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1.
A new classification of coastal wetlands along the coast of China has been generated that is compatible with the Ramsar Convention of 1971. The coastal wetlands have been divided into two broad categories with overall nine subcategories. On this basis, a series of coastal wetland maps, together covering the coast of mainland China, have been produced based on topographic maps acquired in the 1970s and satellite images acquired in 2007. These document substantial wetland losses over this period. In the 1970s, the total coastal wetland area in China was 5.76?×?104?km2, whereas in 2007, it was 5.36?×?104?km2, indicating a loss of 7 %. Over this approximately 40-year period, the area of natural coastal wetlands decreased from 5.74?×?104 to 5.09?×?104?km2, while that of artificial coastal wetlands increased from 240 to 2,740 km2. Due to shoreline and sea-level changes, newly formed coastal wetlands amounted to 2,460 km2, while coastal wetland loss amounted to 6,310 km2 in the period from the 1970s to 2007. When excluding shallow coastal waters (depths between 0 and ?5 m), nearly 16 % of Chinese coastal wetlands have been lost between the 1970s and 2007.  相似文献   

2.
Above- and belowground production in coastal wetlands are important contributors to carbon accumulation and ecosystem sustainability. As sea level rises, we can expect shifts to more salt-tolerant communities, which may alter these ecosystem functions and services. Although the direct influence of salinity on species-level primary production has been documented, we lack an understanding of the landscape-level response of coastal wetlands to increasing salinity. What are the indirect effects of sea-level rise, i.e., how does primary production vary across a landscape gradient of increasing salinity that incorporates changes in wetland type? This is the first study to measure both above- and belowground production in four wetland types that span an entire coastal gradient from fresh to saline wetlands. We hypothesized that increasing salinity would limit rates of primary production, and saline marshes would have lower rates of above- and belowground production than fresher marshes. However, along the Northern Gulf of Mexico Coast in Louisiana, USA, we found that aboveground production was highest in brackish marshes, compared with fresh, intermediate, and saline marshes, and belowground production was similar among all wetland types along the salinity gradient. Multiple regression analysis indicated that salinity was the only significant predictor of production, and its influence was dependent upon wetland type. We concluded that (1) salinity had a negative effect on production within wetland type, and this relationship was strongest in the fresh marsh (0–2 PSU) and (2) along the overall landscape gradient, production was maintained by mechanisms at the scale of wetland type, which were likely related to plant energetics. Regardless of wetland type, we found that belowground production was significantly greater than aboveground production. Additionally, inter-annual variation, associated with severe drought conditions, was observed exclusively for belowground production, which may be a more sensitive indicator of ecosystem health than aboveground production.  相似文献   

3.
Deltaic landscapes, such as the Mississippi River Delta, are sites of extensive conversion of wetlands to open water, where increased fetch may contribute to erosion of marsh edges, increasing wetland loss. A field experiment conducted during a storm passage tested this process through the observations of wave orbital and current velocities in the fringe zone of a deteriorating saltmarsh in Terrebonne Bay, Louisiana. Incident waves seaward of the marsh edge and wave orbital and current velocities immediate landward of the marsh edge were measured. Through a dimensional analysis, it shows that the current and orbital velocities in the marsh fringe were controlled by the incident waves, inundation depth, submergence ratio, and vegetation density. Similarly, it is shown that the longshore currents in the inundated saltmarsh fringe depended on the local wave-induced momentum flux, vegetation submergence, and vegetation density in the fringe zone. The cross-shore current showed the presence of a return flow in the lower region of the velocity profile. A high correlation between the current direction and the local flow-wave energy ratio as well as the vegetation submergence and density is found, indicating the important role of surface waves in the fringe flow landward of an inundated wetland under storm conditions. The field observations shed light on the potential ecological consequences of increased wave activities in coastal saltmarsh wetlands owing to subsidence, sea level rise, limited sediment supply, increases in wind fetch, and storm intensity.  相似文献   

