近海开发影响下底栖生境演变的声学观测与评估研究

发布时间：2018-05-04 06:20

本文选题：围填海 + 人工鱼礁　；参考：《中国科学院烟台海岸带研究所》2017年博士论文

【摘要】：近海开发已成为沿海地区进行空间资源扩展的主要途径。大规模沿海开发活动如围填海工程、海洋牧场建设等在促进了沿海地区社会经济发展的同时,对海洋底栖生境也产生了显著影响。声学方法改变了传统调查方法效率不高、获取信息不全的缺点,为底栖生境调查提供了一种新的技术方法。多波束声呐系统是当代海洋勘测中一项高新技术产品,国内将其应用于近海底栖生境观测、评估的研究还比较少见;声学数据结合分类算法可以实现底栖生境的识别与评估,但目前还缺乏人工鱼礁区底栖生境自动化分类方法的相关研究。本论文在总结多波束数据处理方法的基础上设计了一种底栖生境自动化制图方法,实现人工鱼礁区底质类型的识别;利用高分辨率、高精度的多波束声呐系统,分析人工鱼礁区、围填海区微地形地貌特征。主要研究成果如下:1、设计了一种底栖生境自动分类方法,并将其应用于人工鱼礁区。结果表明:(1)多波束数据量大,包含信息丰富,通过数据挖掘可以提取反映海底底质属性的多种声学变量(如坡度slope、底栖位置指数BPI等);(2)PCA能够在保留主要信息的同时,将多种声学变量实现数据压缩,减少数据冗余(特征值大于1的前3个PCs的累积频率近80%);(3)ISODATA非监督分类算法与人工解译方法相比,处理速度快效率高,可以消除相邻声相边界的不确定性,确保分类结果的正确性,大大降低操作人员的偏差,节省人力成本。这一自动化智能分类方法在山东近海大规模人工鱼礁区取得了良好效果,实现了鱼礁区三种基本底质(沙质海底、泥质海底及人工鱼礁)的分类识别。底质取样、水下摄像验证结果与自动化分类结果保持一致,进一步证明了该方法的有效性。人工鱼礁区底栖生境的自动化分类技术可以将复杂的多波束数据转化为可视化的专题图,能够使用户快速获取感兴趣区的海底底质信息,满足鱼礁管理的需求,具有较强的实际意义。该底栖生境制图方法主要在GIS平台下完成,可以实现进一步的空间分析与算法改进。2、利用多波束系统结合地理空间分析方法实现了大规模人工鱼礁区底栖生境的监测与评估。分析结果显示:(1)采用多波束声呐系统能够快速获取鱼礁的形态、分布及其周围海底的微地形地貌信息,比传统调查方法(如水下探摸)准确度高、效率高、成本低;(2)借助地理信息系统地形分析技术可以提取鱼礁区地形特征变量,坡度、曲率、粗糙度、地形耐用指数以及地形起伏度的高值区均出现在礁石分布区域,能够将礁石从平坦海底区分开来;(3)由于自身重力及水动力作用,礁石发生沉降现象(沉降深度达0.45 m),鱼礁的存在使底层流速减弱、流向发生变化,其周围出现特有的冲淤地形,多波束水深数据可以定量分析投石后引起的海底地形变化特征,为人工鱼礁建设评估工作提供数据支持;(4)不同类型的人工鱼礁,其构造不同,形成的局部流场也不同,为底栖生物创造了不同的底栖环境,实地验证发现水泥预制件礁体比山石鱼礁的聚鱼效果更为明显。高分辨率的多波束数据不仅可以反映出海底鱼礁的宏观信息(分布、规模、占地面积等),还可以提供鱼礁的微观信息(三维结构、大小、形状及沉降深度等),达到人工鱼礁精准监测的目的。3、结合历史海图与多波束数据,在GIS平台下构建龙口湾水下DEM,分析了龙口湾近50年的形态演变过程。结果显示:1960s到2010s半个世纪以来,龙口湾水下地形地貌发生了巨大改变,研究区水域面积减少了13.5 km2。具体来说:(1)1960s~1990s,龙口湾自然演变,受人类活动影响较小;(2)1990s~2000s,龙口港扩建加之航道清淤,龙口湾形态发生了明显变化,龙口浅滩面积缩小,平均水深从7.56 m增加到8.16 m;(3)2000s~2010s,龙口港的进一步扩展及离岸人工岛的建设使龙口湾海底地形发生了剧烈改变,龙口浅滩基本消失,人工岛北部水下地形复杂、海底较为破碎,陆地面积从23.10km2增长到29.35 km2。近几十年频繁的海岸活动(包括港口扩建、航道清淤及人工岛建设)已成为决定龙口湾形态变化的主导因素。高分辨率的多波束数据显示,人工岛吹填工程抽取沉积物后,在海底留下了大量取土坑,平均水深加深了2.34 m,使海底地形地貌发生了极大改变,对海底底栖生境造成了严重破坏。本研究中设计的鱼礁区底栖生境自动化分类方法,是海底声学探测领域的一次尝试,有助于人工鱼礁的科学管理,具有较强的现实意义;利用多波束声呐手段结合地理空间分析方法获取人工鱼礁区、围填海区微地形地貌特征,为监测近海人类活动影响下的底栖生境演变提供了一种新的技术手段。
[Abstract]:The development of coastal areas has become the main way for the expansion of space resources in coastal areas. Large scale coastal development activities such as reclamation projects, marine pasture construction, etc. have promoted the social and economic development of coastal areas, and also have a significant impact on the marine benthic habitat. Acoustic methods have changed the efficiency of traditional investigation methods and obtain letters. A new technical method is provided for the investigation of benthic habitat. The multi beam sonar system is a high-tech product in the contemporary ocean survey, and it is used in the observation of habitat near the bottom of the sea in China. The study of the assessment is rare, but the acoustic data combined with classification algorithm can realize the recognition and evaluation of benthic habitat. At present, there is still a lack of research on the automatic classification method of benthic habitat in artificial reef. On the basis of summarizing the method of multi beam data processing, this paper has designed a benthic habitat automation mapping method to realize the recognition of the bottom quality of artificial reef area, and the analysis of artificial reefs using high resolution and high precision multi beam sonar system. The main research results are as follows: 1, an automatic classification method of benthic habitat was designed and applied to the artificial reef area. The results showed that (1) a large number of multi beam data, including abundant information, can be used to extract a variety of acoustic variables (such as slope slope, benthic benthos) through data mining. Position index BPI, etc.); (2) PCA can compress data with a variety of acoustic variables while retaining the main information and reduce data redundancy (the cumulative frequency of the first 3 PCs with a feature value greater than 1 is nearly 80%). (3) compared with the artificial interpretation method, the ISODATA unsupervised classification algorithm has high processing speed and can eliminate the inaccuracy of the adjacent sound phase boundary. Qualitatively, to ensure the correctness of the classification results, greatly reduce the deviation of the operators and save the human cost. This automatic intelligent classification method has achieved good results in the large-scale artificial reef area of Shandong offshore, and has realized the classification