The coastline demarcation and announcement models in China are outlined in this paper. The issues related to the coastline revision system, coastline zoning, coastline usage and the coastline information management ar...The coastline demarcation and announcement models in China are outlined in this paper. The issues related to the coastline revision system, coastline zoning, coastline usage and the coastline information management are put forward. The concreted research and discussion on these issues are made which are valuable for the coastline management in our country.展开更多
This study adopted IKONOS remote sensing images and selected spectral characteristic areas, through regional pixel statistics and calculating weight coefficients of each band, processed the images with the spectral no...This study adopted IKONOS remote sensing images and selected spectral characteristic areas, through regional pixel statistics and calculating weight coefficients of each band, processed the images with the spectral normalized method, which made the features of islands, land and water features more obviously in the images. On this basis, the OTUS was used to determine the optimal segmentation threshold, and the normalization image binarization was made, thus the island coastline was extracted. This method used the characteristic curve method to separate the land and water, obtained the binarization images and maintained the original edge effectively. The coastline that was extracted by Binary Morphology was continuous, reliable and high signal-to-noise ratio. The results showed that this method could extract the coastline fast, simply and effectively, which had the practical value.展开更多
Spatial scale is a fundamental problem in Geography. Scale effect caused by fractal characteristic of coastline becomes a common focus of coastal zone managers and researchers. In this study, based on DEM and remote s...Spatial scale is a fundamental problem in Geography. Scale effect caused by fractal characteristic of coastline becomes a common focus of coastal zone managers and researchers. In this study, based on DEM and remote sensing images, multi-scale continental coastlines of China were extracted and the fractal characteristic was analyzed. The results are shown as follows. （1） The continental coastline of China fits the fractal model, and the fractal dimension is 1.195. （2） The scale significant differences according to uplift effects with fractal dimensions of coastline have and subsidence segments along the continental coastlines of China. （3） The fractal dimension of coastline has significant spatial heterogeneity according to the coastline types. The fractal dimension of sandy coastline located in Luanhe River plain is 1.109. The dimension of muddy coastline located in northern Jiangsu Plain is 1.059, while that of rocky coastline along southeastern Fujian is 1.293. （4） The length of rocky coastline is affected by scale more than that of muddy and sandy coastline. Since coastline is the conjunction of sea, land and air surface, the study of coastline scale effect is one of the scientific bases for the researches on air-sea-land interaction in multi-scales.展开更多
Coastal regions are threatened by natural processes, such as erosion driven by storm surges and the effect of jetties, as well as by human behavior. The coastline of the Yellow River Delta(YRD) was monitored using the...Coastal regions are threatened by natural processes, such as erosion driven by storm surges and the effect of jetties, as well as by human behavior. The coastline of the Yellow River Delta(YRD) was monitored using the general high-tide line method, which combines Remote sensing(RS) and geographic information system(GIS) technology, using multi-spectral scanner(MSS), thematic mapper(TM), and enhanced thematic mapper plus(ETM+) images of the YRD from 1976 to 2014 as a data source. The results demonstrated that the shape and length of the YRD coastline has changed dramatically since 1976. The course of the Diaokouhe channel has resulted in mainly inland erosion in the north, and is primarily marine erosion; therefore, it was termed an erosion-type estuary. However, the coastline of the Qingshuigou course has moved seaward, demonstrating an accretion stage, and was therefore termed an accretion-type estuary. The coastline advanced forward before 1997 and shrank after 2003 in the southern part of the river mouth, which was due to the shift in the river mouth in 1996. It has continually extended outward in the northern part of the river mouth from 2003 onward. The coastline in the southern part of the river mouth has moved randomly, with the occurrence of both erosion and sedimentation caused by land reclamation and sea wave intrusion. In most cases, the coastline has extended offshore, especially in the northern part of the river mouth. The YRD coastline has changed frequently and rapidly from 1992 to 2014. The river mouth channel, river water and sediments, and precipitation were the major factors affecting the YRD. The YRD coastline was mainly in an accretion stage during flow periods. The erosion rate decreased and tended to be stable during a dry period. The coastline was basically stable when dry periods occurred over a long period. The location of Yellow River ports and sea erosion were the main factors driving coastline changes. The coastline was mainly influenced by the flow path of the Yellow River, with recent human activity also becoming a factor.展开更多
This study examined the spatial distribution of the continent coastline in northern China using remote sensing and GIS techniques, and calculated the fractal dimension of the coastline by box-counting method, with a t...This study examined the spatial distribution of the continent coastline in northern China using remote sensing and GIS techniques, and calculated the fractal dimension of the coastline by box-counting method, with a time span from 2000 to 2012. Moreover, we ana- lyzed the characteristics of spatial-temporal changes in the coastline＇s length and fractal di- mension, the relationship between the length change and fractal dimension change, and the driving forces of coastline changes in northern China. During the research period, the coast- line of the study area increased by 637.95 km, at a rate of 53.16 km per year. On the regional level, the most significant change in coastline length was observed in Tianjin and Hebei. Temporally, the northern China coastline grew faster after 2008. The most dramatic growth was found between 2010 and 2011, with an increasing rate of 2.49% per year. The fractal dimension of the coastline in northern China was increasing during the research period, and the most dramatic increase occurred in Bohai Rim. There is a strong-positive linear relation- ship between the historical coastline length and fractal dimension （the correlation coefficient was 0.9962）. Through statistical analysis of a large number of local coastline changes, it can be found that the increase （or decrease） of local coastline length will, in most cases, lead to the increase （or decrease） of the whole coastline fractal dimension. Civil-coastal engineering construction was the most important factor driving the coastline change in northern China. Port construction, fisheries facilities and salt factories were the top three construction activi- ties. Compared to human activities, the influence of natural processes such as estuarine deposit and erosion were relatively small.展开更多
