A shoreline change analysis along the coast between Kanyakumari and Tuticorin,India, using digital shoreline analysis system

The shoreline is one of the rapidly changing landforms in coastal areas.They are the key element in coastal GIS and provide the most information on coastal land form dynamics.Therefore,accurate detection and frequent monitoring of shorelines is very essential to understand the coastal processes and dynamics of various coastal features.The present study is to investigate the shoreline changes along the coast between Kanyakumari and Tuticorin of south India(where hydrodynamic and morphologic changes occur continuously after the December 2004 tsunami)by using Digital Shoreline Analysis System(DSAS),an extension of ArcGIS.Multidate IRS and Landsat Satellite data(1999,2001,2003,2005,2007,and 2009)are used to extract the shorelines.The data is processed by using the ERDAS IMAGINE 9.1 software and analyzed by ArcGIS 9.2 workstation.The rates of shoreline changes are estimated by three statistical methods,namely,End Point Rate(EPR),Linear Regression Rate(LRR),and Least Me-dian of Squares(LMS)by using DSAS.The study reveals that most of the study area has undergoing erosion.Both natural and an-thropogenic processes along the coast modify the shoreline configuration and control the erosion and accretion of the coastal zones.The coastal zones along the estuary have experienced accretion due to the littoral processes.The zones with headlands have more eroded than other zones along the study area.The study also shows that the coastal zones where sand is mined have relatively more rate of erosion than that of the other zones.Improper and unsustainable sand mining may also lead to severe erosion problem along this area.The shoreline change rates are altered by various geological processes along the coast.Thus,the present study implies that proper beach filling and nourishment projects should be made in the study area to save from hazards.It also indicates the advantage and suitability of DSAS to assess the shoreline changes compared with the traditional manual shoreline change analysis and prom-ising its applications for coastal zone management in other regions.     

Geomorphology and land use pattern of visakhapatnam urban - industrial area

Geomorphology and land use pattern of Visakhapatnam urban – industrial area have been studied using IRS IB and SPOT data. The geomorphic units under structural landforms, fluvial landforms and coastal landforms were identified and appropriate field confirmations were made. The geomorphic units such as inselbergs/residual hills, rolling plains, colluvial plains, fractures, piedmont fans, pediments were identified under structural landforms. The units wind gap, paleo channels, gully land, alluvial plain and natural levee were identified under fluvial landforms. The coastal landforms include sea cave, sea stack, red sediments, beach sands and marshy area. Study of the land use pattern reveals the land use under various categories of residential, planned and un planned, agricultural land, waste land and others. The data will have high relevance and usefulness for urban, industrial and ground water resource evaluations in the context of rapid urbanization and industrialization.     

Evolution of sand encroachment using supervised classification of Landsat data during the period 1987–2011 in a part of Laâyoune-Tarfaya basin of Morocco

Abstract

The study anticipated to understand sand encroachment evolution through analysis of sand contribution across space and time using remote sensing in Laâyoune-Tarfaya basin, Morocco, over the period from 1987 to 2011. The assessment based on supervised classifications of Landsat imagery orthorectified data, using Maximum Likelihood (ML), Minimum Distance (MD) and Support Vector Machine (SVM) classifiers. In order to ameliorate the information, principal components analysis (PCA) and co-occurrence measurement algorithm were used for choosing bands and data transformation. Images differencing was applied on image pairs derived from classification to analyze sand encroachment evolution. All classifiers present enhanced performances, and revealed that area covered by sand was increased by 7%, 4.66% and 4.59% for ML, MD and SVM, respectively. Consequently, images differencing results confirmed that sand material increasing arise not only from coastal area contribution but also mostly from erosion of complicated sand dunes exist in the middle part of the studied area. Evaluating of the presented phenomenon dimensions and its consequences are extremely important to increase the local authorities awareness and mainly for avoiding or minimizing the consequences of the future sand dunes threats.     

