Regional scenarios of sea level rise and impacts on Basque (Bay of Biscay) coastal habitats,throughout the 21st century

Global climate models have predicted a rise on mean sea level of between 0.18 m and 0.59 m by the end of the 21st Century, with high regional variability. The objectives of this study are to estimate sea level changes in the Bay of Biscay during this century, and to assess the impacts of any change on Basque coastal habitats and infrastructures. Hence, ocean temperature projections for three climate scenarios, provided by several atmosphere–ocean coupled general climate models, have been extracted for the Bay of Biscay; these are used to estimate thermosteric sea level variations. The results show that, from 2001 to 2099, sea level within the Bay of Biscay will increase by between 28.5 and 48.7 cm, as a result of regional thermal expansion and global ice-melting, under scenarios A1B and A2 of the Intergovernmental Panel on Climate Change. A high-resolution digital terrain model, extracted from LiDAR, data was used to evaluate the potential impact of the estimated sea level rise to 9 coastal and estuarine habitats: sandy beaches and muds, vegetated dunes, shingle beaches, sea cliffs and supralittoral rock, wetlands and saltmarshes, terrestrial habitats, artificial land, piers, and water surfaces. The projected sea level rise of 48.7 cm was added to the high tide level of the coast studied, to generate a flood risk map of the coastal and estuarine areas. The results indicate that 110.8 ha of the supralittoral area will be affected by the end of the 21st Century; these are concentrated within the estuaries, with terrestrial and artificial habitats being the most affected. Sandy beaches are expected to undergo mean shoreline retreats of between 25% and 40%, of their width. The risk assessment of the areas and habitats that will be affected, as a consequence of the sea level rise, is potentially useful for local management to adopt adaptation measures to global climate change.     

Human impacts overwhelm the effects of sea-level rise on Basque coastal habitats (N Spain) between 1954 and 2004

According to coastal measurements, global mean sea-level has risen at a rate of 1.8 mm yr⁻¹ between 1950 and 2000, with large spatial variability at regional scales. Within the Bay of Biscay, trends computed from coastal tide gauges records have revealed that sea-level rise is accelerating over this period of time; this is in agreement with rates obtained from satellite imagery in the open ocean since 1993. The objectives of the present study are: (1) to assess the evidence of the relative sea-level rise on coastal morphology and habitats in the Gipuzkoan littoral zone (Basque coast, northern Spain) for the period 1954–2004, and (2) to evaluate the relative contribution of local anthropogenic versus sea-level rise impacts for explaining inter-supratidal habitat changes. A high-resolution airborne laser altimetry data (LIDAR) has been used to derive a Digital Terrain Model (DTM) of 15-cm vertical resolution. Coastal habitats were mapped for two periods, using historic airborne photography (1954) and high-resolution imagery (2004). Analysis of tide gauge records from Santander (northern Spain) has revealed that relative mean sea-level has been rising at a rate of 2.08 ± 0.33 mm yr⁻¹ from 1943 to 2004; this is consistent with sea-level trends from other measurements within the area (St. Jean de Luz and Bilbao), obtained over shorter periods of time, and with previous results obtained in the Bay of Biscay. Based upon this sea-level trend and by means of a LIDAR-based DTM, the results have indicated that the predicted change along the Gipuzkoan coast due to sea-level rise was of 11.1 ha within the 50-yr period. In contrast, comparison of historical and recent orthophotography has detected only 2.95 ha of change, originated possibly from sea-level rise, and 98 ha transformed by anthropogenic impacts. Hence, coastal changes due to sea-level rise might be overwhelmed by excessive human impacts, at the spatial and temporal scales of the analysis. This work highlights that local anthropogenic impact is the major threat to Basque coastal and estuarine habitats, compared with natural erosive processes and global climate change driving forces over recent times.     

