Application of Web-GIS and Geovisual Analytics to Monitoring of Seabed Evolution in South Baltic Sea Coastal Areas     

Marcin Kulawiak  Andrzej Chybicki 《Marine Geodesy》2018,41(4):405-426

Regular surveys of coastal zone seabed deliver important information about geomorphologic processes such as silting of waterways. The recent introduction of the Sentinel series of sensors has allowed for the use of satellite sensing for shallow bathymetry morphology monitoring. In this context, this article presents a dedicated Geographic Information System for Baltic Sea shallow water depth monitoring on the basis of Sentinel-2 imagery. The system employs Geovisual Analytics for differential analysis of bathymetry changes as well as monitoring the visibility of known wrecks in the coastal waters of Southern Baltic Sea. Results are verified with regard to known changes in shallow water bathymetry between 28 June 2015 and 3 March 2017.  相似文献   

The Limiting Factor to the Outbreak of Lake Black Bloom: Roles of Ferrous Iron and Sulfide Ions          下载免费PDF全文

Qiushi Shen  Chengxin Fan  Cheng Liu  Chao Chen 《洁净——土壤、空气、水》2018,46(9)

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Subaquatic slope instabilities: The aftermath of river correction and artificial dumps in Lake Biel (Switzerland)     

Nathalie Dubois  Love Råman Vinnå  Marvin Rabold  Michael Hilbe  Flavio S. Anselmetti  Alfred Wüest  Laetitia Meuriot  Alice Jeannet  Stéphanie Girardclos 《Sedimentology》2020,67(2):971-990

River engineering projects are developing rapidly across the globe, drastically modifying water courses and sediment transfer. Investigation of the impact of engineering works focuses usually on short-term impacts, thus a longer-term perspective is still missing on the effects that such projects have. The ‘Jura Water Corrections’ – the largest river engineering project ever undertaken in Switzerland – radically modified the hydrological system of Lake Biel in the 19th and 20th Century. The deviation of the Aare River into Lake Biel more than 140 years ago, in 1878, thus represents an ideal case study to investigate the long-term sedimentological impacts of such large-scale river rerouting. Sediment cores, along with new high-resolution bathymetric and seismic reflection datasets were acquired in Lake Biel to document the consequences of the Jura Water Corrections on the sedimentation history of Lake Biel. Numerous subaquatic mass transport structures were detected on all of the slopes of the lake. Notably, a relatively large mass transport complex (0·86 km²) was observed on the eastern shore, along the path of the Aare River intrusion. The large amount of sediment delivered by the Aare River since its deviation into the lake likely caused sediment overloading resulting in subaquatic mass transport. Alternatively, the dumping since 1963 in a subaquatic landfill of material excavated during the second phase of river engineering, when the channels flowing into and out of Lake Biel were widened and deepened, might have triggered the largest mass transport, dated to 1964 or 1965. Additional potential triggers include two nearby small earthquakes in 1964 and 1965 (M_W 3·9 and 3·2, respectively). The data for this study indicate that relatively large mass transports have become recurrent in Lake Biel following the deviation of the Aare River, thus modifying hazard frequency for the neighbouring communities and infrastructure.  相似文献   

Removal of water‐surface reflection effects with a temporal minimum filter for UAV‐based shallow‐water photogrammetry          下载免费PDF全文

I GD Yudha Partama  Ariyo Kanno  Motoyasu Ueda  Yoshihisa Akamatsu  Ryutei Inui  Masahiko Sekine  Koichi Yamamoto  Tsuyoshi Imai  Takaya Higuchi 《地球表面变化过程与地形》2018,43(12):2673-2682

The recent development of structure‐from‐motion (SfM) and multi‐view stereo (MVS) photogrammetry techniques has enabled semi‐automatic high‐resolution bathymetry using aerial images taken by consumer‐grade digital cameras mounted on unmanned aerial vehicles (UAVs). However, the applicability of these techniques is sometimes limited by sun and sky reflections at the water surface, which render the point‐cloud density and accuracy insufficient. In this research, we present a new imaging technique to suppress the effect of these water‐surface reflections. In this technique, we order a drone to take a short video instead of a still picture at each waypoint. We then apply a temporal minimum filter to the video. This filter extracts the smallest RGB values in all the video frames for each pixel, and composes an image with greatly reduced reflection effects. To assess the performance of this technique, we applied it at three small shallow‐water sites. Specifically, we evaluated the effect of the technique on the point cloud density and the accuracy and precision of the photogrammetry. The results showed that the proposed technique achieved a far denser point cloud than the case in which a randomly chosen frame was used for each waypoint, and also showed better overall accuracy and precision in estimating water‐bottom elevation. The effectiveness of this new technique should depend on the surface wave state and sky radiance distribution, and this dependence, as well as the applicability to large areas, should be investigated in future research. Copyright © 2018 John Wiley & Sons, Ltd.  相似文献   

