help on figuring ditch depth

[dqdave1]

Since many wise people visit this forum; can anyone tell me the formula for how much surface area is drained by how deep a ditch is. Example; Ditch 3 feet deep will drain 6 feet of surface area or 6 feet deep will drain 12 feet of surface area. I know there is aformula, just do not know it.
Dave

 

[Renze]

I dont think there is a formula:

Over here in Holland, they have made many ditches they dug in the 60's and 70's , shallower and wider.
This was done to keep moisture in the dry and dusty summer, because the deeper the ditch, the more water can flow out of the soil and the ground water table will drop.
During the winter, the ditch is still wide enough to carry the amount of excess water.

This is on dry sand soil that lets through a lot of water. Common practice differs a lot depending on rainfall and soil type. there is no rule of thumb that applies to all soils and rainfall areas.

 

[Egon]

As stated there will be no answer. You will have to add a whole lot more information.

 

[charlz]

How you are going to maintain it comes into play as well. Does it need to be narrow enough to straddle with a tractor and re-plow on occasion? Will it be dug out with a hoe?

 

[dqdave1]

I am not doing any ditch digging now. This topic came up during some converstion. If you want to dry up an area with one ditch, how deep do you dig the ditch as the deeper you dig it, the more surface area will be efected by it. I thought there may be a formula or an average. I understand that different soils would effect results.

 

[EddieWalker]

Like the others have said, there are too many variables in your question. Some of the things that will affect the amount of water that you will drain are the types of surface that you have, how long the grass is, how many trees there are and the slope of the land. Steeper land with short grass will move allot of water very quickly. Flat land with lots of trees will hold the water and you will get very little runoff compared to the short grass.

Then there is the design of the ditch. If it's just narrow, it will create more erosion, but take up less land. If it's wide, the water will move slower and you will have less erosion.

I try to make my ditches as wide as possilbe. I want to be able to mow them without risking my life on a steep slope. From a distance, my ditches should look natural and blend in with the surround landscape. That means moving more dirt then a narrow ditch.

Usually I start out digging the ditch as shallow as I think I can get away with and then I see what happens after it rains. It usually takes me a few times to get it right by taking a little away until I get it right.

Eddie