Monitoring and modelling of hydrological processes in the semiarid region of Brazil: The Cariri experimental basins     

Vajapeyam S. Srinivasan  Hugo M. de Alcântara  Carlos de O. Galvão  Ulisses A. Bezerra  John E. de Brito Leite Cunha 《水文研究》2021,35(5):e14194

Catchments have highly variable yields of runoff and soil erosion. The size, land use and the surface cover play a significant role and influence the catchment response and parameter values of simulation models. Two experimental basins—the Cariri basins—were equipped in a semi-arid region of Brazil, for obtaining runoff and sediment yield at different catchment scales, as well as, to evaluate the influence of the land use and surface cover. In the first basin, located in the municipality of Sumé, the field studies were carried out at two different scales: four micro-catchments with an area of around 0.5 ha and nine standard Wischmeier-type erosion plots of 100 m². The experimental units had varied vegetation and management. They were subjected only to natural rainfall events, and were monitored from 1982 to 1991. The total runoff and total sediment yield were determined for each of the events. The installations in the second basin, in the municipality of São João do Cariri, from 1999, include two erosion plots, three micro-catchments, and two sub-catchments of a small basin. These basins are still being monitored for runoff and sediment production. Among the micro-catchments two are nested to detect any scale effect at the micro-catchment level. Nearly 600 events of precipitation, that produced runoff in at least one of the experimental units, have been registered. These data have been used to evaluate the influence of various factors, including cultivation practices and to calibrate hydrological models for plots and micro-catchments. Parameters have been tested by means of cross validations among micro-catchments and sub-catchments. The data sets are made available to all the catchment hydrology researchers and others at https://doi.org/10.5281/zenodo.4690886 .  相似文献   

Hydrological management strategies for the control of algal blooms in regulated lowland rivers     

Jian Li  Wei Yin  Haiyan Jia  Xiaokang Xin 《水文研究》2021,35(6):e14171

Reservoirs of lowland floodplain rivers with eutrophic backgrounds cause variations in the hydrological and hydraulic conditions of estuaries and low-dam reservoir areas, which can promote planktonic algae to proliferate and algal bloom outbreaks. Understanding the ecological effects of variations in hydrological and hydraulic processes in lowland rivers is important for algal bloom control. In this study, the middle and lower reaches of the Han River, China, a typical regulated lowland river with a eutrophic background, are selected. Based on the effect of hydrological and hydraulic variability on algal blooms, a hydrological management strategy for river algal bloom control is proposed. The results showed that (a) differences in river morphology and background nutrient levels cause significant differences in the critical threshold flow velocities for algal bloom outbreaks between natural river and low-dam reservoir sections; there is no uniform threshold flow velocity for algal bloom control. (b) There are significant differences in the river hydrological/hydraulic conditions between years with and without algal blooms. The average river flow, water level and velocity in years with algal blooms are significantly lower than those in years without algal blooms. (c) For different river sections where algal blooms occur and to meet the threshold flow velocities, the joint operation of cascade reservoirs and diversion projects is an effective method to prevent and control algal blooms in regulated lowland rivers. This study is expected to deepen our understanding of the ecological significance of special hydrological processes and guide algal bloom management in regulated lowland rivers.  相似文献   

苏北浅滩沉积物中的大型绿藻微观繁殖体的垂直分布和物种多样性   总被引：1，自引：0，他引：1  

刘峰  刘兴凤  金柘  于仁成  孔凡洲  颜天 《海洋与湖沼》2018,49(5):983-990

本研究通过在2017年秋冬季组织实施的2个绿潮种源调查航次,研究苏北浅滩紫菜养殖区沉积物中的大型绿藻微观繁殖体的垂直分布和物种多样性。对沉积物中的微观繁殖体的定量实验结果表明:表层泥样中绿藻微观繁殖体的丰度最高,随着深度的增加迅速降低。在9月份表层沉积物中丰度为9±2ind./g,而在11月份表层丰度达到98±25ind./g;与9月份相比, 11月份浅滩沉积物中绿藻繁殖体数量呈现出显著升高的趋势。通过对51个绿藻样品的分子鉴定发现:沉积物中存在石莼属(Ulva)、尾孢藻属(Urospora)、盘苔属(Blidingia)等大型绿藻的微观繁殖体;数量占优是石莼属繁殖体,主要包括曲浒苔(Ulva flexuosa)、浒苔(Ulva prolifera)、扁浒苔(Ulva compressa)、缘管浒苔(Ulva linza);其中曲浒苔占据的比例最高,在9和11月份分别达到80.94%和73.33%。在2个调查航次中,都从沉积物中发现了绿潮浒苔的微观繁殖体,这些微观繁殖体是绿潮浒苔在苏北浅滩种源维持的重要方式和关键阶段,也构成了黄海浒苔绿潮连年暴发的"种子库"。  相似文献   