Managing land-use effects on Northland dune lakes: lessons from the past     

Tom Stephens  Paul Augustinus  Brett Rip  Patricia Gadd  Atun Zawadski 《新西兰海洋与淡水研究杂志》2018,52(3):409-429

The Northland region of New Zealand includes numerous high-value, macrophyte-dominated dune lakes. Recent water policy reforms offer limited guidance on managing for aquatic macrophytes. In addition, dune lake histories are poorly known as regular monitoring dates to 2005 AD. Here, ca. 4000 years of lake functional behaviour is reconstructed from sedimentary archives in two Northland dune lakes (Humuhumu and Rotokawau). Results demonstrated that macrophyte dominance is sensitive to catchment erosion and hydrological drawdown. Degradation of macrophyte communities occurred in the nineteenth and twentieth centuries, earlier at Lake Humuhumu than Lake Rotokawau (post-1880 AD and post-1930 AD, respectively). In both lakes, increased erosional influx reduced macrophyte productivity, before later increases to wider trophic state (post-1970 AD). Lake-level decline is linked to increased nutrient loading at Lake Rotokawau but less so, Lake Humuhumu which is more strongly groundwater-fed. In Northland dune lakes, water-level reduction and erosional influx from land use have driven macrophyte degradation.  相似文献   

南海北部陆坡深水区浅层天然气藏特征     

钟广见  张如伟  易海  冯常茂  赵忠泉 《热带海洋学报》2018,37(3):80-85

南海北部陆坡深水区的浅层天然气藏是一种伴随天然气水合物的新型油气藏, 具有埋藏浅、规模大的特点, 其埋藏深度一般小于300m。浅层天然气藏由深部裂解气沿断裂上升被天然气水合物封盖而形成, 识别似海底反射(BSR)是寻找浅层天然气藏有效方法。浅层天然气藏的气源主要有热解气、生物气和混合气, 陆坡张性断裂是气体运移的主要通道, 水合物下部的砂层是浅层天然气藏的主要储集层, 水合物层则是封盖层。从南海发现的天然气水合物分布特征看, 浅层天然气藏在陆坡深水区广泛分布且气藏厚度大, 潜在资源量非常可观, 是一种新型的开采成本相对低廉的油气藏。  相似文献   

柴达木盆地尕斯库勒盐湖区盐生植物吸盐效应及其耐盐性评价<sub><sup> </sup></sub>          下载免费PDF全文

余冬梅  祁兆鑫  胡夏嵩  刘亚斌  杨幼清  李淑霞 《盐湖研究》2020,28(1)

本项研究选取柴达木盆地尕斯库勒盐湖区作为研究区,筛选出了9种优势盐生植物,开展了盐生植物生长区土体颗粒、容重、含水量等物理性质指标,以及土体中HCO<sub>3</sub><sub><sup>-</sup></sub>、Cl<sub><sup>-</sup></sub>、SO<sub>4</sub><sub><sup>2-</sup></sub>、K<sub><sup>+</sup></sub>、Na<sub><sup>+</sup></sub>、Ca<sub><sup>2+</sup></sub>和Mg<sub><sup>2+ </sup></sub>7种易溶盐离子含量试验测试,分析了区内芦苇、海韭菜等9种盐生植物茎叶和根系部分HCO<sub>3</sub><sub><sup>-</sup></sub>、Cl<sub><sup>-</sup></sub>等7种易溶盐离子含量及其分布规律。在此基础上,探讨了区内9种盐生植物对易溶盐离子吸收作用及其差异性；采用盐生植物地上茎叶部分K<sub><sup>+</sup></sub>/Na<sub><sup>+</sup></sub>值结果,定量评价了区内9种盐生植物耐盐性及变化规律,结果表明,区内9种盐生植物茎叶部分K<sub><sup>+</sup></sub>/Na<sub><sup>+</sup></sub>比值,其由大至小依次为：小花棘豆0.84、羊齿天门冬0.58、白刺0.55、盐地风毛菊0.52、海韭菜0.50、无脉苔草0.47、洽草0.41、芦苇0.39和赖草0.34。本项研究结果,利用为尕斯库勒湖区及其周边地区,利用盐生植物有效改良土壤盐渍化方面提供理论支撑。  相似文献   

