|Sustainable Management of Soil Resources in the Humid Tropics (UNU, 1995, 146 pages)|
|VII. Runoff management and erosion control|
High surface runoff and accelerated soil erosion are major degradative problems on newly cleared land. Immediately implementing appropriate erosion management techniques is therefore, essential. Accelerated erosion can be most severe in the very first season after land clearing (Lal, 1981a). Soil erosion is caused by raindrop impact surface sealing, and crust formation leading to high runoff rate and amount, high runoff velocity on long and undulating slopes, and low soil strength of structurally weak soils with high moisture content due to frequent rains. Effective erosion management lies in:
(a) preventing or minimizing the raindrop impact, through mulching and canopy cover;
(b) maintaining favorable soil structure for reducing crusting; (c) managing soil surface to enhance infiltration rate;
(d) reducing slope length to minimize runoff build-up; and
(e) disposing excess runoff safely through protected waterways and graded channels.
Based on these principles, erosion control measures are grouped into two broad categories: erosion preventive techniques and erosion control measures (Fig. 12).