4.
In deltas, subsidence leads to a relative sea-level rise (RSLR) that is often much greater than eustatic rise alone. Because of high RSLR, deltaic wetlands will be affected early by an acceleration of eustatic sea-level rise. If there is sufficient vertical accretion, wetlands can continue to exist with RSLR; however, lack of sediment input eventually leads to excessive water logging and plant death. Areas with low tidal range, such as the Mediterranean and Gulf of Mexico, are especially vulnerable to rising water levels because the elevational growth range of coastal vegetation is related to tide range. Reduction of suspended sediments in rivers and prevention of wetland flooding by river dikes and impoundments have reduced sediment input to Mediterranean and Gulf of Mexico deltaic wetlands. This sediment deficit will become more important with an acceleration in sea-level rise from global warming. Most sediment input occurs during strong pulsing events such as river floods and storms, and management policies and decisions are especially designed to protect against such events. Management approaches must be reoriented to take advantage of pulsing events to nourish marsh surfaces with sediments. We hypothesize that deltas can be managed to withstand significant rates of sea-level rise by taking advantage of pulsing events leading to high sediment input, and that this type of management approach will enhance ecosystem functioning.  相似文献   

5.
One of the most critical problems facing many deltaic wetlands is a high rate of relative sea-level rise due to a combination of eustatic sea-level rise and local subsidence. Within the Rhône delta, the main source of mineral input to soil formation is from the river, due to the low tidal range and the presence of a continuous sea wall. We carried out field and modeling studies to assess the present environmental status and future conditions of the more stressed sites, i.e.,Salicornia-type marshes with a shallow, hypersaline groundwater. The impacts of management practices are considered by comparing impounded areas with riverine areas connected to the Rhône River. Analysis of vegetation transects showed differences between mean soil elevation ofArthrocnemum fruticosum (+31.2 cm),Arthrocnemum glaucum (+26.5 cm), bare soil (+16.2 cm), and permanently flooded soil (?12.4 cm). Aboveground and belowground production showed that root:shoot ratio forA. fruticosum andA. glaucum was 2.9 and 1.1, respectively, indicating more stressful environmental conditions forA. glaucum with a higher soil salinity and lack of soil drainage. The annual leaf litter production rate of the two species is 30 times higher than annual stem litter production, but with a higher long-term decomposition rate associated with leaves. We developed a wetland elevation model designed to predict the effect of increasing rates of sea-level rise on wetland elevation andSalicornia production. The model takes into account feedback mechanisms between soil elevation and river mineral input, and primary production. In marshes still connected to the river, mineral input decreased quickly when elevation was over 21 cm. Under current sea-level rise conditions, the annual amount of riverine mineral input needed to maintain the elevation of the study marshes is between 3,000 and 5,000 g m?2 yr?1. Simulations showed that under the Intergovernmental Panel on Climate Change best estimate sea-level rise scenario, a mineral input of 6,040 g m?2 yr?1 is needed to maintain marsh elevation. The medium term response capacity of the Rhône deltaic plain with rising sea level depends mainly on the possibility of supplying sediment from the river to the delta, even though the Rhône Delta front is wave dominated. Within coastal impounded marshes, isolated from the river, the sediment supply is very low (10 to 50 g m?2 yr?1), and an increase of sea-level rise would increase the flooding duration and dramatically reduce vegetation biomass. New wetland management options involving river input are discussed for a long-term sustainability of low coastal Mediterranean wetlands.  相似文献   

6.
The impact of relative sea-level rise (RSLR), damage to and possible responses in the Ebro Delta (NW Mediterranean) has been analyzed. Impact was determined by delineating delta areas prone to flooding under different RSLR scenarios. The surface areas of the different habitats were then quantified for flooding impact and affected ecosystems were assessed. The obtained results enabled us to characterize the Ebro Delta as a coastal environment that is highly sensitive to changes in sea level, with affected flooded areas likely to range between about 45 and 60 % for different RSLR scenarios, from which about 26 % would be inundated by subsidence only. In absolute terms, the habitat most likely to be affected by flooding was cropland. In relative terms, the most affected habitats were those typical of the lowest areas: saltwater wetlands, riparian buffer and areas of saline vegetation. Under present deltaic evolution with no sediment supply, adaptation is considered a plausible option for managing the Ebro delta under a RSLR scenario. This implies permitting surface area losses or land use changes in the lower parts of the delta, where natural values will be reinforced, and concentrating agriculture in the higher parts of the deltaic plain.  相似文献   

