海洋资源环境承载能力监测预警指标体系和技术方法示范性验证及修改建议——以天津市汉沽海域为例          下载免费PDF全文

马玉艳  张秋丰  陈燕珍  屠建波  孙欢  薄文杰  高文胜 《海洋开发与管理》2018,35(11):52-60

文章采用《海洋资源环境承载能力监测预警指标体系和技术方法指南(草案稿)》(以下简称《技术指南》)开展了天津汉沽海域海洋资源环境承载能力评估试点研究与示范性验证,验证了《技术指南》中指标体系、评估阈值与评估方法的适用性,根据验证结果提出了相应的修改建议。建议:一是调整海洋空间资源承载能力影响因子;二是海洋环境承载状况建议以区域近10年水质达标率最大值作为可载的判断标准并增加沉积物综合污染指数;三是海洋生态承载状况指标建议采用游泳动物生物量指标,增加浮游生物、底栖生物指标并建议以区域10年平均值为基准;四是生态环境风险状态考虑赤潮面积;五是指标权重值确定建议采用层次分析法。综合考虑生态系统的完整性以及区域特点重新构建了天津汉沽海域海洋资源环境承载能力评估模型,该模型得出的评估结果总体上略好于《技术指南》。上述研究成果可为进一步完善国家海洋资源环境承载能力监测预警工作提供技术支撑。  相似文献   

国家应急测绘保障能力建设项目总体技术设计   总被引：2，自引：1，他引：1  

赵勇  武昊  王中祥  朱杰 《测绘通报》2019,(9):121-127

我国是自然灾害多发国家，给人们生命、财产安全造成了极大威胁。应急测绘是我国突发事件应急体系和综合防灾减灾工作体系的重要组成部分。近年来，应急测绘装备和技术水平取得了巨大进展，构建规模化、协同化、覆盖全国的应急测绘保障能力已成为应急测绘保障工作的必然趋势。本文针对应急测绘保障工作的特点，分析了应急测绘业务流程和数据流程，提出了国家应急测绘保障能力建设的总体架构、建设内容设计和系统接口设计，讨论了项目建设的预期效果和下一步努力方向。相关研究可为进一步做好应急测绘保障工作的顶层设计、加强科学统筹工作奠定基础。  相似文献   

Rainfall interception in a lower montane forest in Ecuador: effects of canopy properties     

Katrin Fleischbein  Wolfgang Wilcke  Rainer Goller  Jens Boy  Carlos Valarezo  Wolfgang Zech  Klaus Knoblich 《水文研究》2005,19(7):1355-1371

Rainfall interception in forests is influenced by properties of the canopy that tend to vary over small distances. Our objectives were: (i) to determine the variables needed to model the interception loss of the canopy of a lower montane forest in south Ecuador, i.e. the storage capacity of the leaves S and of the trunks and branches S_t, and the fractions of direct throughfall p and stemflow p_t; (ii) to assess the influence of canopy density and epiphyte coverage of trees on the interception of rainfall and subsequent evaporation losses. The study site was located on the eastern slope of the eastern cordillera in the south Ecuadorian Andes at 1900–2000 m above sea level. We monitored incident rainfall, throughfall, and stemflow between April 1998 and April 2001. In 2001, the leaf area index (LAI), inferred from light transmission, and epiphyte coverage was determined. The mean annual incident rainfall at three gauging stations ranged between 2319 and 2561 mm. The mean annual interception loss at five study transects in the forest varied between 591 and 1321 mm, i.e. between 25 and 52% of the incident rainfall. Mean S was estimated at 1·91 mm for relatively dry weeks with a regression model and at 2·46 mm for all weeks with the analytical Gash model; the respective estimates of mean S_t were 0·04 mm and 0·09 mm, of mean p were 0·42 and 0·63, and of mean p_t were 0·003 and 0·012. The LAI ranged from 5·19 to 9·32. Epiphytes, mostly bryophytes, covered up to 80% of the trunk and branch surfaces. The fraction of direct throughfall p and the LAI correlated significantly with interception loss (Pearson's correlation coefficient r = −0·77 and 0·35 respectively, n = 40). Bryophyte and lichen coverage tended to decrease S_t and vascular epiphytes tended to increase it, although there was no significant correlation between epiphyte coverage and interception loss. Our results demonstrate that canopy density influences interception loss but only explains part of the total variation in interception loss. Copyright © 2004 John Wiley & Sons, Ltd.  相似文献   

分层P2P系统中基于簇缓存的节点选择策略   总被引：1，自引：1，他引：0  

唐瑞春  刘斌  徐仕儒 《中国海洋大学学报(自然科学版)》2010,40(1)

