共查询到20条相似文献，搜索用时 31 毫秒
1.
布容法则及其在中国海岸上的应用 总被引：12，自引：1，他引：11
布容（Ｂｒｕｕｎ）法则是预测海平面上升引起海岸侵蚀最早的方法也是最简单的方法。根据中国砂质和淤泥质海岸的情况,布容法则可定性地解释海平面上升与海岸侵蚀的关系,在满足它要求条件的海岸地段和发育时期,用它预测海岸侵蚀或许是可能的。但是,若不严格审查海岸环境和条件,把它作为海平面上升情况预测海岸侵蚀的普遍模式,有待更多的研究加以证明。 相似文献
2.
I. O. Leont’yev 《Oceanology》2012,52(4):550-560
The proposed model allows the satisfactory reproduction of the changes in the profile geometry in each time step depending on the sediment budgets in a given morphodynamic system. The applied modification to the general Bruun rule governing the conservation of mass must account for the effect of the sediment transport, which is described in terms of the erosion and accretion rates (Er and and Ac, respectively). The scale of the erosion is a function of the total annual wave energy flux reaching the beach. The accretion is governed by the Er, on the one hand, and by the sediment budget in the morphodynamic system, on the other hand. The equilibrium profile obtained for the case of a balanced sediment budget (Er = Ac) shows good agreement with the observed profiles. A deficit or surplus in the sediment budget results in the shoreline??s retreat or advance accompanied by either a decrease or increase in the slope of the bottom profile. The model accounts for different types of shoreline responses to changes in the sea level (the Bruun rule, the development of a coastal barrier, and abrasion). Sediment budget imbalances can be a factor in the profile??s evolution due to changes in the sea level, while the combination of both factors will produce a variety of behaviors of the shoreline, as was shown by our calculations. The model was verified using historical data on the behavior of the Central Holland coast and the Abkhazian coast during the Late Holocene. It was shown that the model satisfactory reproduces the progradation of coastal barriers. An example of a relatively short-term forecast (over a 100-year period) is given. 相似文献
3.
P. K. Banerjee 《Geo-Marine Letters》1993,13(1):56-60
Along the coast of East and South India, a slow and minor sea level fall as an immediate response to the Last Glacial Maximum (LGM) followed by strong aridity and fast retreat of the sea to the outer shelf are indicated by coastal ironstones, traces of channels in nearshore shallow seismic reflectors, and submerged, structureless, multimineral placer sands. Nearshore peat beds and inland beach ridges reflect perturbations during Early to Mid-Holocene sea level rise. The Little Ice Age witnessed shifts in littoral sediment budget, possibly as a result of reduced transport of sediments from the Himalaya to the Bay of Bengal. 相似文献
4.
Morphodynamic modeling is employed in the present work to predict the long-term evolution (over the next 100 years) of typical sedimentary coasts in the western Russian Arctic. The studied objects are the coasts of Varandey (the Barents Sea), Baydaratskaya Bay and Harasavey (the Kara Sea). The model developed takes into account both the short-term processes (storm events) and long-term factors (for example, changes in sea level, inter-annual variations in gross sediment flux, lack or excess of sediment supply). Predicted and observed morphological changes in coastal profiles are shown to agree well for time scales ranging from weeks to decades. It is revealed that under given environmental conditions, the morphological evolution is strongly influenced by storm surges and associated wind-driven circulation. The water level gradient created by a surge generates a seaward flow at the bed. This outflow is shown to be an important destructive mechanism contributing to the erosion and recession of Arctic coasts. The rate of change is found to depend on both the exposure of the coast (relative to the direction of dominant winds) and its height above the sea. The open coast of Varandey is expected to retreat as much as 300–500 m over 100 years, while recession of the less exposed coasts of Baydaratskaya Bay would not exceed about 100 m/century. If long-term sediment losses are insignificant, the rate of erosion decays with time and the morphodynamic system may tend toward equilibrium. It is concluded that the expected relative sea-level rise (up to 1 m over the nearest 100 years) is non-crucial to the future coastal evolution if an erosion activity is already high enough. 相似文献
5.
