Water Lbs Per Cubic Foot

H2o Measurement Units and Conversion Factors

By Salah Taghvaeian

Jump To:

Water Measurement Units
Volume Units
Catamenia Units
Conversion Factors
Using Conversion Tabular array
Conversion between English and Metric Units

Irrigation h2o management begins with knowing the quantity of water available. The purpose of this publication is to provide basic data on water measurement units and convenient conversion factors. Sometimes 1 will want to know simply the volume of water used; while, at other times one will desire to know the rate of flow. Conversion factors simplify changing from one unit of measurement to some other.

Water Measurement Units

At that place are 2 conditions under which h2o is measured—water at rest and water in motion. Water at balance is measured in units of book. Water in motion is measured in units of menses— unit of volume for a convenient fourth dimension unit. It is of import that the difference between a unit of volume and a unit of flow be kept in mind.

Volume Units

H2o at rest; i.due east., ponds, lakes, reservoirs, and in the soil, is measured in units of volume — gallon, cubic pes, acre-inch, and acre-foot.

Cubic Foot – The volume of water that would be held in a container i foot wide by one foot long by one human foot deep.
Acre-lnch – The volume of water that would comprehend one acre (43,560 foursquare feet) i inch deep.
Acre-Pes – The volume of water that would cover one acre one human foot deep.

Menstruation Units

H2o in move; i.e., flowing in streams, canals, pipelines, and ditches, is measured in units of volume per unit of fourth dimension—gallons per infinitesimal (gpm), cubic feet per 2nd (cfs), acre-inches per hr and acre feet per mean solar day. Cubic feet per second, sometimes written second-feet (sec. ft. or cusec) is nigh usually used for measuring menstruation of irrigation water moving by gravity from streams and reservoirs. Gallons per minute is almost commonly used for measuring flow from pumps.

Cubic foot per second – The quantity of water equivalent to a stream ane foot wide by 1 foot deep flowing with a velocity of one foot per second.

Gallon per minute – The quantity of h2o equivalent to a stream which volition fill up a gallon measure once each minute.

A flow of ane cfs is approximately equal to either 450 gpm, ane acre-inch per hour, or two acre-feet per 24-hour interval (24 hours).

Conversion Factors

The following equivalents are useful for converting from one unit to another and for calculating volumes from flow units.

Volume Units
Ane gallon
= 231 cubic inches
= 0.13368 cubic foot weighs approximately viii.33 pounds

One cubic human foot
= 1,728 cubic inches
= 7.481 gallons (seven.5 for ordinary calculations) weights 62.four pounds (62.five for ordinary calculations)

One acre-inch
= iii,630 cubic feet
= 27,154 gallons (27,200 for ordinary calculations)
= 1/12 acre-foot weighs approximately 113.one tons

One acre-foot
= 43,560 cubic anxiety
= 325,851 gallons
= 12 acre-inches weighs approximately 1,357 tons

Flow Units
One gallon per minute
= 0.00223 (approximately one/450 ) cubic foot per second
= 0.00221 acre-inch per hour
= 0.00442 acre-foot per (24 hour) day
= 1 acre-inch in 452.vi hours (450 for ordinary calculations)
= ane acre-foot in 226.3 days

One cubic foot per second
= 448.83 gallons per infinitesimal (450 for ordinary calculations)
= 1 acre-inch in ane 60 minutes and 30 seconds (1 60 minutes for ordinary calculations)
= 1 acre-foot in 12 hours and vi minutes (12 hours for ordinary calculations)
= i.984 acre-feet per (24 hours) day (2 acre-feet for ordinary calculations)

Million gallons per day (mgd)
= 694.4 gallons per minute (695 for ordinary calculations)
= 1.547 cubic feet per 2d (1.five for ordinary calculations)

Conversion Table.

To convert from: To: Multiply by:

Cubic-ft Gallons 7.v
Acre-in Cubic-ft three,630
Acre-ft Cubic-ft 43,560
Acre-ft Acre-in 12
cfs gpm 450
Acre-in per hour cfs 1
Acre-ft per 60 minutes cfs 12

Conversion from gpm to Acre-in for different water application durations.

Figure i. Conversion from gpm to Acre-in for different h2o application durations.

Conversion from gpm to Acre-feet for different water application durations.

Figure 2. Conversion from gpm to Acre-feet for unlike water application durations.