7.
Large areas of natural coastal wetlands have suffered severely from human-driven damages or conversions (e.g., land reclamations), but coastal carbon flux responses in reclaimed wetlands are largely unknown. The lack of knowledge of the environmental control mechanisms of carbon fluxes also limits the carbon budget management of reclaimed wetlands. The net ecosystem exchange (NEE) in a coastal wetland at Dongtan of Chongming Island in the Yangtze estuary was monitored throughout 2012 using the eddy covariance technique more than 14 years after this wetland was reclaimed using dykes to stop tidal flooding. The driving biophysical variables of NEE were also examined. The results showed that NEE displayed marked diurnal and seasonal variations. The monthly mean NEE showed that this ecosystem functioned as a CO2 sink during 9 months of the year, with a maximum value in September (?101.2 g C m?2) and a minimum value in November (?8.2 g C m?2). The annual CO2 balance of the reclaimed coastal wetland was ?558.4 g C m?2 year?1. The ratio of ecosystem respiration (ER) to gross primary production (GPP) was 0.57, which suggests that 57 % of the organic carbon assimilated by wetland plants was consumed by plant respiration and soil heterotrophic respiration. Stepwise multiple linear regressions suggested that temperature and photosynthetically active radiation (PAR) were the two dominant micrometeorological variables driving seasonal variations in NEE, while soil moisture (M s) and soil salinity (PSs) played minor roles. For the entire year, PAR and daytime NEE were significantly correlated, as well as temperature and nighttime NEE. These nonlinear relationships varied seasonally: the maximum ecosystem photosynthetic rate (A max), apparent quantum yield (?), and Q 10 reached their peak values during summer (17.09 μmol CO2?m?2 s?1), autumn (0.13 μmol CO2?μmol?1 photon), and spring (2.16), respectively. Exceptionally high M s or PSs values indirectly restricted ecosystem CO2 fixation capacity by reducing the PAR sensitivity of the NEE. The leaf area index (LAI) and live aboveground biomass (AGBL) were significantly correlated with NEE during the growing season. Although the annual net CO2 fixation rate of the coastal reclaimed wetland was distinctly lower than the unreclaimed coastal wetland in the same region, it was quite high relative to many inland freshwater wetlands and estuarine/coastal wetlands located at latitudes higher than this site. Thus, it is concluded that although the net CO2 fixation capacity of the coastal wetland was reduced by land reclamation, it can still perform as an important CO2 sink.  相似文献   

8.
Tidal wetlands play an important role with respect to climate change because of both their sensitivity to sea-level rise and their ability to sequester carbon dioxide from the atmosphere. Policy-based interest in carbon sequestration has increased recently, and wetland restoration projects have potential for carbon credits through soil carbon sequestration. We measured sediment accretion, mineral and organic matter accumulation, and carbon sequestration rates using 137Cs and 210Pb downcore distributions at six natural tidal wetlands in the San Francisco Bay Estuary. The accretion rates were, in general, 0.2?C0.5?cm?year?1, indicating that local wetlands are keeping pace with recent rates of sea-level rise. Mineral accumulation rates were higher in salt marshes and at low-marsh stations within individual sites. The average carbon sequestration rate based on 210Pb dating was 79?g?C?m?2?year?1, with slightly higher rates based on 137Cs dating. There was little difference in the sequestration rates among sites or across stations within sites, indicating that a single carbon sequestration rate could be used for crediting tidal wetland restoration projects within the Estuary.  相似文献   