Implementation of the water-sediment regulation(WSR) scheme, mainly focused on solving the sedimentation problems of reservoirs and the lower reaches of the Yellow River, has inevitably influenced the sediment distrib...Implementation of the water-sediment regulation(WSR) scheme, mainly focused on solving the sedimentation problems of reservoirs and the lower reaches of the Yellow River, has inevitably influenced the sediment distribution and coastal morphology of the Yellow River Estuary.Using coastline delineation and suspended sediment concentration(SSC) retrieval methods, this study investigated water and sediment changes,identified detailed inter-annual and intra-annual variations of the coastline and SSC in the normal period(NP: 1986-2001, before and after the flood season) and WSR period(WSRP: 2002-2013, before and after WSR). The results indicate that(1) the sedimentation in the low reaches of the Yellow River turned into erosion from 2002 onward;(2) the inter-annual coastline changes could be divided into an accretion stage(1986-1996), a slow erosion stage(1996-2002), and a slow accretion stage(2002-2013);(3) an intra-annual coastline extension occurred in the river mouth in most years of the WSRP; and(4) the mean intra-annual accretion area was 0.789 km^2 in the NP and 4.73 km2 in the WSRP,and the mean SSC increased from 238 mg/L to 293 mg/L in the NP and from 192 mg/L to 264 mg/L in the WSRP.展开更多
Based on measured data of coastline and bathometry, processed by softwares of Surfer and Mapinfo, and combined with sediment loads in different phases at Lijin gauging station, temporal and spatial evolution of coastl...Based on measured data of coastline and bathometry, processed by softwares of Surfer and Mapinfo, and combined with sediment loads in different phases at Lijin gauging station, temporal and spatial evolution of coastline and subaqueous geomorphology in muddy coast of the Yellow River Delta is analyzed. The results show that ~68% of sediments were delivered by the Yellow River deposited around the river mouth and in the littoral area from 1953 to 2000. Coastline in different coasts had distinctive changes in response to shifts of river course. Coastline was stable in the west of the Diaokou river mouth. Coastline from the east of the Diaokou river mouth to the north of the Gudong oilfield had experienced siltation, then serious erosion, and finally kept stable with sea walls conservation. Generally, coastline of the survived river mouth of the Qingshuigou river course stretched seaward, whereas the south side of sand spit at the Qingshuigou old river mouth was eroded after the Yellow River inpouring near the position at the Qing 8. The subaqueous geomorphology off the survived river mouth exhibited siltation from 1976 to 1996, with flat topset beds and steeper foreset beds. From 1996 to 2005, the subaqueous geomorphology off the Qingshuigou old river mouth was eroded in the topset and foreset beds, but silted in the bottomset beds. The subaqueous geomorphology off the new river mouth sequentially performed siltation with small degree compared to that of 1976-1996.展开更多
According to the fractal theory, the spatial fractal character of coastline is preliminarily discussed on the basis of GIS in this paper. Two aspects are considered: one is the length demarcation of coastline with dif...According to the fractal theory, the spatial fractal character of coastline is preliminarily discussed on the basis of GIS in this paper. Two aspects are considered: one is the length demarcation of coastline with different scales, and the other is the confirmation of existence of the fractal character on different boundaries of tidal flats. Finally, some significant conclusions are drawn: (1) The coastline of Jiangsu Province has the fractal character and its dimension is 1.0696. (2) It conforms to the exponential correlation between different lengths (L) of coastline and scales (k). I; conforms to the formula lgL(k) = -1.029 lgk+ 2.9544 in the continental coastline of Jiangsu province. (3) Different boundaries of a tidal flat have fractal characters, and different fractal dimensions indicate different comparative intensities of erosion and deposition on the tidal flat. (4) The reciprocity between land and sea may affect the value of fractal dimension of a coastline, just as the lithology, substantial constituent and geological structure do.展开更多
A coastline is defined as the average spring tide line. Different types of seacoast, such as sandy, silty, and bio- logical coast, have different indicators of interpretation. It is very difficult to develop a univers...A coastline is defined as the average spring tide line. Different types of seacoast, such as sandy, silty, and bio- logical coast, have different indicators of interpretation. It is very difficult to develop a universal method for interpreting all shorelines. Therefore, the sandy, the silty, and the biological coast are regarded as research objects, and with data mining technolog,found the rules of interpretation of those three types of coastlines. Then, an intelligent coastline interpretation method based on rules was proposed. Firstly, the rules for ex- tracting the waterline in Landsat TM/ETM＋ （Thematic Mapper/Enhanced Thematic Mapper Plus） imagery were discovered. Then, through analyzing the features of sandy, silty and biological coast, the indicators of interpreting different types of shoreline were determined. According to the indicators, the waterline could be corrected to the real coastline. In order to verify the validity of the proposed algorithms, three Landsat TM/ETM＋ imageries were selected for case studies. The experimental results showed that the proposed methods could interpret the coastlines of sandy; silty, and biological coasts with high precision and without human intervention, which exceeded three pixels.展开更多
The rip currents induced by waves off arc-shaped coastlines are seriously harmful to humans, but understanding of their characteristics is lacking. In this study, the FUNWAVE model was used to calculate the wave-induc...The rip currents induced by waves off arc-shaped coastlines are seriously harmful to humans, but understanding of their characteristics is lacking. In this study, the FUNWAVE model was used to calculate the wave-induced currents in the Haller experiment and the ideal arc-shaped coast similar to Sanya Dadonghai, Hainan Province,China. The results showed that the FUNWAVE model has considerable ability to simulate the rip currents, and it was used to further simulate rip currents off arc-shaped coastlines to investigate their characteristics. The rip currents were found to be stronger as the curvature of arc-shaped coastline increased. Coastal beach slope exerts a significant influence on rip currents; in particular, an overly steep or overly mild slope is not conducive to creating rip currents. Furthermore, the rip currents were found to become weaker as the size of arc-shaped coast decreased. When the height and period of waves increase, the strength of rip currents also increases, and, in some cases, wave heights of 0.4 m may produce dangerous rip currents.展开更多
Using multitemporal Landsat TM/OLI images at a 10-year interval, in this study, we （1） extracted information of spatial location, length, and sinuosity of coastline and landscape configuration, diversity and fragmen...Using multitemporal Landsat TM/OLI images at a 10-year interval, in this study, we （1） extracted information of spatial location, length, and sinuosity of coastline and landscape configuration, diversity and fragmentation in the bay areas of Xiangshan Bay （XB）, China and Tampa Bay （TB）, USA from 1985 to 2015; （2） constructed indices of artificial coastlines and human disturbance on bay area landscapes; and （3） explored and discussed the impacts of human activities on changes of coastlines and landscape types in the two bay areas. Our analysis results demonstrate the following five points. （1） During the past 30 years, the lengths of natural coastline in XB and TB shrank, while the lengths of their artificial coastline increased first and then maintained stable. Since there were different influences of human activities on coastlines and landscape types between the two bay areas, XB experienced dramatic changes in parts of coastline geomorphologies and continuous decrease of coastline sinuosity, while, in TB, there was a little change in coastline geomorphologies and its coastline sinuosity was almost unchanged. （2） The intensity of