Soil Erosion Assessment In Kaijiang County Based On GIS And RS

Soil erosion evaluation of regional soil erosion prevention and control of formulating policy is of great significance, the traditional soil erosion research needs using the topographic map in the wild, time-consuming to professional and technical personnel to use visual interpretation to drew is erosion map spot, work hard and difficult to achieve large area of soil erosion monitoring and assessment. As the 3S (RS, GIS, GPS) technology rapid development and increasingly mature, soil erosion assessment also ushered in the new opportunity. This paper chosed the Kaijiang county as the study area, to use 2013 annual rainfall, land use, soil, topography, remote sensing image data as data sources, such as modern technology such as GIS, RS and combining the universal soil loss equation (USLE), carried out the Kaijiang county in 2013 soil erosion quantitative evaluation, combining with the evaluation of soil erosion intensity classification result, further analyzes the Kaijiang county different land use types, vegetation coverage, soil types, different height, different slope soil erosion characteristics of the belt. The main research conclusions were as follows:(1) Kaijiang county soil erosion phenomenon was common, not suffering from soil erosion area was less, not have eroded soil area of 107.15 km2,10.41% of the total area of Kaijiang county land, soil erosion has occurred the soil area of 922.43 km2,89.6% of the total area of Kaijiang county land; Kaijiang county in 2013, the average erosion modulus was 2480.6 t/(km2a), total annual soil erosion was 2553985.574 t, maximum erosion modulus of 12866.7 t/(km2a), minimum erosion modulus of 0 t/(km a).(2) Kaijiang county soil erosion types with microscopic degrees of erosion, mild erosion, moderate erosion, the intensity of erosion, erosion intensity of five types; Kaijiang county main types of soil erosion intensity of micro degrees of erosion and the erosion of the mild, the erosion area of 737.37 km2,71.62% of the total area of Kaijiang county, both the erosion amount was 1117624.087 t/a, accounting for 43.76% of the total erosion.(3) Kaijiang county condition of soil erosion in different land use types were more obvious, largest for bare soil erosion index, composite index is 421.04, the soil erosion of soil erosion composite index, the smallest of forest land, its soil erosion index was only 0.74; Upland and paddy field are same as arable land, but soil erosion index has obvious difference, the dryland soil erosion comprehensive index was 207.5, the paddy soil erosion comprehensive index for 52, both differ 155.5.(4) The erosion of different vegetation coverage composite index in the study area from big to small in turn for level 2(10%-30%), level 1(<10%), level 3(30%-50%), level 4(50%-70%), level 5(70%-100%). Soil erosion index is the biggest 2 levels of vegetation coverage, the soil erosion comprehensive index was 407.92, the soil erosion index minimum of 5 levels of vegetation coverage, the soil erosion comprehensive index was 8.90, the overall performance for the vegetation coverage, the higher soil erosion against the stronger; Kaijiang county level 1 vegetation coverage (c< 10%) suffered by soil erosion is not the worst, the composite index of soil erosion was 361, the reason is that Kaijiang county grade 1 vegetation coverage (c< 10%) coverage level contains the bare land, water area, construction land and other land use type, type of land use types in recent weeks, without vegetation, waters and other construction land land use type to resist the ability of the soil erosion is stronger, it occupies a larger proportion in the bare land cover class.(5) Different types of soil erosion degree is different, different soil types soil erosion index difference obvious, composite soil types of soil erosion in the study area of the maximum and the minimum was 164.84; All soil types of composite index of soil erosion from big to small in turn was a typical yellow soil, neutral purple soil and calcareous purple soil and submerged paddy soil, yellow rendzina, etc.for storage paddy soil, permeable paddy soil, gley paddy soil and calcareous chao soil skeleton soil, ash.(6) Kaijiang county, the overall elevation with synthetical index of soil erosion is larger, with a mean of 181.72, shows that Kaijiang county soil erosion are greatly influenced by height; Kaijiang county,400-600 m elevation with the most serious soil erosion, the soil erosion comprehensive index was 325.12; Kaijiang county soil erosion index minimum height is 200 m-400-m, the soil erosion index is 65.06, Kaijiang county, more than 800 m elevation zone regional soil erosion and elevation are negatively related with comprehensive index.(7) Different slope erosion composite index in the study area from big to small in turn for grade 4 (15°and 25°),3 (8°,15°),5 (25°,35°), the level 2 (5°-8°), level 1 (< 5°) and 6th (> 35°); In less than 25°slope area soil erosion index was positively correlated with slope, soil erosion in the region of the gradient was greater than 25°composite index are negatively related with slope.