I have some experience with collecting rainwater in the tropics. Both for household use and for increasing success of tree plantings in semi-arid conditions.
Collecting rainwater from the roof of the house where it is to be used can be very practical in many areas. When living in the northwest corner of Tanzania 1988-89, we built a rainwater tank with a couple of refinements that worked well.
|On the left is the usual rainwater collection tank. The rain that hits the tank itself runs off the roof. The water that enters the tank goes directly to the bottom. When there´s not much water in the tank, there is no "head" (pressure) to send it to a tap of useful height.||On the right is the kind of tank we used. It collects even the rain that falls on the tank itself. The water stays at a high level until the upper tank is filled. This gives enough "head" to supply water even to a shower that is not too high, even when there is little water.|
To a Swedish description
of our use of this water tank
Till en beskrivning av vår användning av denna vattentank
The "Village Forest" tree planting project in Karatu (near Ngorongoro, Tanzania) included som expermental activities. One question was "How can the planting hole influence the survival of the planted trees?" (The number of surviving trees is more important than the the number that are planted.) For example a local Catholic Priest had very good survival of his trees, but each tree had a 1 meter deep and wide hole which is partially filled with compost and manure. These holes needed a lot of work compared to the ordinary 30*30cm holes, but the ordinary holes had a worse result regarding survival of the planted trees.
|I saw a description of an interesting idea called "microcatchments" in a book from VITA. Microcatchments are simply small ditches for catching and leading surace water into planting holes.|
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© Jeff Forssell our-tank.htm Last uppdate 2000-Aug-06