human activities in XB was continuously enhanced from 1985 to 1995, and then the degree of enhancement had slowed down after 1995. However, in the time period, the impacted extent of human activities gradually increased and finally covered almost entire coastlines in XB. In TB area, although the intensity of human activities was enhanced, the degree of enhancement slowed down from 1985 to 2015 and the impacted areas of human activates were concentrated in several coastal city areas. （3） The average area of landscape patches strongly disturbed by human activities in both XB and TB generally showed a trend of decreasing from 1985 to 2005. However, during the period of 2005 to 2015, the average patch area of landscapes disturbed by different degrees of human activities in XB changed differently, while in TB it almost did not change. （4） From 1985 to 2005, the indices of landscape diversity in various areas of human disturbance in XB gradually increased, while in TB, changes in indices of the landscape diversity varied. From 2005 to 2015, the changes in the intensity of human disturbance in both bay areas were from weak to strong, whereas the indices of landscape diversity in XB and TB increased first and then decreased. （5） The landscape fragmentation index in different human disturbance areas in both XB and TB gradually increased from 1985 to 2005, while from 2005 to 2015, in both bay areas, the landscape fragmentation index presented a decreasing trend.展开更多
The goal of our work was to locate and quantify changes that occurred in 66% of the Mexican coastline, based on four land cover maps generated by the Mexican Mangrove Monitoring System(SMMM) of the National Commission...The goal of our work was to locate and quantify changes that occurred in 66% of the Mexican coastline, based on four land cover maps generated by the Mexican Mangrove Monitoring System(SMMM) of the National Commission for the Knowledge and Use of Biodiversity(CONABIO) for the years 1970/81, 2005, 2010, and 2015. Our results showed overall dominance of erosion over accretion processes, beaches being the most affected coastal land cover. Emphasis was placed on identification and description of coastline sites in which land was either continuously lost(erosion) or gained(accretion) during the studied time periods. These sites were defined as continuous unidirectional dynamic sites and were compared with previous knowledge about the geodynamics of Mexican coasts. Continuous unidirectional dynamic sites were distributed throughout the study area and within all land cover types, but predominantly corresponded to areas covered by mangroves in the states of Campeche and Nayarit. Finally, we found an intensification of coastal erosion-accretion processes over time;coastline change rates having duplicated between the earliest(1970/81–2005) and the two more recent(2005–2010, and 2010–2015) analysed time periods, with erosion rates for each corresponding period of –3 m/yr,–7.5 m/yr, and –7.3 m/yr,and accretion rates of 2.8 m/yr, 7.3 m/yr, and 6.9 m/yr, respectively.展开更多
As demonstrated in the first part of this study(Part I),wind-shift boundaries routinely form along the west coast of the Pearl River Delta due to the land-sea contrast of a“trumpet”shape coastline in the summer mons...As demonstrated in the first part of this study(Part I),wind-shift boundaries routinely form along the west coast of the Pearl River Delta due to the land-sea contrast of a“trumpet”shape coastline in the summer monsoon season.Through multiple numerical simulations,this article(Part II)aims to examine the roles of the trumpet-shaped coastline in the mesovortex genesis during the 1 June 2020 tornadic event.The modeling reproduced two mesovortices that are in close proximity in time and space to the realistic mesovortices.In addition to the modeled mesovortex over the triple point where strong ambient vertical vorticity was located,another mesovortex originated from an enhanced discrete vortex along an airmass boundary via shear instability.On the fine-scale storm morphology,finger-like echoes preceding hook echoes were also reproduced around the triple point.Results from sensitivity experiments suggest that the unique topography plays an essential role in modifying the vorticity budget during the mesovortex formation.While there is a high likelihood of an upcoming storm evolving into a rotating storm over the triple point,the simulation's accuracy is sensitive to the local environmental details and storm dynamics.The strengths of cold pool surges from upstream storms may influence the stretching of low-level vertically oriented vortex and thus the wrap-up of finger-like echoes.These findings suggest that the trumpet-shaped coastline is an important component of mesovortex production during the active monsoon season.It is hoped that this study will increase the situational awareness for forecasters regarding regional non-mesocyclone tornadic environments.展开更多
China’s Bohai Bay has experienced large-scale land reclamation since 2000.These reclamation projects create a nearshore ecological imbalance and shift sediment transport by changing the tidal current.However,these ti...China’s Bohai Bay has experienced large-scale land reclamation since 2000.These reclamation projects create a nearshore ecological imbalance and shift sediment transport by changing the tidal current.However,these tidal current changes are not comprehensively understood.In this paper,the coastline changes in Bohai Bay due to reclamation are investigated and the responses of the tidal current are calculated through numerical methods.The results show that the coastline length of the bay increases by more than 500 km from 2000 to 2015 with the largest reclamation rate of 150.9 km^(2)/a.Consequently,the current velocity changes with an uneven distribution near the reclamation due to construction masking and dike protrusion.The tidal symmetry also changes in most nearshore areas,with opposite variations in the current velocity at peak flood and ebb tide.In addition,the tide direction deflects to bypass the reclamation and is usually consistent with the coastline.Harmonic analysis of the dominant M2 tidal constituent shows that the range of the reciprocating current is widely extended.The total influence of the reclamation can reach the-8-m isobaths in Bohai Bay.Changes in the tidal current are the main causes of water environment deterioration.Therefore,the arrangement and structural optimization of reclamation projects should be considered in the future.展开更多
The beach studied in this paper spans a length of 51 km and is one of several long sandy beaches in the southern Bohai Strait. Due to the obstruction of islands in the northeast and the influence of the underwater top...The beach studied in this paper spans a length of 51 km and is one of several long sandy beaches in the southern Bohai Strait. Due to the obstruction of islands in the northeast and the influence of the underwater topography, the wave environment in the offshore area is complex; beach types and sediment transport characteristics vary along different coasts. The coastlines extracted from six aerial photographs in different years were compared to demonstrate the evolving features. Seven typical beach profiles were selected to study the lateral beach variation characteristics. Continuous wind and wave observation data from Beihuangcheng ocean station during 2009 were employed for the hindcast of the local wave environment using a regional spectral wave model. Then the results of the wave hindcast were incorporated into the LITDRIFT model to compute the sediment transport rates and directions along the coasts and analyze the longshore sand movement. The results show that the coastline evolution of sand beaches in the southern Bohai Strait has spatial and temporal variations and the coast can be divided into four typical regions. Region （1）, the north coast of Qimudao, is a slightly eroded and dissipative beach with a large sediment