Flood prediction and mitigation in coastal tourism areas,a case study: Hurghada,Egypt

Flood mitigation involves the management and control of floodwater movement, such as redirecting flood runoff through the use of floodwalls and flood gates, rather than trying to prevent floods altogether. The prevention and mitigation of flooding can be studied on three levels: on individual properties, small communities, and whole towns or cities. The current study area is located in Hurghada on the Red Sea, which is considered an important area for coastal tourism. The study area is located at distance 7.50 km from El Gouna city along the Red Sea and east of Hurghada–Al Ismaileya road. The aim of this research is to derive the runoff flow paths across the study area and their flow magnitudes under different rainfall events of 10, 25, 50, and 100 year return periods in order to design the flood mitigation measures to protect such important areas. Field data (e.g., topographic data and rainfall intensities) were collected for the study area. The results indicated that the site is exposed to high flash flood risk and protection work is required. In order to protect the area from flood risks, locations of number of drainage channels and dams were selected and designed based on flood quantity and direction. The proposed mitigation system is capable of protecting this crucial area from flood risks and increases the national income from tourism. This study can be applied in different areas of Egypt and the world.     

Modelling the geoid and sea-surface topography in coastal areas

This paper looks at the relation between the time-averaged level of the sea surface and a gravimertic geoid, as determined in coastal areas. Measurements in local regions can now be accurate enough to demonstrate that the geoid and mean sea level are not even parallel to each other, let alone identical. The accuracy and pattern structure of surface gravity data in some shelf seas is comparable with those on land, so that a marine geoid can be derived from surface data without using satellite altimetry. The geodetic objective is then to combine the two to determine sea surface topography. In principle, gravimetric studies provide the absolute datum so that local oceanographic models on the shelf can be combined with sea surface topography models related to the global ocean circulation. In contrast, sea surface topography information near deep ocean coasts must come from external sources and satellite altimetry used to give the gravity data needed to offset the less good coverage by ship-borne gravimetry.Marine Bouguer anomalies enable two specific problems of gravity anomaly patterns near the continent ocean transition to be overcome. The necessary extension of Stokes' condensation reduction is developed and illustrated along a north-south profile from the Mediterranean across the Cote d'Azur. The effect on gravity of deep ocean water introduces a geoid correction in the form of a dipolar ridge whose amplitude at the shore is about 11 cm. In addition to geostrophic currents, a semi-quantitative model for the thermohaline effects on sea surface topography is discussed in relation to sea level differences between the Atlantic and Mediterranean.In considering appropriate algorithms for local geoid computation, Kirby's Iterative Fourier Combination routine for combining altimetry and surface gravity is extended to account for global sea surface topography. The impact of very fast spherical harmonic analysis algorithms is discussed and a simple physical model is given which explains the short coherence lengths found for the global gravity field. This necessary assumption for any local geoid computation was hitherto purely empirical.Finally, the use of land data such as tide gauges, ellipsoidal heights from GPS, and orthometric heights from first order levelling are reviewed as ways of corroborating geodetic estimates of sea surface topography and its relation to levelling datums. Successful examples are given from southern England.     

Post-glacial regional climate variability along the East Antarctic coastal margin—Evidence from shallow marine and coastal terrestrial records

We review the post-glacial climate variability along the East Antarctic coastline using terrestrial and shallow marine geological records and compare these reconstructions with data from elsewhere. Nearly all East Antarctic records show a near-synchronous Early Holocene climate optimum (11.5–9 ka BP), coinciding with the deglaciation of currently ice-free regions and the optimum recorded in Antarctic ice and marine sediment cores. Shallow marine and coastal terrestrial climate anomalies appear to be out of phase after the Early Holocene warm period, and show complex regional patterns, but an overall trend of cooling in the terrestrial records. A Mid to Late Holocene warm period is present in many East Antarctic lake and shallow coastal marine records. Although there are some differences in the regional timing of this warm period, it typically occurs somewhere between 4.7 and 1 ka BP, which overlaps with a similar optimum found in Antarctic Peninsula terrestrial records. The differences in the timing of these sometimes abrupt warm events in different records and regions points to a number of mechanisms that we have yet to identify. Nearly all records show a neoglacial cooling from 2 ka BP onwards. There is no evidence along the East Antarctic coastline for an equivalent to the Northern Hemisphere Medieval Warm Period and there is only weak circumstantial evidence in a few places for a cool event crudely equivalent in time to the Northern Hemisphere's Little Ice Age. There is a need for well-dated, high resolution climate records in coastal East Antarctica and particularly in Terre Adélie, Dronning Maud Land and Enderby Land to fully understand the regional climate anomalies, the disparity between marine and terrestrial records, and to determine the significance of the heterogeneous temperature trends being measured in the Antarctic today.     

