Susceptibility to Changes in Coastal Land Dynamics in Bangladesh

Coastal areas of the world are physically dynamic in nature. The present study contributes new knowledge to studies on coastal land dynamics and land susceptibility to erosion. This study developed a raster GIS-based model namely, Land Susceptibility to Coastal Erosion (LSCE) to assess erosion susceptibility of coastal lands under hydro-climatic changes. The devised model was applied to the entire coastal area of Bangladesh. The model required the characterisation of the nature of land dynamics (i.e. erosion and accretion). The analysis showed a net gain of 237 km² of land over the past thirty years but, constant changes in land dynamics were observed in the area. The study then applied the LSCE model to measure the existing levels of land susceptibility of the coastal area to erosion. The validated model outputs were then used as a baseline for generating four possible scenarios of future land susceptibility to erosion in the coastal area. This allowed the model to ascertain the probable impacts of future hydro-climatic changes on land susceptibility to erosion in the area. Additionally, the study assessed seasonal variations of land susceptibility to erosion by using the same model. The model outputs showed that 276.33 km² of existing coastal lands classified as highly and very highly susceptible to erosion, would substantially increase in the future. Using a Fuzzy Cognitive Mapping (FCM) approach, the study elicited expert views to evaluate the model scenarios and to address uncertainties relevant to erosion susceptibility. This study could allow coastal managers and policymakers to develop effective measures in managing highly erosion susceptible coastal lands in the area

A study of land transformation in Savar Upazila, Bangladesh, 1915-2001 : an integrated approach using remote sensing, census, map and field data

EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Geomorphological Evolution and Vulnerability of Low- Lying Coasts in Bangladesh: The Case Study of Sandwip Island

Bangladesh is ranked as the “5th most at-risk country” in the world in terms of disasters with a world risk index of 20.22% in the World Risk Report 2012. Coast and island flooding induced by extreme storms and cyclones born in the Northern Indian Ocean passing through the funnel shaped shallow northern Bay of Bengal are the most dangerous natural hazards in the area. Additionally, remarkable geomorphological change of the lower GBM active delta and relative Sea Level Rise (SLR) have drawn special attention to the environmental scientists and respective managers for the alarming more intense and more frequent upcoming climate change vulnerabilities.The Lower Meghna River Estuary (LMRE) is an extremely dynamic estuarine system with dramatic geomorphological changes of the offshore islands. The erosion and accretion rates are remarkably high and the islands are reducing their original sizes. As populations flock to the coast and offshore islands at threat from erosions, storm inundation and sea level rise, intensive studies must be carried out on the vulnerability of these coastal regions. Sandwip Island, located at the confluence of the Lower Meghna River Estuary, shaped and characterized by both tidal actions of the Bay of Bengal and river streams of the Meghna, was chosen as the only international case study site outside Europe in the framework of the Risc-KIT FP7 European project (http://www.risckit.eu/). The project aims to develop tools and methods to reduce risk and increase resilience of coastal areas. The toolkit will be implemented for each case study. The present works aims to describe the state of the art of knowledge on the island covering geomorphology, sediment characteristics, hydrodynamics and socioeconomics. Community perceptions and indigenous coping strategies aspects of the island are included in a coastal vulnerability perspective to be useful in further research, development of effective preparedness, management and actions plan. To reach this goal, an attempt was taken to find out the answers to the following questions: 1) what is the status of geomorphological changes? 2) What are the sediment characteristics of the erosion-accretion prone shorelines? 3) What is the status of the sea level rise relative to the island 4) What is the total vulnerability/hazard ranking by local perceptions? 5) How much has the land use changed due to erosion and associated hazards ? and finally 6) What strategic changes should be taken? The research questions were answered using topographic surveys, lab based sediment analysis, tide gauge data analysis, erosion-accretion mapping and development of high resolution DEM and TIN using Remote Sensing and GIS-based tools and techniques and questionnaire survey results interpreted with national disaster management plans. The study found that the island is more physically prone to coastal erosion, coupling with storm surges and sea level rise making it more vulnerable in future. The erosion rate considering both shoreline and area changes is much more intense exceeding accretion in the silty clay sedimentary parts and the sea level rise trend is alarming in comparison with other nearby coastal areas in Bangladesh.Tidal data analysis for Sandwip shows semi-diurnal components higher in amplitude than Chittagong. Diurnal amplitudes are comparable and phases are generally higher for Sandwip with a 47 minute delay than Chittagong. The DEM demands more intensive bathymetric information that should be used for more accurate hydrometeorological models for the low elevated island, where as the island is almost flat with the average topography is only 5 meter above MSL and the north-western part is slightly higher than the south-western part as observed in the TIN justified by Topographic survey. The physical assets have been declining stressing on the socioeconomy of the community as found by the social survey as well as land use satellite mapping. So, a relatively high earthen embankment encircling the island, a crossdam connecting north side of the island to mainland is immediately needed to protect the community from erosion as well as relative sea level rise and storm surge inundation hazards. A site specific hydrometeorological warning should be developed and announcement dissemination should be maintained in the local language. Development of roads and transportation system and the health training should be enhanced to make people more aware and adaptive with the associate disasters

