Research On Erosive Rainfall And Characteristics Of Yellow Soil Slop Erosion In The Karst Area Of Guizhou Province

Two typical small watershed of the yellow soil distribution area are used as the study area in this paper. Rainfall, rainfall intensity, runoff and sediment yield characteristic value have been record through the observed experiment by meteorological station and different land use type runoff plots in the last five years. Precipitation features、rainfall erosive agent and erosive rainfall standard、feature of runoff and sediment yield and the relationship between runoff and sediment yield which can provide necessary basis for yellow soil erosion prediction and agroforestry production are explored in the study area. The conclusions of the study can be drawn as follows:The best structure of rainfall erosive agent index is the product of rainfall kinetic energy and maximum 30min rainfall intensity. Rainfall erosive agent index can be also calculated with the product of rainfall amount and maximum 30min rainfall intensity. The erosive rainfall index of bare yellow soil should use maximum 30min rainfall intensity with the value range from 9.6 to 10.2mm·h-1, and the plough use rainfall amount standard better which is about 15mm. Soil and water conservation measures can increase erosive rainfall standard apparently. Erosive rainfall account for 36% and 38% of the total rainfall in the central and western of Guizhou for the average year which mainly distribute form May to August. The infiltration is very intensely on yellow soil slope of the karst area. The volume of runoff and runoff coefficient is at a very low level and there is no significant difference between different land use types. Soil erosion intensity for terrace、 orchard、grassland and soil and water conservative forest are all at the micro level. Terrace and orchard can both effectively reduce the slope erosion intensity. A handful of rainstorms course most of the sediment yield for the land use type of plough. The sediment reduction effect of soil and water conservative forest is the most prominent. Precipitation intensity has a little influence on sediment yield for the high vegetation coverage land use type. There is obvious linear relationship between the volume of runoff and the sediment for every land use type in time distribution rainfall.