Submerged early Holocene coastal and terrestrial landforms on the inner shelves of Atlantic Canada

Coastal and terrestrial landforms that formed with lowered relative sea levels during the early postglacial period in Atlantic Canada were submerged during the Holocene transgression. However, these landforms are seldom seen on sea floor imagery. Factors that contribute to their destruction include the brevity of sea level lowstands and high wave energy on shallow modern shelves. We identify one situation within which preservation has been relatively good: large coastal lakes that existed for many thousands of years before being connected to the ocean by rising sea level in the mid-Holocene. We describe Bedford Basin, near Halifax, Nova Scotia, and deal more exhaustively with the Bras d'Or Lakes, an inland sea in Cape Breton, Nova Scotia. The preservation of shore platforms, barrier beaches and spits, and fluvial systems, was due to the rapid onset of the transgression and the relatively low wave energy in the subsequent marine phases. The well-preserved early Holocene coastlines are highly favourable targets in the search for evidence of human occupation in the early- to mid-Holocene.     

The impact of tourism on coastal areas

The manifold influences of tourism on coastal areas are analysed from three different angles: (1) The development of seaside tourism including the changes of socio-economic and settlement patterns; (2) its cultural impact on the local population; (3) its environmental aspects. Point 1 is described with the help of a model showing four peripheries in space and time: (I) the North Sea and Baltic coasts since the 18th century; (II) Southern Europe during the 19th century; (III) the North African shores around 1950; (IV) the tropical oceans after 1965. Within every periphery, several phases (pioneer, domestic, international) can be distinguished according to the origin of tourists, the investment, the know-how etc. While the beginning of every phase is dominated from abroad, later-on national actors play an increasing role. This applies also to point 2, which refers mainly to developing countries. As for point 3, mass tourism may result detrimentally on water supply, sensitive coastal landscapes, socio-cultural identity etc. Among the questions to be raised are: How far are industrial societies responsible for any negative impacts of tourism, and what are the chances for, and a general consciousness on, a sustainable tourism development?     

Fresh and brackish ground-water under coastal areas and islands

Brackish ground-water bodies under coastal areas and islands often show a regular pattern as to the form and salt content. Two types of theories give an explanation, the Badon GHijben/Herzberg (BGH) approach, based on density differences; and theories on mixing phenomena, like diffusion and disperson. The underlying assumptions of both approaches and their respective merits are discussed. The BG g approach is particularly suited to coastal strips and small islands, whereas the mixing theories give better results for more inland areas. This conclusion is illustrated by a number of case studies, two of them concerning the lowlands of the Netherlands and two others dealing with small oceanic islands. The theoretical aspects of the problem of maximum yield of individual wells and drains situated above brackish ground-water are introduced and some solutions are presented.     

Allometric laws and prediction in estuarine and coastal ecology

A theoretical and quantitative framework of first principles would benefit estuarine and coastal ecologists in search of predictions to enhance our understanding and management of marine resources. The Metabolic Theory of Ecology describes a possible unifying theory for ecology, including mechanistically derived equations that predict scaling exponents observed in empirical, allometric relationships from individuals to ecosystems. The controversy surrounding this theory should stimulate our exploration of its potential use in the coastal realm, where questions specific to an applied science may suggest new refinements and derivations, contributing to the overall progress of ecology.     

Assessment and zonation of storm surge hazards in the coastal areas of China

Natural Hazards - Coastal inundation due to storm tides is computed using ADvanced CIRCulation (ADCIRC) model along the east coast of India. Inland inundation due to storm tides is calculated every...     

