IMPACTS OF FUTURE SEA LEVEL RISE ON SALT WATER INTRUSION IN THE CHANGJIANG RIVER ESTUARY

Sea level rise could increase the salinity of an estuary by altering the balance between fresh water and salt water. The implications of sea level rise for increasing salinity have been examined in the Changjiang (Yangtze) River estuary. By correlative analysis of chlorinity, discharge and tidal level and calculation of two-dimensional chlorinity, distribution of the Changjiang River estuary, the changes of the intensity and lasting hours of salt water intrusion at Wusong Station and the changes of chlorinity distribution in the South Branch of the Changjiang River estuary have been estimated when future sea level rises 50-100 cm. The intensity of salt water intrusion in the future will be far more serious than current trend.     

IMPACTS OF SEA LEVEL RISE ON COASTAL EROSION IN THE CHANGJIANG RIVER DELTA AND NORTH JIANGSU COASTAL PLAINO

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Relative sea level rise and its effects on environment and resources in China’s coastal areas

Due to global climate warming and natural and man-made land subsidence etc., relative sea level rise in the coastal plains of China will exceed 2–3 times over the golbal mean value during the first half part of the 21st century. It will result in a series of adverse impacts on evolution of natural environment and socioeconomic development of the coastal area. This paper analyses environmental and resource effects induced by relative sea level rise in China’s coastal areas on the basis of rough estimate of future relative sea level rise. These effects include inundating tidal flat and wetlands and increase in inundated risk of coastal habitable land, exacerbating storm surge. coastal erosion, flooding and salt water intrusion hazards, as well as endangering land, water, tourism and living resources and their utilization.     

SEA LEVEL RISE OF THE ZHUJIANG RIVER DELTA AND NEOTECTONICS

A linear regression analysis of 28 selected tide-gauge stations of the Zhujiang Estuary shows that there has been a tendency of local sea level rise at a rate of 2.028 mm per year. The origin of the variation is significantly attributed to the local tectonic movement of discrepant fault-block. Based on this, four types of relative local sea level changes are classified. According to calculation, half of the fertile land, or 800 km2 of the delta plain will have been submerged by sea water by about 2040. This will yield a significant influence on the economic construction and human activities.     

Influence of sea level rise on Shanghai astronomical tide and storm surge and estimation of probable water level

reODUCTIONSthtrendanditsinfluencehaveattiactedInanresearchersinrecentyears.He(l994)exPloredthePOssibleeffectofSLRonZhuiang(Pear)fuverdeltaSSbyusingarelativelysimPletecboqUeofcollatingfutUreSthincrementswithrecenily-measuredtidalcharaCteristicvalues.Pengetal.(l994)usedasindlaraPProachtoinvestigatetheSthinf[uenceonTianinSS.SthhasqUitepronouncedimPatontheinteractionbetweenSSandATinshallowwater-SSandATgenesisaxegrealyinfluencedbylocalwaterdepthandtOpography-TocoPewiththenonlinearr…     

EFFECT OF FUTURE SEA LEVEL RISE ON DISASTROUS FLOODS IN THE TAIHU LAKE LOWER REACH DEPRESSIONS AND COUNTERMEASURES

Use of numerical simulation of the tidal flow of the Changjiang River Estuary and the HuangpuRiver to forecast flood in the Taihu Lake lower reach drainage system for the case of future sea level riseof 0.4 m and 0.8 m,and floods preventing and reducing methods are discussed in this paper.     

Impact of future sea level rise on flood and water logging disasters in lixiahe region

Lixiahe region is one of the susceptible area to flood and waterlogging disasters in China due to its low topographic relief and having difficulty in draining floodwater away. The condition will be more serious if sea level rises in the future. The estimated results by some scientists indicate that the sea level could rise probably 20–100 cm by 2050. However, what the effect will future sea level rise exerts on flood drainage and on flood or waterlogging disasters? A hydrological system model has been developed to study the problem in the lower reaches of the Sheyang River basin. Predicted results from the model show that, if sea level rises, drainage capacity of each drainage river will decrease obviously, and the water level will also rise. From the change of drainage capacity of drainage rivers the trends of flood and waterlogging disasters are analyzed in the paper if the severe flood that happened in the past meets with future sea level rise. Some countermeasures for disaster reduction and prevention against sea-level rise are put forward.     