Coastal landform mapping around the Gulf of Khambhat using Landsat TM data

Landsat TM data was utilised for coastal geomorphic mapping around the Gulf of Khambhat. Various landforms like shoreline, estuaries, mudflats, islands, mangroves, relict aluvium, cliffs, dunes, flood plains, paleochannel, paleomeanders, oxbow lake, etc. were delineated. The estuaries were divided into salt-wedge estuary, fully mixed estuary and partially mixed estuary based on amount of freshwater discharge and nature of tidal currents. The mudflats were classified into high tide flats, intertidal slopes and subtidal zones. These classes were further classified based on their composition. It was concluded that TM data has broughtout many new features and improved the classification of coastal landforms. The presence of coastal features like drowned river valleys, paleomudflats, relict alluvium, dunes, paleomeanders, oxbow lake and terraces clearly indicate the sea-level changes of the Quarternary period.     

Use of geo-spatial information and technologies for analyzing morphological changes in the Greater Visakhapatnam coastal region,east coast of India

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.     

Flood intensity and land evaluation in the Cauvery delta,Tamil Nadu,applying modern remote sensing techniques

An area of about 7500 km² covering Cauvery delta has been studied from airphotos (1:60,000), Landsats (1:250,000) and survey of India topographic sheets (1:50,000) with a view to delineate various landforms, soils, land use, hydromorphic units, drainage, and flood intensity of the delta. The delta is composed of mainly ancient channels, delta p ains, fossil islands, levees, beach ridges, mangroves marshes and coastal dunes. The various soil types are clayey soils, silty soils, silty loams, sandy loams, coastal sands and alkaline clays. Paddy and sugarcane are dominant crops. The old channels are found to be zones of high ground water potential. The growth of delta seems to be from south to north with twelve abandoned meander lobes and three delta fronts with gradual influx of material into Bay of Bengal. The old rivet courses lying parallel to the present active Coleroon river in third stage of the growth of the delta seem to be severely affected by floods. Moderate to low growth is noticeable in the second stage of the of the delta. The oldest river course which debouched into Bay of Bengal near Adirama-patnam is less affected by floods. The delta plains, fossil islands, disturbed ridges and beach ridges are unaffected. Basing on landforms, soils, land use, hydrogeomorphology and flood intensity the land capability of the delta has been evaluated. About seven classes of land are interpreted.     

Remote sensing application in the study of migration and offset of coastal inlets

The coastal zone of Kerala with moderate energy, monsoonal-storm-dominated wave climate, together with a microtidal range, falls under the major tectonic class of the Amerotrailing edge coasts. In order to have an effective management of this coastal zone, one requires detailed information on various types of coastal landforms and the related processes acting on them. Coastal inlets are one among such landforms, which are relatively short and narrow tidal channels connecting bays and lagoons to the ocean. Coastal inlets and the related landforms form an important type of coastal feature. An examination of coastal maps from any area in the world will reveal that coastal inlets are of migratory and offset in nature. In the present study the migration pattern and offset behaviour of some of the inlets of Kerala coast have been examined using IRS-IA LISS II data and Survey of India topographic sheets. The study reveals that geocoded IRS-IA LISS II data could provide accurate geometrical information which may considerably minimise the field check.     

Assessment of coastal bio-resources of the Palk Bay,India, using IRS-LISS-III data

Coastal resources viz., coral reefs, seagrasses, mangroves, and coastal land features viz., sandy beach, mudflats and salt pan/aquaculture ponds were classified and assessed in the Palk Bay region of the south-east coast of India using IRS LISS III satellite image (1996, 2000, 2002 and 2004). The study recorded an areal coverage of 286.95 ha of reef area during 2004, which is 177.54 ha lesser than that of the reef area of 1996. The reef vegetation composed mainly of seaweeds has gained over 29.44 ha during the same period. Likewise, sand over reef area has also increased alarmingly i.e. 120.34 ha between 1996 and 2004. The seagrass beds of Munaikkadu region of the Palk Bay are comparatively protected and have gained over 7.5 ha between 1996 and 2004. It has been found that both the dense (2.99 ha) and sparse (36.45 ha) mangroves have gained their areal coverage considerably between 1996 and 2004. Whereas in Devipattinam region, many anthropogenic pressures are exerted only on the seagrass resources which has led to the reduction of over 785.5 ha of dense seagrass beds between 1996 and 2004. The study clearly indicated that the resources are under the pressures of low to high threats, especially the coral reefs and seagrasses, if the pressures continue, coastal resources of the Palk Bay may face serious threats of destruction in this part of the Bay in the years to come.     