江苏沿海地区深层地下水开发利用现状及环境地质问题

江苏沿海地区深层地下水在开发利用过程中，由于开采布局不合理和存在“三集中”(开采层次集中、开采地段集中、开采时间集中)以及水文环境地质条件脆弱等因素，出现水位逐年下降，并形成区域性降落漏斗，致使部分地段地下水资源枯竭、水质成化和诱发地面沉降等诸多环境地质问题。本文着重分析沿海地区深层地下水开发利用的6个阶段(初级、城市开采、城市超采、区域超采、区域控制开采和区域压缩开采阶段)、区域降落漏斗的3个发展过程(1986年、1995年和2002年)和因深层水超量开采诱发的水资源枯竭、水质成化和地面沉降等环境地质问题的发育特征及演化趋势，从地下水资源管理和可持续发展的角度，提出深层水的保护规划、浅层咸水、海水资源的开发利用、实行强制节水、污水资源化和发展海洋性产业的对策建议。     

沿海地区地下水模拟优化管理模型

针对中国一些沿海地区地下水超采及由此带来的海水入侵问题,将地表水补给、抽水量及地下水位等相嵌在一起,建立了沿海地区地下水模拟优化管理模型。将人工鱼群算法和基于MODFLOW2000的变密度地下水流及溶质运移模型耦合起来,对沿海地区地下水模拟优化管理模型进行求解。以山东省威海市节水示范区为例,验证模型的有效性和可靠性。结果表明,10、11、12月份抽水量最大,以后至第2年5月份依次是减少的;从区域分布上看,在临海区域1号井处抽水量是3500～1120m3/月,在其它井处是6540～2920m3/月;与现行方案相比,增加总有效供水1990m3,地下水平均水位升高0.29m,海水入侵问题能够得到解决。计算结果合理可行,为沿海地区地下水资源的科学管理和持续利用提供可靠依据。     

Nutrient flux in a landscape: Effects of coastal land use and terrestrial community mosaic on nutrient transport to coastal waters

Long-term interdisciplinary studies of the Rhode River estuary and its watershed in the mid-Atlantic coastal plain of North America have measured fluxes of nitrogen and phosphorus fractions through the hydrologically-linked ecosystems of this landscape. These ecosystems are upland forest, cropland, and pasture; streamside riparian forests; floodplain swamps; tidal brackish marshes and mudflats; and an estuarine embayment. Croplands discharged far more nitrogen per hectare in runoff than did forests and pastures. However, riparian deciduous hardwood forest bordering the cropland removed over 80 percent of the nitrate and total phosphorus in overland flows and about 85 percent of the nitrate in shallow groundwater drainage from cropland. Nevertheless, nutrient discharges from riparian forests downslope from croplands still exceeded discharges from pastures and other forests. The atomic ratio of nitrogen to phosphorus discharged from the watersheds into the estuary was about 9 for total nutrients and 6 for inorganic nutrient fractions. Such a low N:P ratio would promote nitrogen rather than phosphorus limitation of phytoplankton growth in the estuary. Estuarine tidal marshes trapped particulate nutrients and released dissolved nutrients. Subtidal mudflats in the upper estuary trapped particulate P, released dissolved phosphate, and consumed nitrate. This resulted in a decrease in the ratio of dissolved inorganic N:P in the estuary. However, the upper estuary was a major sink for total phosphorus due to sediment accretion in the subtidal area. Bulk precipitation accounted for 31 percent of the total nongaseous nitrogen influx to the landscape, while farming accounted for 69 percent. Forty-six percent of the total non-gaseous nitrogen influx was removed as farm products, 53 percent either accumulated in the watershed or was lost in gaseous forms, and 1 percent entered the Rhode River. Of the total phosphorus influx to the landscape, 7 percent was from bulk precipitation and 93 percent was from farming. Forty-five percent of the total phosphorus influx was removed as farm products, 48 percent accumulated in the watershed, and 7 percent entered the Rhode River. These nitrogen and phosphorus discharges into the Rhode River, although a small fraction of total loadings to the watershed, were large enough to cause seriously overenriched conditions in the upper estuary.     

