitation Event. ...
- Step 2: Remove Baseflow Contribution. ...
- Step 3: Calculate Volume of Quick-Response Runoff ” ...
- Step 4: Determine Excess Precipitation Depth for the Basin. ...
- Step 5: Adjust The Quick-Response Hydrograph to Represent 1 Unit of Excess. ...
- Step 6: Determine Duration.
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 are the different types of runoff?
There are three major types of runoff depending on the source: surface flow, interflow, and base flow .
What is subsurface runoff?
Subsurface runoff is the water that infiltrates in the vadose zone (unsaturated zone
Is base flow a runoff?
Baseflow is the sustained or “fair-weather” runoff of prior precipitation that was stored temporarily in the watershed , plus the delayed subsurface runoff from the current storm. Some conceptual models of watershed processes account explicitly for this storage and for the subsurface movement.