海岸圈围对雁鸭类种群及生境的影响研究——以长江口横沙东滩为例

滨海湿地是雁鸭类的重要栖息地,然而高强度的海岸圈围工程对滨海湿地生态系统和鸟类栖息地造成了显著影响,因此分析和研究海岸圈围对雁鸭类种群及栖息地的影响,对水鸟保护和滨海湿地资源可持续利用具有重要的理论和实践意义。位于长江口的横沙东滩,于2003年启动了海岸圈围促淤工程,工程的实施导致湿地生境和水鸟种群都发生着快速变化。本研究分别对2013、2015、2016和2017年,横沙东滩雁鸭类种群和生境因子的时空变化进行了调查与分析,通过拟合回归分析了两者的相关关系,探讨海岸圈围后生境的快速变化对雁鸭类种群产生的影响,从而提出海岸带圈围后水鸟栖息地的保护与管理对策。结果表明:1)海岸圈围工程的实施显著改变了滨海湿地的水鸟生境及种群特征。随着工程的推进,自然潮滩的盐沼湿地呈动态变化趋势;促淤区则随着泥沙的补给,新生了大面积的沼泽湿地;成陆区逐渐向淡水生态系统演替。伴随着生境的变化,雁鸭类种群逐渐从成陆区和自然潮滩向促淤区转移。2)不同生境类型影响雁鸭类种群数量特征的生境因子不同。未实施圈围的自然潮滩影响雁鸭类数量的主要因素是海三棱藨草/藨草群落面积;正在实施圈围的促淤区的主要影响因素是挺水植物面积、植被归一化指数(NDVI)和无植被覆盖水域面积;已圈围的成陆区主要影响因素为沉水植物面积。综上,雁鸭类偏向选择具有开阔水域、充足食物供给和相对较低植被盖度的生境类型。对于海岸圈围区域,若能合理利用圈围土地,保留部分区域为湿地,并根据水鸟的生境需求,适当营造水鸟适宜的栖息地,可在一定程度上减缓圈围工程对水鸟的影响,实现滨海湿地水鸟栖息地保护和湿地资源可持续利用的动态平衡。     

长江口大型工程对河口生境破碎化影响的初步研究

通过对工程海域26个站位的调查采样,研究分析了长江口深水航道治理一期工程对河口生境破碎化的影响。结果表明,工程已对长江河口区局部海域水体和底栖生境破碎化产生了明显影响,而对工程海域小尺度海洋水团、底栖生境和渔业资源生境的破碎化影响最大,造成局部小尺度海洋水团改变,部分渔业资源种类洄游通道、产卵场、肥育场、渔场生境破碎化。建议建立长江口生态特别保护区,加强对河口大型工程综合影响研究与生态修复,加强河口生态系统管理与执法力度,为长江口沿岸城市社会经济的可持续健康发展提供良好的海洋生态环境基础。     

联合光谱和纹理特征的滨海湿地高光谱深度学习分类—以黄河三角洲湿地为例

本文基于CHRIS高光谱遥感影像,发展了一种结合地物光谱特征和多纹理空间特征信息,采用双全链接的8层深度卷积神经网络分类算法对滨海湿地高光谱影像进行遥感地物分类,并在黄河口滨海湿地进行了应用。结果表明：1）基于测试样本数据,联合光谱特征和K-L变换的纹理特征信息,采用DCNN模型方法展现了高的分类精度,精度高达99%;2）利用光谱特征和全纹理特征的精度比仅使用光谱特征和光谱特征联合K-L变换后纹理特征的分类精度低。利用K-L变换后的光谱特征和纹理特征的DCNN分类精度达到99.38%,相比于使用全纹理特征信息的精度提高了4.15%;3）基于验证图像,发展的DCNN分类方法精度优于其他算法,DCNN方法总体分类精度为84.64%,Kappa系数为0.80;4）相比于浅层分类方法,本文发展的DCNN模型分类算法保证了所有地物类型的分类精度更加均衡,保持了主要地物类型的分类精度几乎不变,同时提高了滩涂和农田的精度。基于DCNN模型,潮滩和农田的分类精度分别达到79.26%和56.72%。比其它浅层分类方法提高了2.51%和10.6%。     

