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- Improving Water Management
By Professor Nils Nykvist
Managing the flow of water down slopes
It might even be said that the meager mountain slopes with bare rock or thin soil layers, which at most can be used for a meager grazing, are an important precondition for agriculture in many low-lying areas in the dry part of the tropics. The desert city of Marrakech in Morocco is a good example of this.
The increasing population growth in many areas has led to water consumption in the arable soils of the valleys that has become greater than the supply from the slopes. The depth to groundwater has therefore increased, which has forced farmers to drill deeper and deeper wells.
The farmer’s costs have increased so much that many prefer to collect the water in small ponds on hillsides and lead it down to the farming areas in the valleys. This method of water management could be developed considerably, which also should reduce the often disastrous floods that are common in dry tropical areas.
Where the soil is thick enough, the construction of soil terraces or bunds with cultivation of plants is the most common measure to decrease the soil erosion
, by reducing the amount of running water on the slopes and increasing the infiltration of water into the soil (Fig. 26).
Figure 26. Terraces to reduce soil erosion should start high up on the slopes, where the force of the running water is not so great. Java.
The threat of land degradation in the tropics was recognized as early as the 1930s by colonial administrations that initiated building of soil terraces and bunds to minimize runoff.
After the terraces and bunds had been constructed, mostly using heavy machines or tractors, and solemnly handed over to the farmers, the structures were not maintained by the farmers, because the terraces restricted their use of land. Soil conservation was looked upon by liberation movements as a symbol of colonial oppression.
The Kenyan model of soil conservation
The Kenyan government realized that the common methods of soil conservation were not suitable for small-scale farming in the high potential areas of Kenya. With funding from the Swedish International Development Authority (Sida), in 1974 the Kenyan Ministry of Agriculture, in cooperation with farmers, started a soil conservation project based only on simple tools such as hoes and spades .
Training and advice were given at all levels, and after ten years about 40,000 families were constructing terraces every year. The main reason for the successful soil conservation project was that the farmers became convinced of the importance of soil conservation and actively contributed to the project. Increases in income of 50–70% were obtained, which shows that investment in soil conservation pays off.
See the references
for this article.
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