Geospatial Technologies for National Geomorphology and Lineament Mapping Project – A Case Study of Goa State

A three level classification system, based on the genesis of landforms, was used to map the geomorphology of the Goa state. The first level corresponds to the process that was responsible for landform generation, the second level or the intermediate level was assigned based on the morphography, and the third level corresponds to the individual landforms units identified based on the morphostructure. The mapping was carried out using IRS-P6 LISS-III (23.5 m) satellite image as the primary data source. Ancillary data such as geological map, topographic map, digital elevation model (DEM), field data collected by global positioning system (GPS) and web portals for image visualisation, were also used for the mapping purpose. A new software designed for mapping landforms based on the genesis, was used in this study to create a seamless geomorphology and lineament database of the Goa state in a GIS environment. A total of 58 landforms within six types of genetic classes were mapped in this area. Similarly, structural and geomorphic lineaments were also delineated using the satellite data. The database created has multi-purpose usability such as environmental studies, mining activity assessment, coastal zone management and wasteland development, since the classification system used is focused on processes, not theme specific.     

Assessment of Coastal Erosion Vulnerability around Midnapur-Balasore Coast, Eastern India using Integrated Remote Sensing and GIS Techniques

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.     

潮汐和植被物候影响下的潮间带湿地遥感提取

潮间带湿地具有重要的生态和经济价值,但受到全球变化影响,发生大面积退化甚至丧失.掌握潮间带湿地的时空分布特征,对海岸带资源的科学管理具有重要意义.由于受到多云多雨天气和潮汐动态淹没的影响,单时相遥感数据难以获取完整的潮间带湿地信息.因此,本研究开发了一种基于时序遥感指数的潮间带湿地分类算法,并以福建省亚热带海岸带为例,...     

Characterization of spatial and temporal variation of suspended sediments in the Yellow and East China Seas using satellite ocean color data

Total suspended sediment (TSS) data concentrations are retrieved from two sets of satellite ocean color data (the Moderate Resolution Imaging Spectroradiometer (MODIS) onboard Aqua and the Korean Geostationary Ocean Color Imager (GOCI)) using an existing regional model to characterize spatial and temporal variation of TSS in the Yellow and East China Seas. MODIS-derived TSS maps show that TSS concentrations are, in general, high along the Korean and Chinese coasts including the Bohai Sea and the Yangtz River estuary, and lower in the middle of the Yellow Sea and the southeastern area of the East China Sea. The monthly average of 10-year MODIS data reveals that TSS values are highest during winter (January to February) and lowest in summer (July to August). Short-term TSS concentrations retrieved from GOCI data showed the dominant influence of semi-diurnal tidal changes on sediment dynamics through temporal (hourly) and spatial distribution in coastal zones of the Yellow sea. The results presented here demonstrate that the satellite-derived TSS products can be utilized as an application tool for future studies on long- and short-term sediment dynamics of turbid coastal waters. In particular, GOCI observations provide unique important capabilities to characterize and quantify the water properties at high temporal (hourly) and spatial (0.5 km) resolutions in the turbid coastal waters of the Yellow Sea and its vicinities.     

Monitoring coastal zone land use and land cover changes of Abu Dhabi using remote sensing

Coastal zones are most vulnerable for landuse changes in this rapid industrialization and urbanization epoch. It is necessary to evaluate land use — land cover (LULC) changes to develop efficient management strategies. The main objective of this paper is to evaluate and quantity Abu Dhabi coastal zone LULC changes from 1972 to 2000 using multi-temporal LANDSAT satellite data and digital change detection techniques. Supervised classification coupled with expert visual interpretation techniques were used to produce LULC classified images with an accuracy of 88%. Change detection process was achieved by applying post-classification comparison techniques in ENVI software. From this study it has been observed that the important coastal landuse types of Abu Dhabi coast .i.e. wetlands and woody Vegetation (Mangrove, represented by a single species,Avicennia marina) have been reduced drastically in their extent due to reclamation, dredging, tipping and other anthropogenic activities along the coastal zone. However, it has been observed that there is rapid increase in the man-made plantation and managed vegetation from 1990 to 2000 due to the Abu Dhabi government initiation. This study has given good insight into Abu Dhabi coastal zone changes during last 3 decades.     