河控型河口盐度层化对悬沙的捕集机制以洪季磨刀门河口为例

河控型河口盐度混合和层化是控制悬沙输移扩散的重要动力机制。以珠江磨刀门河口为研究对象,基于2017年洪季三船同步大、小潮水文泥沙观测数据,分析河控型河口水体盐度层化结构的时空变化对悬沙分布的影响机制。结果表明：受径潮动力耦合时空变化影响,河口盐度垂向分布表现出时空差异,即受径流主导的M1站(挂锭角),河口盐度在涨落潮周期内垂向混合均匀,受径潮控制的M2站(口门)在整个潮周期内盐度层化结构明显,口门外侧的M3站,潮动力作用较强,盐度垂向分布随涨落潮变化而变化;悬沙空间分布与盐度分布关系密切,盐度混合均匀利于悬沙垂向均匀分布,而盐度层化则使悬沙倾向于滞留在底层水体中,且在盐度层结界面之下出现高悬沙浓度,悬沙浓度垂向分布曲线呈L字型或抛线型,纵向上表现为高浓度悬沙团抑制在盐水楔前端,盐度层化对悬沙的捕集效应明显。通过对比水体标准化分层系数与水流垂向扩散强度系数发现,两者呈现负相关关系,即标准化分层系数愈大,垂向扩散强度愈小,表明水体层化抑制悬沙垂向扩散强度,而且水体层化程度越高,悬沙垂向扩散抑制程度越大,进而促进了河口水体盐度层化对悬沙捕集作用。本研究有助于揭示河口细颗粒泥沙运动机制及河口拦门沙演变机制,并为磨刀门河口拦门沙治理提供科学依据。     

典型入海口海岸带生态环境质量遥感评价研究——以宝山区为例

为了研究入海口海岸带生态环境质量状况,基于遥感信息技术,从土地利用的角度,构建入海口海岸带生态环境遥感评价体系,通过层次分析法并结合专家咨询法,以上海市宝山区岸线向陆5 km区域为例进行评价,得到各区域综合评价值。结果表明,宝山区入海口海岸带以工矿仓储用地为主,该区域生态环境质量自西向东逐渐下降,在练祁河和马路河之间区域到达最低点,向东开始回升,总体生态环境质量呈较差状态。     

基于PSR模型的滨海湿地生态系统健康评价——以辽河三角洲滨海湿地为例

以PSR评价模型为基础,选取人口、经济、环境、资源开发、政策法规和管理决策等指标,诊断和评估滨海湿地生态系统在湿地开发和环境污染等一系列人类活动干扰下的健康现状,将健康等级分为优、良好、一般、较差和极差等5级.结果表明,辽河三角洲滨海湿地生态系统健康状态一般,由于过度的围垦开发,自然湿地面积在1988～2007年间减少了11 072 hm2,其中,碱蓬湿地减少了75%(2 440 hm2),而水产养殖场增加了182%(9 359 hm2).流域及沿岸的工农业排污致使评价区域内水体污染较严重,COD、TIN、活性磷酸盐和Pb的含量分别达到3.06 mg/dm3、795.45、44.01和6.46μg/dm3,普遍为四类或劣四类水质.环境的恶化,导致碱蓬、芦苇湿地面积萎缩,鸟类种类和数量不断减少,底栖生物多样性降低.并据此提出了辽河三角洲滨海湿地的管理与保护措施.     

A diagnostic modelling framework to construct indices of biotic integrity: A case study of fish in the Zeeschelde estuary (Belgium)

We propose a coherent regression model building framework to construct fish-based indices. More specifically, we concentrate on the selection of an optimal set of metrics which remains a difficult problem. The paper departs from the observation that an index of biotic integrity (IBI) is analogous to a diagnostic model in medicine assessing the health condition of a patient from a series of biomarkers. In the same vein, an IBI is a diagnostic model predicting the ecosystem condition of a site from a set of (scored) metrics. Metrics are community attributes sensitive to anthropogenic pressure and their scores express the “distance to target” to a reference condition. In a medical context, Receiver Operating Characteristic (ROC) curves are commonly used to assess the diagnostic accuracy of laboratory tests. An ROC curve plots the sensitivity of a test (Se; the capacity to detect a disease or degradation) as a function of its false positive fraction (FPF) which is the complement of the specificity (Sp = 1 - FPF; the capacity to recognise a healthy person or a reference condition). The ROC curve represents the strength of the index to discriminate between degraded and reference sites. Higher curves correspond to stronger tests as then a higher sensitivity can be combined with a lower false positive fraction. Hence, it is intuitively clear to use summary statistics of the ROC curve as criteria to optimise medical tests or biotic indices. In this paper, we illustrate the value of this modelling framework with a case study in the Zeeschelde estuary in Belgium. In essence, a “traditional” IBI is an average of metrics scoring relevant properties of the ecosystem. We demonstrate this average score model (AVG) is a special member of the more flexible predictive logistic model (PLM) family. The selection of a set of metrics becomes equivalent to variable selection in statistical model building. We apply model building techniques as best subsets regression to facilitate the search for an optimal suite of metrics from a candidate set and use cross-validation to avoid overfitting. The results show that a few metrics suffice to discriminate between most-impacted and least-impacted sites.     