哈达贺休盐湖卤水氢氧同位素特征及成因分析          下载免费PDF全文

马正明  山发寿  姜盼武  李庆宽  魏海成  李永寿 《盐湖研究》2020,28(1)

内蒙古哈达贺休盐湖蕴藏着较为丰富的地下卤水资源，但人们对其成因和演化机制尚缺乏充分的认识。本文采用稳定同位素方法，研究了哈达贺休盐湖地下卤水及其周边水体的氢氧同位素组成特征，并对卤水的成因进行了分析。结果表明：哈达贺休盐湖地下卤水的?D和?18O值平均值分别为-0.53 ‰和4.01 ‰，黑河河水的?D和?18O值平均值分别为-36.73 ‰和-5.51 ‰，居延海湖水的?D和?18O值平均值分别为1.26 ‰和2.73 ‰，当地大气降水的?D和?18O值平均值分别为-5.30 ‰和-1.20 ‰。研究区水体的蒸发趋势线方程为δD=5.32δ18O-20.08，该蒸发线偏离全球大气降水线。黑河河水的氘盈余值（d）最大，湖水和地下卤水的最小，而且湖水和卤水的d值与TDS呈负相关关系。偏正的?D和?18O值以及较小的d值，表明研究区卤水经历了强烈的蒸发，同时还存在与含氧类矿物的同位素交换反应。卤水和居延海湖水氢氧同位素值分布比较集中并且接近，二者都由黑河河水演化而来。  相似文献   

艾比湖原核微生物菌群结构演变与环境因子关系分析          下载免费PDF全文

马雪莉  吕杰  马媛  吕光辉 《盐湖研究》2020,28(4):79-90

用非培养法获得新疆维吾尔自治区艾比湖湖底沉积物原核微生物菌群组成,并与已有盐湖原核微生物菌群数据进行比对,分析湖泊由淡水湖向盐湖演替过程中原核微生物群落结构变化规律。实验获得艾比湖原核微生物16S rRNA基因序列,并从NCBI数据库下载赛里木湖、柴窝堡湖和顿巴斯他乌盐湖3个湖泊的非培养原核微生物16S rRNA基因序列数据。用不同盐湖细菌和古菌16S rRNA序列信息构建系统发育树并与其理化指标进行典型性相关分析。同源比对及聚类结果显示,艾比湖湖底沉积物中细菌包括4个门,拟杆菌门(Bacteroidetes)占克隆文库的64%,变形菌门(Proteobacteria)占9.4%,厚壁菌门(Firmicutes)占3.4%,放线菌门(Actinobacteria)占2.6%,此外含有未分类类群20.6%。古菌含有两个门,广古菌门(Euryarchaeota,98.3%)和盐纳古菌门(Nanohaloarchaeota,1.7%)。不同盐湖系统发育树结果显示,随盐度增加,盐湖细菌从变形菌门向拟杆菌门演替；古菌从奇古菌门和泉古菌门向广古菌门和盐纳古菌门演替。RDA结果显示,Na⁺、Cl-、SO₄2-和矿化度对盐湖原核微生物多样性结构起到决定性的作用,K⁺、Mg²⁺和Ca²⁺对艾比湖菌群结构影响作用最为显著。原核微生物群落会随着湖水盐浓度的增加和盐湖化学成分的不同而发生演替。  相似文献   

利用盐湖常见元素的助烧结作用绿色制备氧化镁及磷酸镁水泥          下载免费PDF全文

李颖  董金美  肖学英  郑卫新  文静  常成功 《盐湖研究》2020,28(2):15-25

低活性氧化镁是制备磷酸镁水泥(MPC)的关键原材料。现行低活性氧化镁的生产方式导致了制备MPC具有能耗高和成本高的缺点,不利于其推广应用。利用盐湖中常见元素如B,Na、K和Cl的助烧结作用,在≤1 200℃煅烧盐湖提锂镁渣、外掺B的轻烧镁粉和水氯镁石的热解产物制备低活性氧化镁。介绍了低活性氧化镁的粒径、比表面积、孔隙率、化学组成、矿物组成和形貌等物理特征,以及低活性氧化镁制备MPC的凝结时间、水化产物、微观结构、抗压强度、体积稳定性等凝结硬化性能,并分析了烧结温度对低活性氧化镁的理化性能及MPC的凝结硬化性能的影响。相比现有技术,利用盐湖共存元素的助烧结作用可将氧化镁的烧结温度由1 500～1 800℃降低到1 200℃以下,有利于实现低活性氧化镁及MPC的低能耗、低成本绿色制备,促进MPC的推广应用。  相似文献