Tariq Masood Ali Khan D. A. Razzaq Qamar-Uz-Zaman Chaudhry Dewan Abdul Quadir Anwarul Kabir Majajul Alam Sarker 《Marine Geodesy》2002,25(1):159-174
The UNEP in its regional seas program in 1989 has included Pakistan in a group of countries which are vulnerable to the impact of rising sea level. If the present trend of sea level rise (SLR) at Karachi continues, in the next 50 years the sea level rise along the Pakistan Coast will be 50 mm (5 cm). Since the rising rates of sea level at Karachi are within the global range of 1-2 mm/year, the trends may be treated as eustatic SLR. Historical air temperature and sea surface temperature (SST) data of Karachi also show an increasing pattern and an increasing trend of about 0.67°C has been registered in the air temperature over the last 35 years, whereas the mean SST in the coastal waters of Karachi has also registered an increasing trend of about 0.3°C in a decade. Sindh coastal zone is more vulnerable to sea level rise than Baluchistan coast, as uplifting of the coast by about 1-2 mm/year due to subduction of Indian Ocean plate is a characteristic of Baluchistan coast. Within the Indus deltaic creek system, the area nearby Karachi is more vulnerable to coastal erosion and accretion than the other deltaic region, mainly due to human activities together with natural phenomena such as wave action, strong tidal currents, and rise in sea level. Therefore, The present article deals mainly with the study of dynamical processes such as erosion and accretion associated with sea level variations along the Karachi coast and surrounding Indus deltaic coastline. The probable beach erosion in a decade along the sandy beaches of Karachi has been estimated. The estimates show that 1.1 mm/year rise in sea level causes a horizontal beach loss of 110 mm per year. Therefore, coast eroded with rise in sea level at Karachi and surrounding sandy beaches would be 1.1 m during a period of next 10 years. The northwestern part of Indus delta, especially the Gizri and Phitti creeks and surrounding islands, are most unstable. Historical satellite images are used to analyze the complex pattern of sediment movements, the change in shape of coastline, and associated erosion and accretion patterns in Bundal and Buddo Islands. The significant changes in land erosion and accretion areas at Bundal and Buddo Islands are evident and appear prominently in the images. A very high rate of accretion of sediments in the northwestern part of Buddo Island has been noticed. In the southwest monsoon season the wave breaking direction in both these islands is such that the movement of littoral drift is towards west. Erosion is also taking place in the northeastern and southern part of Bundal Island. The erosion in the south is probably due to strong wave activities and in the northeast is due to strong tidal currents and seawater intrusion. Accretion takes place at the northwest and western parts of Bundal Island. By using the slope of Indus delta, sea encroachment and the land area inundation with rising sea level of 1 m and 2 m have also been estimated. 相似文献
6.
Tariq Masood Ali Khan D. A. Razzaq Qamar-Uz-Zaman Chaudhry Dewan Abdul Quadir Anwarul Kabir Majajul Alam Sarker 《Marine Geodesy》2013,36(1-2):159-174
The UNEP in its regional seas program in 1989 has included Pakistan in a group of countries which are vulnerable to the impact of rising sea level. If the present trend of sea level rise (SLR) at Karachi continues, in the next 50 years the sea level rise along the Pakistan Coast will be 50 mm (5 cm). Since the rising rates of sea level at Karachi are within the global range of 1-2 mm/year, the trends may be treated as eustatic SLR. Historical air temperature and sea surface temperature (SST) data of Karachi also show an increasing pattern and an increasing trend of about 0.67°C has been registered in the air temperature over the last 35 years, whereas the mean SST in the coastal waters of Karachi has also registered an increasing trend of about 0.3°C in a decade. Sindh coastal zone is more vulnerable to sea level rise than Baluchistan coast, as uplifting of the coast by about 1-2 mm/year due to subduction of Indian Ocean plate is a characteristic of Baluchistan coast. Within the Indus deltaic creek system, the area nearby Karachi is more vulnerable to coastal erosion and accretion than the other deltaic region, mainly due to human activities together with natural phenomena such as wave action, strong tidal currents, and rise in sea level. Therefore, The present article deals mainly with the study of dynamical processes such as erosion and accretion associated with sea level variations along the Karachi coast and surrounding Indus deltaic coastline. The probable beach erosion in a decade