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.     

Spatial variation of the relationship between transport accessibility and the level of economic development in Qinghai-Tibet Plateau,China

As an important component of China' transportation systems, for a long time, the insufficient performance of transport in QinghaiTibet Plateau(QTP) was a bottleneck restricting the economic growth and social development in this area. Nevertheless, the implementation of the western development strategy has accelerated the preliminary construction of comprehensive transport network since 2000. Due to the large area and significant geographical heterogeneity, there is a growing need to understand the relationship between transportation and economic development based on the perspective of spatial difference. By using GIS-based raster analysis and Geographically Weighted Regression(GWR) model, we investigated the spatial-temporal distribution of highway, railway and airport accessibility, respectively, and estimated the correlation and heterogeneity between transport accessibility and the level of economic development. Results revealed that:(1) Transport accessibility in the QTP improved by 53.38% in the past 15 years, which is specifically embodied in the improvement of both highway and railway.(2) Accessibility presented prominent differentiation in the space, increasing from west to east and reducing with the rise of elevation, specifically, the best accessibility area of the highway is below 4000 m above sea level, while the area with an altitude of over 4000 m has the lowest aviation time cost.(3) In general, the long weighted average time cost to critical transport facilities posed significantly negative effect on county economic growth in QTP, more positively, the adverse effect gradually weakened over time.(4) Obvious heterogeneity exists at the influence of different transport accessibility factors on the level of economic development, reflecting both in the horizontal space and altitudinal belt. Therefore, region-specific policies should be addressed for the sustainable development of transport facilities as well as economy in the west mountain areas.     

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。     

VIIRS/DNB夜间灯光月度产品插补方法对比——以北京为例

新一代VIIRS/DNB(Visible Infrared Imaging Radiometer Suite Day/Night Band)夜间灯光数据因其具备更精细的时空分辨率、数据不存在饱和现象、不同年份数据可比性强等优点而迅速代替DMSP/OLS(Defense Meteorological Satellite Program's Operational Linescan System)夜间灯光数据成为新的研究热点。但由于杂散光的污染,VIIRS/DNB夏季数据数值缺失严重,致使数据在空间和时间上不连续,因此,插补缺失数据成为后续应用的前提。鉴于此,论文从插补结果异常值、与参照值对比、计算性能三个方面,系统比较了三次样条插值(样条)、三次Hermite插值(Hermite)、灰色预测模型(GM)、三次指数平滑法(指数)4种插补方法的适用性,以期为插补VIIRS/DNB夜间灯光数据提供方法选择的依据。研究结果表明：①异常值比较方面,Hermite法未出现异常值,另外3种算法仅出现少量异常值(0.02%~1.34%);②与参照值的对比方面,Hermite法与参考值接近程度最高,GM接近程度最低,样条法和指数法介于两者中间;③算法性能比较方面,4种方法都具备计算简单、容易编程的特点,但指数法的算法时长是另外3种方法的10倍以上。因此,综合多方表现,当插补月份前后两侧均有足够长的原始数据时,插补效果好、计算速度快、不会出现过冲现象的Hermite法最适宜,样条法次之;当插补月份仅单侧有足够长的数据时,适宜采用指数法(插补效果好、计算速度较慢)或GM(插补效果偏低、计算速度快)进行插补。     

基于扎根理论与文本分析的海洋旅游目的地意象研究

旅游目的地意象在旅游者决策与目的地开发中具有重要作用,也是旅游研究中的热点领域。海洋旅游目的地意象的研究对于提高目的地竞争力与吸引力具有重要意义。本文以夏威夷为例,基于国内旅游者发布在网络上的游记,利用扎根理论与文本分析法对夏威夷的认知意象、情感意象与总体意象进行分析。研究发现,“海洋自然吸引物”、“海洋人文吸引物”、“海洋旅游活动”、“目的地软环境”、“旅游服务”、“公共场所与服务”是构成海洋旅游目的地认知意象的六个主范畴;在此基础上,通过提取游记中的情感语句并结合“情感环状模型”发现夏威夷的情感意象以正面情感为主;从语义网络与重游意愿来看,夏威夷的总体意象较为积极,并未出现明显的负面感知要素。研究旨在为国内海洋旅游目的地的发展提供一定的经验与借鉴。     

基于深度学习的钨钼找矿靶区预测方法研究

随着矿产勘查工作由浅部矿向深部隐伏矿、由易识别矿向难识别矿发展,找矿难度日益增大,地质专家越来越重视新理论、新方法、新技术的应用。深度学习作为人工智能的前沿领域/技术,对于实现矿产资源预测“智能化预测评价”具有得天独厚的优势。本文以陕西省镇安县西部钨钼矿集区单元素化探异常原始数据为基础,提出了基于深度学习的钨钼矿产评价方法。该方法以归一化地球化学数据作为模型训练数据,通过深度学习中深度自编码网络方法实现异常值提取进而识别重点成矿有利地段,实现矿产资源找矿远景区定性预测。研究结果表明,在对957条单元素化探异常原始数据分类且做好模型标签后,整个过程在计算机的“黑盒子”中自动完成学习和预测,相较于传统预测研究方法,本文方法具有自动化程度高和客观性强的特征。此外,本文利用已知矿点构建训练数据集,采用随机森林方法对预测区进行矿产资源找矿靶区预测圈定,为进一步缩小找矿靶区范围提供科学依据。