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1.
Shoreline is the dynamic interfaces of both terrestrial and marine environment, which constantly affected by natural coastal processes includes wave, tide, littoral drift and cyclonic storms as well as coastal development. Wave induced littoral drift and fluvial discharge causing the gradual inlet migration and has the concurrent impact on shoreline of Chilika lagoon. This study is to determine the long-term shoreline changes along the coast of Chilika lagoon. Historical satellite images were used to analyse the shoreline erosion and accretion based on statistical approach. The satellite data from 1975 to 2015 were processed by using ERDAS Imagine and the shorelines are extracted. The shoreline oscillation was analysed at an interval of 100 m along the coast of Chilika lagoon using DSAS software. Most commonly used statistical methods such as end point rate and linear regression rate are used. The shoreline change analysis for entire coast of the lagoon since 40 years (1975–2015) indicates that 62% is of accretion, 25% is under stable coast and erosion is 13%. The result reveals that the lagoon coast shows high accretion of 9.12 m/year at updrift side of the lagoon inlet whereas the downdrift side shows high erosion of ??10.73 m/year due to the wave induced northeasterly longshore sediment transport round the year and riverine discharge. This study would provide the potential erosion and accretion area at Chilika lagoon coast and would help in adaptive shoreline management plan.  相似文献   

2.
Shoreline changes along the south Gujarat coast has been analyzed by using USGS Digital Shoreline Analysis System (DSAS) version 4.3. Multi-temporal satellite images pertaining to 1972, 1990, 2001 and 2011 were used to extract the shoreline. The High water line (HTL) is considered as shoreline and visual interpretation of satellite imageries has been carried out to demarcate the HTL based on various geomorphology and land use & land cover features. The present study used the Linear Regression Method (LRR) to calculate shoreline change rate. Based on the rate of shoreline changes, the coastal stretches of study area has been classified in to high erosion, low erosion, stable, low accretion and high accretion coast. The study found that about 69.31 % of the South Gujarat coast is eroding, about 18.40 % of coast is stable and remaining 12.28 % of the coast is accreting in nature. Field investigation was carried out which confirmed the coastal erosion/accretion derived from the analysis. The high erosion area are mostly found along the Umergaon (near Fansa, Maroli, Nargol, Varili river mouth, Umergaon light house) and Pardi (Kolak, Udwara)Taluka in Valsad district. Stable coastal length of the study area is 21.59 km and mostly found in Nani Dandi and near Onjal. High accretion (3.70 %) was only found near Hajira and low accretion (8.58 %) are distributed the study area. The main causes of coastal erosion of the study area were the strong tidal currents accompanied by wave action and reduced the sediment load of the river.  相似文献   

3.
Rameswaram Island located on the southeast coast of India bounded by Gulf of Mannar (GoM) on the south and Palk Bay (PB) on the north, respectively, is unique in nature. The southeastern part of Rameswaram Island known as Dhanushkodi foreland is a long sand spit of about 20?km length. Shoreline erosion/accretion rates are computed based on End-Point Rate, Linear Regression Rate and Net Shoreline Change from Indian Remote sensing Satellite, Linear Imaging Self scanning Sensor III images from 1998 to 2012. Along the PB coast of Dhanushkodi foreland, eroding shorelines are dominant except Arichamunai, whereas it is reversing along GoM. Inter-annual shoreline change revealed that changing trend and stability of Island are affirmed with statistical approaches. An equilibrium shoreline trend is noticed on both the sides of Dhanushkodi foreland. Annual shoreline change rate indicates erosion and accretion in northern and southern coastline of Dhanushkodi foreland varies, respectively.  相似文献   

4.
Coastal zone is highly volatile ecosystem which is always in adjustments. Loss of shore line will cause severe impact on human life and as well as their properties. Remote sensing is a reliable technique to study the historical shoreline changes. Therefore in this paper long term shoreline oscillations of Cauvery delta shorelines at Poompuhar, Tharangambadi and Nagapattinam were studied using satellite imageries and the same was physically observed at the above three locations with the help of reference pillars and compared mutually. It was observed that the shoreline at Poompuhar is under accretion at the rate of 1.79m/ year and other shoreline stretches at Tharangambadi and Nagapattinam were under erosion at 0.4888m/ year and 0.4985m/ year respectively. It was also observed that the remote sensing study qualitatively matches with the physical observation for all the three coastal stretches of the study area.  相似文献   

