Development Project: Irrigation Dam for Dry Season Farming

5 Sep

This week I attended the commissioning of a new irrigation dam located about a half an hours drive West over bumpy dirt roads from Kpandai town.  The dam has been built to store water during the rainy season so that 20 acres of land can be dry season farmed (an acre equals 4,047m^2 – about the size of a football field). 

Here is a picture from the top of the earth dam with water filling up on one side and the current regular season crop of rice on the other.


The Agriculture Extension Agent (AEA) who I visited the dam with said that, with the higher market prices during the dry season when food is scarce, farmers might be able to clear 2,000GHC/acre/year growing something valuable like okra or onions.  For the entire 20 acres, this equates to 40,000GHC/year from their dry season crop, plus they would still have their regular season crop (rice this year). 

The project consists of an earthen dam with an impermeable key made of clay.  It was constructed primarily with a dozer.  There is a simple penstock consisting of a pipe inside a concrete box culvert to intake water from behind the dam.  From a main isolation valve, PVC piping branches off to 20 concrete box culvert water points – one per acre.  The idea is that during the dry season the farmers can open small isolation valves to fill up the box culverts and then water their vegetables using buckets filled from the culverts.

Here is a picture of one of the box culverts and another of the main isolation valve, which currently has a leaking flange (I could only see a gasket on one side of the valve).

DSC01063 DSC01066

Present at the commissioning was the Owner (Kpandai District Assembly), Contractor, Engineering Consultant from Accra, and myself and an AEA representing the Ministry of Food and Agriculture (MoFA).  It was really interesting to listen to the various stakeholders, as it reminded me a lot of my work at home.  The Owner complained that the Consultant didn’t spend enough time on site during the project.  The Consultant complained that the schedule had been extended by the Contractor and that the Owner had not allowed any extra money for resulting the extra supervision time.  The Contractor with his gold watch and gold tooth just grinned and agreed with everything (I got the impression he made out pretty well on the job).  

I asked the Consultant how much the project had cost and he said he recalled that it was about 300,000GHC (about C$240,000).  At 40,000GHC/year extra profit from dry season cropping, this yields a 7.5 year payback IF the dam is properly maintained and there are no major problems.  The Consultant said that, in his experience, farmer groups do not maintain facilities like this very well, thus the big IF.

The Consultant regularly gets involved in the project justification phase with the Government and Donors.  I had a really interesting conversation with him about how there is a low financial payback on this project, but a potentially high social payback resulting from improved dry-season food security, the ability to feed livestock in the dry season, encouragement of farmer group formation, flood control, etc…

Main risks:

  • Hopefully the Hydrologist from the Consulting team got the water volumes right, because the farmers might waste a lot of money on seeds, fertilizer, and other inputs if they run out of water too early and lose their crops.

  • It is a new farmer group that is working together to share the 20 acres.  I attended a meeting earlier in the week where they said they were having a problem getting everyone to share the work evenly.  So MoFA is going to have to do some work to strengthen this group to make sure that they share the land properly and work together to plan and save for dam maintenance.

  • Only about 0.5% of the Kpandai District farmland is currently irrigated.  Dry season farming represents a big change for farmers, so hopefully they will have the time and resources that are required.  Fortunately this dam is located not far from the Oti river, where some farmers are already practicing dry season farming using river water, so there are some good examples nearby.

  • Land is actually plentiful in the Kpandai District and most farmers are used to wearing out their soil after a few years and then moving to new fertile land.  That’s obviously not going to be possible in this case, as they certainly aren’t going to move the dam, so the Farmers are going to have to learn to manage this land more conscientiously (i.e. crop rotation, better application of fertilizer, etc…).  More work for MoFA.

This is very much a project that is still underway.  I would say that was design and construction was the easy part and the more risky and challenging work lies ahead.

Based on what you have read, can you think of any other potential risks?  What about ideas to help ensure the project is successful?  

One Response to “Development Project: Irrigation Dam for Dry Season Farming”

  1. Gary Watson September 6, 2010 at 3:28 am #

    A risk I see is that areas in the dam and behind, that are not lined with clay, may lose a lot of surface water to groundwater. If that is an issue a cheap fix is a plastic liner, but it would probably be difficult to get there. Very interesting work!

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