transport rate; Region （II）, the southwest coast of Gangluan Port, is a slightly deposited and dissipative beach with moderate sediment transport rate; Region （III）, in the central area, is a beach that is gradually transformed from a slightly eroded dissipative beach to a moderately or slightly strong eroded bar-trough beach from west to east with a relatively moderate sediment transport rate. Region （IV）, on the east coast, is a strongly eroded and reflective beach with a weak sediment transport rate. The wave conditions exhibit an increasing trend from west to east in the off- shore area. The distribution of the wave-induced current inside the wave breaking region and the littoral sediment transport in the nearshore region exhibit a gradual weakening tendency from west to east, which is opposite to the trend of the wave conditions out- side the breaking region. The presence of submerged shoal （Dengzhou Shoal）, deep trough （Dengzhou Channel）, islands and irregu- lar topography influnces the wave climate, beach types, wave-induced current features, littoral sediment transport trends and coast- line evolution patterns in the southern Bohai Strait. Human activities, such as the sand exploitation of Dengzhou Shoal and other coastal engineering projects, also influence the beach morphology and coastline evolution.展开更多
Cellular Automata(CA) is widely used for the simulation of land use changes. This study applied a vector-based CA model to simulate land use change in order to minimize or eliminate the scale sensitivity in traditiona...Cellular Automata(CA) is widely used for the simulation of land use changes. This study applied a vector-based CA model to simulate land use change in order to minimize or eliminate the scale sensitivity in traditional raster-based CA model. The cells of vector-based CA model are presented according to the shapes and attributes of geographic entities, and the transition rules of vector-based CA model are improved by taking spatial variables of the study area into consideration. The vector-based CA model is applied to simulate land use changes in downtown of Qidong City, Jiangsu Province, China and its validation is confirmed by the methods of visual assessment and spatial accuracy. The simulation result of vector-based CA model reveals that nearly 75% of newly increased urban cells are located in the northwest and southwest parts of the study area from 2002 to 2007, which is in consistent with real land use map. In addition, the simulation results of the vector-based and raster-based CA models are compared to real land use data and their spatial accuracies are found to be 84.0% and 81.9%, respectively. In conclusion, results from this study indicate that the vector-based CA model is a practical and applicable method for the simulation of urbanization processes.展开更多
Coastline configuration indexes of 34 typical arc-shaped coasts in South China are investigated by the method of principal component analysis, and meanwhile deposition and geomorphologic features of arc-shaped coast a...Coastline configuration indexes of 34 typical arc-shaped coasts in South China are investigated by the method of principal component analysis, and meanwhile deposition and geomorphologic features of arc-shaped coast are also analyzed. The results show: (1) The configuration of arc-shaped coast in South China is of the characteristic of variability and complexity. (2) The wave power and the openings of the bay are the decisive factors to result in the changes of the configuration of the arc-shaped coast in South China, however, incidence direction of the wave has no effect on configuration development of the coast. (3) Commonly, geomorphologic modes of the arc-shaped coast system in South China consist of barriers, lagoons and tidal-inlets, and can be divided into four types:the openings of the bay leaning to the east, the openings of the bay leaning to the south, the openings of the bay leaning to the west and the openings of the bay leaning to the north.展开更多
A reformed numerical model based on the 'one-line theory' for beach deformation is presented. In this model, the change of beach slope during coastline procession is considered.A wave numerical model combined ...A reformed numerical model based on the 'one-line theory' for beach deformation is presented. In this model, the change of beach slope during coastline procession is considered.A wave numerical model combined with wave refraction, diffraction and reflection is used to simulate wave climate to increase numerical accuracy.The results show that the numerical model has a good precision based on the adequate field data. The results can be applied to practical engineering.展开更多
Fractal theory was applied to a preliminary discussion of the fractal character and formation mechanism of the coastline of the bedrock coast of China on the basis of GIS (Geographical Information System). Some signif...Fractal theory was applied to a preliminary discussion of the fractal character and formation mechanism of the coastline of the bedrock coast of China on the basis of GIS (Geographical Information System). Some significant conclusions were drawn:(1) The fractal dimensions of the coastline and linear structures of Liaodong Peninsula are 1.0093 and 1.0246 respectively, those of Shandong Peninsula are 1.019 and 1.021 respectively, etc.(2) The fractal dimensions of coastlines of Liaodong Peninsula, Shandong Peninsula, Zhejiang and Fujian-Guangdong tend to increase with the spatial change from north to south.(3)The regional linear structures(including faults)control the basic trends and fractal dimensions of coastlines as a whole in the regions of the bedrock coast of China:the more the controlling effect of linear structures, the smaller the fractal dimensions of coastlines.(4)The substantial constituents of coast and biologic function both play an important role in affecting the fractal dimensions of coastlines of Liaodong Peninsula, Shandong Peninsula, Zhejiang, Fujian-Guangdong and Taiwan Island.展开更多
MANDELBROT enunciated the uncertainty of the length of a coastline in his paper"How long is the coastline of Britain?"published in "Science" in 1967. The fractal concept was presented for the first...MANDELBROT enunciated the uncertainty of the length of a coastline in his paper"How long is the coastline of Britain?"published in "Science" in 1967. The fractal concept was presented for the first time in that paper and has been applied to many fields ever since. According to the fractal theory and conditions of fractal research of coastline,the controls of faults and biologic function on the fractal character of coastline are preliminarily discussed on the basis of GIS in this paper . Finally,some significant conclusions are drawn:1)the faults control the basic trends of coastlines of two study areas;2)the fractal dimension of coastline of Taiwan is smaller than that of Changle-Lufeng,because the faults of Taiwan more intensely control the trend and fractal dimension of the coastline;3)the larger the fractal dimension of the faults or the major faults,the more the controlling effect of them on the trend and fractal dimension of coastline; 4)the larger fractal dimension of the coastline of Changle-Lufeng indicates that the biologic function intensely shapes the coastline. In a word,the controls of faults and biologic function on the fractal character of coastline are discussed with a case study of China in this paper,it can be seen that faults and biologic function both have influence over the trend and fractal dimension of coastline,the fractal mechanism of coastline of two study areas may be so.展开更多
文摘The coastline demarcation and announcement models in China are outlined in this paper. The issues related to the coastline revision system, coastline zoning, coastline usage and the coastline information management are put forward. The concreted research and discussion on these issues are made which are valuable for the coastline management in our country.
