基于摄影测量的黑土坡面细沟间与细沟侵蚀时空过程研究

Interrill and rill erosion play important roles in hillslope erosion. Their evolution process is one of current frontiers and hot topics in soil erosion research field. While there are few research about hillslope interrill and rill detachment rates as well as surface morphology changes in Chinese Mollisol region. This study focuses on natural-rainfall induced interrill and rill erosion processes in this region. We will use bare plot to study the spatial and temporal evolution of interrill and rill detachment rates, as well as surface morphological characteristics. The research methods in this study will cover terrestrial stereo photogrammetry, in-situ measurement and erosion model. Digital terrain models of bare plot with 0.3 mm ground resolution after individual rainfall events will be taken through terrestrial stereo photogrammetry. Interrill and rill detachment rates, as well as hillslope eroded surface and rill morphological characteristics at any place within the bare plot, will be obtained by comparison and analysis of DEMs before and after individual rainfall event. Total erosion amount from bare plot will be calculated through situ runoff and sediment monitoring device also. The mutual responses and feedbacks between detachment rate and hillslope morphological characteristics will be analyzed. Besides, hillslope erosion process will be simulated by water erosion process model (WEPP). Thus, the results about spatial and temporal evolution of interrill and rill erosion of black soil will contribute to improve our knowledge about hillslope erosion process, and provide scientific evidences of how to optimize soil conservation practices in Chinese Mollisol region.

细沟间与细沟侵蚀是坡面侵蚀的主要组成部分，二者侵蚀过程的空间变异及演化既是坡面侵蚀机理研究的热点，又是难点。目前缺乏有关东北黑土区坡面细沟间与细沟侵蚀率及其塑造的坡面侵蚀形态特征的研究。本项目采用地面立体摄影测量、标准径流小区定位观测、坡面侵蚀物理模型模拟相结合的方法，研究揭示降雨径流作用下细沟间与细沟侵蚀率及其塑造的坡面侵蚀形态与细沟形态的空间变异及动态变化，探讨侵蚀率与坡面侵蚀形态、细沟形态的互馈机制，阐明坡面细沟间与细沟侵蚀过程，为黑土侵蚀机理研究和侵蚀预测模型构建提供理论支持。

细沟间与细沟侵蚀是坡面侵蚀的主要组成部分，二者侵蚀过程的空间变异及演化既是坡面侵蚀机理研究的热点，又是难点。目前缺乏有关东北黑土区坡面细沟间与细沟侵蚀率及其塑造的坡面侵蚀形态特征的研究。本项目采用地面立体摄影测量、标准径流小区定位观测、坡面侵蚀物理模型模拟相结合的方法，研究揭示降雨径流作用下细沟间与细沟侵蚀率及其塑造的坡面侵蚀形态与细沟形态的空间变异及动态变化，探讨侵蚀率与坡面侵蚀形态、细沟形态的互馈机制，阐明坡面细沟间与细沟侵蚀过程，为黑土侵蚀机理研究和侵蚀预测模型构建提供理论支持。结果表明，应用全站仪作为地面控制点测量方式，应用索尼微单地面拍摄方式，获取的精度最高。应用无人机能够提高拍摄便利性，应用“精灵4”或“悟”，效果较好。基于单点和点云验证方法的结果均表明，优化过程可降低误差约40%。相对于默认参数设置下的验证点误差（20.0 mm），优化后的验证点误差为11.0 mm，与细沟侵蚀深度标准相当（沟深≥10 mm），因此优化后的径流小区三维重建过程更适宜于细沟侵蚀过程的三维表达。叠加的两期地面数字模型在ArcGIS 10.2中经相减计算后，求得降雨前后坡面小区有4条细沟的体积增加，侵蚀量增大。4条细沟的沟头分别前进了355 mm、482 mm、150 mm与92 mm；沟深分别增加了11 mm、21 mm、10 mm与15 mm；体积分别增加了3928 mm3、5488 mm3、2493 mm3与2577 mm3。根据土壤容重进一步求得4条细沟的侵蚀量分别为4635 g、6476 g、2917 g与3041 g。