共查询到20条相似文献，搜索用时 234 毫秒
1.
近年来我国海洋灾害损失及防灾减灾策略 总被引：2，自引：0，他引：2
我国是世界上海洋灾害最为严重的少数国家之一。近年来，由风暴潮、灾害性海浪、赤潮、海冰、海平面上升等海洋灾害带来的经济损失和人员伤亡越来越严重，其中，风暴潮是影响我国沿海地区最为严重的海洋灾害。通过建立海岸生态防护网、提高沿海地区防潮工程标准、开发海洋灾害监测和预报系统、实行海洋数据资料和信息共享等方法，降低海洋灾害发生的机率，减少海洋灾害损失。 相似文献
2.
美国：构建干旱防灾减灾体系美国是一个干旱频发的国家,据美国联邦应急管理署测算,美国因干旱造成的经济损失年均达60亿～80亿美元,远远超过了其他气象灾害。美国政府为了防治干旱灾害,建立了比较完善的干旱防灾减灾体系。 相似文献
3.
4.
5.
黄河下游断流已引起全国上下的严重关注,是我国最大的环境问题之一。最近5年来,黄河断流天数和断流长度都不断增加,人海水量越来越少,已由50年代的480亿立方米,到1997年只有17亿立方米,利津水文站226天无黄河水人海。造成断流的原因主要是黄河流域近年工衣业及城市用水量大增及水资源管理工作薄弱。黄河流域的耗水量50年代为122亿立方米,90年代增至300亿立方米以上。黄河断流问题比较复杂,也比较严重,除直接影响两岸人民生活和工农业生产,每年造成直接经济损失超过人民币百亿元外,还引起了一系列重大环境问题。首先是增加了防洪压力,下游河道淤积严重,多处主槽已经淤积到与河滩一样,一旦大汛期来临,洪水无 相似文献
6.
黄河三峡系指黄河上游甘肃省永靖县境内的刘家峡、盐锅峡和八盘峡,其中盐锅峡移民区共安置移民986户,5527人,主要分布在永靖县盐锅峡镇所辖的黑方台台塬上下的10余个村庄中。黄河三峡移民区地质灾害主要为大规模群发性滑坡灾害,集中分布在黑方台台塬边坡地带。黑方台台塬面积约13.7 km2,台塬地面高出周围地形约100~133 m,自1968年上水灌溉以来,已累计发生滑坡灾害100余次,已造成40人死亡,直接经济损失约2.00亿元,间接经济损失5.00亿元。台塬长期大水漫灌是诱发本区大规模群发性滑坡反复发生的主要原因。 相似文献
7.
《中国地质灾害与防治学报》2014,(2):135-136
一、起草背景与依据
我国是地质灾害多发的国家,地质灾害种类多、分布广、活动频繁、危害重,是世界上地质灾害最为严重的国家之一。每年因崩塌、滑坡和泥石流等地质灾害造成的死亡人数占自然灾害死亡人数比例较大,造成的经济损失也达数百亿,受到党中央、国务院和各级政府及社会各界的高度重视和关注。 相似文献
8.
9.
《水文地质工程地质技术方法动态》2006,(5):10-12
地面沉降是地面由于地下物质运移而发生的渐进下陷或急剧下沉。这是一个全球性问题，仅在美国，已经有遍及45个州，超过44030km0的土地受到了地面沉降的影响，相当于新汉布什尔州与佛蒙特州的总和。由此引发的经济损失更是惊人：仅在圣克拉拉山谷，沉降所造成的直接经济损失，在1979年大约为1．31亿美元，而到了1998年则高达3亿美元。造成这一灾害的原因主要有含水层的压实、有机质土的疏干排水、地下采矿、自然压实、溶坑以及永冻土的解冻等。 相似文献
10.
我国有关专家估计地质灾害约占自然灾害的1/5~1/4,经济损失约75亿到125亿元/年.因此,对它的防治是关系到国家经济建设、人民生命财产安全和社会安定的重大问题,党中央和国务院都十分重视.为做好地质灾害的防治工作,贯彻预防为主,防治结合的方针,减少灾害所造成的损失,国家决定结合国土整治,支持地方和企业开展地质灾害防治工作,自1991年以来,从国家预算的地勘费内划出少数经费,作为地质灾害直接危害人民生命财产安全的少数地区开展地质灾 相似文献
11.
Based on the in-depth investigation of the temporal and spatial relationship between aerosols and red tide events in the East China Sea (ECS), a model of the potential correlation between the paths of aerosol input and red tides in the ECS has been suggested. This study shows that red tides are closely related to aerosol events which come from northwest of the sea (winter monsoon direction) and descend to the ECS surface. Two principal paths of aerosol input are established that are relevant to the red tide events in the ECS. The first path contains aerosols from the northwest that are usually related to the red tide events covering an area of more than 1,000 km2. A second path is characterized by aerosols that first move from the northwest to east and then to south, finally settling in the red tide areas in the ECS. These aerosol paths are usually related to the red tide events that cover a smaller area, except in cases where stopover and follow-up re-supply of these aerosols may result in larger red tide events. The aerosols from southeast and southwest are not related with red tide events in the ECS. Downward vertical air currents play a key role in the relationship between ECS red tides and aerosol events. Without downdraughts, aerosols will have nothing to do with the red tide events. The study provides new information for discovering the occurrence mechanism of red tides in the ECS and essential parameters for red tide prediction and early warning. 相似文献
12.