5.
Digha coastal region in the northeastern part of the Bay of Bengal is potentially vulnerable to erosional hazard. The present study assessed the coastal erosion vulnerability along this 65 km long coastal stretch located between Rasulpur (Midnapur) and Subarnarekha (Balasore) estuarine complex, which had been subjected to anthropogenic intervention. Multi-resolution Landsat satellite imagery were used for shoreline change study from 1972 to 2010. During this period, accretion was recorded updrift of artificial structures, viz, seawall, groin, pylons and jetties; while, extensive erosion was recorded in downdrift areas of these structures. Assessment was subsequently divided into four categories ranging from “high erosion” to “accretion”. Data from several sources were compiled to map landuse and human activities in the coastal zone. This map was divided into four categories, ranging from “very high capital” to “no capital” landuse. Population density map of the surrounding coastal villages was generated using census data, and divided into four categories ranging from “high density area” to “very low density area”. Subsequently, coastal erosion vulnerability was assessed by combining coastal retreat with landuse type and population density in this study area using simple vector algebraic technique. Zones of vulnerability of different magnitude (viz., very high, high, moderate, and low) have been identified. Furthermore, calculation of “imminent collapse zone (ICZ)” shows that maximum values are around artificial structures and anthropogenic activities. The coastal erosion vulnerability map prepared from this study can be used for proper planning and management of this coastal region.  相似文献   

6.
Coastal zone is very dynamic, being the meeting place of land and sea water. The development in coastal area and subsequent population growth have given rise to problems such as erosion, sedimentation, saltwater intrusion, degradation of natural resources, etc. Satellite data has proved to be more appropriate for change detections quantifying and monitoring coastal zones compared to conventional sources. An attempt is being made to elucidate the effect of shoreline changes with reference to the spatial and field data observed along the Tharangampadi area. The base map was prepared on 1:50,000 scale for delineation and identification of shoreline changes. The spatial variability of shoreline changes are studied using IRS 1B LISS-II 1991, IRS 1C LISS-III 2004 and IRS P6 LISS-IV and IRS 1D PAN merge data 2006. The corresponding Survey of India toposheets of 1852, 1972 and survey and land record village map of 1918 also supplemented for this study. The kind and extent of shoreline changes were investigated by using GPS during ground truth verification. The results are analyzed and presented in this paper. The study results revealed that 180 m receding of the shoreline occurred in the past 155 years.  相似文献   

7.
This article reveals an application of multi-spectral satellite data for analysing the dynamics of different coastal landform features along the southern coastal Tamil Nadu of India. An integrated approach comprising visual image interpretation and maximum-likelihood supervised classification has been employed to classify the coastal landforms by using IRS data (during the period 1999–2006). The quality of image classification has been assessed by performing the accuracy assessments with the existing thematic maps and finally the coastal landforms have been mapped. The study reveals that the dynamics of coastal landforms such as sandy beaches, mud-flats, sand dunes and salt marshes along the study area are mostly influenced by the coastal processes, sediment transport, geomorphology and anthropogenic activities. Major anthropogenic sources for the perturbation of beach sediment budgets and a cause of beach erosion along the study area are excessive sand mining, removal of sand dunes, coastal urbanization, tourism and developmental activities.  相似文献   

8.
Changes in shoreline, coral reef and seafloor have been mapped using remote sensing satellite data of IRS LISS-III (1998), IRS LISS-II (1988), Survey of India Topographic sheet (1969), Naval Hydrographic Chart (NHO) 1975 and bathymetry data (1999) with ARC-INFO and ARC-VIEW GIS. The analysis of multi-date shoreline maps showed that 4.34 and 23.49 km2 of the mainland coast and 4.14 and 3.31 km2 areas of island coast have been eroded and accreted, respectively, in the Gulf of Mannar. The analysis of multi-date coral reef maps showed that 25.52 km2 of reef area and 2.16 km2 of reef vegetation in Gulf of Mannar have been lost over a period of ten years. The analysis of multi-date bathymetry data indicates that the depth of seafloor has decreased along the coast and around the islands in the study area. The average reduction of depth in seafloor has been estimated as 0.51m over a period of twenty four years. The increased suspended sediment concentration due to coastal and island erosion, and raised reef due to emerging of coast by tectonic movement are responsible for coral reef degradation in the Gulf of Mannar. Validation by ground truth has confirmed these results.  相似文献   