河口海岸铁板砂研究进展

铁板砂是一种特殊的沉积地貌,其性质和形成演化涉及海洋沉积动力、海洋工程地质等学科方向,对海岸防护、航运安全和海洋工程建设有重要影响。介绍了铁板砂的概念、特征和分布,以铁板砂形成和演化机制为主线,从原生沉积、冲刷分选和液化渗流3种模式出发,对国内外铁板砂研究现状进行总结和论述,分析了3种模式的优缺点和适用条件,从研究思路和研究方法等方面对铁板砂的研究趋势进行了展望,指出基于海洋土力学与沉积动力学相结合的思路,开展水体-床面-床内耦合的多要素同步观测,构建机制清晰的物理模型和定量评价的数学模型是今后铁板砂研究的发展方向。     

中国沿海地区地面沉降问题思考

中国沿海地区地面沉降主要发生在大河三角洲及沿海平原区。文章主要以我国两大沿海城市——上海及天津为例，分析和阐述了沿海地区发生地面沉降的机理以及影响地面沉降发生发展的诸多因素。指出，孔隙水承压含水层中抽取地下水将引起承压水位降低进而引起土颗粒承担的有效压力的增大，从而使土层压缩。影响沿海地区地面沉降的因素有新构造运动、全球海平面上升、软土地基自然沉降、过量抽取地下流体以及建筑施工造成的局部沉降等。文章认为，在诸多影响因素中，人类过量开采地下流体是导致地面沉降发生的主要原因，人类应在资源利用和环境保护方面力争双赢。     

Sterol geochemistry of sediments from the western North Atlantic Ocean and adjacent coastal areas

Core sections from coastal bay, continental slope, and continental rise surface sediments of the western North Atlantic were analyzed for sterols. Changing rate or type of sediment input, bioturbation, and chemical conversion appear to be processes important in controlling the distribution of sterols in these sediments. Comparisons of individual sterol distributions and variations in the ratio of Soxhlet-extractable to non-extractable saponified sterols indicate that for the western North Atlantic, the extent to which each process is dominant varies with proximity to shore. Evidence is presented to show that sterols in the deep sea may be at least partially terrigenous in origin and not all biogenically derived in the surface waters. These sterols, and by analogy other labile organic compounds, may serve as a source of carbon for benthic organism metabolism.     

Climatic influences on riverine nitrate flux: Implications for coastal marine eutrophication and hypoxia

The average nitrate flux of the lower Mississippi River increased 3.3-fold between 1954–1967 and 1983–2000. During the same time period, the average nitrate concentration increased 2.3-fold while the average discharge increased 40%. Partitioning of the observed trend in nitrate flux among the two flux components, nitrate concentration and discharge, revealed that about 80% of the observed increase in flux could be explained by the increase in nitrate concentration. This indicates that a historical increase in the anthropogenic nutrient inputs has had a far greater impact on the lower Mississippi River nitrate flux than a change in climate. The influence of climatic factors on nitrate flux has been significant and may further increase as a result of global climate change. This argument is supported by two lines of evidence. The residual component of nitrate flux, obtained by removing a trend from the time series, is controlled primarily by the variability in discharge, i.e., climatic factors. Also, there is a highly significant relationship between discharge and nitrate concentration at the low end of the discharge spectrum (<13,000 m³ s^?1). The differences in nitrate flux between flood and drought years are significantly larger than the variations in discharge. This makes the Mississippi River nitrate flux potentially sensitive to future changes in the frequency of extreme climatic events. Because of the importance of nitrate for the productivity of coastal phytoplankton, future climate change would likely have important implications for coastal marine eutrophication and hypoxia.     

Climatic and environmental variability during the termination of the Last Glacial Stage in coastal eastern Australia: a review

By comparison with the Northern Hemisphere, there is a paucity of high-resolution, continuous records extending into the Last Glacial Maximum from the Southern Hemisphere. With specific reference to coastal eastern Australia, there are long records of paleoclimatic and paleoenvironmental variability available from the tropical north and temperate south. However, there are significant spatial gaps between such records: in particular, until relatively recently, little attention had been paid to the subtropics. This review paper summarises understanding of regional paleoenvironmental and paleoclimatic variability in coastal eastern Australia during the termination of the Last Glacial Stage, with the aim of highlighting gaps in the current state of knowledge. Recommendations for future research are prioritised to answer knowledge gaps in understanding climate variability in eastern Australia between ca 33–18 kyr BP.     

