Use Barriers to Harvest Run-off Water for Crops

Water management

Notes to broadcasters

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Run-off is the water that flows across the surface of the soil. It flows away because it is moving too fast to be absorbed into the soil. Farmers can construct barriers to slow and trap run-off water and use it for their crops. Barriers are structures such as grass strips, ridges and ditches, hedges, and tree rows. All these structure are built on the contour of the slope to prevent run-off.

In this script, Mrs. Gowri Banda, a fictional character, is interviewed about her use of ditches to catch run-off water and channel it to her crops. This script can be used in combination with Farm Radio Network Package 68, number 7 (Save time with rainwater harvesting), in which the same Mrs. Banda describes her experiments catching rainwater from her roof.

Script

Characters:

Host

Mrs. Gowri Banda:
innovative woman farmer

Host (Intro):
Welcome to our program today. And a special welcome to all the farmers who are listening. We have a question for you, and that is: how can we solve one of our most difficult problems – getting enough water to our crops? To help us answer this question, we’ve invited Mrs. Gowri Banda to the studio. Mrs. Banda has been experimenting with different methods of harvesting water for many years. You may remember her from our program a few months ago. Welcome back Mrs. Banda.

Mrs. Banda:
Thank you for having me.

Host
: Mrs. Banda, you are well known for your experiments in water harvesting. I recall that the last time you were with us we talked about your system to catch rain from your roof.

Mrs. Banda:
Yes – I was experimenting with different kinds of gutters to catch water from my roof. I used a number of materials to make the gutters. But I’ve taken many steps and made a lot of progress since then.

Host:
So, is it true that the water you captured from your roof didn’t meet your needs?

Mrs. Banda:
Well, it didn’t provide enough water for both my garden and my field crops. But it did serve as a model, and good example to help me design other water harvesting projects.

Host:
A model? That sounds interesting. Tell us a little more.

Mrs. Banda:
Well, I used gravity to catch water from a high place – my roof, and channel it to a lower place – my gutter, and then to the soil. I realized I could use gravity to do the same thing for me in the field.

Host
: But in the field, there is no gutter.

Mrs. Banda:
No, but I knew I could dig a structure that was like a gutter – a ditch.

Host:
So are you saying that your idea was to stop the water flowing so quickly downhill by digging a ditch across the slope?

Mrs. Banda:
Yes. If I stopped the water from moving so quickly – with the ditches – the water could slow down and soak into my soil.

Host:
And where did you dig these ditches?

Mrs. Banda:
I dug the ditches high up on the slope – above my coffee plot. My plan was to use the water from the ditches to irrigate the coffee plot below.

Host:
Okay. Let’s go over this again, so that our listeners can get a picture in their minds.

Mrs. Banda:
Of course. First, I dug two ditches on the contour – that is, across the slope of the hill. The ditches channeled water to another waterway that moved water gently down the slope – directly to my coffee plantation.

Host:
And did these ditches work as you hoped?

Mrs. Banda:
For a while my ditches worked well. They stopped the run-off water from rushing down the slope. But one day, after a very heavy rainfall, I noticed that my coffee plot was flooded with soil from the upper fields.

Host:
So soil from the upper slopes was still washing away.

Mrs. Banda:
Most certainly. I didn’t have enough ditches – and they were too far apart. I needed more ditches closer together down the slope to spread the water out.

Host:
So you needed more ditches – and ditches that were closer together.

Mrs. Banda:
Exactly. My sons and I went back to work and dug more ditches and ridges.

Host:
And did this work better?

Mrs. Banda:
Well, with more ditches across the slope, the run-off water was able to slow down, and go more directly to the crops that need it.

Host:
Mrs. Banda, we’re almost out of time. I’d like to thank you for coming here today and sharing your successful method for catching run-off water.

Mrs. Banda:
It was a pleasure to be here.

Host:
Today we learned from Mrs. Banda how to use ditches to trap and catch run-off water on sloping fields. Before I go, I’d like to congratulate Mrs. Banda for her innovative ideas and her willingness to adapt and improve her methods. That’s the number one secret of success!

Thanks for listening today. I’m your host, ________________.

– END –

Acknowledgements

  • Contributed by Jennifer Pittet, Thornbury, Ontario, Canada.
  • Reviewed by Chris Reij, International Cooperation Center, Vrije Universiteit, Amsterdam, The Netherlands.

Information sources

  • Barrow, Christopher J. Alternative Irrigation: The Promise of Runoff Agriculture. London: Earthscan Publications Ltd., 1999.
  • Carter, Mike. “How soil erosion happens.” Footsteps. June 1993.
  • Reij, Chris, and Ann Waters-Bayer, eds. Farmer Innovation in Africa: A Source of Inspiration for Agricultural Development. London: Earthscan Publications Ltd., 2001.