Monday, October 11, 2010
My Work, Part Two
The Mozambican government built this concrete dam near the community of Marara a few years ago. It is gigantic, expensive, and, well, it doesn't exist anymore. We went out last week to assess what we could do with the remains. We can't do much, but I guess we can learn from what went wrong here. I listed a few things, but I'm hoping that some of you brainiacs out there can give me some insights here.
1) The first one is unbelievable, but according to the community members, the dam was constructed directly on top of the sand in the riverbed. They didn't excavate to bedrock before construction. So not only did it fail as soon as water started flowing under the dam, but the dam wouldn't have held water even if it stood. At best, it would have been a pretty concrete bridge across a shallow river.
2) The spillway is the portion of a dam that you build to allow water to leave the reservoir safely. Spillways are important for bigger floods because you don't want the river to leave the riverbed and flood neighboring areas. From what I could see, there wasn't much of a spillway on this dam. You can see a little notch at the top of the dam that I think served as the spillway, but I bet flood flows commonly exceed the capacity designed for in this notch. This dam probably would have caused major flooding in the area. So in a sense,the community is lucky the dam failed.
3) There is water in river late in the dry season. I'm not convinced the community would have benefited from a working dam, anyway. I'm no expert but if you asked me, the money would have been better spent working with the community to separate their water uses. In this picture, you can see a dog, cooking pots, children fetching water, and women doing laundry in the same stretch of river.
This is just overwhelming for me. And unfortunately, this is a common story of development work here in Africa. It makes you want to laugh, but mostly you don't know how to react. I sometimes swear, though I'm not proud of it (don't follow my example you FMCSF sunday school kids). But seeing this sure made me use some colorful language last week.