Severe Coastal Erosion Research Articles

Impact of coastal erosion and landscape changes on place attachment and the sense of belongingness: a case study in Oluvil, Sri Lanka

Oluvil is a coastal village on the east coast of Sri Lanka with significant resources of fisheries and agricultural lands. The coastal community of Oluvil has a strong socio-cultural and economic attachment to its natural landscape. The community relies heavily on fishing and agriculture for their economic activities, with the vast coastal lands and rich marine resources providing the main source of livelihood. The haphazard development of the fishery and commercial harbour in 2008 resulted in coastal erosion and related landscape changes. This highly impacted the sensitive coastal belt in the region, resulting in many environmental and social issues. This paper investigates the social impact associated with the related negative environmental changes. The research revealed a significant negative impact on income, livelihood, resources and property due to severe coastal erosion. These economic impacts and landscape changes negatively influenced the cultural identity, social dynamics, social structure and interactions, resulting in the loss of place attachment and the sense of belongingness.

Shoreline evolution in adjacent to a coastal structure in Hiep Thanh commune, Duyen Hai district, Tra Vinh province

Coastal erosion is significant along the coastline in Hiep Thanh commune, Duyen Hai district, Tra Vinh province, Viet Nam. In order to address this severe coastal erosion, the local community has constructed a concrete embankment as an emergency solution to protect the coastline. However, this solution exacerbates the issue since the fundamental processes of coastal erosion remain inadequately explored and understood. Specifically, in beach sections without the concrete embankment, erosion still occurs. Therefore, this paper aims to investigate the shoreline changes adjacent to the embankment using an integrated approach with remote sensing and diffusion theory. The results show that beach erosion is occurring near the embankment at a rate of 44 meters per year, and the diffusion coefficient for longshore sand transport in the study area is 130 square meters per day. This study offers a practical approach to examining changes in the shoreline adjacent to a coastal structure, particularly valuable in situations where there is a scarcity of measured field data.

Seasonal benthic species composition linked to coastal defense structures (CDS) in Kuala Nerus, Terengganu, Malaysia.

The natural hydrodynamic process of Kuala Nerus, Terengganu, has changed since the extension of Sultan Mahmud Airport runway in 2008. Consequently, severe coastal erosion has occurred in the area, particularly during the northeast monsoon season (NEM). Numerous types of coastal defense structures (CDS) have been constructed to protect the coastline. Despite the loss of esthetic values, the effect of CDS construction on marine organisms in the area remains unknown. Hence, this study aims to assess the ecological aspects of macrobenthic compositions at the CDS area of Kuala Nerus, Terengganu, based on the differences between the southwest (SWM) and northeast (NEM) monsoon seasons. Macrobenthos were collected from the sediment in July (SWM) and December 2021 (NEM) using the Ponar grab at 12 substations from five sampling stations. The density of macrobenthos was higher in SWM (48,190.82 ind./m2) than in NEM (24,504.83 ind./m2), with phylum Mollusca recording the highest species composition (60-99.3%). The macrobenthos species had a low to moderate level of diversity (H' = 1.4-3.1) with the species were almost evenly distributed (J' = 0.2-0.8). Windward substations exhibited coarser grain sizes (38.56%-86.84%), whereas landward substations exhibited very fine grain sizes (44.26%-86.70%). The SWM season recorded a higher organic matter content (1.6%-6.33%) than the NEM season (0.4%-3.1%). However, metal concentrations in the surface sediment were within the safe range and permissible limits for both seasons, inferring that the macrobenthos composition was unaffected. This study demonstrated that the CDS associated with the monsoon system has controlled the hydrodynamics and nearshore sedimentary processes in the Kuala Nerus coastal zone, thereby affecting the macrobenthos population, in terms of richness and density. The ecological and energetic effects of the coastal structures in different seasons have resulted in a more significant result, with the SWM exhibiting a higher macrobenthos composition than the NEM.

