The Lrgr Slope Factor Research On The Impact On Soil Erosion

Soil erosion,one of the several serious environmental problems, has haunted almost every corner of the world, and threatens human existence and social development. Soil erosion can result in land degradation and sediment deposition of a river, where soil erosion is connected with some natural factors and human activities.Yunnan is a mountainous province with high cliffs and deep valleys being seen in most places. The area of mountain region accounts 94% of total. This study was carried out in Yangbi. Yangbi is located at the mid-west of Yunnan Province. This region is typically full of resources, but underdeveloped. Because of these, it' s very helpful and meaningful to make the slope erosion study in this region.Through observation of runoff plots, analyzing the rainfall data and experimentation of soil, we introduction discuss the commonly mechanism and disciplinarian when happen slope erosion and the slope effect. These mostly results indicate that:(1) Erosion quantity is increase with slope steepness increase. From 25°, 30°to 35°, erosion quantity increases sharply: 162.65%,194.67%, in 2006; 157.16%,200.52% in 2007. From 35°to 40°, the increase intensity slow down: 194.67%,203.01% in 2006; 200.52%�'�200.87% in 2007. That means, there is limit in the increase intensity in the slope.(2)Pre-rainfall is the main effect that rainfall quantity could cause slope erosion. Erosion quantity is increase with rainfall intensity increase in most months during our observation period. For example, June & September in 2006, June & July in 2007. Slope erosion has a very closely relationship with rainfall intensity. (3) Soil erosion modulus is affected by slope steepness. We make soil erosion models with soil erosion modulus by Regression analysis. They are:M₂₀₀₆=53.84S^0.5297, M₂₀₀₇=74.758S^0.5336,M_均=64.301S^0.5312.(4) Based on the runoffplots of 25°, we made slope models with soil erosionmodulus by Regression analysis. It is:S=1.0905(θ/25)^1.5224.(5) In order to tetify the rationality and serviceability of S factor, using different ways (the soil classifying and classing standard and the Universal Soil Loss Equation) calculate the general loss volume in the sustain of 3S technology. The calculating results of the first method are: the loss volume is 4013625t, the average loss modulus is 4502. 76t/km²·a. And the results of the second method are: the loss volume is 4561842. 09t, the average loss modulus is 5438. 92t/km²·a. According to the local situation, use the second method, take the slope factor as the emphasis point, the estimate result is more reliable.The results of this study can be used to control soil loss, manage water and soil resources and evaluate soil erosion in Yangbi.