and identification of three basic bases in the reef area (sandy seabed, muddy seabed and artificial reefs). Bottom sampling, underwater The automatic classification of the benthic habitat in the artificial reef area can convert the complex multi beam data into a visual thematic map, and can quickly obtain the bottom quality information of the region of interest and meet the needs of the reef management. It is of great practical significance. The mapping method of the benthic habitat is completed mainly on the GIS platform. The further spatial analysis and algorithm improvement.2 can be realized. The monitoring and evaluation of the benthic habitat in large artificial reefs are realized by using multi beam system combined with geospatial analysis. The results show that (1) multi beam sonar system is adopted. The formation, distribution of the reefs and the Microtopographic information of the surrounding seabed can be quickly obtained, which are more accurate, efficient and less expensive than the traditional investigation methods (such as underwater exploration). (2) the topographic features of the reef area, slope, curvature, roughness, terrain durability index and terrain can be extracted with the aid of geographic information system topographic analysis. The high value area of the volt appears in the reef distribution area and can distinguish the reef from the flat seabed. (3) the reef settles (the settlement depth is 0.45 m) due to its own gravity and hydrodynamic action, and the existence of the reef reduces the velocity of the bottom and changes the flow direction, and there is a special erosion and siltation topography around it, and the data of the multi beam depth can be obtained. It provides data support for the evaluation of artificial reef construction by quantitative analysis of the characteristics of seabed terrain changes after the stone throwing. (4) different types of artificial reefs have different structures and different local flow fields, which create different benthic environment for benthos, and verify the discovery of cement preform reefs more than the fish reefs. The high resolution multi beam data can not only reflect the macro information (distribution, size, area, area and so on) of the marine reefs, but also provide the microscopic information of the reefs (three-dimensional structure, size, shape and depth of settlement) to achieve the purpose of the accurate monitoring of artificial reefs,.3, combined with the historical chart and multi beam data, in GIS Under the platform, the underwater DEM of Longkou Bay is constructed and the morphological evolution process of Longkou Bay has been analyzed for nearly 50 years. The results show that the underwater topography and geomorphology of Longkou Bay has been greatly changed from 1960s to 2010s for half a century, and the area of water area in the study area has been reduced by 13.5 km2. specifically: (1) 1960s~ 1990s, Longkou Bay natural evolution is less affected by human activity; (2) 199 0s~2000s, Longkou expansion and channel silting, Longkou bay shape changed obviously, the area of Longkou Bay reduced, the average water depth increased from 7.56 m to 8.16 m; (3) 2000s~2010s. The further expansion of Longkou port and the construction of offshore artificial island made a dramatic change in Longkou sea bottom topography, the Longkou shoal disappeared basically, the northern artificial island was in the north. The underwater terrain is complex and the seabed is relatively broken. The land area from 23.10km2 to 29.35 km2. in recent decades has become the dominant factor in determining the morphological changes in Longkou Bay. At the bottom, a large number of soil craters were left, the average depth of water deepened by 2.34 m, which made the seabed topography and geomorphology greatly changed, causing serious damage to the benthic benthic habitat. The automatic classification method of the bottom habitat of the reef area in this study is a trial in the field of acoustic exploration in the sea bottom, which is helpful to the scientific management of artificial reefs and is strong. A new technical means is provided for monitoring the evolution of the benthic habitat under the influence of human activities in the coastal waters.

【学位授予单位】：中国科学院烟台海岸带研究所
【学位级别】：博士
【学位授予年份】：2017
【分类号】：P714

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