9.
We report on a decadal trend of accretionary dynamics in the wetlands of several northwestern Mediterranean deltas and a lagoon system, all of them with high rates of wetland loss. Wetland vertical accretion and surface elevation change were measured at 55 riverine, marine, and impounded sites in four coastal systems: the Ebro delta, Spain; the Rhône delta, France; and the Po delta and Venice Lagoon, Italy. Vertical accretion and elevation change ranged between 0 and 25 mm year?1 and were strongly correlated. The highest rates of elevation gain occurred at riverine sites where vertical accretion was highest. We conclude that areas with high sediment input, mainly riverine, are the only ones likely to survive accelerated sea-level rise, especially if recent higher estimates of 1 m or more in the twenty-first century prove to be accurate. This is the first study where the importance of river input on wetland survival has been demonstrated at a decadal time scale over a broad geographical area.  相似文献   

10.
Growing wetland loss along a coastal area in China was examined through shoreline recession and land use changes. Carbon storage or sequestration in coastal wetland soils was based on vertical marsh accretion and aerial change data. Marshes sequester significant amounts of carbon through vertical accretion; however, large amounts of carbon previously sequestered in the soil profile are lost through rapid land use changes and shoreline recessions. The Liaohe Delta (LHD) was divided into nine landscape types based on Landsat TM digital images from 1991 to 2011. The distributed areas and transfer matrices of each landscape type were calculated. Combined with the organic carbon content and bulk density of 202 soil surface samples from field investigations in 2012, the soil organic carbon pools and stocks were estimated. Results showed that the soil organic carbon pools varied from 0.58 to 9.75 kg m?2, and organic carbon storage in the upper 20 cm of soil was 1935.92 × 104 and 1863.87 × 104 t in 1991 and 2011, respectively. We attributed these large losses of carbon to rapid land use changes. The construction of levees along the shoreline has triggered large instantaneous losses of previously sequestered carbon through the destruction of 278.06 km2 of tidal flats. Our results reveal that the LHD wetlands might not serve as a desired sink of carbon if maladministration practices are applied. These results can provide scientific guidance for decision makers in determining an effective way to maintain the soil carbon pool in the wetlands of the LHD.  相似文献   

11.
The climate change-induced expansion of mangroves into salt marshes could significantly alter the carbon (C) storage capacity of coastal wetlands, which have the highest average C storage per land area among unmanaged terrestrial ecosystems. Mangrove range expansion is occurring globally, but little is known about how these rapid climate-driven shifts may alter ecosystem C storage. Here, we quantify current C stocks in ecotonal wetlands across gradients of marsh- to mangrove-dominance, and use unique chronological maps of vegetation cover to estimate C stock changes from 2003 to 2010 in a 567-km2 wildlife refuge in the mangrove-salt marsh ecotone. We report that over the 7-yr. period, total wetland C stocks increased 22 % due to mangrove encroachment into salt marshes. Newly established mangrove stands stored twice as much C on a per area basis as salt marsh primarily due to differences in aboveground biomass, and mangrove cover increased by 69 % during this short time interval. Wetland C storage within the wildlife refuge increased at a rate of 2.7 Mg C ha?1 yr.?1, more than doubling the naturally high coastal wetland C sequestration rates. Mangrove expansion could account for a globally significant increase of terrestrial C storage, which may exert a considerable negative feedback on warming.  相似文献   

