基于时空数据融合模型的丹江口库区土壤侵蚀时空格局演变与治理优先区识别研究

Danjiangkou reservoir area is the main water source and the submerged area of the Middle Route South-to-North Water Transfer Project of China. Soil erosion is a factor that significantly influences the quality and transfer of water from the Danjiangkou reservoir. This study take Danjiangkou reservoir area as the study area, and integrate multi-sensor and multi-temporal remote sensing data and fieldwork data, using the multi-size segmentation and classification object-oriented techniques to get the time-space continuum land cover maps for 1990-2020. Base on spatio-temporal data fusion model extracting the time series vegetation coverage of Danjiangkou reservoir area to meet the needs of the soil erosion risk assessment.The objective of this study is to assess the water erosion (rill and sheet erosion) risk and dynamic change trend of spatial distribution in erosion status and intensity between 1990 and 2020 in the Danjiangkou reservoir area using a multicriteria evaluation method. The multicriteria evaluation method synthesizes the vegetation fraction cover, slope gradient, precipitation factor and land cover. Base on the multi-object decision model and erosion risk assessment results and spatiotemporal dynamic change in nearly 30 years, the research obtained the conservation priority map. The priority map can provide the scientific data for preventing and governing the soil erosion of Danjiangkou reservoir area. The study results can assist government agencies in decision making for determining erosion control areas, starting regulation projects, and making soil conservation measures, thereby improving the ecological environment of Danjiangkou reservoir area and ensuring the safety running of the Middle Route South-to-North Water Transfer Project.

丹江口库区是我国南水北调中线工程的主要水源地和淹没区，库区土壤侵蚀是影响水质和调水安全的重要因素。以丹江口库区为研究区，基于多源多时相遥感影像，结合野外调查建立的典型地物遥感解译标志和多尺度分割，采用耦合地学知识的面向对象分类方法提取库区1990-2020年时空连续土地覆被数据集；基于时空数据融合模型获取满足库区土壤侵蚀风险评价需求的时序植被覆盖度；结合地形、降水等因子，基于多指标综合方法建立土壤侵蚀风险模型，开展库区土壤侵蚀风险时空格局动态变化特征研究；基于库区土壤侵蚀现状和近30年时空动态变化，构建多目标决策模型，确定库区土壤侵蚀治理优先区域，为库区土壤侵蚀预防与治理提供科学数据支持。研究结果可辅助管理部门对库区有针对性的采取保护治理措施、启动治理工程、为资源分配与管理等提供科学依据和数据支持，从而改善库区生态环境、保障南水北调中线工程的安全运行。

土壤侵蚀是世界范围内最重要的土地退化问题，严重的土壤侵蚀破坏宝贵的水土资源，引起生态环境恶化。丹江口库区是我国南水北调中线工程的核心水源地和淹没区，同时也是土壤侵蚀易发区。土壤侵蚀将严重影响水库水质和调水安全，如果不及时控制治理，将对南水北调中线调水工程带来一系列危害，甚至威胁中线工程的安全运行。因此，深入推进水源区水土保持工作，增强水源涵养能力，持续改善库区及上游地区生态环境，对保障南水北调中线工程平稳运行、促进区域经济社会可持续发展，具有十分重要的意义。然而，土壤侵蚀具有空间可变性，如果对土壤侵蚀风险的空间分布缺乏了解，则会影响对侵蚀治理的投资，可能造成资源和资金浪费。为了使治理政策更有目的性、针对性，合理分配资金，节约治理成本，对库区土壤侵蚀风险进行有效评估，开展其时空分布格局变化及治理优先区识别研究，具有重要的意义。本项目针对丹江口库区土壤侵蚀问题，提出土壤侵蚀治理优先区概念，开展库区土壤侵蚀时空格局演变与治理优先区识别研究，提取并优化了库区1990-2020年土地覆被数据，遥感反演了植被覆盖度等因子。在此基础上，建立了土壤侵蚀风险评估模型，开展库区土壤侵蚀风险时空格局动态变化研究，分析土壤侵蚀转化趋势，揭示库区土壤侵蚀空间格局变化。基于土壤侵蚀风险强度现状与时空动态变化，构建决策模型，确定土壤侵蚀治理优先区域空间分布数据。相关结果可以辅助管理部门确定侵蚀控制区域、启动治理工程、设置治理措施，为丹江口库区土壤侵蚀治理及生态建设提供科学依据和数据支撑，也为其他区域的水土流失治理相关研究提供了可供借鉴参考的研究方法。