Eco-Geomorphological zonation of The Bangaram Reef, Lakshadweep

Coral reefs, which are known for rich biological diversity and productivity, are being threatened throughout the world by various natural and anthropogenic activities. The present study concentrates on establishing methodology to zone the geo-morphological and ecological zones of the Bangaram reef (of atoll type), Lakshadweep islands, using remotely sensed data and adequately supported by field data. Classification system has been evolved to zone the reefs. Comparative studies have also been carried out using image processing techniques in order to establish the suitable technique for studying the Indian reefs. The IRS LISS III images representing three different tidal conditions of the period 1998-2000 were analyzed. The unsupervised classification of both the raw images as well as principal component images gave similar information. The classified product was subjected to contextual editing. Misclassification among various classes was found to increase with the increase in the depth of the water column present over the reef. The zones identified on the image are central deep lagoon, reef knolls (rising steeply from the central deep lagoon floor), reef edge, reef platform, coralline shelf, broad shallow sandy-bottomed lagoon, beach and two islets. The zonation has helped in getting information on the presence of live corals on the Bangaram reef. This kind of study is a valuable input in assessing the health of the reefs and its diversity.     

Object-oriented extraction of beach morphology from video images

The ARGUS system is a shore-based, optical video system offering a suitable remote sensing technique for the purpose of long-term, high-resolution monitoring of coastal morphodynamics. Ten-minute time-exposure (timex) images obtained by the ARGUS cameras during low tide show the intertidal morphology (bars, troughs and rips) by the differences between water, wet sand and dry sand, where dry sand represents bars, and wet sand and water represent troughs and rips. A semi-automatic object-oriented algorithm was developed for classification of intertidal beach in low-tide video images and was tested on 13 low-tide ARGUS images collected at Noordwijk aan Zee, The Netherlands. Because of the strong relation between the visual observations and object-oriented image analysis, the ARGUS images are subdivided in small homogeneous areas (i.e. objects) by segmentation. Maximum likelihood classification creates a model for each day using a random selection of the objects, which are manually labelled, and their accompanying variables. Of the three classes, class wet sand had a classification fit of 43.4% when compared to an in situ classification; class water was correctly classified for 90.1% and dry sand could be classified best (92.8%). By combining their cross-shore position and their classification, objects can be directly linked with the respective morphological features.     

Assessment of coastal wetland resources of central west coast, India, using LANDSAT data

The part of central west coast (Maharashtra and Goa) of India has been classified and quantified for coastal wetlands using LANDSAT data of 1985-86. The classification accuracy of the maps and area estimates achieved was 84% at 90% confidence level and the planimetric accuracy at 1:2,50,000 scale was 0.3 mm. The total coastal wetland areas in Maharashtra and Goa, have been estimated to be 1567 and 115 km:2, respectively. The estuarine and backwater regions contribute 44.6% of the wetland, followed by open mudflats (32%), mangroves (8.8%) and beach/spit (7.8%). Mangroves comprised of 17 species and are dominated by Rhizophora mucronata, Avicennia officinalis, A. marina, Sonneralia alba, Excoecaria agallocha and Acanthus ilicifolius. The sand-dune flora comprised of 63 species while rocky intertidal regions harboured > 100 species of marine algae. Erosional changes have been noticed to be predominant along the Maharashtra coast while progradation of beaches is noticed in Goa.     

