基于无人机遥感的水生植物覆盖度测算方法探索

Exploration on the method of measuring the coverage of aquatic plants by using UAV remote sensing

人类活动造成大量的氮、磷等营养物质进入水体,造成水体污染和富营养化,导致水生植物或浮游藻类大量繁殖,了解水生植物覆盖度对了解水域生态环境质量和污染状况具有重要意义。常规的水生植物覆盖度测算方法耗时长、成本高,且容易受环境限制,但随着无人机技术的进步,通过无人机遥感平台获取水生植物覆盖度图像具有高时效、高分辨率、低成本、快速和准确等特点。在水生植物覆盖度测算方面,目前使用率最高的是利用无人机搭载多光谱摄像头采集信息并分析。采用大疆无人机对上海市水产研究所一处池塘进行航拍测绘,经大疆智图导出正射遥感影像,运用region growing算法对图像像素分析计算,得出池塘中水生植物的面积为1 262.27 m^(2),覆盖度为56.11%。该技术方法具有成本相对较低、统计测算上效率更高、灵活方便、易学易用等特点,在对水生植物覆盖度测算的同时,还可对池塘湖泊等提供时空监测,可为鱼菜共生系统、稻田养殖或中华绒螯蟹(Eriocheir sinensis)混养等提供有力支持。

Human activities cause a large amount of nitrogen,phosphorus and other nutrients to enter the water body,resulting in water pollution and eutrophication,leading to the mass propagation of a large number of aquatic plants or phytoplankton.It is of great significance to understand the coverage of aquatic plants for the quality and pollution of water ecological environment.Conventional methods for measuring the coverage of aquatic plants are time-consuming,costly,and easily restricted by the environment.However,with the progress of UAV(unmanned aerial vehicle,UAV) technology,obtaining the coverage of aquatic plants through the remote sensing platform of UAV has the characteristics of high efficiency,high resolution,low cost,high speed and accuracy.In terms of measuring the coverage of aquatic plants,the most widely used method is to collect and analyze the information with the multi spectral camera mounted on the UAV.A pond in Shanghai Fisheries Research Institute was surveyed by aerial photography with Dajiang UAV.The orthophoto remote sensing image was derived from Dajiang intelligent map.The area of aquatic plants in the pond was 1 262.27 m^(2) and the coverage was 55.78% by using region growing algorithm to analyze and calculate the image pixels.The technical method has the characteristics of relatively low cost,higher efficiency in statistical calculation,flexible and convenient,easy to learn and easy to use.While measuring the coverage of aquatic plants,it can also provide space-time monitoring for ponds and lakes.The method can provide strong support for fish and vegetable symbiosis system,rice field culture or Chinese mitten crab mixed culture.