12.
Shennan  Ian  Tooley  Michael  Green  Frances  Innes  Jim  Kennington  Kevin  Lloyd  Jeremy  Rutherford  Mairead 《Geologie en Mijnbouw》1998,77(3-4):247-262
Analyses of geomorphologically contrasting sites in Morar, NW Scotland, describe the forcing mechanisms of coastal change. Isolation basins (i.e. basins behind rock sills and now isolated from the sea following isostatic uplift) accumulated continuous marine and freshwater sediments from c.12 to 2 ka BP. Raised dune, marsh and wetland sites register breaching, migration and stability of dunes from c. 9 to 2 ka BP. High-resolution methods designed to address issues of macroscale and microscale sea-level changes and patterns of storminess include 1-mm sampling for pollen, dinocyst and diatom analyses, infra-red photography, X-ray photography and thin-section analysis. The data enhance the record of relative sea-level change for the area. Major phases of landward migration of the coast occurred during the period of low sea-level rise in the mid-Holocene as the rate of rise decreased from c. 3 to < 1 mm/year. Relative sea-level change controls the broad pattern of coastal evolution at each site; local site-specific factors contribute to short-term process change. There is no record of extreme events such as tsunami. Within a system of dynamic metastable equilibrium, the Holocene records show that site-specific factors determine the exact timing of system breakdown, e.g. dune breaching, superimposed on regional sea-level rise. The global average sea-level rise of 3 to 6 mm/yr by AD 2050 predicted by IPCC would only partly be offset in the Morar area by isostatic uplift of about 1 mm/yr. A change from relative sea-level fall to sea-level rise, in areas where the regional rate of uplift no longer offsets global processes, is a critical factor in the management of coastal resources.  相似文献   

13.
The formation of short-lived backswamps along the Carmel coast of Israel coincides with the rapid global sea-level rise during the late Pleistocene-early Holocene transition. The current study shows that the wetland phenomena originated around 10,000 yr ago and dried up shortly before the local Pre-Pottery Neolithic humans settled on the wetland dark clay sediments 9430 cal yr BP. Palaeontological and stable-isotope data were used in this study to elucidate previously published sedimentological reconstruction obtained from a core drilled into the western trough of the Carmel coastal plain. The water body contained typical brackish calcareous fauna, with variable numerical abundance and low species richness of ostracods and foraminifera. The δ18O and δ13C of the ostracod Cyprideis torosa show close similarity to the present Pleistocene coastal aquifer isotopic values. This study therefore concludes that the wetlands were shallow-water bodies fed by groundwater, with no evidence of sea-water mixing. It seems that they developed as the result of high groundwater levels, transportation of sediments landward, and deposition of sand bars at the paleo-river mouths. It is still not fully understood why these wetlands deteriorated abruptly and disappeared within less than 1000 yr.  相似文献   

14.
The estuarine environment can serve as either a source or sink of carbon relative to the coastal ocean carbon budget. A variety of time-dependent processes such as sedimentation, carbon supply, and productivity dictate how estuarine systems operate, and Mobile Bay is a system that has experienced both natural and anthropogenic perturbations that influenced depositional processes and carbon cycling. Sediments from eight box cores provide a record of change in bulk sediment accumulation and carbon burial over the past 110 years. Accumulation rates in the central part of the basin (0.09 g cm?2) were 60–80 % less than those observed at the head (0.361 g cm?2) and mouth (0.564 g cm?2) of the bay. Sediment accumulation in the central bay decreased during the past 90 years in response to both anthropogenic (causeway construction) and natural (tropical cyclones) perturbations. Sediment accumulation inevitably increased the residence time of organic carbon in the oxic zone, as observed in modeled remineralization rates, and reduced the overall carbon burial. Such observations highlight the critical balance among sediment accumulation, carbon remineralization, and carbon burial in dynamic coastal environments. Time-series analysis based solely on short-term observation would not capture the long-term effects of changes in sedimentation on carbon cycling. Identifying these relationships over longer timescales (multi-annual to decadal) will provide a far better evaluation of coastal ocean carbon budgets.  相似文献   

