基于DEM的冲沟纵横剖面谱系研究

The gully development and gully erosion destroy the soil and land. How to control the gully erosion is a sticky issue, which needs to acquire the deep laws of gully development. In the whole life cycle of the gullies, the longitudinal sections and cross sections adjust themselves dynamically, and combine themselves together in an orderly fashion. In this project we name the organic combination between longitudinal sections and cross sections as Spectrums of Longitudinal and Cross Sections (abbreviated as SLCS). The SLCS not only can reveal the difference between the development stages of gully, but also can be used to probe the soil erosion variation. In order to do that, the research regions are located in the Jinshajiang Dry-hot Valley. Based on multi-source and multi-period DEMs, the SLCS will be built and the uncertainty of SLCS will be probed. On this basis, qualitative and quantitative indicators of SLCS are designed. Then the differences of SLCS will be investigated not only among the gully development period, but also among the different gully samples under different environmental conditions. The coupling characteristics of morphological parameters of SLCS also will be probed, and the parameters include the volume, the plan area, etc. For example, the relationship between the volume and SLCS will be established, which can be used to estimate the erosion amount in the gullies. Finally, the response characteristics can be achieved between the morphological evolution of gullies and gully erosion variation. The study combines outdoor high-precision observation with indoor fine simulation, and combines the fixed point observation and the spatial differentiation analysis, and also combines static modeling with multi-period point cloud data comparison. In theory, this study will innovate the quantitative method to evaluate gully development, and excavate the quantitative relation between the SLCS and gully erosion. This project also hopes to form original results, and will further enrich the theory and practice of digital terrain analysis. If the project can be funded, it will provide support not only for regional soil and water conservation, but also for ecological restoration in practice.

冲沟发育蚕食耕地，其治理应把握冲沟发展深层次的规律。在冲沟整个生命周期中，其纵剖面、横剖面动态调整、有序组合形成冲沟纵横剖面谱系，揭示了冲沟发育进程差异，是研究冲沟形态演变与侵蚀特征变化的良好切入点。研究以金沙江干热河谷区冲沟为研究对象，以多源、多期DEM数据为基础，构建冲沟纵横剖面谱系，分析冲沟纵横剖面谱系构建的不确定性，构建描述剖面谱系的指标体系；探讨冲沟不同发育阶段、环境条件下纵横剖面谱系差异及其形态参数耦合特征，以及沟谷侵蚀响应特征。研究将室外高精度观测与室内精细模拟相结合、定位定点观测和空间分异分析相结合、静态建模与多期点云数据对比相结合，研究冲沟纵横剖面谱系构建的不确定性、时空变异性及其侵蚀响应的机理。在理论上将创新分析冲沟发育阶段的定量方法，挖掘纵横剖面谱系与沟谷侵蚀的定量关系，可望形成原创成果，并将进一步充实数字地形分析理论和实践；实践中可为区域水土保持与生态恢复提供支撑。

冲沟是流水地貌和土壤侵蚀研究的对象之一，其形态特征及其演化过程一直是相关学科关注的重要内容。作为冲沟重要的形态表征，其纵剖面和横剖面从沟道、坡面两个不同侧面刻画了冲沟发育过程中的形态差异性，有助于定量甄别冲沟活跃程度。项目以地貌学、土壤侵蚀学等学科的基本原理为理论基础，综合野外实测和点云数据，提取和分析了冲沟纵横剖面，对比了不同环境条件下冲沟形态特征及其差异性。项目的主要研究成果如下：（1）冲沟纵横剖面的提取与定量分析：基于点云数据和实地观测，定量分析了冲沟纵剖面、横剖面的差异性；建立基于多维信息识别侵蚀沟发育程度的方法。（2）构建了估算冲沟体积的经验公式：基于实测数据，建立了冲沟形态特征如沟道长度、宽度、深度、横剖面的面积等与侵蚀体积关系的经验模型，总体上元谋干热河谷典型冲沟侵蚀体积可以表示为V=aL^b的函数形式，不同活跃程度的冲沟，a、b系数存在差异。（3）冲沟侵蚀-沉积室内模拟与对比分析：从坡面、沟道等不同侧面，模拟和分析了栅格尺度带来的侵蚀-沉积不确定性特征，并与自然降雨过程中的侵蚀-沉积分布进行了对比。（4）冲沟形态特征与侵蚀的关系：提出和实现了基于反地形洼地汇流、反地形谷地汇流等坡长新的计算方法，并与LSTools、SAGA等软件的结果进行了对比分析，发现在洼地汇流方法计算坡长结果存在一定局限性，但反地形谷地汇流方法与其它软件计算结果存在较好的相似性；研究了地形湿度指数、复合地形指数、S-A等方法识别沟谷起源的适应性。（5）探究了开源DEM数据融合，对沟谷表达的影响，发现数据融合较好的改善了高程最大正负偏差，初步消除了单一开源数据提取LS等因子曲线的毛刺现象。项目丰富了干热河谷区高精度冲沟数据库，深化了对侵蚀沟空间差异性和发育阶段的认识，有利于侵蚀沟发育的控制和治理。团队1人晋升高一级职称，获地厅级科技奖励3次；发表的相关论文，SCI检索6篇、EI检索3篇，申报专利3项、授权发明专利1项，获省政府奖励1项。