太平洋深海沉积物来源的菌株Tenacibaculum sp.HMG1对孔雀石绿降解特性的研究     

曲武  洪国粦  赵晶 《海洋学报(英文版)》2018,37(6):104-111

本文在太平洋深海沉积物中分离得到一株孔雀石绿降解菌株，鉴定命名为Tenacibaculum sp.HMG1。通过菌株生长实验和高效液相色谱的研究表明， HMG1菌株可以在20 mg/L的孔雀石绿中维持较快的生长速率，并且在12 h内可降解98.8%的孔雀石绿，这证明该菌株具有很高的孔雀石绿耐受能力和降解活性。通过基因组测序在HMG1菌株发现一条过氧化物酶基因可能参与了孔雀石绿的降解，随后利用原核表达获得了相应的重组蛋白。实验表明，该重组过氧化物酶具有极强的活性，可在1000 mg/L的孔雀石绿中发挥降解功能。本文利用液相色谱-质谱联用（LC-MS）技术对孔雀石绿的菌株降解产物和重组酶降解产物进行鉴定，并基于鉴定结果推测了两种降解途径。结果发现两种降解方式存在共同的降解途径。此外，孔雀石绿降解条件的实验结果证明重组过氧化物酶可以在低温（20℃）、复杂的pH值（6.0–9.0）、高盐度（100 mmol/L）、金属离子和EDTA等反应条件下依旧维持很高的孔雀石绿降解活性。以上实验结果表明，HMG1菌株和重组过氧化物酶均在孔雀石绿污染生物修复方面具有很大潜力。  相似文献   

张力腿平台筋腱支撑浮筒结构设计研究     

王火平  金文学  吕东  范志峰  王立权 《海洋工程》2018,36(3):69-75

在张力腿平台筋腱与海底桩基连接后,需要筋腱支撑浮筒为筋腱提供足够的浮力,保证筋腱在平台运抵工作海域之前不会发生倾覆。针对南海油田自主研发的张力腿平台筋腱实际尺寸及设计要求,设计了适用于1 061 mm(40英寸)筋腱、500米水深的张力腿平台筋腱支撑浮筒,并对筋腱支撑浮筒主要受力进行了分析计算,根据所计算的载荷情况对关键部件进行了有限元仿真分析,验证了结构强度的可靠性,并得到了结构的应力集中点与最大变形点,为筋腱支撑浮筒的结构设计提供了参考。  相似文献   

Seafloor Geomorphology and Processes on the Western Continental Margin of India based on Multibeam Acoustic Backscatter Data Analysis     

Sumanta Dandapath  Andrew Menezes  Bishwajit Chakraborty  John Kurian  Koppella N. Prudhvi Raju 《Marine Geodesy》2018,41(2):177-200

An assessment of the multibeam sonar data of the central Western Continental Margins of India has been carried out to evaluate the seafloor geomorphology and processes by examining the geomorphological attributes e.g., slope, sediments, structures, etc. associated with geomorphic features. The variation in relief and the features located in the region have been mapped and interpreted collectively by utilizing several geospatial mapping tools. The backscatter strength across the area, apparently congruent with the local relief, has helped to examine the sediment movement on the seafloor. The prominent features found in the region include faults, pockmarks, mounds, submarine terraces, and submerged fossil reefs. Several areas with varying topography engender comparable fractal dimension at short scale breaks, and the probability density functions (PDFs) utilizing backscatter data depicting overlapping classes. The present study highlights how fractals and scale break parameters can be utilized to determine the seafloor processes and associated sedimentological dynamics in a complex geographical environment with strong bottom currents, seasonal upwelling, and faulted structure. The role and impact of the various geomorphic processes on the reworking of sediment movement and the overall progression of the seafloor morphology has been revealed for the first time in this part of the ocean bottom.  相似文献   

