One inch equals 25.4 mm. In Europe and elsewhere, rainfall is measured in millimeters and usually it is considered to fall onto 1 square meter. If 1 mm rain accumulates on 1 m2 surface, you will get exactly 1 liter of water. So if you get an inch of rain on there, you get 25.4 liters of rainwater.
With a rainfall of 1 mm, every square metre receives 1 litre of rain water. A rainfall of 1 mm supplies 0.001 m3, or 1 litre of water to each square metre of the field. Thus 1 ha receives 10 000 litres.
Here's what you'll need to do:
- Measure the diameter of the bucket at the level of the rain.
- Measure the diameter of the bucket at the bottom in the same way.
- Calculate the average of the two diameters.
- Divide by two to find the average radius.
- Find the average volume of rain = Depth x radius x radius x 3.14.
State-wide averages of annual rainfall plus snowfall range from a high of 63.7 inches (1618 millimetres) in Hawaii to a low of 9.5 inches (241 millimetres) in Nevada. For the entire United States, excluding Hawaii and Alaska, the average amount of moisture falling as rain and snow is 30.21 inches (767 millimetres).
It doesn't matter because it is not the volume but the height of the water we measure. For example, on a yearly average, all oceans, lakes, outdoor swimming pools and rain gauges increase by nearly one meter!
The water falling into the rain gauge will be routed to one bucket by the funnel. Once that bucket is filled, usually after 0.2 mm of rain falls, it is designed to automatically tip, meaning that the other bucket will now be beneath the funnel.
Answered Dec 10, 2015. 1mm rainfall means every one square meter area is filled with the water of height 1mm. 1 square meter = 1000mm length ×1000mm breath. So 1mm rain means 1000mm length × 1000mm breath × 1mm height = 1litre of water.
10 mm rainfall means that if rainfall fell on a flat land surface , with no slope ,no evaporation, and no percolation of water I.e. water does not go underground, then the amount of rainfall would be 10 mm measured from the ground.
When you look at the numbers, it's surprising how much water you can collect every time it rains. Just a half inch of rain falling on a 1,000-square-foot roof will yield 300 gallons of water.
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 to collect.
Approximately 550 gallons of rainwater can be collected for every 1000 square feet of collection surface per inch of rain. To estimate amount collected in one year, take the square footage of your collection surface, divide by 1000, multiply by 550 and then multiply by the average annual rainfall for your 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.Most rain is perfectly safe to drink and may be even cleaner than the public water supply. Rainwater is only as clean as its container. Only rain that has fallen directly from the sky should be collected for drinking. Boiling and filtering rainwater will make it even safer to drink.
To calculate the minimum number of downpipes, divide the roof catchment area by the allowable maximum catchment per downpipe. To calculate the average catchment per downpipe, divide the roof catchment area by the number of downpipes.
This capacity can be calculated using the following formula: Annual rainfall (in millimetres) x Roof surface area (in square metres) = Roof catchment capacity. This is an important figure to understand so you can design a Rain Harvesting system and choose a tank size that will meet your water volume requirements.
Sizing a Catchment Area – The size of the catchment area or roof will determine how much rainwater that you can harvest. The area is based on the “footprint” of the roof, which can be calculated by finding the area of the building and adding the area of the roof's overhang.
Heavy rainfall is one of the most frequent and widespread severe weather hazards to affect New Zealand. It is defined as rainfall greater than 100 mm in 24 hours. Often, a significant amount of precipitation occurs in only a few hours, leading to severe flooding and landslide risk.
Slight rain: Less than 0.5 mm per hour. Moderate rain: Greater than 0.5 mm per hour, but less than 4.0 mm per hour. Heavy rain: Greater than 4 mm per hour, but less than 8 mm per hour. Very heavy rain: Greater than 8 mm per hour.
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.
Moderate rain: Greater than 0.5 mm per hour, but less than 4.0 mm per hour. Heavy rain: Greater than 4 mm per hour, but less than 8 mm per hour. Moderate shower: Greater than 2 mm, but less than 10 mm per hour. Heavy shower: Greater than 10 mm per hour, but less than 50 mm per hour.
A measure of the intensity of rainfall by calculating the amount of rain that would fall over a given interval of time if the rainfall intensity were constant over that time period. The rate is typically expressed in terms of length (depth) per unit time, for example, millimeters per hour, or inches per hour.
1mm rainfall means every one square meter area is filled with the water of height 1mm. So 1mm rain means 1000mm length × 1000mm breath × 1mm height = 1litre of water.
5 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.
I read somewhere, 2 inches = 2 gallon. Another article says 4-5 gallons per week in hot weather.
One inch of rain falling on 1 acre of ground is equal to about 27,154 gallons and weighs about 113 tons.
One gallon is 231 cubic inches, so an area of 231 square inches (roughly 23 inches x 10 inches) would hold one gallon of water if one inch of rain fell on it. That will depend on the surface, this rain amount collects on. Precipitation is measured either in mm, cm or inches.
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.
- Divide by 231 to get the number of gallons (because 1 gallon = 231 cubic inches).
| conversion result for two water volume vs. weight units: |
|---|
| From unit Symbol | Equals Result | To unit Symbol |
|---|
| 1 cubic inch of water in3 - cu in | = 0.0043 | US gallons of water gal |
Gallon to Square feet Calculator
| 1 gallon = | 0.2614 ft2 | 7.4805 gallon |
|---|
| 5 gallon = | 0.7645 ft2 | 83.6348 gallon |
| 6 gallon = | 0.8633 ft2 | 109.9407 gallon |
| 7 gallon = | 0.9567 ft2 | 138.5412 gallon |
| 8 gallon = | 1.0458 ft2 | 169.2648 gallon |
