| Soil erosion has become the worldwide serious environment problem, threatening the existence and development of humankind. The sustaining development need effectively control the soil loss and protect the environment. It is important to keep on knowing the present situation and change trend of soil erosion at large scale and analyze the macro effects of soil erosion to regional eco-environmental, which is the necessary precondition for eco-construction of soil and water conservation and the establish and implement of environmental protection. In this dissertation, based on integrated on techniques and methods including GIS, Remote sensing and fast information processing means, with the theoretical support of soil erosion science, the rapid approach for soil erosion assessment at regional scales was studied. Taking the Hubei Province as a case study area, the regional soil erosion states in 2000 and 2005 were evaluated. Based on the assessment results, the spatio-temporal change features of the 5 years were analyzed. The study aimed at providing new ideas for regional soil erosion research. The main content of this dissertation are as following:1. Supported with GIS and remote sensing, the evaluating indicators of environment factor for regional soil erosion assessment and analyze were generated, including slope gradient, land use, vegetation cover, rainfall erosivity and soil texture. The spatial database of evaluating indicators was established, which were as the data infrastructures for the regional scales assessment and spatial-temporal analyze of soil erosion in this study.2. With the similar spirit as the prevailing rapid biological assessment methods for water body, the rapid assessment of regional soil erosion using neuro-fuzzy system combined with GIS was developed, which contains the main steps as following, the study area were partied into minimum polygons as proper assessment units for soil erosion assessment. The neuro-fuzzy model was adopted to extract fuzzy rules for individual units assessment from available ground truth data. According to the optimized assessment criteria generated by the neuro-fuzzy model, the soil erosion state of the entire study area was then assessed. Supported with GIS technique, it was easily to scale up erosion assessment from field-plot scale to regional scale. Application of this approach to Hubei Province, The validation indicated that an overall accuracy of the assessment result in 2005 achieved 88% and the kappa coefficient was 0.89, proving that the resulting map was in conformity with actual conditions, which indicates this assessment approach was reasonable and applicable.3. According to the interpretation results of remote sensing images, the changes of land use and vegetable cover were analyzed. The trend analyze of land use change shows that: from 2000 to 2005, the dry field and paddy filed decreased, and the forest, shrub and grassland increased. Obviously, the dry field areas decreased by 10.30% to 28144km2, the forest increased by 4.04% to 82252km2, and the shrub and grassland increased by 9.83% to 20696km2.The main land use shift was from farmland to natural woodland. From the index of landscape pattern, the patch number of natural woodland decrease and their size increased. Due to the expended of natural woodland, the landscape dominance increased, and the index of diversity and fragmentation decreased. As far as the vegetable coverage characteristic in the study area, the areas of the coverage degree of low level and extreme low level reduced, and the areas of other higher coverage degree increased. Obviously, the percentage of extreme high coverage increased from 28.04% to 30.55% during the period of 2000 and 2005. Analysis results show that the water and soil conservation rehabilitation and the environmental ecosystem rehabilitations have achieved marked results.4. Comparing the assessment results of soil erosion degree of 2000 and 2005, the total areas affected by different levels of soil erosion problem decreased obviously from 60843km2 in 2000 to 55873km2 in 2005, which decreased 7.38%. The areas affected by moderate level soil erosion decreased 3494km2, The areas affected by strong level soil erosion decreased 1374km2, the areas affected by very strong level soil erosion decreased 140km2. On the other side, the areas affected by slight level soil erosion increased from 28797km2 to 29281km2, the severe level soil erosion increased form 391km2 to 461km2. The overall states of soil erosion were going to positive tendency, as the result of effective management for soil erosion during the period from 2000 to 2005. The landscape pattern index of landscape level showed that the variation tendency became less heterogeneity, less fragmentation and more regularization. The pattern number of lower level soil erosion decreased, with the mean pattern size increasing, and the regularization of pattern edges became higher. On the contrary, the pattern number of higher level soil erosion increase, with the mean pattern size decreased, and the degree of the landscape fragment is to be rather higher. It showed that the soil erosion states became taking a turn for the better for the remarkable improvement.5. Based on the analysis the relationship with environment background, high soil erosion sensitivity mostly occurred at altitude from 150 to 500 meters, in the slope gradient between 8 to 25°, and land use type of dry land, especially in areas with surface material vulnerable to erosion. As far as different physical geographical districts, Western high mountains and eastern low mountains suffered from the most serious erosion damage, a strong level of soil erosion was widely observed in these mountains. Large areas of moderate level erosion occurred in the northern hills. In contrast, most of the central plains were characterized as slight level erosion effect. After 5 year of effectively treat treatment, the states of sever soil erosion areas improved markedly, but they still were the focus of the soil and water conservation work.
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