## How do you calculate rainfall runoff?

## How do you calculate rainfall runoff?

To calculate the runoff from any given rainfall:

- 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 the SCS runoff equation?**

The SCS Runoff equation is used with the SCS Unit Hydrograph method to turn rainfall into runoff. It is an empirical method that expresses how much runoff volume is generated by a certain volume of rainfall.

### What is NRCS method?

The NRCS method of estimating direct runoff from rainfall was developed by SCS hydrologists during the early 1950’s. The primary uses for such estimates are to establish safe limits for hydrologic design and to compare the effects of alternative conservation measures in a watershed.

**How do you find the runoff curve number?**

The weighted CN is calculated by taking the sum of each CN value multiplied by its fraction of the total subcatchment area. The sum is (usually) rounded to the nearest whole number, as described below. The rounded result is used for all calculations and reports.

## What are the methods of runoff estimation?

The curve number method (SCSâ€“CN, 1972) is an adaptable and widely used for runoff estimation. This method is important properties of the watershed, specifically soil permeability, land use and antecedent soil water conditions which take into consideration (Bansode et al.

**How do you calculate rainfall?**

Find the average volume of rain = Depth x radius x radius x 3.14. Find the area at the top of the bucket (this is the area over which the rain is collected). Divide the rainfall volume by this area to get the rainfall.

### What does SCS method stand for?

Soil Conservation Service

The SCS Runoff Curve Number method is developed by the United States Department of Agriculture (USDA) Soil Conservation Service (SCS) and is a method of estimating rainfall excess from rainfall (Hjelmfelt, 1991).

**What is NRCS curve number?**

The NRCS curve number is related to soil type, soil infiltration capability, land use, and the depth of the seasonal high water table. To account for different soils’ ability to infiltrate, NRCS has divided soils into four hydrologic soil groups (HSGs).

## How do you calculate rainfall intensity?

Rainfall intensities can be accurately measured by means of a continuously recording autographic rain gauge. It is also possible to time the length of individual rainstorms and to calculate the average intensities by dividing the measured rainfall depths by the corresponding duration of the storms.