15.
The prairie wetlands of northern USA and Canada exist in numerous topographical depressions within the glaciated landscape. The wetlands are disconnected from each other most of the time with respect to surface-water drainage. The wetland water balance is controlled by snowmelt runoff and snowdrift from the surrounding uplands, precipitation, evapotranspiration, groundwater exchange, and occasional “fill-spill” connections to other wetlands. Salinity of water and the seasonal variability of water level in these wetlands have a strong influence on the ecosystem. Clay-rich glacial tills, covering much of the region, have very low (0.001–0.01 m/yr) hydraulic conductivity, except for the top several meters where the factures and macropores increase conductivity up to 1,000 m/yr. Transpiration in the wetland margin induces infiltration and lateral flow of shallow groundwater from wetland ponds through the high-conductivity zone, which strongly affects the water balance of wetlands. In contrast, groundwater flow in the deeper low-conductivity till has minor effects on water balance, but has a strong influence on salinity because the flow direction determines if the salts accumulate in wetlands (upward flow) or are leached out (downward flow) under wetlands. Understanding of the roles of shallow and deep groundwater systems will improve the hydrological conceptual framework for the management of wetland ecosystems.  相似文献   

16.
黄河三角洲进积与滨海湿地地质环境演替模式   总被引：1，自引：0，他引：1  
本文通过对黄河三角洲5个钻孔岩芯的沉积学观测、微古分析、14C测年,同时结合历史记录及遥感资料,分析了本区末次冰后期以来的沉积序列,重建了近10ka以来古环境演变过程,分析了古环境演化对滨海湿地演替的控制作用。本文着重讨论了黄河三角洲进积与湿地形成演替规律,总结了从水生系统、浅海湿地系统、潮滩湿地直至上三角洲平原湿地向陆地生态系统的演替模式。同时通过对现代黄河三角洲与老黄河三角洲演化模式进行对比,提出气候变化、人类活动会加速和改变湿地地质环境演替进程和方向的一般规律。笔者等还进一步提出,由于人类活动的影响,1855年之后湿地演替速率明显加快,约达8~33倍。古环境的重建与滨海湿地响应机制研究可更清楚地理解湿地如何对未来环境变化进行响应,包括海平面上升,从而为滨海湿地保护与管理实践活动提供科学导向。  相似文献   

17.
Climate impacts on coastal and estuarine systems take many forms and are dependent on the local conditions, including those set by humans. We use a biocomplexity framework to provide a perspective of the consequences of climate change for coastal wetland ecogeomorphology. We concentrate on three dimensions of climate change affects on ecogeomorphology: sea level rise, changes in storm frequency and intensity, and changes in freshwater, sediment, and nutrient inputs. While sea level rise, storms, sedimentation, and changing freshwater input can directly impact coastal and estuarine wetlands, biological processes can modify these physical impacts. Geomorphological changes to coastal and estuarine ecosystems can induce complex outcomes for the biota that are not themselves intuitively obvious because they are mediated by networks of biological interactions. Human impacts on wetlands occur at all scales. At the global scale, humans are altering climate at rapid rates compared to the historical and recent geological record. Climate change can disrupt ecological systems if it occurs at characteristic time scales shorter than ecological system response and causes alterations in ecological function that foster changes in structure or alter functional interactions. Many coastal wetlands can adjust to predicted climate change, but human impacts, in combination with climate change, will significantly affect coastal wetland ecosystems. Management for climate change must strike a balance between that which allows pulsing of materials and energy to the ecosystems and promotes ecosystem goods and services, while protecting human structures and activities. Science-based management depends on a multi-scale understanding of these biocomplex wetland systems. Causation is often associated with multiple factors, considerable variability, feedbacks, and interferences. The impacts of climate change can be detected through monitoring and assessment of historical or geological records. Attribution can be inferred through these in conjunction with experimentation and modeling. A significant challenge to allow wise management of coastal wetlands is to develop observing systems that act at appropriate scales to detect global climate change and its effects in the context of the various local and smaller scale effects.  相似文献   