脐带缆螺旋滑移分析及力学性能研究   总被引：1，自引：0，他引：1  

李英  吴潘  冯雅萍  曹静萱 《海洋工程》2018,36(6):58-68

针对脐带缆内部螺旋层,应用Darboux标架建立螺旋结构空间坐标系,推导弯曲载荷下螺旋结构的局部变形和滑移。考虑螺旋构件间的接触和摩擦作用,建立螺旋结构的受力平衡偏微分方程,并研究螺旋角和摩擦系数对螺旋结构滑移的影响。基于同层螺旋结构本构关系相同假设,将所有螺旋结构力学性能线性叠加,拟合脐带缆整体弯曲刚度。运用建立的理论解析方法,对某双层铠装脐带缆的力学性能进行研究,并与数值模拟结果进行对比验证。对比结果表明,理论解析得到的螺旋滑移结果与数值模拟结果一致,理论解析得到的脐带缆弯曲刚度与数值模拟结果在全滑动阶段比较接近。  相似文献   

潮流界以下河段航道整治水位确定方法研究——以长江江阴以下河段为例     

徐元  贾雨少 《海洋工程》2018,36(2):64-72

在总结分析现有整治水位确定方法的基础上,根据潮流界以下河段的水沙运动特性,本文提出一种基于输沙能力的航道整治水位确定方法。考虑上游来水、下游潮汐为独立事件,统计潮流界以下河段上游来水、下游潮汐不同等级组合出现的频率,采用数学模型计算相应组合下河段沿程的潮位、流速过程,以流速四次方代表水流的输沙能力,统计不同潮位等级对应的综合净输沙能力,确定最大综合净输沙能力对应的水位为(最优)航道整治水位。以长江下游白茆沙水道和福姜沙水道为例,计算了所在河段的航道整治水位,并探讨了起动流速对整治水位计算的影响和最高整治水位概念对工程的意义。  相似文献   

Population connectivity of an overexploited coastal fish,Argyrosomus coronus (Sciaenidae), in an ocean-warming hotspot     

R Henriques  WM Potts  CV Santos  WHH Sauer  PW Shaw 《African Journal of Marine Science》2018,40(1):13-24

The West Coast dusky kob Argyrosomus coronus is a commercially exploited fish with a distribution confined to the Angola–Benguela Frontal Zone (ABFZ) of the southeastern Atlantic Ocean. A previous study revealed that during a recent period of local warming the species extended its distribution into Namibian waters, where it hybridised with the resident and congeneric Argyrosomus inodorus. Environmental changes are a major threat to marine biodiversity and when combined with overfishing have the potential to accelerate the decline of species. However, little is known regarding the evolutionary history and population structure of A. coronus across the ABFZ. We investigated genetic diversity, population structure and historical demographic changes using mtDNA control region sequences and genotypes at six nuclear microsatellite loci, from 180 individuals. A single, genetically homogeneous population was indicated across the distributional range of A. coronus (φ_ST = 0.041, F_ST = 0.000, D = 0.000; p > 0.05). These findings imply that the oceanographic features within the ABFZ do not appear to significantly influence population connectivity in A. coronus, which simplifies management of the species. However, reconstruction of the demographic history points to a close link between the evolutionary history of A. coronus and the environmental characteristics of the ABFZ. This outcome suggests the species’ vulnerability to the rapid environmental changes being observed across this region, and highlights a pressing need for transboundary management to mitigate the impacts of climate change in this global hotspot of seawater temperature changes.  相似文献   

基于分区间泛化Kriging近似模型的船舶局部结构形状优化     

张干锋  王德禹 《海洋工程》2018,36(6):46-57

为提高Kriging近似模型在船舶结构性能多维度响应预测方面的适用性,对常规Kriging近似模型进行分区间泛化改进:一是对设计样本点的各个维度(分量)进行划区,并在每一个分区间内采用最优拉丁超立方(OLhd)取样;二是引入比例系数w1组合高斯与指数型相关函数提高模型对数据的泛化能力,从而在每个划分的区间内建立泛化的Kriging近似模型。通过SCH测试函数,验证了构造的分区间泛化Kriging模型有效性。结合参数化建模和改进Kriging近似模型对某过渡肘板和舱口角隅边界进行形状优化,优化第一阶段由改进的近似模型通过多岛遗传算法得到全局初步的最优解,第二阶段在初步解的基础上缩小优化变量范围,由少量的FEM计算即可在小范围内搜寻到精确的最优设计变量。结果表明:分区间泛化Kriging近似模型在预测多维度响应时较常规Kriging模型预测精度更高;分阶段的形状优化流程在保证极小误差和缩小计算成本的情况下能够得到理想的应力分布和重量优化结果,有助于船舶结构的轻量化研究。  相似文献