Morphodynamics of an Artificial Cobble Beach in Tianquan Bay,Xiamen, China

By tracking and monitoring the profile configuration, topography, and hydrodynamic factors of an artificial cobble beach in Tianquan Bay, Xiamen, China over three consecutive years after its completion, we analyzed the evolution of its profile configuration and plane morphology, and its storm response characteristics. The evolution of the profile configuration of the artificial cobble beach in Tianquan Bay can be divided into four stages. The beach was unstable during the initial stage after the beach nourishment the profile configuration changed obviously, and an upper concave composite cobble beach formed gradually, which was characterized by a steep upper part and a gentle lower part. In the second stage, the cobble beach approached dynamic equilibrium with minor changes in the profile configuration. At the third stage the beach was in a high-energy state under the influence of Typhoon Meranti, and the response of the artificial cobble beach differed significantly from that of the low-tide terrace sandy beach. Within a short time, there was net onshore transport of cobbles in the cross-shore direction. The beach face was eroded, the beach berm was accumulated, and the slope of the beach was steepened considerably. In the alongshore direction, there was notable transport of cobbles on the beach from east to west along the shore, and the total volume of the beach decreased by 4.5×103 m~3, which accounted for 50% of the total amount of beach volume lost within three years. The fourth stage was the restoration stage after the typhoon, characterized by a little gentler profile slope and the increase in width and the decrease in height of beach berm. Because of the action of waves and the wave-driven longshore current caused by the specific terrain and landform conditions along the coast(e.g., coastal headlands, near-shore artificial structures, and reefs), the coastline of the artificial cobble beach gradually evolved from being essentially parallel to the artificial coast upon completion to a slightly curved parabolic shape, and three distinct erosion hotspots were formed on the west side of the cape and the artificial drainpipe, and the reefs. Generally, the adoption of cobbles for beach nourishment on this macro-tidal coast beach with severe erosion has yielded excellent stability and adaptability.     

Mechanism of toppling and deformation in hard rock slope: a case of bank slope of Hydropower Station,Qinghai Province,China

Recently, various toppling slopes have emerged with the development of hydropower projects in the western mountainous regions of China. The slope on the right bank of the Laxiwa Hydropower Station, located on the mainstream of the Yellow River in the Qinghai Province of Northwest China, is a typical hard rock slope. Further, its deformation characteristics are different from those of common natural hard rock toppling. Because this slope is located close to the dam of the hydropower station, its deformation mechanism has a practical significance. Based on detailed geological engineering surveys, four stages of deformation have been identified using discrete element numerical software and geological engineering analysis methods, including toppling creep, initial toppling deformation, intensified toppling deformation, and current slope formation. The spatial and time-related deformation of this site also exhibited four stages, including initial toppling, toppling development, intensification of toppling, and disintegration and collapse. Subsequently, the mechanism of toppling and deformation of the bank slope were studied. The results of this study exhibit important reference value for developing the prevention–control design of toppling and for ensuring operational safety in the hydropower reservoir area.     

基于云模型的海岸脆弱性评估 ——以厦门岛为例

脆弱性评估很大程度上存在着模糊性和随机性,为有效解决评估过程中定性概念与评估指标按隶属函数定量描述这一不确定转换问题,本文基于云理论本文选取海岸地貌、海岸高程、海岸坡度、海岸缓冲能力、有效波高、道路价值和建筑价值为指标,构建了厦门岛海岸脆弱性评估指标体系,运用云模型评估手段定量测度了厦门岛海岸脆弱性空间分异特征。评估结果与客观情况比较吻合,检验了指标体系的合理性和评估模型的适用性。本文提出了海岸脆弱性综合评估模型,实用有效,可以推广到与厦门岛类似的区域,为海岸管理及规划提供科学指导。     

基于层次分析法的南麂列岛海域人工鱼礁社会效果评价

人工鱼礁建设具有生态效果、经济效果和社会效果。为科学指导人工鱼礁的建设方向,进一步促进海洋牧场建设以及海洋渔业资源和海洋生态环境的可持续发展,文章采用改进的层次分析法,从人工鱼礁与社会的适应性、对社会环境的影响、对社会生活的影响以及对其他行业发展的影响4个方面,选取政策符合性等10个评价指标,通过问卷调查的方式,对南麂列岛海域人工鱼礁的社会效果进行评价,填补该研究领域的空白。研究结果表明:根据各评价指标的权重和效果判定值,南麂列岛海域人工鱼礁产生了较好的社会效果,其中海洋生态环境、项目长远性、改善渔民生活质量和海洋捕捞业等指标发挥作用较大;未来将开展长期和连续的调查研究,提高评价可信度。     

气候变化背景下海南东寨港红树林生态系统的脆弱性评估

鉴于红树林生态系统对气候变化背景下海平面上升和极端台风事件有高度敏感性,应用1980—2018年的海洋大气观测资料和实地调查数据,分析了海口东寨港地区的海平面、温度和台风最大风速的变化特征,并基于IPCC气候变化综合风险的理论框架,构建了"暴露度-敏感性-适应性"的脆弱性评价指标体系和估算方法,评估了海平面上升和台风事件背景下东寨港红树林生态系统的脆弱性主要特征。结果显示:①东寨港红树林生态系统的致灾影响因子主要为该地区沿海海平面的快速上升,其上升速率可达4. 6 mm/a,远高于全球和中国沿海平均值;其次为1993年之前和2006年之后,在海口地区250 km范围内出现的热带气旋或台风事件;②东寨港红树林脆弱性指数的平均值为0. 31,属于中度脆弱等级,其中三江片区的红树林脆弱性相对最高,演丰片区最低。构建的评价指标体系可较好地反映出海平面快速上升和热带气旋或台风影响下红树林生态系统的脆弱性特征。     