Influence of the Pacific Decadal Oscillation on regional sea level rise in the Pacific Ocean from 1993 to 2012

The rate of regional sea level rise(SLR) provides important information about the impact of human activities on climate change.However,accurate estimation of regional SLR can be severely affected by sea surface height(SSH) change caused by the Pacific Decadal Oscillation(PDO-SSH).Here,the PDOSSH signal is extracted from satellite altimeter data by multi-variable linear regression,and regional SLR in the altimeter era is calculated,before and after removing that signal.The results show that PDO-SSH trends are rising in the western Pacific and falling in the eastern Pacific,with the strongest signal confined to the tropical and North Pacific.Over the past 20 years,the PDO-SSH accounts for about 30%-40%of altimeter-observed SLR in the regions 8°-15°N,130°-160°E and 30°-40°N,170°-220°E.Along the coast of North America,the PDO-SSH signal dramatically offsets the coastal SLR,as the sea level trends change sign from falling to rising.     

Causes of land loss in Tuvalu,a small island nation in the pacific

Studies on land loss in Tuvalu reveal the following findings. Although both sea level rise and coastal erosion can cause land loss in the tropic Pacific oceanic islands, their mechanisms are different. When sea level rises, the low elevation coastal zone submerges and the erosion datum plane rises, the beach process progresses normally as always, resulting in no beach sediment coarsening. When the sea level is stable, coastal erosion removes finer sediment from reef flat, beach and land, resulting in beach sediment coarsening. The human-induced coastal erosion in the tropic Pacific oceanic islands has the following features. 1) Erosion occurs or intensifies immediately after inappropriate human activities. 2) It occurs near the places having human activities and places related to the above places in sediment supply. 3) It often occurs on original prograding or stable coasts (on lagoon coasts for atolls) because there are more coastal engineering projects and other human activities on such coasts. 4) It is chronic, covering a long period of time. The coastal geological events in Tuvalu islands do not accord with the features resulted from sea level rise but do accord with the features resulted from coastal erosion, particularly from human-induced erosion. The land loss in Tuvalu is mainly caused by inappropriate human activities including coastal engineering and aggregate mining, and partly caused by cyclones. Moreover, all recent measurements (satellite altimetry,thermosteric sea level data and tide observations) so far have not been able to verify any sea level rise around Tuvalu islands.     

CHEMICAL CHARACTERISTICS OF THE COASTAL SEA OFF TIANHENG ISLAND

Chemical characteristics of the coastal sea off Tianheng Island were investigated from May 1990 toFebruary 1991 in this study which included distribution pattern,seasonal variability and the controlling fac-tors of oxygen,pH,nutrients.The rich nutrient salt content is suited for phytoplankton growth andmariculture.The coastal sea waters is of good quality based on the national standard of seawater qual-ity in terms of pH,oxygen,and nutrients,the main controlling factors for which in the investigated seaarea are hydrographic(salinity,temperature,river runoff,etc.),biological(photosynthesis of plankton),andanthrogenic(fertilizing in the nearby land and sea).     

Middle Holocene warm period and sea level high in coastal areas,North China

Relevant geological, geographical, archaeological data were collected to study the characteristics of middle Holocene warm period and sea level high on North China coast. Middle Holocene climate and sea level change on North China coast were correlated to warm marine environment events in about 8-3 ka B.E The sea level in about 8 ka B.E was higher than present mean sea level, then fluctuated for 5 000 years and after that it became even in 3 ka B.E The highest sea level occurred in about 6-5 ka B.E; the maximum was about 2-3 m and minimum was about 1-2 m.     

Long term sea level change and water mass balance in the South China Sea

Sea level anomalies observed by altimeter during the 1993–2006 period, thermosteric sea level anomalies estimated by using subsurface temperature data produced by Ishii and SODA reanalysis data, tide gauge records and HOAPS freshwater flux data were analyzed to investigate the long term sea level change and the water mass balance in the South China Sea. The altimeter-observed sea level showed a rising rate of (3.5±0.9) mm yr-1 during the period 1993–2006, but this figure was considered to have been highly d...     