along the sandy beaches of Karachi has been estimated. The estimates show that 1.1 mm/year rise in sea level causes a horizontal beach loss of 110 mm per year. Therefore, coast eroded with rise in sea level at Karachi and surrounding sandy beaches would be 1.1 m during a period of next 10 years. The northwestern part of Indus delta, especially the Gizri and Phitti creeks and surrounding islands, are most unstable. Historical satellite images are used to analyze the complex pattern of sediment movements, the change in shape of coastline, and associated erosion and accretion patterns in Bundal and Buddo Islands. The significant changes in land erosion and accretion areas at Bundal and Buddo Islands are evident and appear prominently in the images. A very high rate of accretion of sediments in the northwestern part of Buddo Island has been noticed. In the southwest monsoon season the wave breaking direction in both these islands is such that the movement of littoral drift is towards west. Erosion is also taking place in the northeastern and southern part of Bundal Island. The erosion in the south is probably due to strong wave activities and in the northeast is due to strong tidal currents and seawater intrusion. Accretion takes place at the northwest and western parts of Bundal Island. By using the slope of Indus delta, sea encroachment and the land area inundation with rising sea level of 1 m and 2 m have also been estimated. 相似文献
7.
径流量和海平面变化对河口最大浑浊带的影响 总被引：2，自引：0，他引：2
应用改进的ECOM模式,耦合泥沙输运方程,研究径流量和海平面变化对河口最大浑浊带的影响.河口最大浑浊带位于滞流点处,底层上下游余流均向该处输运泥沙,造成该处泥沙汇合,而由流场辐合产生的上升流又使该处的泥沙不易落淤.由于盐水入侵带来的高盐水位于北岸的底层,其斜压效应使底层的横向环流由北向南流动,把底层高浓度的泥沙向南岸平流,使得最大浑浊带位于南岸.研究河口最大浑浊带现象必须使用三维泥沙输运模式.在径流量增大的情况下,与控制试验相比底层向陆的密度流减弱,滞流点下移,导致最大浑浊带也下移;因上游来沙量增加,在最大浑浊带中心和河口拦门沙处悬浮泥沙浓度趋于增加.在径流量减少的情况下,最大浑浊带的变化趋势与径流量增大情况的结果相反.在海平面上升的情况下,拦门沙区域底层向陆的密度流趋于增强,滞流点上移,最大浑浊带也相应向上游移动;最大浑浊带中心处泥沙浓度趋于增大,但口门拦门沙处泥沙浓度趋于减小.径流量和海平面变化对最大浑浊带影响明显. 相似文献
8.
Adrian St?nic? Sebastian Dan José A. JiménezGheorghe V. Ungureanu 《Ocean & Coastal Management》2011,54(12):898-906
The most severe shoreline retreat (over 20 m/year) along the Danube Delta coast has been recorded in the coastal stretch confined by the Sulina branch (north) and Sahalin spit island (south). This erosive trend is caused by the natural evolution of some stretches of the Danube Delta coast, but strongly enhanced by the human activities. Human interventions result in the dramatic decrease in quantity of sediments reaching the coast and in the disruption of natural sediment circulation in the coastal area. EUROSION FP5 Project developed four concepts to be used in coastal studies: coastal sediment cell, coastal resilience, favourable sediment status and strategic sediment reservoir. The main objectives of this study regard the application of the CONSCIENCE methodology and test of the concepts in order to identify and understand the main threats for Sulina - Sahalin littoral cell, especially the coastal erosion one, as well as to provide a sound working methodology for coastal managers to deal with these threats. The sediment budget computed in previous studies, as well as the field observations, indicate a lack of sediments for the littoral cell (unfavourable sediment status). In order to asses the vulnerability of the coast to short term extreme events (especially storms), simulations of water level changes were performed and calibrated with the field observations. A processes based numerical model was used to simulate the storm induced water level variations and the main input data were the bathymetry of the active beach, wind direction and speed (storm scenarios) and the characteristics of water and air. The results show large water level increases for the central part of the study zone, especially for northern wind directions.The main solution proposed to deal the problems arising from a sediment-starved coast, vulnerable to the extreme events, is artificial nourishment. Two strategic sediment reservoirs were identified, both of them at the northern boundary of the cell: the sediments dredged periodically from Sulina mouth and the sediments accumulated in Musura Bay, just north of Sulina jetties. The transfer of these sediments towards the central part of the littoral cell Sulina - Sahalin would decrease the erosion rates to a natural level and restore the natural coastal resilience. The methodology developed in CONSCIENCE Framework and applied to Danube Delta coastal zone provided good results when problems and solutions for the coastal zone were to be identified and tested. This methodology and its related results can be applied by the local coastal managers to Sulina - Sahalin littoral cell, while this experience can be extended to other similar environments facing the same problems. 相似文献
9.
