【作者】 朱惇；

【导师】 蔡崇法；

【作者基本信息】 华中农业大学 ， 资源环境信息工程， 2010， 博士

【摘要】 土壤侵蚀已成为是全球性的环境问题之一,严重威胁着人类生存与社会可持续发展。迅速掌握大尺度范围内的土壤侵蚀状况,分析土壤侵蚀的时空变化可以为土壤侵蚀综合治理和生态恢复建设提供重要的理论依据与决策参考。本研究以土壤侵蚀学为理论基础,以遥感、GIS技术和现代信息处理手段为技术依托,以湖北省为研究对象,开展省域尺度下土壤侵蚀快速评价方法的研究,分别对研究区2000年和2005年的土壤侵蚀状况进行评价；在此基础之上,从不同角度对研究区5年问土壤侵蚀时空变化特征进行分析。本研究以期为区域土壤侵蚀研究提供新的思路。论文主要包括以下内容：1.利用遥感和GIS技术,提取用于区域土壤侵蚀评价与分析各项自然环境因素指标的空间数据图层,包括地形坡度、植被覆盖度、土地利用类型、降雨侵蚀力及土壤质地5项指标,在此基础上建立了区域土壤侵蚀评价空间数据库,为区域土壤侵蚀评价与分析提供数据准备。2.对区域土壤侵蚀评价进行了探索性研究,提出了一种基于模糊神经系统和GIS技术的快速评价方法。该方法主要包括以下主要步骤：通过GIS空间叠置分析划分最小图斑作为基本评价单元。借鉴快速生物评价方法的基本原理,从已有的地面监测及调查数据中选取一系列内部因子较为均一的基本评价单元作为标准参照单元,参考土壤侵蚀强度分级标准,构建不同土壤侵蚀强度等级的参照组。利用神经-模糊系统建立区域土壤侵蚀快速评价模型,提取土壤侵蚀强度模糊评价规则,以侵蚀环境因子相似性作为判别依据,将待评估单元匹配到各个参照组中,从而建立区域土壤侵蚀评价规则知识库。在此基础上结合GIS技术,实现从单元评价到区域评价的尺度转换。采用该方法对2005年土壤侵蚀强度状况评价结果的总体精度为88%,kappa系数为0.89,经验证,评价结果与实际情况具有较好的一致性。3.根据2000年和2005年遥感影像的解译结果,对引起区域土壤侵蚀变化的环境影响因素进行动态分析,主要包括土地利用变化和植被覆盖度变化。结果表明,研究时段内研究区土地利用／覆被变化的整体趋势表现为林地、灌草地面积增加,旱地和水田面积减少。其中,旱地减少的面积最大,减少了3230km2；林地增加的面积最大,增加了3197km2。耕地多转换成为林地和灌草地。土地利用的景观格局呈斑块减少,斑块平均面积增大的趋势,由于林地、灌草地面积扩大,景观优势度进一步升高,从而引起多样性减少、破碎度降低的变化特征。研究区植被覆盖度变化趋势表现为,中高植被覆盖度地区的面积都明显增加,而较低植被覆盖面积呈快速下降态势。其中,高覆盖度地区面积由2000年的52132km2增加到2005年的56807km2,增加面积和幅度均为最高。由于研究区耕地面积减少,林地面积增多,因此植被覆盖度也明显升高。结果表明,研究区的水土保持生态环境的修复取得明显的成效。4.根据2000年和2005年两期土壤侵蚀评价结果,对研究区土壤侵蚀的时空演变进行分析。结果表明,5年来研究区土壤侵蚀总面积明显减少,从2000年的60843km2减少到2005年的55873km2,减少了7.38%。从土壤侵蚀强度变化来看,中度、强度和极强度侵蚀面积明显减少,多转化为轻度和微度侵蚀；其中,中度侵蚀面积减少了3494km2；强度侵蚀面积减少了1374km2；极强度侵蚀面积减少了140km2。而轻度侵蚀和剧烈侵蚀面积稍有增多,其中轻度侵蚀强度面积增加了484km2,多由侵蚀等级高的地区转化而来；剧烈侵蚀面积也增加了70km2,多由局部地区开发建设项目引起的比较严重自然环境破坏所致。研究区的土壤侵蚀综合指数从2000年的112.05,下降到2005年的100.39,整体而言研究区侵蚀强度呈下降趋势。研究区的侵蚀景观尺度的格局特征表现为低异质性,低破碎化和规则化的变化趋势。整体上低强度的土壤侵蚀多表现为斑块数减少和平均斑块面积的增加,边缘规则化,而高强度土壤侵蚀则相反,表现为斑块数增加而平均斑块面积减少,破碎化程度提高。可以看出5年来治理取得显著成效,研究区土壤侵蚀整体状况有所好转。5.对2000-2005年研究区不同环境背景因素条件下和不同自然地理分区内的土壤侵蚀变化状况进行研究。将两个时间段的土壤侵蚀评价结果与不同自然环境背景因子图层进行叠加分析,分析不同自然环境背景下土壤侵蚀分异特征与规律。结果表明,150～500m的相对高程带、8～15°的坡度带、年均植被覆盖低、土质疏松、土地利用类型以坡耕旱地为主的地带的土壤侵蚀综合指数最高,因此土壤侵蚀风险高的地区主要位于这些地带。经过5年的治理,这些侵蚀严重的地带侵蚀状况明显好转,其中以坡耕地地区治理最为突出。就不同自然地理分区的土壤侵蚀状况而言,鄂西北、鄂西南高山区土壤侵蚀情况最严重,鄂东北、鄂东南低山丘陵区次之,鄂北岗地中度侵蚀面积较大,而江汉平原基本无明显侵蚀。经过5年的治理,山区、丘陵区的土壤侵蚀状况有所好转,但今后仍然是水土保持工作的重点地区。更多还原

【Abstract】 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.更多还原