Selection of cross sections for solitary wave transmission efficient for submeged vertical porous breakwater using Flow-3D model

Climate change is causing progressively severe coastal erosion, especially in beaches and tourist areas. Vertical porous breakwaters were chosen to protect the beaches for their effectiveness in reducing waves and preventing erosion. However, submerged vertical porous breakwaters must be applied due to the characteristics of beaches that do not allow shielding. Thus, the width of the porous breakwaters should be increased, incurring construction costs. This study proposes cross-sections of submerged vertical porous breakwaters that have the same width and determines the selected cross-section in those sections that effectively meets the wave height reduction. The Flow-3D numerical model with porous structures and solitary wave boundary conditions was used to simulate 72 scenarios of the interactions between solitary waves and submerged vertical porous breakwaters. The selected cross-section is a parallel configuration, where the distance between the two breakwaters is twice the width of the first breakwater. Dimensionless graph systems defining parallel breakwater parameters according to incoming solitary waves were established.

Coastal Erosion Caused by River Mouth Migration on a Cuspate Delta: An Example from Thanh Hoa, Vietnam

Coastal erosion poses a significant threat to the infrastructure of the coastal community at the mouth of the Ma River in Thanh Hoa Province, Vietnam. In response, emergency solutions such as hard, protective structures are often implemented. However, this approach exacerbates the problem as the underlying mechanisms of coastal erosion are not adequately investigated and understood. In this study, the long-term configuration of the mouth of the Ma River in Thanh Hoa Province, Central Vietnam, is investigated using Landsat imagery spanning from 1987 to 2023. An analytical solution of a one-line model for shoreline change was also used to examine the sand discharge from the Ma River and the diffusion coefficient for the sand transported along the shore by breaking waves. The results showed an asymmetric configuration of the mouth of the Ma River over the past 37 years. The supply of sand from the Ma River is around 350,000 m3/year. The majority of sand (ranging from 55% to 75%) is mainly transported to the northern beach of the Ma River delta. This uneven distribution of sand from the Ma River has led to the asymmetrical morphology of the delta apex in which the northern part of the Ma River delta is experiencing northward movement while the southern part of the Ma River Delta is moving southward and landward. The asymmetrical morphology of the delta at the mouth of the Ma River has recently been identified as the cause of severe coastal erosion. The diffusion coefficient value determined for the transportation of longshore sand along the deltaic lobes of the Ma River delta corresponds to 90 m2/day. This study offers a practical method for investigating morphological changes in cuspate deltas, especially when measured field data are limited.

Ignoring environmental change? On fishing quotas and collapsing coastlines in Bykovskiy, Northern Sakha (Yakutiya)

The Indigenous village of Bykovskiy is located 40 km from Tiksi, the administrative center of Bulunskiy District (Ulus), in the northern part of the Republic of Sakha (Yakutiya), Russia. Founded as a Soviet fishing cooperative, it became home to Indigenous Sakha, Evenkis, Evens, as well as to Russian settlers and political prisoners from the Baltic states. Post-Soviet transformations, coupled with escalating environmental change processes, has been altering the local economy and subsistence activities since the 1990s. Although our interlocutors directly observed and experienced such changes, they seemed to ignore the visible problem of severe coastal erosion that was destroying a local cemetery. This article is based on ethnographic fieldwork conducted in the study region in 2019, and combines approaches from the anthropology of climate change with reception and communication studies. It examines “ignorance” as a strategy of adaptation to multiple stressors under historically reproduced colonial structures of governance.