An analysis of the steric sea level change by introducing sea surface temperature

In this paper, we use the optimum interpolation sea surface temperature (OISST) provided by the National Center for Environmental Prediction (NCEP) to replace the temperature in the top three layers in the ISHII data, and make use of the modified ISHII temperature data to calculate the thermosteric sea level (called modified steric sea level (SSL) hereafter). We subtract the modified SSL and the steric sea level (called ordinary SSL hereafter) derived from the ISHII temperature and salinity from the steric sea level (SSL) provided by the Gravity Recovery and Climate Experiment (GRACE), respectively, and find that the rms error of the difference of the former is obviously smaller than that of the latter. Therefore we reach the conclusion that under the assumption that the GRACE SSL is accurate, the modified SSL can reflect the true steric sea level more accurately. Making use of the modified SSL, we can find that the modified SSL in sea areas of different spatial scales shows an obvious rising trend in the upper 0-700 m layer for the period 1982-2006. The global mean SSL rises with a rate of 0.6 mm year-1 .The modified SSLs in sea areas of different spatial scales all show obvious oscillations with period of one year. There are oscillations with periods of 4-8 years in global oceans and with periods of 2-7 years in the Pacific. The Empirical Orthogonal Function method is applied to the sea areas of different spatial scales and we find that the first modes all have obvious 1-year period oscillations, the first mode of the global ocean has 4-8 year period oscillations, and that of the Pacific has 2-6 year period oscillations. The spatial distribution of the linear rising trend of the global modified SSL in the upper 0-700 m layer is inhomogeneous with intense regional characteristics. The modified SSL linear trend indicates a zonal dipole in the tropical Pacific, rising in the west and descending in the east. In the North Atlantic, the modified SSL indicates a meridional dipole, rising in the latitude band of 20°N-40°N and 45°N-65.5°N and descending obviously in the latitude band of 40°N-45°N.     

Seasonal change of steric sea level in the GIN seas

The Greenland Sea,Iceland Sea,and Norwegian Sea (GIN seas) form the main channel connecting the Arctic Ocean with other Oceans,where significant water and energy exchange take place,and play an important role in global climate change.In this study steric sea level,associated with temperature and salinity,in the GIN seas is examined based on analysis of the monthly temperature and salinity fields from Polar science center Hydrographic Climatology (PHC3.0).A method proposed by Tabata et al.is used to calculate steric sea level,in which,steric sea level change due to thermal expansion and haline contraction is termed as the thermosteric component (TC) and the halosteric component (SC),recpectively.Total steric sea level (TSSL) change is the sum of TC and SC.The study shows that SC is making more contributions than TC to the seasonal change of TSSL in the Greenland Sea,whereas TC contributes more in the Norwegian and the Iceland Seas.Annual variation of TSSL is larger than 50 mm over most regions of the GIN Seas,and can be larger than 200 mm at some locations such as 308 mm at 76.5 N,12.5 E and 246 mm at 77.5 N,17.5 W.     

The interannual and decadal variability of the sea level in the Japan/East Sea

Sea level observed by altimeter during the 1993–2007 period and the thermosteric sea level from 1945 through 2005 obtained by using the global ocean temperature data sets recently published are used to investigate the interannual and decadal variability of the sea level in the Japan/East Sea (JES) and its response to El Niño and Southern Oscillation (ENSO). Both the interannual variations of the sea level observed by altimeter and those of the thermosteric sea level obtained from reanalyzed data in the JES are closely related to ENSO. As a result, one important consequence is that the sea level trends are mainly caused by the thermal expansion in the JES. An ‘enigma’ is revealed that the correlation between the thermosteric sea level and ENSO during the PDO (Pacific Decadal Oscillation) warm phase (post mid-1970s) is inconsistent with that during the cold phase (pre mid-1970s) in the JES. The thermosteric sea level trends and the Southern Oscillation Index (SOI) suggest a strong negative correlation during the period 1977–1998, whereas there appears a relatively weak positive correlation during the period 1945–1976 in the JES. Based on the SODA (Simple Oceanographic Data Assimilation) datasets, possible mechanisms of the interannual and decadal variability of the sea level in the JES are discussed. Comprehensive analysis reveals that the negative anomalies of SOI correspond to the positive anomalies of the southeast wind stress, the net advective heat flux and the sea level in the JES during the PDO warm phase. During the PDO cold phase, the negative anomalies of SOI correspond to the positive anomalies of the southwest wind stress, the negative anomalies of the net advective heat flux and the sea level in the JES.     