Automatic Feature Extraction Module for Change Detection in Al Ain,UAE: Analysis by Means of Multi-temporal Remote Sensing Data

Monitoring new changes in cities adjacent to dynamic sand dunes requires precise classifier technique. Unlike traditional techniques of supervised classification which use training sites, the integration of image transformation tasseled cap and automatic feature extraction module based on spectral signatures has provided to be sensitive and realistic techniques with time and cost effective. The proposed module was applied to Al Ain district, United Arab Emirates (UAE). The module consists of four steps in terms of segmentation, thresholding and clustering and computing attributes. The obtained greenness and classified maps were then enhanced by applying a 3?×?3 Sobel filter. The new changes were detected by combining the multi-temporal greenness and classification maps. Accuracy assessment and quantitative analysis were performed using confusion matrix and ground truthing. The results showed significant increasing in urban and agricultural areas from the year from 1990 to 2000 compared with the period of time from the year 2000 to 2006. The image difference showed that the vegetation and building classes had increased 7.58 and 20.28 km² respectively. This study showed that image difference and fuzzy logic approach are the most sensitive techniques for detecting new changes in areas adjacent to dynamic sand dunes.     

杭州湾滨海湿地时空格局变化遥感调查研究

采用TM、SPOT-5卫星遥感数据,通过建立杭州湾滨海湿地分类体系和解译标志并进行人机交互解译,完成了杭州湾1987、1995、2003和2009年滨海湿地提取和分类。研究了4期杭州湾滨海湿地的利用状况、面积,以及时空格局变化情况,研究显示:1987~2009年期间,杭州湾滨海湿地主要表现为滩涂湿地的逐年减少和库塘湿地的逐年增加;1995年之前湿地变化以自然驱动力为主,之后人类活动影响明显,对近海域、滩涂不断开发,尤以南岸为主;以杭州湾湿地公园为典型的沼泽草甸湿地得到了较好的保护。     

Land transformation in Punjab — A case study of Kapurthala district

The map showing the extent of salt affected and sand dune soils was prepared at 1:50,000 scale using Landsat TM data for March 1987 and compared with the soil map of Kapurthala district based on 1965 aerial photographs and semi detailed survey of the district during 1975–76. The study revealed that in a span of 22 years (1965 to 1986) the area of sand dunes decreased from 22.7 per cent to 2.3 per cent and that of salt affected soils from 20.95 per cent to 4.38 per cent respectively as a consequence of reclamation of salt affected soils and clearing and levelling of sand dunes. Salt affected soils after reclamation have been brought under paddy-wheat rotation. Whereas sand dunes after clearing and levelling, have been brought under wheat or wheat -rice/fodder/oilseed crops.     

Photogeological mapping in parts of Cuddapah basin Kurnool and Prakasam Districts of Andhra Pradesh

An area of 2500 sq. Km. has been covered by photogeological mapping with selected field checks which forms a part of Cuddapah basin in the Kumool and Prakasam Districts of A.P. The rocks exposed in the area belong to the Cumbum and Bairankonda Formations of Cuddapah Super Group. They occur more or less as an alternating sequence. These formations are bound on the east by Dharawar gneisses and on the west by Nandyal Shales. The Bairankonda Formation is predominantly arenaceous with quartzite as the main member, being easily identifiable in the aerial photographs by its characteristic topography, coarse drainage, light grey tone etc. The Cumbum Formation is mainly argillaceous with slate/phyllite as the main member, intercalated with minor quartzite band and is expressed on the photographs in dark tone with dendritic to sub-parellel drainage and occurs relatively at lower elevations, mostly in plains. The Dharwar (Archaean) gneisses underlying the vast plains in the east are recognised by the sandy nature of soil and by the thrusted contact of this unit with the Bairankondas. The Nandyal Shales occupying the large cultivated area in west have a darker tone and a dendritic drainage pattern. They are Upper Kurnool in age. All the litho-units have undergone pre-Kurnool deformation resulting into plunging/doubly plunging antiforms and synforms trending NNE-SSW and a few shear zones and faults. Due to severe deformation a very prominant foliation has developed in the Cumbum unit. Groove lineation has also been developed in the hinge portions of major folds. The magmatic activity in these formations has been witnessed with the emplacement of reibeckite syenite and Kimberlite plugs and veins. Geomorphologically the area may be divided into two prominant units namely (i) Denudational landforms comprising (a) hills, ridges, inselbergs, bornhardts and hogbacks on Bairankonda quartzites and phyllites (b) pediment and dissected pediment on Cumbum Shales and Dharwar gneisses and (ii) Depositional landforms such as (a) alluvial fans and colluvial fans (b) alluvial valley fills along river courses and (c) sand dunes in Dharwar gneisses.