文摘This study adopted IKONOS remote sensing images and selected spectral characteristic areas, through regional pixel statistics and calculating weight coefficients of each band, processed the images with the spectral normalized method, which made the features of islands, land and water features more obviously in the images. On this basis, the OTUS was used to determine the optimal segmentation threshold, and the normalization image binarization was made, thus the island coastline was extracted. This method used the characteristic curve method to separate the land and water, obtained the binarization images and maintained the original edge effectively. The coastline that was extracted by Binary Morphology was continuous, reliable and high signal-to-noise ratio. The results showed that this method could extract the coastline fast, simply and effectively, which had the practical value.
基金Chinese Academy of Sciences Program, No.KZCX1-YW-12-04 National Natural Science Foundation of China, No.40571129+1 种基金 Natural Science Foundation of Jiangsu Province, No.BK2009627 National High Technology Research and Development Program of China （863 Program）, No.2011BAH23B04
文摘Spatial scale is a fundamental problem in Geography. Scale effect caused by fractal characteristic of coastline becomes a common focus of coastal zone managers and researchers. In this study, based on DEM and remote sensing images, multi-scale continental coastlines of China were extracted and the fractal characteristic was analyzed. The results are shown as follows. （1） The continental coastline of China fits the fractal model, and the fractal dimension is 1.195. （2） The scale significant differences according to uplift effects with fractal dimensions of coastline have and subsidence segments along the continental coastlines of China. （3） The fractal dimension of coastline has significant spatial heterogeneity according to the coastline types. The fractal dimension of sandy coastline located in Luanhe River plain is 1.109. The dimension of muddy coastline located in northern Jiangsu Plain is 1.059, while that of rocky coastline along southeastern Fujian is 1.293. （4） The length of rocky coastline is affected by scale more than that of muddy and sandy coastline. Since coastline is the conjunction of sea, land and air surface, the study of coastline scale effect is one of the scientific bases for the researches on air-sea-land interaction in multi-scales.
基金Under the auspices of National Natural Science Foundation of China(No.41602356)China Postdoctoral Science Foundation(No.2017M622240)+2 种基金Key Research and Development Plan of Shandong Province(No.GG201712050002)Geological Exploration Fund of Shandong Province(No.2013(55),2016(7))Shandong Provincial Key Laboratory of Depositional Mineralization and Sedimentary Minerals Open Fund(No.DMSM2018024)
文摘Coastal regions are threatened by natural processes, such as erosion driven by storm surges and the effect of jetties, as well as by human behavior. The coastline of the Yellow River Delta(YRD) was monitored using the general high-tide line method, which combines Remote sensing(RS) and geographic information system(GIS) technology, using multi-spectral scanner(MSS), thematic mapper(TM), and enhanced thematic mapper plus(ETM+) images of the YRD from 1976 to 2014 as a data source. The results demonstrated that the shape and length of the YRD coastline has changed dramatically since 1976. The course of the Diaokouhe channel has resulted in mainly inland erosion in the north, and is primarily marine erosion; therefore, it was termed an erosion-type estuary. However, the coastline of the Qingshuigou course has moved seaward, demonstrating an accretion stage, and was therefore termed an accretion-type estuary. The coastline advanced forward before 1997 and shrank after 2003 in the southern part of the river mouth, which was due to the shift in the river mouth in 1996. It has continually extended outward in the northern part of the river mouth from 2003 onward. The coastline in the southern part of the river mouth has moved randomly, with the occurrence of both erosion and sedimentation caused by land reclamation and sea wave intrusion. In most cases, the coastline has extended offshore, especially in the northern part of the river mouth. The YRD coastline has changed frequently and rapidly from 1992 to 2014. The river mouth channel, river water and sediments, and precipitation were the major factors affecting the YRD. The YRD coastline was mainly in an accretion stage during flow periods. The erosion rate decreased and tended to be stable during a dry period. The coastline was basically stable when dry periods occurred over a long period. The location of Yellow River ports and sea erosion were the main factors driving coastline changes. The coastline was mainly influenced by the flow path of the Yellow River, with recent human activity also becoming a factor.
文摘This study examined the spatial distribution of the continent coastline in northern China using remote sensing and GIS techniques, and calculated the fractal dimension of the coastline by box-counting method, with a time span from 2000 to 2012. Moreover, we ana- lyzed the characteristics of spatial-temporal changes in the coastline＇s length and fractal di- mension, the relationship between the length change and fractal dimension change, and the driving forces of coastline changes in northern China. During the research period, the coast- line of the study area increased by 637.95 km, at a rate of 53.16 km per year. On the regional level, the most significant change in coastline length was observed in Tianjin and Hebei. Temporally, the northern China coastline grew faster after 2008. The most dramatic growth was found between 2010 and 2011, with an increasing rate of 2.49% per year. The fractal dimension of the coastline in northern China was increasing during the research period, and the most dramatic increase occurred in Bohai Rim. There is a strong-positive linear relation- ship between the historical coastline length and fractal dimension （the correlation coefficient was 0.9962）. Through statistical analysis of a large number of local coastline changes, it can be found that the increase （or decrease） of local coastline length will, in most cases, lead to the increase （or decrease） of the whole coastline fractal dimension. Civil-coastal engineering construction was the most important factor driving the coastline change in northern China. Port construction, fisheries facilities and salt factories were the top three construction activi- ties. Compared to human activities, the influence of natural processes such as estuarine deposit and erosion were relatively small.