9.
Beach heights and tidal variation have large impacts on the accuracy of estimates of coastline position and its historical changes of a wider and flatter beach based on remote sensing data. This study presents an approach to analysis of waterline movement based on the beach slope, estimated from two effective images with Landsat images data. Two images acquired at different stages of the tide were processed to delineate accurately the position of the waterline. Then waterlines were assigned heights using elevations predicted by a two-dimensional non-linear tidal assimilation model. Beach slope can be calculated piecewise using the heighted shorelines based on the equiangular triangle theory. The positions of the national tidal height datum coastline can be obtained by the beach slope calculation method to accurately monitor the changing of coastline. A change in the coastline of the southwest tidal flat of the Yellow River delta, from Tianshuigou to the Xiaoqing River mouth, was detected by combining field measurements of profiles and bathymetric data. The root mean squared error (RMSE) of the calculated slope of the intertidal zone was one order of magnitude less than the measured slope. The minimum error of self-consistency check is 0.2%. The RMSE between the coastlines estimated by the proposed method and those surveyed data varies from 53.98 m to 217.72 m. It is shown that this method is more suitable for the two years and over the time scales of shoreline change monitoring. To assess erosion/accretion patterns in the tidal flat, and the controlling factors, the volume of the beach was investigated as a possible indicator. The accepted coastline position and changes in the beach volume were used to monitor the changing pattern of accretion and erosion along the coast southwest of the recent Yellow River mouth.  相似文献   

10.
This study compares two automated approaches, the transect‐from‐baseline technique and a new change polygon method, for quantifying historical coastal change over time. The study shows that the transect‐from‐baseline technique is complicated by choice of a proper baseline as well as generating transects that intersect with each other rather than with the nearest shoreline. The change polygon method captures the full spatial difference between the positions of the two shorelines and average coastal change is the defined as the ratio of the net area divided by the shoreline length. Although then change polygon method is sensitive to the definition and measurement of shoreline length, the results are more invariant to parameter changes than the transect‐from‐baseline method, suggesting that the change polygon technique may be a more robust coastal change method.  相似文献   

11.
刘鑫 《地理空间信息》2012,(1):102-106,4
基于RS和GIS技术对铁山港地区4个时期的Landsat卫星遥感数据进行处理,分析岸线特征,提取海岸线,研究该区海岸线近20年来(1987年～2006年)的变化特征。结果显示:研究区海岸线总体处于向海推进状态,其变化主要受人为因素影响。岸线变化的主要表现在铁山港与丹兜海湾顶两侧,以养殖开发、港口码头建设为主。  相似文献   

12.
National policies and legal decisions are very much dependent on the position of the shoreline. Shoreline change rates are frequently employed to summarize historical shoreline movements. This also helps to predict the future position of the shoreline based on the perceived historical trends. In this regard, the future shoreline positions at both the long-term, that is 2050, and short-term, that is 2015, time interval was predicted using the End Point Rate (EPR) model along the Junput Coast of West Bengal, India. The whole project work was divided into five parts. The first part showed the detection of shoreline from satellite data like IRS LISS Ⅳ and Landsat 7 ETM+ and from the Survey of India Toposheet. The second part gave the glimpse of the dynamic segmentation of the shoreline to get the dynamically segmented nodal points along the shoreline. Shoreline prediction for the years 2015 and 2050 using End Point Rate (EPR) model was done in the third part. In the fourth part, Coastal Terrain Model (CTM) was prepared, and the digital shoreline estimated. The model result was validated and accuracy assessed with respect to the GPS data collected from the field at the fifth stage. Finally at the end of the present work, limitations of the project and the future scope of the work was sited.  相似文献   