中国沿海及内陆地区长周期脉动特征分析

地脉动台阵观测作为一种低成本的剪切波速度构造探测方法,预计将在中国地震灾害预防中起到重要作用。为了研究地脉动台阵观测中长周期信号的特征以及中国长周期地脉动的特点和适用性,开展了中国从沿海到内陆地区地脉动信号的观测和分析,探查由沿海到内陆地区地脉动的变化规律以及内陆地区广域的地脉动特征,发展适合于我国内陆地区的基于地脉动的地下构造勘探方法,在中国大陆上海市、西安市、天水市及兰州市进行了长周期地脉动观测。现场试验结果表明,上海地脉动特征与日本关东平原地区的观测结果类似,可以认为在海岸地区深部结构调查的地脉动台阵观测有良好的适用性。然而,西安、兰州、天水长周期地脉动能量只有上海的千分之一,因此需要进一步研究更加灵敏的仪器性能和更加稳定的观测方法。     

Local engineering practices of erosion control in the coastal areas of the Niger Delta

 The paper reviews local engineering practices of erosion control in the coastal areas of the Niger Delta, influenced by tidal activities, and analyses the physical conditions and criteria for the application of control measures. The control methods utilized include the use of sand-cement and sand-gravel bags, used rubber tire networks, wooden groins, concrete retaining walls, sheet pile walls, and rock gabions. The effectiveness of typical cases of these measures are evaluated and suggestions made on improvements in design to ensure enhanced performance. Received: 22 February 1996 · Accepted: 30 July 1996     

Tectonic environment of mesozoic volcanic rocks in the coastal areas of SE China

Mesozoic volcanic rocks in the coastal areas of SE China consist predominantly of rhyolites and pyroclastic rocks, obviously distinct from island-arc volcanic rocks which consist mainly of andesitic rocks. Volcanic rocks in these areas mostly belong to the cale-alkaline series, and their geochemical characteristics are dissimilar to those of island-arc rocks. For example, the SiO₂ content varies greatly from 47 to 81 percent, Fe₂O₃+FeO/MgO>2, K₂O/Na₂O>0.8, the contents of Rb, Sr, Ba, Th, U, and Zr are higher than those of island-arc calc-alkaline rocks, and K/Rb <400. Andesite in the coastal areas of SE China, for the most part, belongs to the alkali-calcic series (CaO<Na₂O+K₂O), typical of a continental tectonic environment. Geotectonic studies have shown that the ancient Eurasian continental margin in Mesozoic times was located to the east of the line linking Japan and Taiwan, and the present location of Mesozoic rocks is not an island-arc. area. In the light of their characteristically high alkalinity, the Mesozoic volcanic rocks are considered to have been formed in a continental environment rather in an island-arc environment. Their formation was controlled by a compresso-shear tranform fault system.     

广东沿海地区基性岩脉地球化学及成因

广东沿海地区基性岩脉的成岩年龄是146~54 Ma,主要形成于白垩纪,次为侏罗纪和第三纪。可将工作区基性岩脉的形成时代分为5期：第一期146Ma,第二期138~132Ma,第三期112~105Ma,第四期99~82Ma,第五期75~54Ma。根据K₂O/Na₂O比值和K₂O含量,以及不相容元素分配模式的“Nb-Ta”异常,可以划分出两类基性岩脉。第一类K₂O/Na₂O比值<0.5和K₂O含量<1.3%,在微量元素MORB标准化图解中具有弱的“Nb-Ta”负异常。第二类K₂O/Na₂O比值>0.5和K₂O含量>1.3%,在微量元素MORB标准化图解中具有显著的“Nb-Ta”负异常。在K₂O-SiO₂图解中,第一类基性岩脉样品落入中钾岩石范围,第二类基性岩脉样品落入高钾岩石或钾玄岩范围。基性岩脉分布的重要特点是中钾基性岩脉分布于本区北部上地幔拗陷区,而高钾基性岩脉分布于本区南部地幔隆起区或斜坡区。两类基性岩脉有着不同的岩浆来源。在本区北部,软流圈物质入侵和熔蚀Ⅰ型富集地幔混合形成中钾基性岩脉,随着时代的由老至新和熔蚀作用的不断进行,岩浆中Ⅰ型富集地幔成分增加。晚期,岩浆活动向连平、新丰一带迁移。在本区南部,软流圈物质入侵并熔蚀Ⅱ型富集地幔,形成具有软流圈物质和Ⅱ型富集地幔混合特征的高钾基性岩脉。随着熔蚀作用的不断进行,岩浆中Ⅱ型富集地幔成分增加,晚期基性岩浆活动向三水裂谷、南澳裂谷迁移。