18.
Estuaries are important subcomponents of the coastal ocean, but knowledge about the temporal and spatial variability of their carbonate chemistry, as well as their contribution to coastal and global carbon fluxes, are limited. In the present study, we measured the temporal and spatial variability of biogeochemical parameters in a saltmarsh estuary in Southern California, the San Dieguito Lagoon (SDL). We also estimated the flux of dissolved inorganic carbon (DIC) and total organic carbon (TOC) to the adjacent coastal ocean over diel and seasonal timescales. The combined net flux of DIC and TOC (FDIC?+?TOC) to the ocean during outgoing tides ranged from ??1.8±0.5?×?103 to 9.5±0.7?×?103?mol C h?1 during baseline conditions. Based on these fluxes, a rough estimate of the net annual export of DIC and TOC totaled 10±4?×?106?mol C year?1. Following a major rain event (36 mm rain in 3 days), FDIC?+?TOC increased and reached values as high as 29.0 ±?0.7?×?103?mol C h?1. Assuming a hypothetical scenario of three similar storm events in a year, our annual net flux estimate more than doubled to 25 ±?4?×?106?mol C year?1. These findings highlight the importance of assessing coastal carbon fluxes on different timescales and incorporating event scale variations in these assessments. Furthermore, for most of the observations elevated levels of total alkalinity (TA) and pH were observed at the estuary mouth relative to the coastal ocean. This suggests that SDL partly buffers against acidification of adjacent coastal surface waters, although the spatial extent of this buffering is likely small.  相似文献   

19.
Pasquier  Ulysse  He  Yi  Hooton  Simon  Goulden  Marisa  Hiscock  Kevin M. 《Natural Hazards》2019,98(3):915-937

Coastal regions are dynamic areas that often lie at the junction of different natural hazards. Extreme events such as storm surges and high precipitation are significant sources of concern for flood management. As climatic changes and sea-level rise put further pressure on these vulnerable systems, there is a need for a better understanding of the implications of compounding hazards. Recent computational advances in hydraulic modelling offer new opportunities to support decision-making and adaptation. Our research makes use of recently released features in the HEC-RAS version 5.0 software to develop an integrated 1D–2D hydrodynamic model. Using extreme value analysis with the Peaks-Over-Threshold method to define extreme scenarios, the model was applied to the eastern coast of the UK. The sensitivity of the protected wetland known as the Broads to a combination of fluvial, tidal and coastal sources of flooding was assessed, accounting for different rates of twenty-first century sea-level rise up to the year 2100. The 1D–2D approach led to a more detailed representation of inundation in coastal urban areas, while allowing for interactions with more fluvially dominated inland areas to be captured. While flooding was primarily driven by increased sea levels, combined events exacerbated flooded area by 5–40% and average depth by 10–32%, affecting different locations depending on the scenario. The results emphasise the importance of catchment-scale strategies that account for potentially interacting sources of flooding.

  相似文献   

20.
胶州湾滨海湿地的景观格局变化及环境效应   总被引：3，自引：0，他引：3  
在湿地景观类型分类基础上,利用RS及GIS技术提取了1986、1995和2010年胶州湾滨海湿地的Landsat卫星假彩色合成影像的空间属性数据,利用斑块动态度、斑块密度指数、景观多样性指数、斑块破碎化指数研究了胶州湾滨海湿地的景观格局变化及累积环境效应。结果表明,1986～2010年胶州湾滨海湿地总面积减少,河流与河口湿地面积稍有增大,潮间带滩涂和潮上带湿地面积和斑块数减小;养殖池面积增大、斑块数增多,盐田面积减小、斑块数基本未变,增加了湿地公园这种新的人工湿地景观类型。期间,湿地的景观斑块密度指数、多样性指数和景观斑块破碎化指数增大了。上述湿地面积和景观格局变化是由围垦、城市化、港口和道路建设、河流径流量和输沙量减少、海岸侵蚀、海水入侵、全球变暖、海面上升等因素引起的,并导致湿地生物多样化水平下降、有害植物入侵、环境净化功能降低、污染和赤潮灾害加重、植被退化演替、渔业资源衰退和湿地生态系统服务价值降低等累积环境效应。为减轻这些不利的累积环境效应,应采取建设湿地自然保护区、控制养殖池和盐田规模、发展工业循环经济和生态农业等措施保护胶州湾滨海湿地。  相似文献   

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