Root biomechanical features and wind erosion resistance of three native leguminous psammophytes for coastal dune restoration

Taiwan is a subtropical mountainous island with fragile geological conditions and about 1566 km of coastline. Monsoon usually bring severe coastal erosion and dust storms. Canavalia lineata, Canavalia rosea and Vigna marina, three native pioneer leguminous psammophytes occurring on coastal sand dune areas, play important roles in reducing wind erosion in coastal regions. Nonetheless, its root biomechanical properties and wind erosion resistance are still unexplored. In this study, the root biomechanical properties of these plants were inspected using uprooting and tensile tests. Wind erosion resistance was estimated by wind tunnel tests. Our results showed that the growth charactersitics of C. lineata are superior than those of C. rosea and V. marina. Furthermore, the root pullout force of C. lineata (0.36 ± 0.04 kN) and C. rosea (0.36 ± 0.05 kN) are remarkably higher than that of V. marina (0.22 ± 0.02 kN). Root tensile strength of C. rosea (291.24 ± 11.89 MPa) plants is significantly greater than those of C. lineata (231.33 ± 9.47 MPa) and V. marina (95.78 ± 8.83 MPa) plants. Moreover, wind tunnel tests show that C. lineata has superior wind erosion resistance than C. rosea and V. marina. Altogether, these results clearly demonstrate that the priority species order for coastal dune restoration is: C. lineata > C. rosea > V. marina. These results contribute important strategy for ecological engineering of coastal management in sand dune areas.

Nghiên cứu ảnh hưởng của công trình tới trường sóng, trường dòng chảy khu vực Cửa Tùng – Quảng Trị bằng mô hình số

For many years, Cua Tung area has suffered from the effects of rising water and waves, especially during storms. That situation leads to changes in water environment and coastal erosion, directly affecting people's lives and properties; affect the development of tourism, economy - society. The presence of the works here has led to a change in the hydrodynamic regime (waves, currents) and negatively affects the coast and water environment. Confirmed results show that wave height and flow rate are 73.6% and 55.2% according to Nash criteria, at a satisfactory level or higher. Before and after two constructions, the Southern Embankment and the North Embankment of Cua Tung, have shown a clear change in wave regime and flow, causing the waves to be strengthened and causing severe coastal erosion important. The author has proposed a breakwater construction measure off Cua Tung beach, through simulations, it has been shown that the breakwater has a great effect on breaking waves and protecting the coast. Wave height has decreased markedly at the rear of the breakwater. In addition, the barrier dyke also causes the sediment moving from the shore to the sea to be deposited inside the dyke and in the middle of the dyke there is a gap where the offshore sediment enters. The research results contribute to the assessment of the current status of the coastal zone and serve as a basis for ensuring the stability of the water environment, minimizing coastal erosion in order to develop tourism and promote socio-economic development.

Identification of littoral cell and its impact on shoreline dynamics along the Purba Medinipur–Balasore coastal stretch, Bay of Bengal, India: A numerical modelling and geospatial study

The northern boundary of Bay of Bengal, between Subarnarekha and Rasulpur River is divided into five coastal sectors by the four inlets, namely, Talsari, Ramnagar, Jaldha, and Pichaboni. Each sector being characterized by severe coastal erosion, beach lowering and narrow beach segments. To bring such coastal areas under proper coastal management, delineation of littoral cell and sub-cell boundaries and assessment of sediment budget is required. This study attempts to identify these hydrodynamic characteristics, by investigating the wave-induced radiation stress of dominant wave, derived from offshore wave in order to simulate longshore current and associated sediment transport using the two-dimensional deterministic MIKE 21/3 Coupled Model that is based on two dimensional shallow water, Reynolds averaged Navier–Stokes equations and fully spectral wave action conservation equation. The shoreline dynamics in terms of shoreline retreat or spit formation, is quantified by Digital shoreline analysis system (DSAS)The result of the simulation shows the dominant westerly and comparatively weaker easterly longshore flow and the resultant bed level changes. By analysing the diverging and converging flow pattern of littoral current, rate of bed level change and magnitude of shoreline oscillation, six and five littoral sub-cell (LSC) have been identified for westerly and easterly circulation respectively. The coastal inlets indirectly influence the flow direction through the development of different depositional features at mouth. Because of that inlet mouths often function as littoral cell boundaries.Periodic observation reveals that the introduction of shore-normal engineering structures has positive impact on beach nourishment and inlet stability.