我国海岸带面临的挑战与综合治理 总被引：3，自引：2，他引：3
中国海岸带背靠中国大陆，面向世界上最大的边缘海，具有东南地形差异、南北气候分带的宏观背景，在此基础上建立起来的物质平衡相对比较脆弱。中国内地经济的发展和大型工程的建设、全球变化引起的海平面上升和严峻的环境形势，是我国海岸带无法回避的三大挑战。以地学为基础的海岸带综合治理，旨在寻求人与自然的和谐，是确保海岸带可持续发展和解决人中、资源、环境矛盾的一项系统工程，是多学科结合的高科技技术集成，也是确保我国海岸长期稳定繁荣的惟一出路。 相似文献
10.
11.
Visualising coastal zone inundation is crucial for both a quick assessment of coastal vulnerability and a full understanding of possible implications to population, infrastructure and environment. This study presents a simple but effective method of assessing the spatial extent of coastal zone inundation due to predicted sea level rise using commonly available elevation and image data as well as GIS software. The method is based on the geometrical principle of matching the raised sea level with the corresponding elevation contour line on land. Results for a test area along the south-west coast of Western Australia (∼200 km of coast line) show that a sea level rise of less than 0.5 m over the 21st century will have only minor impact but will become important when added to an extreme sea level event (e.g. storm surge). Both century-scale (∼0.5 m) based on tide gauge records and larger (>few metres) longer-term sea level rise predictions based on the melt of ice covered areas show essentially the same areas that are most vulnerable. Furthermore, the effectiveness of the method is demonstrated by the detection of areas that can be protected by relatively small flood protective structures at river and estuary entrances, thus providing valuable information for policy makers and local councils. 相似文献
12.
长江口南汇嘴近岸海床近期演变分析--兼论长江流域来沙量变化的影响 总被引：24，自引：6，他引：18
长江口南汇嘴地处长江口和杭州湾的交汇处,是长江三角洲南翼向海延伸部分,是长江入海径流和泥沙进入杭州湾和东南沿海的主要输沙通道.在丰富的长江入海泥沙供应下,随着长江三角洲的向海伸展,南汇嘴近岸海床不断淤积.进入20世纪90年代,由于长江流域下泄泥沙的减少,引起南汇嘴近岸海床由淤积过程转向冲刷过程.此外,沿岸滩地的大规模的促淤造地工程,亦拦截了长江口入海的过境泥沙,从而加速近岸海床的冲刷.在今后相当长的一段时期内,随着长江流域大中型水库的不断兴建,长江入海泥沙量将持续保持在较低水平上,海床冲刷将不可逆转地持续下去,这应引起海洋工程建设部门的重视. 相似文献
13.
海平面上升对中国沿海地区影响初析 总被引：2，自引：0，他引：2
近五十年来中国沿岸海平面变化总的呈上升趋势，年变率平均为１．４ｍｍ／ａ，中国沿岸地形复杂，未来海平面上升可能影响的主要脆弱区为黄河、长江和珠江三大三角洲和滨海平原，其可能受害区域估计达３５０００ｋｍ＾２。影响中国沿岸相对海平面上升的主要因素有：近代地壳垂直运动和地面沉降，台风和风暴潮，海岸侵蚀和海咸水入侵等。 相似文献
14.