Possible effects of climate change on estuarine nutrient fluxes: a case study in the highly nutrified Schelde estuary (Belgium, The Netherlands)

Global change models predict effects of climate change on hydrological regimes at the continental scale in Europe. The aim of this study was to gain a better understanding of the possible effect of changing external forcing conditions on the functioning of estuarine ecosystems. In densely populated areas, anthropogenic nutrient enrichment and consequent alteration of nutrient biogeochemical cycles have already had a big impact on these ecosystems. The average yearly discharge of the upper Schelde estuary increased nearly threefold over the period 1996–2000, from 28 m³ s⁻¹ in 1996 to 73 m³ s⁻¹ in 2000. The continuously rising discharge conditions over the five-year period were used as a reference situation for possible future effects of climate on ecological functioning through increase of discharge. At high discharges, nutrient (NH₄⁺, NO₃⁻, dissolved silica and PO₄³⁻) concentrations in the tidal fresh- and brackish water showed a decrease of up to 50% while total discharged nutrient loadings increased up to 100%. Opposite effects of increasing discharge on NH₄⁺, NO₃⁻ and dissolved silica concentrations in summer and winter, resulted in the flattening out of seasonal cycles for these nutrients. Under high discharge conditions, silica uptake by diatom communities was lowered. Dissolved silica loadings to the coastal area increased concurrently with total silica loadings upstream. Salt intrusion to the marine parts of the estuary decreased. This resulted in a downstream shift of the salinity gradient, with lower salinity observed near the mouth. As a result, TDIN, NO₃⁻ and dissolved silica concentrations doubled at the mouth of the estuary.     

Investigation of the generation and propagation of low frequency internal waves: A case study for the east coast of India

SAR (Synthetic Aperture Radar) images in the northwest Bay of Bengal indicate the existence of internal waves and their occurrence and intensity is topography dependent as indicated by in-situ data and satellite information. To complement and comprehend the observations, a three-dimensional Princeton Ocean Model is applied to study the generation and propagation of internal waves. The model domain is configured with a variable curvilinear grid and the input fields comprise bathymetry, initial temperature and salinity, wind stress, air-sea heat flux and tidal information. The numerical investigation indicated a predominant activity of internal waves in the north, and the rationale is three-fold. The first one could be the stable stratification due to fresh water discharge from head-bay major river system, secondly, the significant magnitude/range of the tides and finally, the bathymetry in the coastal waters off Paradip is about 12% shallower compared to that of Visakhapatnam and further south. The cumulative effect of these causes the predominance of internal waves in the north. The core of the energy is essentially in the low-frequency range and the model is able to simulate semi-diurnal and diurnal components reasonably well up to 6 h frequency (0.162 cph).     