Investigation of Waves Generated by Tropical Cyclone Kyarr in the Arabian Sea: An Application of ERA5 Reanalysis Wind Data

In this study, the wave conditions in the Arabian Sea induced by tropical cyclone Kyarr (2019) have been simulated by employing the 3rd generation wave model MIKE 21 SW. The model was run from 24 October to 1 November 2019, a total of 8 days. The MIKE 21 SW model was forced by reanalyzed ERA5 wind data from the European Centre for Medium-Range Weather Forecasts (ECMWF). The results are compared with buoy data from the Indian National Centre for Ocean Information Services (INCOIS), which is located at 67.44° E, 18.50° N. In addition, the satellite altimeter data (CryoSat-2, SARAL and Jason-3 satellite altimeter data) was utilized for validation. Three wave parameters are considered for the validation: the significant wave height; the peak wave period; and the mean wave direction. The validation results showed that the significant wave height, the peak wave period, and the mean wave direction could be reasonably predicted by the model with reanalysis wind data as input. The maximum significant wave height reached to 10.7 m (with an associated peak wave period of 12.5 s) on 28 October 2019 at 23:00:00 in the middle of the Arabian Sea. For coastal areas, the significant wave height along the Iran and Pakistan (north Arabian Sea) coasts increased to a range of 1.4–2.8 m when tropical cyclone Kyarr moved northward. This wave height along with elevated sea level may cause severe coastal erosion and nearshore inland flooding. Impacts of cyclones on coastal zones critical facilities and infrastructure can be reduced by timely and suitable action before the event, so coastal managers should understand the effect of cyclones and their destructive consequences. The validated model developed in this study may be utilized as input data of evaluating the risk to life and infrastructure in this area.

A Study on Developing Structural Measure for the Prevention of Coastal Erosion

The impact of coastal erosion has adversely affected the socioeconomic conditions of the coastal communityworldwide. The coastal environment is experiencing a wide range of natural and anthropogenic pressurein India. The coastal zone has been receiving increased attention due to pressure of population growth,developmental activities, trade and transport and presence of vital and critical habitats. Severe coastalerosion, loss of marine ecosystem, industrial pollution, sedimentations in harbours and portsare some ofthe major concerns to the coastal zone managers. Thus, the presented study identifies the effects of existingmethods and suggesting an inventive structural measure to prevent the coastal erosion. Further, the suggestedmeasure supports the development of marine ecosystem as intact as an artificial coral reef which improvesthe coastal community’slivelihoodsand sustenance of coastal ecosystem.

Historical reconstruction of shoreline evolution at the Nam Dinh Coast, Vietnam

ABSTRACT Hai Hau, located in northern Vietnam, has suffered from severe coastal erosion with a retreat rate reaching 20 m/yr in recent years. Based on a systematic review of the literature, the shoreline recession trend along the Hai Hau is associated with the decline of water and sediment discharged from the So River, assumed to be active after a great flood in 1787, resulting in channel bifurcation and abandonment of the former channel. A historical analysis of the shoreline evolution of approximately a thousand years (the year 1000 – present) was conducted along this scenario using a modified one-line model. The simulated shorelines agreed well with the results of carbon-14 dating analysis, the historical reference points and shoreline positions extracted from the old maps, and the recently measured shoreline change derived from Landsat imagery. The present study demonstrates that the erosion at the Hai Hau has been ongoing from the end of the 18th century rather than the beginning of the 20th century, as proposed by some previous works. We regard the combined effects of the decrease in river sediment load, and other processes (subsidence and sea level rise (SLR)) are the major causes of long-term erosion on Hai Hau Coast.