S. O. Razumov 《Oceanology》2010,50(2):262-267
Some regularities that are generally accepted in the theory about the development of sea coasts as applied to the East Arctic
coast of Russia do not conform to reality. To find out the reasons for these contradictions, the connection between the coastal
processes and the perennially frozen sediment of the underwater coastal slope in the Laptev Sea and the East Siberian Sea
was studied. The frozen state of the deposits of the coastal zone exerts a substantial influence on the coastal dynamics and
determines several features of the thermoabrasion development. In particular, the subaqual permafrost does not allow the forming
of a storm profile with dynamic balance. This fact causes the more effective action of the sea on the coastal cliffs and the
more active recession of the frozen coasts as compared with their counterparts outside the cryolitozone. 相似文献
15.
ＴｒｅｎｄａｎａｌｙｓｉｓｏｆｒｅｌａｔｉｖｅｓｅａｌｅｖｅｌｒｉｓｅｏｒｆａｌｌｏｆｔｈｅｔｉｄｅｇａｕｇｅｓｔａｔｉｏｎｓｉｎｔｈｅＰａｃｉｆｉｃ￥ＭａＪｉｒｕｉ；ＴｉａｎＳｕｚｈｅｎ；ＺｈｅｎｇＷｅｎｚｈｅｎａｎｄＣｈａｉＸｉｎｍｉｎＩｎｓｉｔ... 相似文献
16.
I. O. Leont’yev 《Oceanology》2008,48(1):123-128
A method based on mathematical modeling of the near-shore dynamics is suggested to calculate the annual mean cross-shore sediment flux q* at the coastal zone boundary. This method is applied to several sand coast profiles located in various geographical regions and exposed to energetic impacts of different scale. It is shown that the fluxes can be either positive (directed to the shore) or negative, and the magnitudes found agree with the known estimates based on other approaches. A conclusion is made that the resulting direction of q* is controlled by moderate storms with regime cumulative exedence from 1 to 10%. The wave periods, bottom slope, and sediment grain size play a special role in the process. An empirical criterion is found that allows one to predict the direction of the sediment flux crossing the coastal zone boundary. 相似文献
17.
海平面上升的风险评估研究进展与展望 总被引：3，自引：0，他引：3
海岸带是海陆交互作用的集中区域,人类活动密集,面对未来海平面上升带来的影响具有敏感性和脆弱性。评估未来海平面上升对海岸带的风险,具有理论与实际意义。根据海平面上升风险评估研究框架,总结了海平面上升、海岸侵蚀、风暴潮淹没、海水入侵、湿地丧失等方面的研究现状,在此基础上,分析了目前研究存在的不足,并提出了海平面上升风险评估未来研究的关键问题。 相似文献
18.
19.
中国河口海岸面临的挑战 总被引：29，自引：1，他引：29
河口海岸是地球四大圈层交汇、能量流和物质流的重要聚散地带。该区域经济发达、人口集中、开发程度高，导致严重的环境变异、资源破坏，对区域持续发展造成重大影响，特别是我国流域高强度开发河口和邻近海岸带有直接和深远的影响。新世纪我国的河口海岸面临着4个方面的挑战：入海泥沙量急剧减少；入海污染物质显著增加；滨海湿地丧失；全球海平面上升对中国低海岸的严重威胁。为此，开展河口海岸环境变异的研究，为解决国家目标和海岸带资源可持续利用，无疑是非常重要而迫切的问题。 相似文献
20.
辽河三角洲地区海平面上升趋势及其影响评估 总被引：11，自引：1，他引：10
根据潮位资料分析,辽河三角洲平原和辽东湾东岸近四五十年来相对海平面处于上升趋势,从70年代以来平均每年上升量为5mm左右.考虑到辽河三角洲平原地面下沉以及全球性海平面将加速上升,预计下个世纪内,辽河三角洲平原相对海平面上升的速率将达到8-10mm/a,到2050年相对海平面上升量将达到40～55cm.利用遥感和地理信息系统,对不同的海平面上升量将造成的土地淹没损失进行了预测.如不加防护,相对海平面上升0.5m时,将淹没近4000km2,包括整个营口市区和半个盘锦市区;上升1.0m时,将淹没5000km2.对海平面上升将造成海岸侵蚀、风暴潮和洪涝等灾害加剧等影响也进行了分析. 相似文献