RECOGNITION OF EFFECTIVE FACTORS ON SOIL EROSION AND SEDIMENT YIELD

The vast variety of human activities had important ecological problems on natural ecosystems. Woodcutting and rangeland deterioration for increasing urban and agricultural lands without considering their suitability and potential has continued in the intervening years until there is little land left that has not suffered man-made degradation. Accelerated erosion is the result of two factors: improper management of productive soils and exploitation of marginal lands; both mean using lands without considering their suitability. The primary energy causing erosion by water is gravity, through falling precipitation and flow down the terrain slope. Raindrop splash and overland flow detach soil particles which are then transported down-slope by the kinetic energy transferred from the water flow to the sediment. The sorting action by erosion agents causes removal of a high proportion of the clay and humus from the soil and leaves the coarse sand and rock fragments behind. Most of the soil fertility is associated with clay and humus. These components also are important in microbial activity, soil structure, permeability, and water storage. Thus, an eroded soil is degraded chemically, physically and biologically. The eroded soil becomes sediment that covers bottomlands and manmade structures. Gullies, sand dunes, and other obvious signs of erosion are examples of using the lands without proper management. Deterioration in the quality of cropping and grazing land as a result of erosion reduces productivity and increases expenditure on fertilizers to maintain fertility. In extreme cases yields become so poor that land has to be taken out of cultivation. Erosion adds to the cost of producing food and other soil products and thereby increases the cost of living. Taking ruined land out of production places a greater load on the remaining land and drives up production costs. Implementing expensive erosion control practices also adds to production costs. Developing practical methods associated with improving the soil conservation and management fundamentals are necessary for reducing soil erosion. Integration of planning with soil erosion control and management are essential tools in resolving land degradation problems. In general strategic planning is a systematic approach that supports the management. It insures all the basics that lead to the definition of goals and determining of appropriate strategies of achieving to those goals of a specific organization. On this basis recognition of effective factors on soil erosion and sediment yield strategic plan is one of the fundamentals and goals in the watershed management and natural resources researches as an effective way for controlling soil erosion and land degradation.