13.
The objective of this study was to investigate the land use/land cover, landforms, shoreline and coastal regulation zone (CRZ) changes of Greater Visakhapatnam coastal region using Indian Remote Sensing-IRS P6 (Resourcesat-I) satellite data and collateral information. Prominent changes have been observed during the past 30 years through land use/land cover analyzes which clearly indicate that thecoastal regulatory zones have altered in respect of both natural and anthropogenic activities. Various geomorphic units were identified and confirmed with appropriate field work. Significant changes have been recognized in the shoreline map, which denote that the area of erosional shoreline is larger than the accretional and stable prone shoreline. The availability of high resolution data has helped to prepare large-scale maps for implementation of CRZ measures. The results were promising and suggest that the modern geo-spatial information and technological tools are extremely helpful for conducting coastal morphological studies.  相似文献   

14.
This study describes a method to map shoreline indicators on a sandy beach. The hypothesis is that, on this beach, spectral albedo is predominantly determined by moisture content and water lines can, therefore, be detected as albedo contrasts. A laboratory experiment is performed to relate moisture content to image albedo, and supervised edge detection is subsequently used to map the shoreline indicators with remote sensing imagery. The algorithm is tested with data from visible, near-infrared and shortwave-infrared wavelength regions. These results are compared to shoreline indicators obtained by a field survey and a shoreline indicator derived from a digital elevation model. Both the water line present when the imagery was acquired, as well as the maximum extent of the last flood, can be detected as a single edge. Older high water lines are confused with the last high water line and appear dispersed, as there are multiple debris lines present on the beach. The low water line, usually in saturated sand, also appears dispersed due to the presence of channels and troughs. Shorelines are constant moving boundaries, which is why shoreline indicators are used as a proxy. Unlike a mathematical indicator that is based on an elevation model, our method is more sensitive to the dynamic nature of shorelines. Supervised edge-detection is a technique for generating reproducible measurements of shoreline indicator positions over time, and aids in the monitoring of coastline migration.  相似文献   

15.
The city of Mangalore is situated at the confluence of rivers Gurpur and Netravati. Two spits are formed in this area, i.e., northern spit of “Bengre” and the southern spit of “Ullal” as the rivers flow close and parallel to the seashore for some distance. The spits have been subjected to constant geomorphological changes in length, width, position, accretion and erosion patterns etc., for the past several decades. A seawall was constructed in 1984 around the tip of Bengre spit and another one along the shoreline of Ullal spit in 1987, by the Government of Karnataka in order to prevent the spits from being eroded. Two breakwaters were also constructed in 1992 near the estuarine mouth as part of the development of old Mangalore Port. The paper presents the results of a study undertaken to identify the geomorphologic changes that occurred in the area, using 1RS-1A/1C data for the years of 1988, 1994. 1996. The study clearly demonstrated that the 1RS data could be effectively utilized for monitoring the geodynamics of an area. It was observed that the spits were highly unstable earlier. However, the construction of seawalls was helpful in arresting the migration of the estuarine mouth and in stabilizing the spits against coastal erosion.  相似文献   

16.
TOPSAR wave spectra model and coastal erosion detection   总被引：2，自引：0，他引：2  
This paper presents work done utilizing TOPSAR data to detect shoreline change along the Terengganu coast (Malaysia). TOPSAR data were used to extract information on wave spectra. This wave spectra information was then used to model shoreline changes by investigating the wave refraction patterns. From these patterns, the volume transport at several locations was estimated. The shoreline change model developed was designed to cover a 20 km stretch of shoreline of Kuala Terengganu. The model utilized data from aerial photographs, TOPSAR data and ground truth data. The location of sedimentation and erosion along the shoreline of Kuala Terengganu was estimated. The wave spectra extracted from TOPSAR data showed wavelengths ranging from 20 m to 175 m. The main direction of the waves given by the spectra was from the northeast. The wave refraction patterns varied, showing both convergence and divergence, indicating erosion and sedimentation locations, respectively. A comparison between the TOPSAR shoreline change model and aerial photographs and ground truth data showed a significant relationship. Finally, the regression model showed that erosion occurred particularly at Sultan Mahmed Airport, at a rate of −1.5 m/year. The maximum rate of sedimentation along the 20 km stretch was 1 m/year.  相似文献   