研究P2P流媒体点播中普遍存在的启动时间长、传输抖动大的问题,提出了1种基于簇缓存的节点选择策略.通过在簇内缓存节点的查询记录和部分媒体块,并在带宽优先的基础上,结合节点寿命进行资源节点选择,降低播放抖动率.仿真实例说明了该策略的有效性.  相似文献   

Contaminant transport and biodegradation in saturated porous media: model development and simulation     

Song‐Bae Kim 《水文研究》2005,19(20):4069-4079

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Measured and calculated spudcan penetration profiles for case histories in sand-over-clay     

《Applied Ocean Research》2019

This paper reports five case histories of jack-up rig installation in layered soil profiles where a dominate feature was a stronger sand layer overlaying a weaker clay layer. In all cases a relatively continuous load-penetration profile was measured during installation of each of the three spudcan foundations. Summary site-investigation data is provided and consisted of mainly torvane, minature vane, unconsolidated undrained triaxial and pocket penetrometer tests for determining undrained shear strength of the clays and blow counts for deriving the relative density of sand. A statistical averaging method recommended in the InSafeJIP guidelines was used to provide the best fit of the undrained shear strength profile in the clay as this then allowed for spudcan load-penetration profiles to be estimated without introduction of user interpretation or bias. Sand properties were taken as provided in the original site-investigation report. Comparisons between load-penetration profiles calculated using the industry-standard ISO guideline, more recently proposed mechanism-based calculation method and three-dimensional large deformation finite element simulations are made with the measured data, leading to valuable insights for practitioners for estimating behaviour of jack-up installations in problematic sand-over-clay soil profiles.  相似文献   

Evaluating the effectiveness of road‐crossing drainage culverts in ephemeral streams     

C. Conesa‐García  R. García‐Lorenzo 《水文研究》2013,27(12):1781-1796

The present study proposes a method for evaluating the effectiveness of road‐crossing drainage culverts in ephemeral streams. This approach is focused on estimating the culvert capacity in road–stream crossings and the probable runoff generated on the road from hydrological thresholds associated with hydromorphological criteria. In particular, discharges at bankfull and flood‐prone stages have been used in combination with 2.5 and 100‐year peak discharges. Different hydraulic variables have been considered for calculating the discharge through culverts under these conditions (e.g. tailwater and headwater depth, inlet control, pipe roughness, pipe cross‐area and slope, pipe outlet velocity, critical water depth, and flow rate over the road). Geomorphological factors such as bed stability, bed load transport, and channel roughness have also been considered because of their potential for obstructing the drains in this type of channel. In addition, a potential obstruction index (PI_OBSTR) has been calculated, as a dependent parameter of the obstacle index (I_OBST) and the potential build‐up of coarse sediments (PB_CS). The study has been carried out on the Mediterranean coast in the region of Murcia (Spain), where there are numerous examples of road–stream crossings equipped with culverts in ephemeral channels that could cause highly dangerous situations for road traffic. Copyright © 2012 John Wiley & Sons, Ltd.  相似文献   

Bearing capacity of two interfering strip footings from lower bound finite elements limit analysis     

Jyant Kumar  Paramita Bhattacharya 《国际地质力学数值与分析法杂志》2013,37(5):441-452

A rigorous lower bound solution, with the usage of the finite elements limit analysis, has been obtained for finding the ultimate bearing capacity of two interfering strip footings placed on a sandy medium. Smooth as well as rough footing–soil interfaces are considered in the analysis. The failure load for an interfering footing becomes always greater than that for a single isolated footing. The effect of the interference on the failure load (i) for rough footings becomes greater than that for smooth footings, (ii) increases with an increase in ?, and (iii) becomes almost negligible beyond S/B > 3. Compared with various theoretical and experimental results reported in literature, the present analysis generally provides the lowest magnitude of the collapse load. Copyright © 2011 John Wiley & Sons, Ltd.  相似文献   

P_(350)萃取色谱分离石墨炉原子吸收光谱法测定化探样品中镓     

冯静 《国土资源》2000,(1)

应用P350 萃取分离干扰元素 ,采用石墨炉原子吸收光谱法测定化探样品中镓 ,方法检出限为0 0 14× 10 - 6 ,相对标准偏差为 7 0 % ,回收率为 94 %～ 114%。  相似文献   

The distant activity of short-period comets – I     

E. Mazzotta Epifani  P. Palumbo  M. T. Capria  G. Cremonese  M. Fulle  L. Colangeli 《Monthly notices of the Royal Astronomical Society》2007,381(2):713-722

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