The First Global Integrated Marine Assessment: World Ocean Assessment I

We used satellite-derived sea-surface-temperature (SST) data along with in-situ data collected along a meridional transect between 18.85 and 20.25°N along 69.2°E to describe the evolution of an SST filament and front during 25 November to 1 December in the northeastern Arabian Sea (NEAS). Both features were ∼ 100 km long, lasted about a week and were associated with weak temperature gradients (∼ 0.07°C km⁻¹). The in-situ data were collected first using a suite of surface sensors during a north–south mapping of this transect and showed the existence of a chlorophyll maximum within the filament. This surface data acquisition was followed by a high-resolution south–north CTD (conductivity–temperature–depth) sampling along the transect. In the two days that elapsed between the two in-situ measurements, the filament had shrunk in size and moved northward. In general, the current direction was northwestward and advected these mesoscale features. The CTD data also showed an SST front towards the northern end of the transect. In both these features, the chlorophyll concentration was higher than in the surrounding waters. The temperature and salinity data from the CTD suggest upward mixing or pumping of water from the base of the mixed layer, where a chlorophyll maximum was present, into the mixed layer that was about 60 m thick. A striking diurnal cycle was evident in the chlorophyll concentration, with higher values tending to occur closer to the surface during the night. The in-situ data from both surface sensors and CTD, and so also satellite-derived chlorophyll data, showed higher chlorophyll concentration, particularly at sub-surface levels, between the filament and the front, but there was no corresponding signature in the temperature and salinity data. Analysis of the SST fronts in the satellite data shows that fronts weaker than those associated with the filament and the front had crossed the transect in this region a day or two preceding the sampling of the front

Dead men's eyes: embodied GIS, mixed reality and landscape archaeology

Archaeology has been at the forefront of attempts to use Geographic Information Systems (GIS) to address the challenges of exploring and recreating perception and social behaviour within a computer environment. However, these approaches have traditionally been based on the visual aspect of perception, and analysis has usually been confined to the computer laboratory. In contrast, phenomenological analyses of archaeological landscapes are normally carried out within the landscape itself, computer analysis away from the landscape in question is often seen as anathema to such approaches. This thesis attempts to bridge this gap by using a Mixed Reality (MR) approach. MR provides an opportunity to merge the real world with virtual elements of relevance to the past, including 3D models, soundscapes and immersive data. In this way, the results of sophisticated desk-based GIS analyses can be experienced directly within the field and combined with phenomenological analysis to create an embodied GIS. The thesis explores the potential of this methodology by applying it in the Bronze Age landscape of Leskernick Hill, Bodmin Moor, UK. Since Leskernick Hill has (famously) already been the subject of intensive phenomenological investigation, it is possible to compare the insights gained from 'traditional' landscape phenomenology with those obtained from the use of Mixed Reality, and effectively combine quantitative GIS analysis and phenomenological fieldwork into one embodied experience. This mixing of approaches leads to the production of a new innovative method which not only provides new interpretations of the settlement on Leskernick Hill but also suggests avenues for the future of archaeological landscape research more generally

Monitoring vegetation dynamics in East Rennell Island World Heritage Site using multi-sensor and multi-temporal remote sensing data

East Rennell of Solomon Island is the first natural site under customary law to be inscribed on UNESCO’s World Heritage List. Potential threats due to logging, mining and agriculture led to the site being declared a World Heritage in Danger in 2013. For East Rennell World Heritage Site (ERWHS) to ‘shed’ its ‘Danger’ status the management must monitor forest cover both within and outside of ERWHS. We used satellite data from multiple sources to track forest cover changes for the entire East Rennell island since 1998. 95% of the island is still covered by undisturbed forests; annual average normalized difference vegetation index (NDVI) for the whole island was above 0.91 in 2015. However, vegetation cover in the island has been slowly decreasing, at a rate of –0.0011 NDVI per year between 2000 and 2015. This decrease less pronounced inside ERWHS compared to areas outside. While potential threats due to forest clearing outside ERWHS remain the forest cover change from 2000 to 2015 has been below 15%. We suggest ways in which the Government of Solomon Islands could use our data as well as unmanned air vehicles and field surveys to monitor forest cover change and ensure the future conservation of ERWHS