On Delimitation of Soil and Water Loss,Erosion as well as Relevant Concepts

Soil and water loss, soil erosion, soil and water and so on are common concepts in discipline of soil and water and territorial management in mountainous district. But it may be said that explanations of these concepts were multifarious over a long time, even if regular teaching materials, dictionaries and popular reading materials were so. This state is very unfavorable to work of preventing and controlling soil and water loss in mountainous district. The author in paper has approached and analyzed process of soil erosion, connotation of soil and water loss, measure unit of soil erosion or loss amount and so on, appraised all sorts of present explanations of above-mentioned concepts at home and abroad. On basis of above-mentioned approach and appreciation, from fundamental objectives and special tasks of soil and water as well as gist and substance of The Law of Soil and Water Conservation (in China) , author in paper has delimited rationally basic concepts of soil and water loss, soil erosion, soil and water and so on. The main understandings and conclusions are as follows: 1. The substance of soil erosion is soil and water loss, expression of two concepts has somewhat difference, but both are same things in fact. Soil erosion leads inevitably to loss of soil and water at same time, i. e. loss of soil and water; on contrary, loss of soil (as well as corresponding loss of water) means soil has been eroded. 2. Loss of soil and water includes loss of soil and loss of water, both is always together lost. But its kernel is loss of soil, loss of soil means water is also lost inevitably. It is best illustration that (i. e. runaway of soil, water and nutrition) , which was summed up by Chinese agricultural producer on the farmland of three runaway, integrates loss of solid matter of soil with loss of soil water and soil nutrient organically. 3. Water loss in loss of soil and water, includes mainly loss of part of runoff that led to erosion and loss of soil water in districts of water erosion, but imply mainly loss of soil water in districts of wind erosion. In addition, it can include loss of water that was caused by evaporating unduly because of slacking in measures or lacking measures. 4. Soil and water loss is relative to certain space unit, which may be theoretically a certain spot, a piece of land, a small basin, a large basin, and even whole of land of earth within scope of human activities. But space unit of measuring soil and water (soil erosion) should be pieces of land, which show units of map composition of land use types on map. That is to say, it should be considered that soil has been lost, provided soil on a piece of land was eroded (detached and transported) and left piece of land. It can't say that soil has been lost only when soil had flowed into trunk stream or tributary of big river. 5. From of soil and water (or prevention and control of soil and water loss), of water is mainly: (1) to avert loss of water in soil by way of the of soil; (2) to do our possible to retain certain runoff and decrease certain evaporative loss by relevant soil and water measures , so that plants (or crops) can obtain relatively liberal water supply. This shows that measures of soil are also basic measures of conserving water. Three conservation (i. e. of soil, water and nutrition), which was summed up by Chinese agricultural producer in the farmland of three conservation, integrates of solid matter of soil with of soil water and soil nutrient, fundamental cause lies in their organic unity. 6. The kernel of soil and water should be prevention and control of soil erosion on pieces