Vertical Ground Displacements and Its Impact on Erosion along the Karachi Coastline, Pakistan

This study employed remote sensing (optical and synthetic aperture radar) and data analysis techniques to quantify vertical ground displacements and assess their contribution to coastline erosion. To provide evidence from Pakistan, we selected the coast of Karachi—a mega-city located along the dynamic coastline of the Indus River Delta—which has been experiencing severe coastal erosion during the last few decades. Observations from the C-band Envisat/ASAR and Sentinel-1A sensors over the 2004–2010 and 2014–2016 periods, respectively, enabled us to study vertical ground displacements in the study area, providing a long-term assessment during 2004–2016. Results suggest that some areas along the Karachi coastline are subsiding at comparable rates to or even much higher than the relative sea-level rise (SLR, ~1.9 mm/yr), which may amplify the rates of relative SLR in coming years, along with accelerating coastal erosion. Various parts of the study area along the coast are unstable and undergoing displacement. Landsat images from 1989 to 2018 (10-year temporal resolution) were further used to examine the state of coastline erosion using three statistical approaches (i.e., End Point Rate (EPR), Linear Regression Rate (LRR), and Least Median of Squares (LMS)). While the erosion underlaid the majority of the eastern sections of the study area, the ground displacements were spatially heterogeneous across the study area and along the coastline. Erosion rates of ~2.4 m/yr spatially corresponded with ground displacement rates of up to ~−1.4 cm/yr, but not all the coastline segments with high annual mean erosion rates were associated with local mean subsidence. The causes of ground displacements and coastline erosion were analyzed, and results were interpreted by integrating spatial ancillary information. Results indicate that rapid urbanization, construction on reclaimed land, coastline erosion favoring seawater intrusion, failed drainage/sewerage networks, and soil liquefaction are contributing to the site-specific variations in the land displacement in Karachi.

Derosion Lattice Performance and Optimization in Solving an End Effect Assessed by CFD: A Case Study in Thailand’s Beach

Thailand’s beach had a severe coastal erosion problem at the end of rock dams called the “end effect”. One of the innovative solutions to solve this problem is to use the derosion lattice (DL). However, since the DL performance depends on installing conditions such as angle of attack, placement position, terrain, and climate, computational fluid dynamics (CFD) was applied to assess the end effect’s occurrence and optimize the performance of DL’s installation. Based on Khao Rup Chang’s condition, a suffered beach in Thailand was used as a case study, and a free surface flow simulation was performed in the transient state using ANSYS Fluent, a CFD software, which revealed water waves flow through the beach with and without the DL installation cases. Furthermore, the CFD-assessed results indicated that the angle of attack and placement position affected the DL performance as expected. In optimization, the 15° angle of attack with the DL placement adjacent to the rock dam was the proper condition. After being applied at the actual site, the DL can help reduce erosion, increase sedimentation, and solve the end effect with excellent performance.

The late Pleistocene-Holocene changing morphology of the Volturno delta and coast (northern Campania, Italy): Geological architecture and human influence

The present geomorphology of the Volturno River delta system and related strandplain is largely a product of complex, long-lived relationships between geological evolution and human impacts.In order to assess the main drivers of the changed landscape in the last centuries, a multidisciplinary study was carried out by combining geological and historical data. The study was based on geological and geophysical data, including about 1800 stratigraphic well logs to reconstruct the stratigraphic architecture of the delta plain and ca. 180 km of very high resolution single channel reflection profiles to image the stratigraphic pattern of the continental shelf and the offshore delta. Cartographic sources from the last 150 years were acquired, georeferenced and managed into a GIS environment, to support geomorphological interpretation. Land use maps were reconstructed for the 1957, 1990 and 2012. The Late Pleistocene and Holocene reconstruction of the Volturno coastal plain evolution evidenced the control of climatic changes (and consequently sediment supply and global eustatic variations) on the depositional history. The present landscape appears largely inherited by the past MIS5 and LGM landscapes.A progressive increment of anthropic forcing took place in the last 2000 years but the strongest modifications of the landscape occurred since the end of the XVII century, when, during the Spanish vice-kingdom, it was subjected to major land reclamation. More than 500 km of canals were built in the coastal area and resulted in the development of agriculture and farming on reclaimed land, promoting urbanization and increasing landscape fragmentation. A peak of major alterations of the deltaic environment, and retreat of the coastline was attained between the 1960s and the 1990s. Severe urbanization along the coastline, coupled with intensification of agricultural and tourism activities, resulted in a significant loss of natural ecosystems including humid coastal areas, lacustrine/marshy back-dune areas and mostly the beach-dune system. The negative sedimentary balance resulting from the reclamation works on the river courses, along with the interventions along the Volturno river basin, resulted in an accelerated and severe coastal erosion. The latter, coupled with subsidence rates and sea level rise, increase the vulnerability of the coast to flooding and storm surge and aquifer salinization.