Spatio-temporal variability of small fishes related with environmental factors in a typical domestic tap water lake,Eastern China

The knowledge of prey small ?sh stock, distribution and abundance is necessary to guide stocking of piscivorous ?sh for the biomanipulation in domestic tap water lakes. This study describes the current status of small ?sh community in Kuilei Lake(China), and examines the spatial and seasonal variations of the community in relation to key environmental factors. Based on submerged macrophyte cover and water depth, the lake was divided into ?ve major habitats:(1) macrophyte covered shallow habitat of water depth< 2.00 m,(2) uncovered or less-covered shallow habitat(2.00 m–3.50 m),(3) uncovered medium shallow habitat(3.50 m–5.00 m),(4) uncovered medium deep habitat(5.00 m–6.50 m) and(5) uncovered deep habitat(6.50 m–8.50 m). The abundance and composition of small ?sh were monitored by benthic fykenet sampling from April 2013 to January 2014. A total of 2881 individuals belonging to 5 families and 21 species were collected. Based on their abundance(accounted for 88.96% of the total) and occurrence(more than 33.33%), Acheilognathus chankaensis, Acheilognathus macropterus, Microphysogobio microstomus,Pseudorasbora parva and Rhinogobius giurinus were recognized as dominant small ?sh species. The results of correlation analysis identi?ed that species richness( Sr), Shannon-Wiener diversity index( H′)and Margalef′s richness index( D) were signi?cantly negatively correlated with water depth, but positively correlated with biomass of submerged macrophytes.Redundancy analysis(RDA) revealed that the spatial distributions of most small ?shes were negatively associated with water depth. The details of these ?ndings are bene?cial to understanding the adaptation of the small ?shes in degraded environments, and to developing suitable biomanipulation strategies for the management of ?sh resources and water quality in the lakes along the lower reach of the Changjiang(Yangtze) River basin.     

新工科理念下的实验课程教学改革与实践探索

近年来为适应创新人才的培养,"卓越计划"开启了全新教学模式。基于新工科理念,为了更好地进行实验课程教学,以"3ds Max软件三维建模"为例,笔者从课程内容安排、教学方式、考核机制等方面进行了教学探索和实践。本文以应用软件实验类课程项目教学的实践经验为基础,注重学生团队合作和交流能力、实践能力、创新能力培养,以及多渠道快速学习新事物的能力,通过与测绘新技术下多软件融合,使学生拥有知识整合能力,为提高实践教学提供参考和借鉴,以更好地适应新工科理念下的创新人才培养。     

An improved building detection approach using L-band POLSAR two-dimensional time-frequency decomposition over oriented built-up areas

The objective of this study is to efficiently extract detailed information about various man-made targets in oriented built-up areas using polarimetric synthetic aperture radar (POLSAR) images. This paper develops an improved approach for building detection by utilizing Two-Dimensional Time-Frequency (2-D TF) decomposition. This method performs outstandingly in distinguishing between man-made and natural targets based on the isotropic behaviors, frequency-sensitive responses, and scattering mechanisms of objects. The proposed method can preserve the spatial resolution and exploit the advantages of TF decomposition; specifically, the exact outlines of buildings can be effectively located, and more types of features (e.g., flat roofs, roads, and walls that are oblique to the radar illumination) can be distinguished from forests in complex built-up areas by 2-D TF decomposition. The coarser-resolution subaperture images that are produced in the azimuth direction, which correspond to different looking angles, are beneficial for detecting man-made structures with main scattering centers oriented at oblique angles with respect to the radar illumination. In the range direction, the obtained subaperture images, which correspond to various observation frequencies, can be helpful in distinguishing flat roofs and roads from forests. This method was successfully implemented to analyze both NASA/JPL L-band AIRSAR and L-band EMISAR data sets. The building detection results of the proposed method exhibit a significant improvement over those of other methods and reach an overall accuracy over 80%, with approximately 20% higher than the accuracies of K-means clustering and the entropy/alpha-Wishart classifier and approximately 10% higher than the accuracy of the support vector machine method. Moreover, building details can be precisely detected, obliquely oriented buildings can be identified, and the distinction between buildings and forests is significantly improved, as both visually and statistically indicated. This method is highly adaptable and has substantial application value.     

基于面片裁切技术的点云轮廓线生成算法

随着点云在各个领域的广泛应用,对点云处理相关技术的研究更为活跃。目前,研究的热点主要集中在点云去噪、配准、分割、增强、特征提取和重建等方面。其中,特征提取起着承前启后的作用,具有十分重要的研究价值。基于面片裁切技术的点云轮廓线生成算法。首先,对点云数据进行面片提取,通过面片生长、融合生成特征面片,并根据提出的面片双向索引法快速构造特征线,最终实现点云平面轮廓线的生成。实验证明,本算法可快速、准确、有效地实现点云轮廓线的生成。