The Research Of Soil Erosion Characteristics Based On Slope Factor In Jinan Runoff Plot

The problem of soil and water loss in Shandong province is serious, which seriously restricts the sustainable development of local economy and society. Wide hill area, low cover degree of the vegetation forest land, the extensive economic development way, is the main cause of serious soil and water loss in Shandong province. As the capital of Shandong province, Jinan in the mountain between the Yellow River and the mountain plain ecotone, low-lying north, the southern mountain as one branch of Mount Tai is an important water source of Jinan groundwater and surface water, which is of great significance for Jinan environment and quality of life of residents. Because of the high mountains and steep slopes, the barren soil, low vegetation coverage, a large number of production and construction projects making great damage to vegetation and soil, and many other factors, the soil and water loss in southern mountainous area is serious. In order to have a full grasp of soil and water loss situation in Jinan, a systematic study on the process and mechanism of soil and water loss in typical soil and water loss region is urgently needed, which can provide scientific basis for the prevention and control of soil erosion and ecological environment in Jinan.On the basis of analyzing the soil erosion environment in southern mountainous area, this paper makes a full use of the measured data of runoff plot and artificial rainfall experimentation area of Jinan's Monitoring Experiment Station in 2014 and 2015, and systematically analyses the effect that slope factor makes to runoff and sediment yield on slope. It will provide theoretical support for analyzing the development of runoff and soil erosion under the condition of different natural factors in Jinan, as well as provide reliable basis for making preventive and controlling measure. The main conclusions are as follows:(1)The relationship between the runoff yield and the slope gradient:As the slope gradient increasing, at first the runoff yield increases gradually, and then it falls slightly, but it presents an increasing trend overall. The highest or second highest value of the runoff yield has appeared several times at about 20°, so 20° is the critical gradient.The greater the rainfall intensity, the bigger the runoff yield, under the same conditions. The yield of runoff has an increasing tendency as the slope gradient increasing on the whole, and the critical gradient is in the range of 15°~ 20°.The runoff rate speeds up as the slope gradient increasing. The longer the time of runoff, the more stable the runoff rate, the smaller the fluctuation amplitude of the runoff rate.The initial runoff time appears in advance as the slope gradient increasing. Soil crust is not conducive for water to penetrate, but good for the runoff. The new plowing soil is conducive for water to penetrate, but not good for the runoff.(2)The relation of the soil erosion amount and the slope:The variation trend of the soil erosion amount on slope with the slope gradient increasing is basically consistent with the runoff yield.But the critical gradient increases to the range of 20°~ 25°The soil erosion rate speeds up as the slope gradient increasing. The longer the time of soil erosion, the more stable the soil erosion rate, the smaller the fluctuation amplitude of the soil erosion rate.The sediment concentration increases as the slope gradient increasing. The longer the time of soil erosion, the more stable the sediment concentration, and the fluctuation amplitude of the sediment concentration decreasing gradually.(3)Comparison of measured soil erosion modulus and model simulation:The verification and analysis of soil erosion amount on different slope based on USLE, are proved that the difference between the actual measured data from the runoff plot and the artificial simulated rainfall experimentation area is not very large, and have higher reliability.(4)Under the condition of different slope, the relation of the runoff yield and the soil erosion amount:On the whole, with the increasing of the runoff yield,the growth rate of soil erosion amount is a gradual growth, but under the condition of early rainfall period or heavy rainfall, the relationship is not obvious.