不同流路时期黄河三角洲沿岸余流场的数值对比研究

黄河入海流路改道变迁频繁,有关不同流路时期沿岸余流场变化的认识将为理解入海泥沙输送特征的变动和沿岸泥沙动态提供重要的水动力基础,通过数值对比实验,以分处黄河三角洲北、东两岸的钓口和清水沟流路为例,对比研究了两个流路基本稳定后的初期黄河三角洲沿岸余流场结构及其流速的变化.结果表明,虽然两个不同流路时期沿岸流系的总体趋势存在一致性,但不同岸段的局部余流场结构、流速及其分布在不同季节都发生了程度不一的变化.在流场结构上,夏、冬季的差异很小,而春、秋季的差异相对较大,特别是在10m以浅的近岸海域的变化明显.高流速区分布,在钓口流路时期具有随各突出沙嘴而生的特点,清水沟流路时则是沿岸线走向、呈条带状延伸,且其分布范围更大、中心流速更高.沿岸余流流速在清水沟流路时期比钓口流路时期大很多,以清水沟口以南海域的流速增加最显著,北岸海域其次,清水沟口以北、神仙沟以南岸段的变化最小,在季节上以冬季增幅最明显.两个不同流路时期沿岸潮致余流场的总体特征也是基本一致的,分布于甜水沟沙嘴(清水沟口)南、北部的涡环结构在清水沟流路时期明显向东北方向移动,清水沟流路时期神仙沟和甜水沟等原沙嘴附近的潮致余流流速存在明显的减小.     

亚热带沿海景观的旅游保护性开发及建设探讨--以福建沿海为例

依据地貌学和风景学的角度,福建沿海景观以闽江口和九龙江口为界可分为3个景观亚区,并具有多样性与复杂性、动态性与脆弱性和关联性与分异性等特征.本文运用景观生态的原理研究沿海景观的构成与格局,在沿海景观的分类和特征概括的基础上,探讨福建沿海景观旅游开发与建设的模式.通过维护沿海景观系统的稳定,优化沿海各景观亚区的分布格局,提高沿海景观的整体舒适性和挖掘文化景观的内涵等应对措施以实现福建沿海旅游的科学发展.     

海岸带土地发展潜力评价——以杭州湾南岸为例

土地潜力评价是编制土地利用规划的前提,把握土地的潜在经济效能是城镇化、工业化快速推进背景下土地资源合理配置的重要命题。本文甄选自然条件、生态敏感性、经济发展和空间结构指标建立了土地发展潜力评价体系,分别采用模糊综合评价法与网络层次分析法赋权指标体系与计算权重,测度发展潜力值并划分了杭州湾南岸余姚、慈溪和镇海的海岸带土地发展潜力区。结果显示:(1)低发展潜力区面积为237.14 km²,占比为17.73%;中发展潜力区面积为323.08 km²,占比为24.15%;高发展潜力区面积为473.34 km²,占比为35.38%;极高发展潜力区面积为304.27 km²,比例为22.74%。(2)按照地类的级别面积分析,交通运输用地和自然保留地面积在极高潜力区中达到峰值,呈由高向低等级面积递减态势;耕地、其他农用地、城乡建设用地和其他建设用地在高潜力区中占比最大,且基本布局于极高、高潜力区;园地、河流水面、水利建设用地集中于中潜力区,而沿海滩涂与林地基本分布于低、中潜力区。(3)余姚、慈溪和镇海海岸带土地发展潜力分区呈现不同特点,余姚属于待提升型,慈溪为均衡发展型,镇海是高质发展潜力型。     

Influence of environmental data of different sources on marine species habitat modeling: A case study for Ommastrephes bartramii in the Northwest Pacific Ocean

The quality of environmental data and its possible impact on the marine species habitat modelling are often overlooked while the sources for these data are increasing. This study selected sea surface temperature(SST) from two commonly used sources, the NOAA Ocean Watch and IRI/LDEO Climate Data Library, and then constructed habitat suitability index model to evaluate the influences of SST from the two sources on the outcomes of Ommastrephes bartramii habitat models for the months of July–October...     

基于水质状态和生态响应的综合富营养化评价模型——以山东半岛典型海域富营养化评价为例

对前期构建的长江口及其邻近水域的富营养化评价模型作了进一步改进,并根据2006年至2007年春夏秋冬四个季节的山东半岛典型海域的调查资料,将该模型应用于山东半岛典型海域的富营养化评价。评价结果表明:在"优、良、中、差、劣"五个富营养化等级中,山东半岛大部分海湾和近岸海域出现"中"到"差"程度的富营养化状况,且海湾内富营养化程度明显高于近岸海域。较突出的富营养化症状主要是夏秋季节高浓度的叶绿素水平和周期性发生的有毒有害藻华。烟台四十里湾、丁字湾和青岛胶州湾是山东半岛富营养化状况较严重的三个海湾。仅少数海域,如日照北部近海和黄岛近海的富营养化程度处于"良"的等级。评价模型同时包含富营养化压力因素(水质状态)和效应因素(生态响应)两个方面,在指标评分上不仅考虑评价浓度,还考虑浓度出现的频率和空间覆盖度等方面,以及对各指标合理分配权重,使得评价模型更能准确、全面地反映海域富营养化状况。     

