Study On Differentiation Characteristics Of Slope Ephemeral Gully Erosion In Granite Red Soil Region

The red soil hilly region of southern China is the most serious area of soil erosion after loess plateau,and soil erosion is the main erosion form on granite red soil slope.The soil erosion in the sloping land is performed by splashing,pitting and gully erosion,gully erosion plays a key role in the process of erosion and sediment production on the slope,and ephemeral gully developed in serious degradation lands in granite red soil region is the main erosion form of the southern.Therefore,through the field investigation,it is very important to study the law of the erosion characteristics and erosion characteristics of the erosion gullies on the slope,which is of great practical significance to the treatment of soil and water loss on the slope.In this paper,a typical representative Hetian Township of Changting County in the hilly red soil region of southern China was chosen as the object of study.By selecting three slope samples of 18°,25° and 30°in the field,(0～10m,10～20m,20～30m,30～40m,40～50m)from the bottom of the slope to the top of the slope.The morphological characteristics of the ephemeral gully and the erosion characteristics were analyzed.Ephemeral trench depth,ephemeral trench depth,ephemeral trench density,ephemeral trench fissure,ephemeral trench complexity,and ephemeral trench erosion.The erosion index is characterized by erosion modulus.The method of field investigation,measurement,laboratory experiment and statistical analysis are adopted.Based on the topographic factors and the development of the ephemeral trenches,the morphological and erosion characteristics of the ephemeral trench under the influence of slope gradient and slope position are systematically studied.The main conclusions are as follows:(1)The changes of the morphological characteristics of the ephemeral trench under the influence of the slope were analyzed.The morphological characteristics of the ephemeral trenches under three different slope conditions are:the process of the gradient changes from small to large,and other ephemeral trench shape indicators except the ephemeral trench are firstly increased and then decreased,all the 25°slope The index values were the largest,followed by 18° slope and 30° slope,showing the most obvious differentiation characteristics.(2)The variation of erosion capacity under the influence of slope is analyzed.The erosion characteristics of the three different gradient conditions are as follows:when the gradient is small and large,the erosion modulus firstly increases and then decreases,and 25° is the largest slope,followed by the 18° slope and the 30° slope,But the slope erosion modulus 18° and 25° are very close.Indicating that the erosion intensity of 25° slope is the strongest,followed by 18° slope and 30° slope.(3)The changes of the morphological characteristics of the ephemeral trench under the influence of the slope is analyzed.The results showed that the indexes of the ephemeral trench varied with the slope position,but also showed some regularitities.The other ephemeral trench shape indexes except the ephemeral trench depth ratio decreased from the downhill slope to the uphill slope,And the maximum value appeared in 0～10 or 10～20m,and the minimum appeared in the 40～50m.(4)The changes of erosion characteristics under the effect of slope position is analyzed.The erosion modulus of the gully under different slope conditions showed a trend of increasing firstly and then decreasing from the downhill slope to the uphill slope,and the maximum value appeared at the slope position of 10～20m,and the minimum value appeared Uphill 40～50m.It shows that the erosion intensity is also increased from the downhill slope to the uphill slope firstly,then decreased,and the erosion intensity of the downhill slope is 10～20m.(5)Selection of optimal index under different slope and different slope position.According to the correlation analysis,the relationship between the slope width and the ephemeral trench width is very significant(P<0.01).Therefore,when studying the slope gradient characteristics of ephemeral gully erosion,the ephemeral trench width Degree is more representative of the characteristics of gully erosion under the influence of slope.Slope depth,density,width-depth ratio and complexity are very significant(P<0.01),so these four indexes can be preferentially selected when studying the slope gradient characteristics of slope gully erosion.It is revealed that the characteristics of gully erosion are more representative under the influence of slope position.