Using Conversion Table

To convert from the units in the first cavalcade to units in the second column multiply the value in the get-go unit of measurement by the gene provided in the 3rd column. To become in opposite direction and convert from the units in the second column to units in the first column only divide by the number in the third column.

The higher up tabular array can exist also used to convert from a flow unit of measurement to a volume unit and vice-versa, or to gauge the operating hours required to deliver a desired volume of water. The following examples and graphs provide a amend understanding on how such conversions can be carried out.

Example 1. The boilerplate daily crop h2o use during the month of June was 0.45 inches at a 60-acre corn field in Oklahoma Panhandle. What is the total volume of water used up by this field in June?

Step i. The total depth of water employ during June was 0.45 × 30 (days) = thirteen.v inches.
Stride two. The total book of water utilise was 13.5 × 60 (acres) = 810 acre-in.
Step 3. This book is equal to ii,940,300 cubic-ft (row ii in conversion table) or 22,052,250 gallons (row i in conversion table).

Example 2. How many hours a well yielding 400 gpm should operate to fill an irrigation swimming that is 150 ft long, 100 ft broad, and 10 ft deep?

Pace 1. The volume of this pond is 150 × 100 × 10 = 150,000 cubic-ft. This volume is equal to 1,125,000 gallons (row 1 in conversion table).
Step two. A well with 400 gpm should operate two,813 minutes (1,125,000 ÷ 400) to fill the swimming. This period of fourth dimension is equal to about 47 hours (two days).
* In this example the seepage from the pond is ignored. Longer times will be required depending on the magnitude of seepage.

Instance three. What would exist the volume of practical water if a well yielding 700 gpm operates for 24 hours?

Using conversion table:
Stride 3. Look at row 5 in conversion table. We want to catechumen gpm to cfs (moving from right to left in table), thus nosotros divide 700 gpm by 450, obtaining 1.55 cfs.
Step 4. Based on row six in conversion table, 1.55 cfs is equal to ane.0 acre-in per each hour of water application.
Step 5. If the well operates for 24 hours, the total volume of applied h2o will be 1.55 × 24 = 37 acre-inch or most 3 acre-feet.

Using conversion graphs:
Step 1. The volume of iii acre-feet can exist read from graph two, knowing the well capacity (700 gpm) and duration of functioning (24 60 minutes).

Example 4. How many cubic anxiety per second are required to make a 4 inch gross application on xl acres of land in 72 hours?

Using conversion table:
Pace ane. The full required volume of h2o is 4 × 40 = 160 acre-inch.
Step ii. Applying this amount during a 72-hr period requires a flow rate of 160 ÷ 72 = 2.22 acre-in per hour.
Step 3. Based on row 6 in the conversion tabular array, a flow rate of ii.22 acre-inch per hour is equal to the same corporeality in cfs (ii.22).

Using conversion graphs:
Step 1. The total volume of 160 acre-in is equal to 13.33 acre-anxiety (row iv in conversion table).
Step 2. Based on graph 2, applying this amount of water during a 72 60 minutes catamenia requires i,000 gpm.
Step 3. 1,000 gpm is equal to 2.22 cfs (1,000 ÷ 450 = 2.22, row 5 in conversion table).

Conversion betwixt English language and Metric Units

Agricultural producers in many parts of the world use Metric (too called SI) units in their routine water measurements. The virtually commonly-used book units in Metric organization include liter, cubic meter, and hectare-millimeter, while common flow units are liter per minute (lpm) and cubic meter per second (cms). The post-obit conversion table tin can be used to convert between English language and Metric units.

Irrigation water management does begin with knowing how much water is available and involves some arithmetic. The most common mistake when working with water measurement units is to accidentally substitute one period unit or volume unit for some other without proper conversion. Usually the final reply appears manifestly wrong; withal, this is non always truthful. When checking your arithmetics, likewise check the measurement unit to see they are correct.

English/Metric Conversion Tabular array.

To convert from: To: Multiply past:

Gallons Liters 3.8
Cubic-meter Cubic-ft 35.iii
Cubic-ft Liters 28.three
Acre-in Hectare-mm x.3
gpm lpm 3.8
cfs lpm 1700
cms cfs 35.3

Saleh Taghvaeian
Assistant Extension Specialist

Was this information helpful?

YESNO