Response of coastal marine eco-environment to river fluxes into the sea: a case study of the Huanghe (Yellow) River mouth and adjacent waters

The impact of the Huanghe (Yellow) River outflows on its estuary was investigated with river gauging and shipboard hydrographic observations. The river flux has been decreasing dramatically; the discharges of water and sediment in the 1990s dropped to 27.4% and 31.9% of those in the 1950s, respectively, resulting in frequent and lengthy events of downstream channel dry-up since the 1970s. There were accumulatively 897 zero-flow days during the 1990s in the river course below the Lijin Hydrological Station, 100 km upstream from the river mouth, which is 82.4% of that in 1972. As freshwater input decreases, river-borne nutrients to the estuarine increased significantly. Concentration of dissolved inorganic nitrogen (DIN) in the 1990s was four times of that in 1950s. Changes in amount and content of the riverine inputs have greatly affected the estuarine ecosystem. Over the past several decades, sea surface temperature and salinity in the estuary and its adjacent waters increased and their distribution pattern altered in response to the reduction of freshwater inflow. The distribution of and seasonal succession in nutrient concentrations in the surface layer have also changed with a shift of river outlet and the decrease in riverine nutrient loads. Furthermore, deterioration of estuarine ecosystem by less river input has decreased primary productivity in the deltaic region waters, and in turn depressed the fishery.     

Whether human-induced activities could change the gradient pattern of coastal land use along the sea-land direction: a case study in Manila Bay,Philippines

Increasing intense human activities have largely changed the coastal landscape and caused many environmental issues. However, whether human-induced activities could change the coastal land use gradient pattern, an important coastal zonal characteristic along the sea–land direction, remains unclear. Manila Bay was selected as the study area in this work. According to the distance of the land use and land cover(LULC) to the coastline, we clustered the typical coastal land use sequence patterns(CLU...     

砂质海岸整治修复效果模糊综合评价研究——以营口月亮湾为例

本文采用模糊综合评价方法,从自然环境效果、景观生态效果、沙滩资源效果和社会经济效果4个方面研究构建了砂质海岸整治修复效果综合评价指标体系与评价方法,并以营口月亮湾为例进行了实证研究。结果表明:本文提出的砂质海岸整治修复效果综合评价方法涵盖内容全面,指标获取可行,评价结果明确,整体方法实用。营口月亮湾砂质海岸整治修复效果总体评价结果为优秀,综合评分为2.636 2,其中社会经济效果贡献率为30.52%,沙滩资源效果贡献率为30.17%,自然环境效果和景观生态效果贡献率分别为19.88%和19.44%。     

Estimating boundary currents from satellite altimetry: A case study for the east coast of India

We present a methodology to derive surface geostrophic current from a newly released altimetric sea-level data set. TOPEX/Poseidon data were first completely reprocessed from Geophysical Data Records using new algorithms accommodating marginal seas and coastal conditions. The methodology applied to the reprocessed data essentially consists of a smoothing of the raw along-track coastal altimetric data at scales at which the geostrophic equilibrium holds. This was reduced to a computational procedure using a set of objective criteria. We have applied the method to the East India Coastal Current (EICC) at the western boundary of the Bay of Bengal. This paper first examines the quality of the new data set, which compares well with tide-gauge data; the current we derived is consistent with independent estimates. Our methodology reveals the full spectrum of the along-shore current, ranging from intra-seasonal to inter-annual time scales, from the deep ocean to the shelf-break area where the EICC exists. The algorithm can be applied to any coastal region where an order of the Rossby radius can be defined, and it therefore opens up bright prospects for mapping the variability of other boundary-current systems in the world ocean from altimetry.