August 3, 2007

The need for a Gabion

Here in Arivaca, AZ I had about 12-inches of rain in the past 30-days (July 3-August 3). In Last year during our monsoon season, I had just over 4-inches for the same time period.

My normally dry wash, flash-flooded about three times and removed about 1-foot of sand from the wash. As the picture to the left shows, my entry drive to my property crosses this wash. It's hard to see in the picture, but now my truck dips when crossing the wash.

Earlier in the year I was meaning to build a Gabion (a.k.a. check-dam) just downstream of where my driveway crosses the wash, but I've been busy with other projects like my cob studio.
But with the erosion to date and still a month to 6-weeks of monsoon season left, I decided to tackle the project. the goal for building this gabion is to allow the buildup of sand upstream of the gabion in order to make access across my driveway easier.

Gabions have other other benefits also: 1) They slow water down so it can percolate into the soil and recharge the aquafer. 2) Spread water out in bottomland areas to reduce erosion and soak soil for trees and other vegetation.

The next photo to the left was taken downsteam looking upstream. The truck indicates the crossing and the gabion will be constructed where the clump of grass is in the wash. The width of the wash at this location is about 8-feet.

The photo below shows the wash running following a thunderstorm during last year's monsoon season. The photo was taken looking upstream at the the driveway crossing.


Gabions said...

Gabions are nice. I like the way you made your gabion. I hope it will work very successful in many years. The gabion looks to good.

Andy said...

When I first stared, I was trying to protect a sloping road and the gabions filled up with material and went around taking the entire road with it.

I've been working on the lower road for years with the advice of Dave Seibert and Bill Zeedyk's book "A Good Road Lies Easy on the Land" (I can send you a pdf of it). I tried wire and rocks that eventually were overwhelmed by the flow, but not before enough material was deposited to make another "lift", this time with big rocks. I also put storm fence down flat with large rocks distributed over it so the flow would be broken up and slowed down. So far so good.

Also, Pima county highway maintenance guys and the DHS/Forest Service team gave me some tips about swales up stream and to keep flow below 10mph.That's the magic number I guess.