When gravity survey accuracies of a few microgals are sought, many correction factors must be accounted for, including meter calibration constants, water-table level fluctations, solid-earth tides, ocean tides and in some cases rapid atmospheric fluctuations. Calculation of most of these correction factors is relatively straightforward. However, the effects of ocean tide loading are not as easily estimated, partly due to the lack of knowledge of the ocean tides themselves. Amplitude and phase factors for the better-known ocean tide components O1 and M2 have been theoretically computed for a grid in southern California in order to correct gravity survey data at arbitrary locations for these ocean tidal-loading components. The gravity data from a three-month period were recorded on a tidal gravimeter at the station PAS and then hand-digitized in order to test the ocean tide estimation program. The O1 and M2 ocean tidal components were effectively reduced to less than 0.5 μGal. The remaining high-frequency tidal components appear to be K1 and S2. If the ocean tides are not taken into account, as much as 16–20 μGal of error can occur solely due to the effect of ocean loading on the gravitational tides when comparing two surveys near Pasadena. The effect increases towards the coastline and decreases inland. Examples of reduced data from the CIT gravity survey network, which has been observed on an approximately monthly basis since 1974, will be shown. 相似文献
13.
Anne Rudloe 《Estuaries and Coasts》1980,3(3):177-183
Breeding activity of the horseshoe crab,Limulus polyphemus, was quantitatively monitored in Apalachee Bay, Florida, throughout one breeding season. Breeding peaked at times of full and new moon at the hour of high tide. Breeding activity was heavier on night tides than on corresponding day tides of the same date. Males routinely outnumbered females and indications of sperm competition were present. Many horseshoe crabs buried in the intertidal zone throughout the subsequent low tide and returned to the beach to breed again on the following high tide. A tagging study of the horseshoe crab indicated that male animals return to breeding beaches more frequently than females. Most animals tagged at breeding beaches did not move away from the tagging site during a breeding season and were recovered at the point of release. No long-range movements were noted. The sex ratio of animals tagged near breeding beaches was predominately male while it was predominately female for animals collected and tagged 3–6 miles offshore. A nine percent recovery rate was achieved. Existing localized populations are potentially subject to depletion due to heavy collecting pressure on breeding beaches. 相似文献
14.
Using time series analysis to assess tidal effect on coastal groundwater level in Southern Laizhou Bay,China 
下载免费PDF全文
下载免费PDF全文 Chen She-ming Liu Hong-wei Liu Fu-tian Miao Jin-jie Guo Xu Zhang Zhou Jiang Wan-jun 《地下水科学与工程》2022,10(3):292-301
Sea water intrusion is an environmental problem cause by the irrational exploitation of coastal groundwater resources and has attracted the attention of many coastal countries. In this study, we used time series monitoring data of groundwater levels and tidal waves to analyze the influence of tide flow on groundwater dynamics in the southern Laizhou Bay. The auto-correlation and cross-correlation coefficients between groundwater level and tidal wave level were calculated specifically to measure the boundary conditions along the coastline. In addition, spectrum analysis was employed to assess the periodicity and hysteresis of various tide and groundwater level fluctuations. The results of time series analysis show that groundwater level fluctuation is noticeably influenced by tides, but the influence is limited to a certain distance and cannot reach the saltwater-freshwater interface in the southern Laizhou Bay. There are three main periodic components of groundwater level in tidal effect range (i.e. 23.804 h, 12.500 h and 12.046 h), the pattern of which is the same as the tides. The affected groundwater level fluctuations lag behind the tides. The dynamic analysis of groundwater indicates that the coastal aquifer has a hydraulic connection with seawater but not in a direct way. Owing to the existence of the groundwater mound between the salty groundwater (brine) and fresh groundwater, the maximum influencing distance of the tide on the groundwater is 8.85 km. Considering that the fresh-saline groundwater interface is about 30 km away from the coastline, modern seawater has a limited contribution to sea-salt water intrusion in Laizhou Bay. The results of this study are expected to provide a reference for the study on sea water intrusion. 相似文献
15.
Harmful algal blooms commonly known as red tides have been observed at increasing frequencies, which are causing serious economic and ecologic problems in Haizhou Bay off the eastern coast of China. It is important to study the inducing factors of red tides including a wide variety of environmental variables and the complex interactions between them. This study explores the possibility of predicting the occurrence of red tides using support vector machine (SVM) with environmental variables. Seventeen in situ environmental variables which are known to affect the occurrence of red tides were collected between May and October of 2004–2006. Seven characteristic factors were extracted from these variables via factorial analysis to reduce computation complexity. Three of them are related to nutrients, others are contributed by temperature, oxygen depletion, pH, hydrodynamics, and precipitation, respectively. The classification models based on SVM were constructed to identify the red tides samples using the seven factors as independent variables and radial basis function as the kernel function. The model with the combination parameters of C = 10, γ = 0.7, and ζ = 0.1 has the highest accuracy of 92.06 %. It indicates that the model is highly valuable in predicting the occurrence of red tides by environmental variables in this region for its conservative threshold of surface algae concentration. 相似文献
16.
