# How Much Rain Falls On A Roof?

## How do I calculate the square footage of my roof?

Total Square Footage Find this number by measuring the length and width of each plane on the roof (including dormers) then multiplying length times width.

To find your roof’s total square footage, simply add the square footage of each of the planes together.

For example, this shed roof has one roof plane..

## How much water is in an inch of rain?

Water Equivalents (approximate) One inch of rain falling on 1 acre of ground is equal to about 27,154 gallons and weighs about 113 tons. An inch of snow falling evenly on 1 acre of ground is equivalent to about 2,715 gallons of water.

## How long does it take to water 1 inch?

To determine how long you need to water to get one inch, place a plastic container in your yard and set a timer. On average, it will take 30 minutes to get a half inch of water. So, 20 minutes, three times per week will give a lawn about an inch of water. This formula works best with healthy, well-cultivated soil.

## How do you convert inches of rain to gallons?

The result is that one inch of rain yields 4,014,489,600 cubic inches of water per square mile. Divide the result by 231 cubic inches per gallon, and obtain the result of 17,378,743 gallons per square mile for an inch of rainfall.

## How do you calculate drainage area?

Drainage areas are determined by tracing all of the water bodies flowing into the stream or river upstream of the proposed site. A divide or ridge surrounds every drainage basin. A divide is defined as “the line of separation or dividing ridge marking the boundary between two drainage systems.”

## What is duration of rainfall?

Due to the historic practice of reading rain gauges on a daily basis, most rainfall distributions use a 24-hour duration. Although shorter durations are sometimes used for special purposes (such as water quality events), most studies are performed with a 24-hour nested synthetic storm.

## How do you calculate rainfall on a roof?

How Much Rain Water Runs Off Your Roof?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. … Divide by 231 to get the number of gallons (because 1 gallon = 231 cubic inches).

## How do you calculate 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 is total runoff?

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.

## Is 1 to 2 inches of rain a lot?

Rainfall rate is generally described as light, moderate or heavy. Light rainfall is considered less than 0.10 inches of rain per hour. Moderate rainfall measures 0.10 to 0.30 inches of rain per hour. Heavy rainfall is more than 0.30 inches of rain per hour.

## How many inches of rain does it take to fill a 5 gallon bucket?

2 inches5 gallons is about 2/3 of a cubic foot, and 2 inches is 1/6 of a foot. 2/3 cubic feet divided by 1/6 feet is 4 square feet, so 2 inches of rain falling over an area of 4 square feet is enough to fill a 5-gallon bucket.

## How do they measure rainfall DIY?

Instructions:Using a plastic disposable water bottle you can make a simple rain gauge. … 1-liter plastic water bottle. … Invert the top to make a funnel. … Using your ruler and pen, place a mark every 1/2 inch on the bottle. … An empty plastic bottle, being light, will fall down or fly away in the slightest breeze.

## How do you calculate roof catchment area?

Calculating your catchment capacity Roughly speaking, 1 millimetre of rain over 1 square metre of roof equals 1 litre of water. This capacity can be calculated using the following formula: Annual rainfall (in millimetres) x Roof surface area (in square metres) = Roof catchment capacity.

## How many gallons does it take to cover 1000 square feet?

Multiply the square footage to be watered by . 62 gallons or 1 inch of water per square foot. Example: 1,000 square feet x . 62 gallons = 620 gallons.

## How do you calculate rainfall over area?

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.

## How many gallons are in an inch of rain per square foot?

Every square foot of roof space collects . 6 gallons of water in a 1 inch rainfall.

## How much water will my roof catch?

To calculate how much rainwater can be harvested, multiply your rainfall (mm) by your roof surface area (m2) being used to catch rainwater. The resulting number represents how many litres of water you can expect can collect.

## How many inches of water are in a gallon?

Gallons to Cubic Inches Conversion 1 US gallon is equal to 231 cubic inches.

## How much surface area does a gallon of water cover?

Our rule of thumb is you get 6.4 square feet of coverage when applied at 1/4” thick or . 59 square meters. So 231 cubic inches of epoxy applied at 1/4” thick will yield 924 square inches of surface area which when divided by 144 square inches per square foot equates to the 6.4 square feet per US gallon.

## How do you calculate rain runoff?

3.7 Assessment of annual or seasonal runoff This is defined as the total runoff observed in a year (or season) divided by the total rainfall in the same year (or season).

## How is rain water calculated?

Simple Rainwater Harvesting Formula – For every 1” of rain and 1,000 square feet of impermeable surface (roof, driveway, etc), about 620 gallons are generated. Meaning, you can capture about . 62 gallons per sq ft. To figure out the square footage of a surface, multiply the width x length.