Vulnerability and Risk Assessment to Climate Change in Sagar Island, India

Inhabitants of low-lying islands face increased threats due to climate change as a result of their higher exposure and lesser adaptive capacity. Sagar Island, the largest inhabited estuarine island of Sundarbans, is experiencing severe coastal erosion, frequent cyclones, flooding, storm surges, and breaching of embankments, resulting in land, livelihood, and property loss, and the displacement of people at a huge scale. The present study assessed climate change-induced vulnerability and risk for Sagar Island, India, using an integrated geostatistical and geoinformatics-based approach. Based on the IPCC AR5 framework, the proportion of variance of 26 exposure, hazard, sensitivity, and adaptive capacity parameters was measured and analyzed. The results showed that 19.5% of mouzas (administrative units of the island), with 15.33% of the population at the southern part of the island, i.e., Sibpur–Dhablat, Bankimnagar–Sumatinagar, and Beguakhali–Mahismari, are at high risk (0.70–0.80). It has been concluded that the island has undergone tremendous land system transformations and changes in climatic patterns. Therefore, there is a need to formulate comprehensive adaptation strategies at the policy- and decision-making levels to help the communities of this island deal with the adverse impacts of climate change. The findings of this study will help adaptation strategies based on site-specific information and sustainable management for the marginalized populations living in similar islands worldwide.

Multi-decadal changes of mangrove forest and its response to the tidal dynamics of thane creek, Mumbai

Mangroves are one of the world threatened ecosystems, which is protected and categorised under CRZ-I according to the Coastal Regulation Zone (CRZ) notification. The present study marked the decadal (1990–2017, Landsat series) change of mangroves and mapped the species distribution (2017, Sentinel-2) around Thane creek, Mumbai using SMLC with QGIS-SCP software. ADCIRC model was used to simulate the tidal flooding/ebbing towards mangroves, and the model was validated with the in-situ observation of tides and currents. From 1990 to 2017, the mangrove area increased from 79.14 km2 to 154.5 km2 and expanded towards landward and seaward regions. Between 2010 and 2017, there was a fluctuation in the mangrove area with ups and downs in their distribution caused by different climatic conditions and anthropogenic activities. The increase in built-up area was two times than mangrove area increase. The dominance of Avicennia marina species confirms the increased anthropogenic activity along the landward side. To understand the response of mangroves to the tidal dynamics, the model was simulated with two scenarios; with mangroves and without mangroves. In the absence of mangroves (without mangroves), Thane Creek demonstrated a perfect funnelling effect by increased tidal amplification with strong flood currents, resulting in severe coastal inundation and erosion. While with mangroves, tidal currents attenuated 80% of its magnitude and favoured the sediment deposition in mangrove areas, which further enhanced mangrove growth, thereby stabilising the coast. The present study has found that the mangroves in the Thane creek are in the saturation stage and reached the maximum growth towards the landward. The study envisages that the stakeholders should adopt a proper management plan for the restoration of mangroves. The highlight of the present study is the combination of satellite imagery and hydrodynamic modelling. Satellite imagery provides the estimated extent of the mangroves, and this information will be used when simulating the model, which provides maximum inundation and attenuation. The utilisation of LULC classification and ADCIRC model results would be helpful to examine the threatening built-up area due to the tidal inundation. The combination of satellite classification and hydrodynamic model findings will be decisive for management authorities towards the conservation and regeneration activities for a balanced mangrove-creek ecosystem.