Forecast of impacts of sea-level rise on the low colonized islands and their surrounding waters in the Changjiang River mouth

Thethreatagainstthecoastallowlandcausedbysea-levelriseisoneofthefocusesoftheworid'sat-tention.Thebestestimatevalueofglobaltheoreticalsea-levelriseinthe2lstcenturyisO.66m(SCOR,l99l)byworldwideauthoritativeorganizationsuchasIPCC(IntergovernmentPanelofClimateChange)etal.ThecrustofChangiiangDeltaissubsiding.Theaveragesubsidencerateinthelast2OOOaisl.2mm/a(PANetal.,l985).TheislandsoftheChangiiangRivermouthareaccumulatinglowlandislandsandtheirnat-uralelevationisbelowthehightidallevelofsprin…     

MEAN SEA LEVEL AND SEA SURFACE VARIABILITY OF NQRTHWEST PACIFIC OCEAN AND EASTERN CHINA SEAS FROM GEOSAT ALTIMETRY

Collinear analysis technique is widely used for determining sea surface variability with Geosat altimeterdata from its Exact Repeat Mission(ERM).But most of the researches have been only on global scaleor in oceans deeper than 2000 m.In shallow shelf waters this method is hampered by the inaccuracy ofocean tide data supplied with Geosat Geophysical Data Records(GDRs).This work uses a modified collinearanalysis technique characterized by simultaneous separation of mean sea level and ocean tide with theleast squares method,to compute sea surface variability in the Northwest Pacific Ocean and eastern ChinaSeas.The mean sea level map obtained contains not ouly bathymetric but also dynamic features such asamphidromes,indicating considerable improvement over previous works.Our sea surface variability mapsshow clearly the main current system,the well-known Zhejiang coastal upwelling,and a northern East Chi-na Sea meso-scale eddy in good agreement with satellite sea surface temperature(SST)observation and his-to     

SOIL EROSION AND ITS IMPACTS ON ENVIRONMENT IN YIXING TEA PLANTATION OF JIANGSU PROVINCE

Soil erosion on sloping field has led to a lot of environmental problems. In order to reveal the seriousnessof the damage of soil erosion on sloping fields 137^Cs tracer method was used to estimate soil erosion rate. 137^Cs referenceinventory of 2200Bq/m^2 in Yixing, southern Jiangsu Province, was estimated and a model for estimating erosion of cultivat-od soil was established in order to avoid overestimating soil erosion rates. Then based on the soil erosion rates and mea-sured soil physical and chemical properties, direct and indirect impacts of soil erosion on environment were further dis-cussed. Direct impacts of erosion on environment included on-site and off-site impacts. The on-site impacts were thatsoil layer became thin, soil structure was deteriorated and soil nutrients decreased. The off-site impacts were that waterbodies were polluted. The indirect impacts of soil erosion on environment were the increase of fertilizer application andenergy consumption, and change of adaptability of land uses. Although erosion intensity was not serious in the studyarea, its environmental impacts should not be ignored because of great soil nutrient loss and coazseness of soil particles.     

Dynamics of Coastal Land Use Patterns of Inner Lingdingyang Bay in the Zhujiang River Estuary

To satisfy the growing of land demand from economic development,a large scale of land reclamation from sea has been carried out in Inner Lingdingyang Bay in the Zhujiang(Pearl)River estuary in recent years.As a result,the tidal flat and the water channels became narrow,the frequency of floods increased,and the environment was un-dermined.Guangzhou Marine Geological Survey(GMGS)conducted an integrated project for marine geo-environ-ment and geo-hazards survey in 2003.With the integration of multi-temporal remote sensing images of 1977,1978,1988,1996,and 2003,GIS spatial analyzing approach and GPS technique,as well as field data and other background data of the region,this research investigated the comprehensive characteristics and the drivers of coastal land use dy-namics and shoreline changes in Inner Lingdingyang Bay.The results reveal that the reclaimed coastal land was mainly for agriculture and aquaculture in early years,but now they are used for construction sites of harbors and in-dustries,especially high-tech industry.     

INTERDECADAL SEA LEVEL VARIATION AT THE JAPANESE COAST AND LARGE SCALE CLIMATE STATE

Thirty years of monthly mean anomalies of sea level(SL) at 15 Japanese coastal stations, sea sur-face temperature (SST) and sea level pressure (SLP) in or over the northern Pacific were analyzed bycanonical correlation analysis (CCA) to study the relationship between the interdecadal SL variationand large scale climate state. Given two time-varying fields this technique identifies the pair ofspacial patterns with optimally correlated time series.The results show that there are two important air-sea interactive processes in the extratropicalPacific region for the variation of the SL at the Japanese coast on interdecadal scale. One is theocean heating or cooling of the atmosphere over the Kuroshio extension region, which results in ahuge SLP anomalous vortex with planetary spacial scale big enough to change the global climate. An-other is the large Kuroshio meander phenomenon controlled by the large-scale wind-stress curls oneyear earlier in the adjacent region of the Hawaiian Islands. The first process im