Category: Rain Water

Slow the flow …. One Rock Dam

To slow the flow off water run off in drainage the use of One Rock Dam is very important. As we have seen the the post, the forces of water are extreme. By slowing the flow of the water we can drastically reduce the erosiveness of the the flow and capture the topsoil using the One Rock Dam. This earth works is not attempting to stop the flow , just slow it enough to capture the sediment and repeat the process over and over till the water is at a trickle down the hill.
One Rock dam is laid out approximately 12″ high and twice as long as it is wide.
example: 4 foot wide wash, the rocks would be laid 4 ft across and 8 ft long in the wash.
The steeper the wash the closer the dams.

Bill Zeedyk Structures

The Wyoming Game and Fish Department

Understanding New Mexico High Desert Rain Water Erosion Forces

Where to start with Land Restoration in a drainage landscape?

Have you every calculated the forces of water in a drainage channel?

Let’s start by understanding how much water and what forces it generates. When the monsoon rains come in the end of summer during July and August we invariably get ‘gully washers’ that dump more rain than the land can absorb. The clay soils are overwhelmed and sheet flow of water begins to wash into the ditches caring away the soil. This soil, while may seem like silt is actually the top soil of the aired land. We need to hold on to this soil and slow the flow of the heaviest rainfall to promote growth.
VOLUME:
So, how much rain falls on:
1 acre of land in a 1 inch rain? Believe it or not, 27,154 Gallons of water lands on the ground.
10 acres in 1 inch rain? 271,540 Gallons of water, oh my I had no idea.

Ok now we are starting to get a sense of the volume of water, what about the weight that will become the force of the water as we try to slow or stop the water?
MASS:
1 acre with 1″ of rain will weigh 226,600 pounds or 113 tons.
10 acres with 1″ rain will weigh 2,266,001 pounds or 1,133 tons.

Now you start to see why the flooding damage occurs.
How are we going to hold back that much water with such a heavy force behind it? In rural ranch land you are considering hundreds of acres draining into auroras. Its no wonder there is mass erosion.

Rock dam

containing topsoil in shallow drainage with rock dam