Are Current UK Coastal Defences Good Enough for Tomorrow? An Assessment of Vulnerability to Coastal Erosion

Coastal vulnerability and its physical, economic and social consequences at national and international scales is of high scientific, political and policy interest. Anthropogenic climate change and coastal erosion threaten the very fabric of a society. Indications, that coastal hazards are impacting diverse coastal areas severely across the world, and it is no longer a vague future threat that can’t be ignored. Rising eustatic sea levels synthesized by the growing frequency and scale of coastal hazards like storm surges, coastal erosion and coastal landslides threaten low-lying and unprotected coastal areas in the United Kingdom even if they have coastal defenses. However, there is still significant uncertainty about the degree of vulnerability along different coastal stretches, particularly in England. To fill this uncertainty, the current study estimated the coastal vulnerability of the coastal erosion hotspot Camber, England, by establishing a coastal vulnerability index. This index was developed by compounding various existing parameters and termed as Erosion Coastal Vulnerability Index (ECVI). Results illustrate that 67% of coastal area fall between high and very high vulnerability categories, and current coastal defenses are not strong enough to tackle the severe coastal erosion in Camber. Within the evaluation, thematic maps were generated to enable the intensity of the vulnerability for different coastal stretches to be identified. The evaluated vulnerable hotspot should be treated urgently by regional and national policy organizations to ameliorate the impacts of coastal erosion and other associated risks. Without action, the hotspot is likely to encounter unprecedented new vulnerabilities, disasters and humanitarian catastrophes. The current study results allow for a local, regional and national comparison that may help to evaluate changes in coastal erosion vulnerability.

Comparative Assessment of Livelihood Vulnerability of Climate Induced Migrants: A Micro Level Study on Sagar Island, India

The effects of climate change are causing large scale human displacements over the past few decades. Climate refugees are putting the biggest challenges to the geophysical biological and social system all over the world. This paper attempts to assess and compare the vulnerability of the climate-induced migrants and regular settlers of selected mouzas of Sagar Island, south 24parganas, India. People are witnessing their lands vanishing under their feet in these constantly sinking and shrinking deltaic estuaries of Sundarban. Findings of LVI and LVI-IPCC analysis indicate that the climate-induced migrant communities are more exposed to climatic variability due to the poor adaptive capacity. Moreover, poor access to food, water, health facilities is making them extremely vulnerable with lower resilience as these mouzas are facing frequent flooding, severe coastal erosion, embankment breaching and higher storm surge on annual basis. The outcomes of this study could be beneficial ineffective on-site risk management and planning propositions.

Effects of Holocene climate changes and anthropogenic river regulation in the development of a wave-dominated delta: The São Francisco River (eastern Brazil)

The São Francisco River is the fourth longest river in South America and one of the most regulated. Severe coastal erosion has affected the delta shoreline since 1985, leading to the complete destruction of Cabeço village between 1997 and 1999. In this study, we mapped and radiocarbon dated the beach ridge sets occurring on the delta plain and performed a detailed analysis of the delta shoreline changes since 1960. During the Holocene, the delta plain construction was punctuated and took place during episodes of higher river discharges coincident with Bond events 4, 2 and 1 and periods of higher precipitation in the river basin, as reconstructed by δ18O measurements in cave speleothems. The last major episode of delta construction apparently ended at approximately 1.0 ka cal. BP. Since that time, riverine sediment input has been just sufficient to maintain the shoreline. A comparison of historical maps and aerial photographs showed that from 1853 to 1960, the shoreline at the river mouth remained in approximately the same position. A decrease in rainfall in combination with river regulation, particularly after 1985, triggered extensive erosion at the delta shoreline. This erosion was not caused by sediment retention behind the major dams but instead resulted from changes in the backwater/drawdown effects deriving from river regulation. Shoreline erosion mostly affected the river mouth. The mobilized sediments caused progradation of the downdrift shoreline. Updrift of the river mouth, the shoreline remained stable, as it had already reached an equilibrium orientation in which the net longshore transport was zero.