17.
The impact of wave spectra modulation transfer function (MTF) in shoreline change model accuracy has been presented. The MTF consisted of real aperture radar (RAR) and velocity-bunching which is utilized to map the wave spectra observed from ERS-1 into the observed real ocean wave spectra. Based on this information, the shoreline change model have developed. Two hypotheses were concerned with the shoreline change model based on ERS-1 wave spectra. First, there is a significant difference between RAR and velocity-bunching modulations for ERS-1 wave spectra modeling. Second, this significant difference is induced a different spatial variation for shoreline change pattern.This study shows that there was the significant difference between velocity-bunching and quasi-linear models. The study shows that velocity-bunching model produces wave spectra pattern approximately close to the real ocean wave compared to the quasi-linear model. The error percentage occurred with velocity-bunching and quasi-linear models were 33.5 and 46.7%, respectively. The highest rate of erosion occurred to the shore south of Chendering with −5 m per year and the highest rate of sedimentation occurred to north of Chendering headland with 3 m per year. It can be concluded that ERS-1 data could be used to model shoreline change and identify the locations of erosion and sedimentation. The sedimentation was occurred due to the effect of lowest wave spectra energy captured along the range direction while the erosion was occurred due to highest spectra energy captured near azimuth direction.  相似文献   

18.
Abstract

Shoreline extraction is fundamental and inevitable for several studies. Ascertaining the precise spatial location of the shoreline is crucial. Recently, the need for using remote sensing data to accomplish the complex task of automatic extraction of features, such as shoreline, has considerably increased. Automated feature extraction can drastically minimize the time and cost of data acquisition and database updating. Effective and fast approaches are essential to monitor coastline retreat and update shoreline maps. Here, we present a flexible mathematical morphology-driven approach for shoreline extraction algorithm from satellite imageries. The salient features of this work are the preservation of actual size and shape of the shorelines, run-time structuring element definition, semi-automation, faster processing, and single band adaptability. The proposed approach is tested with various sensor-driven images with low to high resolutions. Accuracy of the developed methodology has been assessed with manually prepared ground truths of the study area and compared with an existing shoreline classification approach. The proposed approach is found successful in shoreline extraction from the wide variety of satellite images based on the results drawn from visual and quantitative assessments.  相似文献   

19.
利用 LiDAR 点云提取有地形约束的光滑海岸线   总被引：1，自引：0，他引：1  
针对传统海岸线提取算法误差大、在地形突变区域形变大的缺点,提出了一种基于离散 LiDAR 点云提取有地形约束海岸线的方法.首先,通过离散点云构建约束三角网,减少内插规则格网的误差并且保证海岸线不穿越地形结构;其次,进行顾及地形结构的点云高程修正,在数据源上缓解海岸线的平滑问题;最后采取二次多项式法消除毛刺,利用动态阈值张力样条函数内插生成光滑海岸线.  相似文献   

20.
The precise delineation of coastal areas subject to past, present, and future erosive processes plays a fundamental role in coastal risk management. Within this framework, satellite data represent a valuable synoptic and multi-temporal information source. Therefore, this research integrated remote sensing and GIS techniques for mapping and modeling shoreline evolution through time. Long-term shoreline’s proxy rates of advance and retreat were determined using Landsat data from the mid-1980s to 2011 and subsequently, a short-term scenario (3 years) was predicted and validated. Two different coastal environments, Oceanic and Mediterranean, were investigated. In the first, different proxies were analyzed, thereby enabling a multi-proxy analysis. Findings showed that the method provided more accurate results in higher energy environments (Oceanic) and where the coastline is not urbanized. Results also highlighted the importance of performing multi-proxy analyses in given study areas, to more reliably define shoreline modeling. Importantly, during the analyses, particular attention was given to assessing uncertainty, which is crucial when outcomes of scientific research are considered for management.  相似文献   

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