TAILIEUCHUNG - Erosion control in the tropics - Part 2

2 How to recognize erosion The previous chapter explained how erosion can impede development of large areas and even whole countries. Now an attempt will be made to illustrate the ways in which a farmer is confronted with the physical characteristics of erosion in the daily work. | 2 How to recognize erosion The previous chapter explained how erosion can impede development of large areas and even whole countries. Now an attempt will be made to illustrate the ways in which a farmer is confronted with the physical characteristics of erosion in the daily work. For this it is important to know how to recognize erosion in the field. Always keep the course of the erosion process in mind when looking for signs of erosion in the field. When a certain characteristic is noticed one should ask oneself just why it should occur in that particular place and why it has that appearance. More attention will then perhaps be given to the causes of erosion and the more subtle characteristics of erosion will be observed. An important rule of thumb is always to work upstream in the same way as when looking for water. So I am now standing in a gully where water has accumulated. Where did this water come from That is where erosion is likely to be. Up the hill I go again . Keep in mind though that there might always be other causes for the erosion which are not easily seen. Symptoms of erosion This section lists the symptoms that can arise from erosion. Of course several symptoms can manifest themselves at the same time. Gullies Gullies are deep fissures occurring in the soil and being caused by large quantities of water that have to be transported in a short time. Gullies are sometimes many meters deep see figure 1 . Developing gully A developing gully is less deep than a gully. If a number of these gullies are more or less parallel and close together then a whole gullysystem has formed. 10 Erosion control in the tropics Rills Rills are fissures in the soil that resemble a small gully to about 30 cm deep . A rill may run into a gully. A system is formed which tends to expand in an upslope direction. Bad lands A bad land is an area being made inaccessible by a very close system of gullies. This is especially a problem when using agricultural machines. Figure 1 .

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