基金supported by the Open Fund of the State Key Laboratory of Hydraulic Engineering Simulation and Safety(Grant No.HESS-1705)the National Natural Science Foundation of China(Grant No.41101561)+1 种基金the Scientific and Technological Project of Henan Province(Grant No.162102410066)the China Institute of Water Resources and Hydropower Research(Grant No.IWHR-SKL-201701)
文摘Implementation of the water-sediment regulation(WSR) scheme, mainly focused on solving the sedimentation problems of reservoirs and the lower reaches of the Yellow River, has inevitably influenced the sediment distribution and coastal morphology of the Yellow River Estuary.Using coastline delineation and suspended sediment concentration(SSC) retrieval methods, this study investigated water and sediment changes,identified detailed inter-annual and intra-annual variations of the coastline and SSC in the normal period(NP: 1986-2001, before and after the flood season) and WSR period(WSRP: 2002-2013, before and after WSR). The results indicate that(1) the sedimentation in the low reaches of the Yellow River turned into erosion from 2002 onward;(2) the inter-annual coastline changes could be divided into an accretion stage(1986-1996), a slow erosion stage(1996-2002), and a slow accretion stage(2002-2013);(3) an intra-annual coastline extension occurred in the river mouth in most years of the WSRP; and(4) the mean intra-annual accretion area was 0.789 km^2 in the NP and 4.73 km2 in the WSRP,and the mean SSC increased from 238 mg/L to 293 mg/L in the NP and from 192 mg/L to 264 mg/L in the WSRP.
基金National Natural Science Foundation of China, No.41201006
文摘Based on measured data of coastline and bathometry, processed by softwares of Surfer and Mapinfo, and combined with sediment loads in different phases at Lijin gauging station, temporal and spatial evolution of coastline and subaqueous geomorphology in muddy coast of the Yellow River Delta is analyzed. The results show that ~68% of sediments were delivered by the Yellow River deposited around the river mouth and in the littoral area from 1953 to 2000. Coastline in different coasts had distinctive changes in response to shifts of river course. Coastline was stable in the west of the Diaokou river mouth. Coastline from the east of the Diaokou river mouth to the north of the Gudong oilfield had experienced siltation, then serious erosion, and finally kept stable with sea walls conservation. Generally, coastline of the survived river mouth of the Qingshuigou river course stretched seaward, whereas the south side of sand spit at the Qingshuigou old river mouth was eroded after the Yellow River inpouring near the position at the Qing 8. The subaqueous geomorphology off the survived river mouth exhibited siltation from 1976 to 1996, with flat topset beds and steeper foreset beds. From 1996 to 2005, the subaqueous geomorphology off the Qingshuigou old river mouth was eroded in the topset and foreset beds, but silted in the bottomset beds. The subaqueous geomorphology off the new river mouth sequentially performed siltation with small degree compared to that of 1976-1996.
基金The research was supported by the National Natural Science Foundation of China(Grant No.49601019)
文摘According to the fractal theory, the spatial fractal character of coastline is preliminarily discussed on the basis of GIS in this paper. Two aspects are considered: one is the length demarcation of coastline with different scales, and the other is the confirmation of existence of the fractal character on different boundaries of tidal flats. Finally, some significant conclusions are drawn: (1) The coastline of Jiangsu Province has the fractal character and its dimension is 1.0696. (2) It conforms to the exponential correlation between different lengths (L) of coastline and scales (k). I; conforms to the formula lgL(k) = -1.029 lgk+ 2.9544 in the continental coastline of Jiangsu province. (3) Different boundaries of a tidal flat have fractal characters, and different fractal dimensions indicate different comparative intensities of erosion and deposition on the tidal flat. (4) The reciprocity between land and sea may affect the value of fractal dimension of a coastline, just as the lithology, substantial constituent and geological structure do.
基金The Science and Technology Development Plan Projects of Shandong Province of China under contract No.2011YD15005the National Natural Science Foundation of China under contact Nos 91130035 and 40906094
文摘A coastline is defined as the average spring tide line. Different types of seacoast, such as sandy, silty, and bio- logical coast, have different indicators of interpretation. It is very difficult to develop a universal method for interpreting all shorelines. Therefore, the sandy, the silty, and the biological coast are regarded as research objects, and with data mining technolog,found the rules of interpretation of those three types of coastlines. Then, an intelligent coastline interpretation method based on rules was proposed. Firstly, the rules for ex- tracting the waterline in Landsat TM/ETM＋ （Thematic Mapper/Enhanced Thematic Mapper Plus） imagery were discovered. Then, through analyzing the features of sandy, silty and biological coast, the indicators of interpreting different types of shoreline were determined. According to the indicators, the waterline could be corrected to the real coastline. In order to verify the validity of the proposed algorithms, three Landsat TM/ETM＋ imageries were selected for case studies. The experimental results showed that the proposed methods could interpret the coastlines of sandy; silty, and biological coasts with high precision and without human intervention, which exceeded three pixels.
基金The National Natural Science Foundation under contract Nos 41206163,41076048 and 41376012the Operation Expenses for Universities'Basic Scientific Research of Central Authorities under contract Nos 2011B05714 and 2014B06514
文摘The rip currents induced by waves off arc-shaped coastlines are seriously harmful to humans, but understanding of their characteristics is lacking. In this study, the FUNWAVE model was used to calculate the wave-induced currents in the Haller experiment and the ideal arc-shaped coast similar to Sanya Dadonghai, Hainan Province,China. The results showed that the FUNWAVE model has considerable ability to simulate the rip currents, and it was used to further simulate rip currents off arc-shaped coastlines to investigate their characteristics. The rip currents were found to be stronger as the curvature of arc-shaped coastline increased. Coastal beach slope exerts a significant influence on rip currents; in particular, an overly steep or overly mild slope is not conducive to creating rip currents. Furthermore, the rip currents were found to become weaker as the size of arc-shaped coast decreased. When the height and period of waves increase, the strength of rip currents also increases, and, in some cases, wave heights of 0.4 m may produce dangerous rip currents.
