基于地-空-天立体观测的三峡库区消落带草地生物量估算研究

The grassland vegetation in the Three Gorges Reservoir area will be decomposed into a large number of nutrients, DOC and toxic and harmful metal ions, which may bring a serious threat to the safety of water environment in the reservoir area. Grassland types and grassland biomass are the key supporting parameters for quantitative assessment of the effects of inter annual variation on the water environment. In this study, with the help of a variety of advanced satellites, unmanned aerial vehicles (UAV) and ground observation methods, we will carry out the ground air sky observation experiment and obtain the data of multi source and multi scale synchronous observation. Using analysis method and mathematical model, constructed with grassland type division method and biomass estimation model of multi-source remote sensing data acquisition based on fluctuating, Three Gorges Reservoir Area on the macro scale. The distribution and biomass of grassland types fall with the space, the key control factors to identify the impact of grassland types and spatial distribution of biomass accumulation. The successful implementation of this project will provide the key data support for the follow-up study of the water environment, water ecology and the development and management of the Three Gorges Reservoir area.

三峡库区消落带的草地植被在蓄水淹没后，将腐烂分解产生大量的营养元素、DOC和有毒有害金属离子，可能给库区水环境安全带来严重威胁。草地类型和草地生物量是定量评估消落带草地年际生消变化对库区水环境影响的关键支撑参数。本研究拟借助多种先进的卫星、无人机和地面观测手段，开展地-空-天立体观测试验并获取多源多尺度同步观测数据。利用地学分析方法和数学模型，构建基于多源遥感观测数据的消落带草地类型划分方法和生物量估算模型，从宏观尺度上获取三峡库区消落带的草地类型和生物量的空间分布，识别影响草地类型空间分布和生物量蓄积的关键控制因子。本项目的顺利实施将为三峡库区水环境、水生态及消落带管理开发等后续研究提供关键数据支撑。

三峡库区消落带的草地植被在蓄水淹没后，将腐烂分解产生大量的营养元素、有机碳和有毒有害金属离子，可能给库区水环境带来严重威胁。获取准确的消落带空间范围和草地生物量是开展后续研究的关键支撑。项目的主要研究内容包括：开展天-空-地同步观测试验，获取研究区立体观测数据集，基于最高/最低水位附近的合成影像提取三峡库区消落带，建立消落带草地生物量与遥感观测的回归模型，估算三峡库区消落带草地生物量总重。结果显示，三峡库区干支流消落带面积约240平方千米，重庆段面积占比86.64%，湖北段面积占比13.4%。主要分布在重庆涪陵-丰都-忠县-万州-云阳-奉节-巫山等库区中游区域，其中长江干流消落带面积占比50.7%，支流消落带面积占比49.3%。支流中消落带面积最大的为流经云阳和开县的小江流域，共有消落带27.4平方千米。建立了消落带草地生物量RVI遥感估算模型，方程决定系数0.747，估算得到三峡库区消落带草地生物量总重为8.33万吨，单位面积生物量干重为346克/立方米。消落带生物量总重较高的区县分别包括涪陵、忠县、云阳、万州等库区中游区域，单位面积生物量较高的区县包括重庆主城、巴南、渝北、长寿等库区上游区域，而临近大坝的巴东、兴文、秭归的消落带面积和生物量均较低。研究获取的具有较高精度的三峡库区消落带和生物量空间分布数据对于库区水环境监测与模拟、水生态保护等研究具有关键支撑作用。