17.
利用快速Fourier变换分析方法,对厦门台数字化潮汐资料的背景变化及其主要干扰因素进行了初步探讨,并对其存在的原因给出了可能的解释;和内陆台站的相应资料对比后表明,并非所有的台站测项所观测到的固体潮资料中,M2波都会占绝对优势;临海台站在作资料分析时,对M2波的分析应该是主要的,而内陆型台站应该综合考虑其它波群的影响;同一台站的不同测项受到主要干扰的机制是不同的,厦门台受海潮的干扰机制是,厦门台处于相干海潮波的波峰或波谷处,且该海潮波的周期又和M2波的非常接近,气压的干扰机制是,气压扰动形成的压力差以波动形式直接作用在洞体应变仪的含铌特种因瓦棒或传感器探头上,使得其记录曲线中叠加了多种波的成份。 相似文献
18.
地应变固体潮对微渗漏作用的动力贡献研究 总被引：2，自引：0，他引：2
目前国内外对构造应力作用下地球内部流体运动的规律与特征的研究已经很多 ,但面向地应变固体潮对地壳微裂缝系统的微渗漏作用影响的研究尚属空白。地球在太阳、月球的引力作用下 ,一方面在其表面的海洋、湖泊形成直观的潮汐现象 ;另一方面固体地球自身还形成肉眼无法看到的粘弹性形变 ,称为固体潮。固体潮不仅能引起重力变化、地面倾斜和地面伸缩等地球物理现象 ,而且还为地壳内微裂缝系统提供了永恒的、周期性的伸缩开合变化的动力 ,大大提高了流体在微裂缝系统中微渗漏的规模和距离 ,造成流体中物质元素的迁移和变化的地球化学现象。文中主要阐明了地壳裂缝系统和流体微渗漏作用的客观存在 ,探讨并总结了地应变固体潮对微裂缝系统的应力作用特点以及为流体微渗漏作用所作出的重要动力贡献 ,并将固体潮与地球化学有机联系在一起 ,从理论上说明流体携带包含深部矿藏 (体 )信息的特征元素或物质完全有可能通过微渗漏作用迁移至地表并形成该元素或物质的地球化学异常 ,为当前的地表土壤法、地气法、电提取法、电吸附、吸附丝等多种地球化学找矿方法提供可信的理论依据。 相似文献
19.
Susanne M. Moskalski Christopher K. Sommerfield Kuo-Chuin Wong 《Estuaries and Coasts》2011,34(4):800-813
Influences of tides, freshwater discharge, and winds on water properties in the St. Jones River estuary (USA), a Delaware
National Estuarine Research Reserve, were investigated using multiyear records of sea level, salinity, and turbidity, supplemented
by a current profiler time series in 2007. Results demonstrate that instantaneous properties fluctuate with semidiurnal tides
and resonant overtides, whereas tidal mean variations are forced by seasonal freshwater inflow and offshore winds. Mean sea
level and salinity are highest in summer and vary with seasonal water temperature and rainfall, whereas sea level variability
and turbidity are highest in winter on account of storm effects. Salinity and discharge modeling suggest that much (43–65%)
of the freshwater resident in the estuary is derived from non-point sources below the head of tide. This diffuse freshwater
inflow produces a seaward surface slope and weak mean current, which temporarily reverses under the influence of storm–wind
setup within Delaware Bay. 相似文献
20.
The arrangement of sediment couplets preserved in Thalassinoides shafts suggests that tides regulated the passive filling of these trace fossils and, thus, represent tubular tidalites. The thickness variation in individual layers and couplets implies a mixed diurnal, semi‐diurnal tidal signature where packages of either thick‐layered or thin‐layered couplets alternate. Calcarenitic sediment accumulated when tidal current velocity was too high to allow deposition of mud, whereas a marly mud layer is interpreted to have formed during more tranquil times of a tidal cycle (in particular, low‐tide slack water). The tidal record within the burrows covers a few weeks and the corresponding spring–neap cycles. The fill of the Thalassinoides shafts is the only known record to decipher the tidal signature from otherwise totally bioturbated sediments. These deposits accumulated in a lower‐shoreface to upper‐offshore setting during the late Miocene on a shallow shelf extending from the Atlantic Ocean to the west into northern Patagonia. The fill of all investigated burrows started around spring tide and, thus, the behaviour of the burrow producers – probably crustaceans – is speculated to have been affected by tides or the high water level because all studied burrows became abandoned around the same period of a tidal cycle. 相似文献