基金NSFC-Zhejiang Joint Fund for the Integration of Industrialization and Informatization,No.U1609203Natural Science Foundation of Zhejiang Province,No.LY16G030014The K.C.Wong Magna Fund of Ningbo University and Natural Science Foundation of Ningbo City,No.2017A610300
文摘Using multitemporal Landsat TM/OLI images at a 10-year interval, in this study, we （1） extracted information of spatial location, length, and sinuosity of coastline and landscape configuration, diversity and fragmentation in the bay areas of Xiangshan Bay （XB）, China and Tampa Bay （TB）, USA from 1985 to 2015; （2） constructed indices of artificial coastlines and human disturbance on bay area landscapes; and （3） explored and discussed the impacts of human activities on changes of coastlines and landscape types in the two bay areas. Our analysis results demonstrate the following five points. （1） During the past 30 years, the lengths of natural coastline in XB and TB shrank, while the lengths of their artificial coastline increased first and then maintained stable. Since there were different influences of human activities on coastlines and landscape types between the two bay areas, XB experienced dramatic changes in parts of coastline geomorphologies and continuous decrease of coastline sinuosity, while, in TB, there was a little change in coastline geomorphologies and its coastline sinuosity was almost unchanged. （2） The intensity of human activities in XB was continuously enhanced from 1985 to 1995, and then the degree of enhancement had slowed down after 1995. However, in the time period, the impacted extent of human activities gradually increased and finally covered almost entire coastlines in XB. In TB area, although the intensity of human activities was enhanced, the degree of enhancement slowed down from 1985 to 2015 and the impacted areas of human activates were concentrated in several coastal city areas. （3） The average area of landscape patches strongly disturbed by human activities in both XB and TB generally showed a trend of decreasing from 1985 to 2005. However, during the period of 2005 to 2015, the average patch area of landscapes disturbed by different degrees of human activities in XB changed differently, while in TB it almost did not change. （4） From 1985 to 2005, the indices of landscape diversity in various areas of human disturbance in XB gradually increased, while in TB, changes in indices of the landscape diversity varied. From 2005 to 2015, the changes in the intensity of human disturbance in both bay areas were from weak to strong, whereas the indices of landscape diversity in XB and TB increased first and then decreased. （5） The landscape fragmentation index in different human disturbance areas in both XB and TB gradually increased from 1985 to 2005, while from 2005 to 2015, in both bay areas, the landscape fragmentation index presented a decreasing trend.
文摘The goal of our work was to locate and quantify changes that occurred in 66% of the Mexican coastline, based on four land cover maps generated by the Mexican Mangrove Monitoring System(SMMM) of the National Commission for the Knowledge and Use of Biodiversity(CONABIO) for the years 1970/81, 2005, 2010, and 2015. Our results showed overall dominance of erosion over accretion processes, beaches being the most affected coastal land cover. Emphasis was placed on identification and description of coastline sites in which land was either continuously lost(erosion) or gained(accretion) during the studied time periods. These sites were defined as continuous unidirectional dynamic sites and were compared with previous knowledge about the geodynamics of Mexican coasts. Continuous unidirectional dynamic sites were distributed throughout the study area and within all land cover types, but predominantly corresponded to areas covered by mangroves in the states of Campeche and Nayarit. Finally, we found an intensification of coastal erosion-accretion processes over time;coastline change rates having duplicated between the earliest(1970/81–2005) and the two more recent(2005–2010, and 2010–2015) analysed time periods, with erosion rates for each corresponding period of –3 m/yr,–7.5 m/yr, and –7.3 m/yr,and accretion rates of 2.8 m/yr, 7.3 m/yr, and 6.9 m/yr, respectively.
基金supported by the National Natural Science Foundation of China(Grant Nos.U2242203,42275006,and 42030604)the Guangdong Basic and Applied Basic Research Foundation(2023A1515011705)the Science and Technology Research Project for Society of Foshan(2120001008761).
文摘As demonstrated in the first part of this study(Part I),wind-shift boundaries routinely form along the west coast of the Pearl River Delta due to the land-sea contrast of a“trumpet”shape coastline in the summer monsoon season.Through multiple numerical simulations,this article(Part II)aims to examine the roles of the trumpet-shaped coastline in the mesovortex genesis during the 1 June 2020 tornadic event.The modeling reproduced two mesovortices that are in close proximity in time and space to the realistic mesovortices.In addition to the modeled mesovortex over the triple point where strong ambient vertical vorticity was located,another mesovortex originated from an enhanced discrete vortex along an airmass boundary via shear instability.On the fine-scale storm morphology,finger-like echoes preceding hook echoes were also reproduced around the triple point.Results from sensitivity experiments suggest that the unique topography plays an essential role in modifying the vorticity budget during the mesovortex formation.While there is a high likelihood of an upcoming storm evolving into a rotating storm over the triple point,the simulation's accuracy is sensitive to the local environmental details and storm dynamics.The strengths of cold pool surges from upstream storms may influence the stretching of low-level vertically oriented vortex and thus the wrap-up of finger-like echoes.These findings suggest that the trumpet-shaped coastline is an important component of mesovortex production during the active monsoon season.It is hoped that this study will increase the situational awareness for forecasters regarding regional non-mesocyclone tornadic environments.
基金Supported by the National Natural Science Foundation of China(Nos.52109097,51979185)。
文摘China’s Bohai Bay has experienced large-scale land reclamation since 2000.These reclamation projects create a nearshore ecological imbalance and shift sediment transport by changing the tidal current.However,these tidal current changes are not comprehensively understood.In this paper,the coastline changes in Bohai Bay due to reclamation are investigated and the responses of the tidal current are calculated through numerical methods.The results show that the coastline length of the bay increases by more than 500 km from 2000 to 2015 with the largest reclamation rate of 150.9 km^(2)/a.Consequently,the current velocity changes with an uneven distribution near the reclamation due to construction masking and dike protrusion.The tidal symmetry also changes in most nearshore areas,with opposite variations in the current velocity at peak flood and ebb tide.In addition,the tide direction deflects to bypass the reclamation and is usually consistent with the coastline.Harmonic analysis of the dominant M2 tidal constituent shows that the range of the reciprocating current is widely extended.The total influence of the reclamation can reach the-8-m isobaths in Bohai Bay.Changes in the tidal current are the main causes of water environment deterioration.Therefore,the arrangement and structural optimization of reclamation projects should be considered in the future.
