无人机技术在潮滩地貌演变研究中的应用

Application of unmanned aerial vehicle technology in geomorphological evolution of tidal flat

随着海平面上升和人类活动加剧,潮滩正面临着严重威胁,掌握其形态变化规律是研究潮滩系统对外在条件响应的直接手段。以江苏斗龙港潮滩为研究对象,利用无人机倾斜摄影测量技术,结合运动恢复结构(Structure from Motion,SfM)算法,重建潮滩三维点云,生成数字高程模型和正射影像,分析潮滩滩面及潮沟系统年内变化规律。研究结果表明:潮滩高程测量精度优于9 cm,水平精度优于2 cm;高程年内变化较大,变幅高达±0.5 m;潮沟短历时变化剧烈,无明显季节性变化特征;潮沟发育过程中,宽深比范围为10~25。无人机技术不仅可以监测粉砂淤泥质潮滩滩面变化趋势,还可以观测到卫星难以捕获的中小型潮沟短历时发育过程,可为监测河口海岸短周期动力地貌过程提供有力的技术支持。

Tidal flats are fragile and delicate. Studies show that anthropogenic pressures and sea level rise due to climate changes have an effect and play a vital role in the morphodynamics of tidal flats worldwide. It is very important to understand the regularities and morphodynamic variations of tidal flats whilst investigating the external condition responses to tidal flats. Seasonal variations regularity on tidal networks and dissects of Doulong River intertidal flats located in Jiangsu Province,China were analysed,observed and researched. With the applications of Unmanned Aerial Vehicle (UAV) coupled with Structure-from Motion (SFM) algorithm,the Digital Elevation Modes (DEM) and orthoimage of the Doulong River intertidal flats were obtained. Results from the research clearly show the variations in tidal flats elevations are remarkable. With an increase as high as ±0.5 m within the period studied. The vertical and horizontal error of the tidal flats are less than 9 cm and 2 cm respectively. The tidal creek meanders are active with no regular changes in season throughout the year studied. The ratio of width to depth ranges from 10 cm to 25 cm during the development of a tidal creek. UAV technology provides a platform to monitor the variation trend of tidal flats elevation and the short-term evolution of small-scale tidal creeks. Thus,providing strong technical support for monitoring the short-term morphodynamic evolution of estuary and coast,which can be hard to sense by traditional remote sensing.