基金supported by the National Natural Science Foundation for the Youth(No.41106039)
文摘The beach studied in this paper spans a length of 51 km and is one of several long sandy beaches in the southern Bohai Strait. Due to the obstruction of islands in the northeast and the influence of the underwater topography, the wave environment in the offshore area is complex; beach types and sediment transport characteristics vary along different coasts. The coastlines extracted from six aerial photographs in different years were compared to demonstrate the evolving features. Seven typical beach profiles were selected to study the lateral beach variation characteristics. Continuous wind and wave observation data from Beihuangcheng ocean station during 2009 were employed for the hindcast of the local wave environment using a regional spectral wave model. Then the results of the wave hindcast were incorporated into the LITDRIFT model to compute the sediment transport rates and directions along the coasts and analyze the longshore sand movement. The results show that the coastline evolution of sand beaches in the southern Bohai Strait has spatial and temporal variations and the coast can be divided into four typical regions. Region （1）, the north coast of Qimudao, is a slightly eroded and dissipative beach with a large sediment transport rate; Region （II）, the southwest coast of Gangluan Port, is a slightly deposited and dissipative beach with moderate sediment transport rate; Region （III）, in the central area, is a beach that is gradually transformed from a slightly eroded dissipative beach to a moderately or slightly strong eroded bar-trough beach from west to east with a relatively moderate sediment transport rate. Region （IV）, on the east coast, is a strongly eroded and reflective beach with a weak sediment transport rate. The wave conditions exhibit an increasing trend from west to east in the off- shore area. The distribution of the wave-induced current inside the wave breaking region and the littoral sediment transport in the nearshore region exhibit a gradual weakening tendency from west to east, which is opposite to the trend of the wave conditions out- side the breaking region. The presence of submerged shoal （Dengzhou Shoal）, deep trough （Dengzhou Channel）, islands and irregu- lar topography influnces the wave climate, beach types, wave-induced current features, littoral sediment transport trends and coast- line evolution patterns in the southern Bohai Strait. Human activities, such as the sand exploitation of Dengzhou Shoal and other coastal engineering projects, also influence the beach morphology and coastline evolution.
基金Under the auspices of National Natural Science Foundation of China(No.41101349)Surveying and Mapping Scientific Research Projects of Jiangsu Province(No.JSCHKY201304)+1 种基金Program of Natural Science Research of Jiangsu Higher Education Institutions of China(No.13KJB420003)Priority Academic Program Development of Jiangsu Higher Education Institutions
文摘Cellular Automata(CA) is widely used for the simulation of land use changes. This study applied a vector-based CA model to simulate land use change in order to minimize or eliminate the scale sensitivity in traditional raster-based CA model. The cells of vector-based CA model are presented according to the shapes and attributes of geographic entities, and the transition rules of vector-based CA model are improved by taking spatial variables of the study area into consideration. The vector-based CA model is applied to simulate land use changes in downtown of Qidong City, Jiangsu Province, China and its validation is confirmed by the methods of visual assessment and spatial accuracy. The simulation result of vector-based CA model reveals that nearly 75% of newly increased urban cells are located in the northwest and southwest parts of the study area from 2002 to 2007, which is in consistent with real land use map. In addition, the simulation results of the vector-based and raster-based CA models are compared to real land use data and their spatial accuracies are found to be 84.0% and 81.9%, respectively. In conclusion, results from this study indicate that the vector-based CA model is a practical and applicable method for the simulation of urbanization processes.
文摘Coastline configuration indexes of 34 typical arc-shaped coasts in South China are investigated by the method of principal component analysis, and meanwhile deposition and geomorphologic features of arc-shaped coast are also analyzed. The results show: (1) The configuration of arc-shaped coast in South China is of the characteristic of variability and complexity. (2) The wave power and the openings of the bay are the decisive factors to result in the changes of the configuration of the arc-shaped coast in South China, however, incidence direction of the wave has no effect on configuration development of the coast. (3) Commonly, geomorphologic modes of the arc-shaped coast system in South China consist of barriers, lagoons and tidal-inlets, and can be divided into four types:the openings of the bay leaning to the east, the openings of the bay leaning to the south, the openings of the bay leaning to the west and the openings of the bay leaning to the north.
文摘A reformed numerical model based on the 'one-line theory' for beach deformation is presented. In this model, the change of beach slope during coastline procession is considered.A wave numerical model combined with wave refraction, diffraction and reflection is used to simulate wave climate to increase numerical accuracy.The results show that the numerical model has a good precision based on the adequate field data. The results can be applied to practical engineering.
文摘Fractal theory was applied to a preliminary discussion of the fractal character and formation mechanism of the coastline of the bedrock coast of China on the basis of GIS (Geographical Information System). Some significant conclusions were drawn:(1) The fractal dimensions of the coastline and linear structures of Liaodong Peninsula are 1.0093 and 1.0246 respectively, those of Shandong Peninsula are 1.019 and 1.021 respectively, etc.(2) The fractal dimensions of coastlines of Liaodong Peninsula, Shandong Peninsula, Zhejiang and Fujian-Guangdong tend to increase with the spatial change from north to south.(3)The regional linear structures(including faults)control the basic trends and fractal dimensions of coastlines as a whole in the regions of the bedrock coast of China:the more the controlling effect of linear structures, the smaller the fractal dimensions of coastlines.(4)The substantial constituents of coast and biologic function both play an important role in affecting the fractal dimensions of coastlines of Liaodong Peninsula, Shandong Peninsula, Zhejiang, Fujian-Guangdong and Taiwan Island.
文摘MANDELBROT enunciated the uncertainty of the length of a coastline in his paper"How long is the coastline of Britain?"published in "Science" in 1967. The fractal concept was presented for the first time in that paper and has been applied to many fields ever since. According to the fractal theory and conditions of fractal research of coastline,the controls of faults and biologic function on the fractal character of coastline are preliminarily discussed on the basis of GIS in this paper . Finally,some significant conclusions are drawn:1)the faults control the basic trends of coastlines of two study areas;2)the fractal dimension of coastline of Taiwan is smaller than that of Changle-Lufeng,because the faults of Taiwan more intensely control the trend and fractal dimension of the coastline;3)the larger the fractal dimension of the faults or the major faults,the more the controlling effect of them on the trend and fractal dimension of coastline; 4)the larger fractal dimension of the coastline of Changle-Lufeng indicates that the biologic function intensely shapes the coastline. In a word,the controls of faults and biologic function on the fractal character of coastline are discussed with a case study of China in this paper,it can be seen that faults and biologic function both have influence over the trend and fractal dimension of coastline,the fractal mechanism of coastline of two study areas may be so.
