Showing papers in "Journal of Coastal Conservation in 2020"

A review on coastal erosion and flooding risks and best management practices in West Africa: what has been done and should be done

Abstract: The West African coast is vulnerable to natural hazards and human interventions. Although various measures have been taken at different scales, mostly at the local level, there is a need to improve management at the regional level. We examine these actions and possible solutions from different perspectives and provide conclusions and recommendations on the integration of solutions to improve coastal management. From North West Mauritania to across the Gulf of Guinea a system of coastal zoning that can be managed holistically is encouraged. The development of holistic planning is seen as a sustainable approach to management that seeks to link users/processes together rather than focus on a single particular issue and solution. Strengthening, monitoring, promoting the observation network and generalising open data centralisation and exchange for a better understanding of coastal dynamics and pressures is encouraged. There is a need for capacity building, expertise and federative actions. Furthermore, the need to identify and involve not only stakeholders, but also communities and scientists with multilevel inputs. All must agree on coordinated plans to achieve stakeholder objectives, using an approach adapted to the multi-spatial scale (e.g at the scale of sediment cells, integrating from the sources of sediment in river basins to their redistribution along the coast, perturbed by climate changes and anthropic stresses), so that only regional solutions are appropriate and will be effective. These must follow sustainable strategies with a multi-temporal sequenced solution and anticipate changes, or adaptive solutions using solutions in synergy with different time frames as well as managing natural and human systems responsibly. A plan that considers changes in coastal systems and anticipates impacts and adapts plans accordingly will be key.

Comparative assessment of the GIS based bathtub model and an enhanced bathtub model for coastal inundation

Abstract: Coastal zones are dynamic spaces where human activities and infrastructure are exposed to natural forces, climate change and extreme weather events such as storm surges. Coastal inundation is regarded as one of the most dangerous and destructive natural hazards, and while there are many studies to analyse these events, GIS based methods are limited. This research aimed at developing a GIS based enhanced Bathtub Model (eBTM) that improves on the widely used simple Bathtub Model (sBTM) to make it more appropriate to a storm surge related coastal inundation context. The eBTM incorporates beach slope, surface roughness and instils hydrological connectivity relevant for event scale coastal flooding, unlike the sBTM which only uses topographic elevation above sea level as input. For a test site in Cape Town, South Africa, inundation levels for 3 independent scenarios were calculated using the average spring tides level, extreme sea level for a 1-in-100-year storm and two sea-level rise scenarios. Each scenario was run on both the sBTM and the eBTM developed through this study. Comparing the results, the eBTM method overall produced more conservative inundation results and also produced less disconnected areas of (unrealistic) inundation. The eBTM also produces inundation water levels relative to structures, thus showing the potential for quantifying the coastal inundation risk to infrastructure, which is of relevance in the disaster response context. Additionally, the impact of using Digital Terrain Models (DTMs) instead of Digital Surface Models (DSM) on the inundation results was tested. The use of a DSM, including buildings and other objects, showed more realistic trajectories of the inundation water moving through the model area.

Spatio-temporal modelling of shoreline migration in Sagar Island, West Bengal, India

Abstract: Sagar Island is a very popular pilgrimage destination located in the western part of Indian Sundarbans. This study employs Digital Shoreline Analysis System (DSAS) extension tool in ArcGIS platform to study and analyse the shoreline dynamics of Sagar Island by utilizing satellite images extending 40 years (1975–2015). 44 transects with 100 m spacing were laid and divided into six littoral cells (LCs). End Point Rate (EPR) and Linear Regression (LR) models were utilized to analyze the shoreline change patterns and also for predicting the future shoreline positions. It was observed that almost the entire southern portion of Sagar Island is susceptible to high rate of shoreline erosion. Most of the erosion occurred in Dhablat (LC 4 (a)) in the south eastern part at a rate of 11.695 ± 2.1 m/year. The mean shoreline change rate was also high in LC5 (±23.525 m/year). However, the overall shoreline change rate for the island was 4.94 m/year and uncertainty of total shoreline change rate was ±4.4 m/year. The study shows the usefulness of DSAS as a scientific tool for shoreline change studies and highlights state of erosion in the study area.

Assessing the effect of flight altitude and overlap on orthoimage generation for UAV estimates of coastal wetlands

Abstract: There has been a constant increase in technology regarding unmanned aerial vehicle (UAV) systems in the last decade; yet the possibility of surveying large areas with such aerial platforms has been hampered by their low endurance. This situation has been exacerbated in low institutional capacity countries with high biodiversity coastal environments where constant monitoring is required for conservation purposes. The objective of this study was hence to determine an optimal flight mission over an initial area of 40 ha of coastal wetlands using a low-cost UAV system. The UAV missions were planned at altitudes of 60, 80, 100, and 120 m. Several orthoimages were generated with different along/across track overlaps (in intervals of 10% from 40 to 90%) in order to determine the minimum flight duration and computational efficiency. Results indicated that flight altitude and across track overlap were the most relevant variables in terms of flight distance, flight duration, number of generated images, and computer processing time. The optimal flight mission was found to be at 120-m altitude with an along/across track overlap of 60/50%. Based on the aforementioned parameters, we were able to survey a larger area of 200 ha with minimum flight duration and computer processing time. Our study highlights the feasibility and limitations of using a consumer-grade UAV in order to assess coastal wetland areas rapidly when field-based surveys approaches are not possible.

Rapid impact assessment of extremely severe cyclonic storm Fani on morpho-dynamics & ecology of Chilika Lake, Odisha, India

Abstract: This article evaluates the impacts of ‘Fani’, a category four cyclone on the shoreline and ecology of the largest brackish water lagoon of Asia, Chilika, on the East Coast of India. The cyclone forced open two New Tidal Inlets (NTI) along the northern shore of the lagoon’s outer channel leading to erosion of the embankments and spits. The average rate of change due to cyclonic storm ‘Fani’ was – 6.12 m while 66.03% of the total transects registered symbol of erosion along the shoreline of Chilika lagoon. Post Fani the information made available on its impact on Chilika was minimal which made us to look into published news articles, online news channels,past published scientific literature to corroborate the likely impact of such erosion and new tidal inlets on the lake ecosystem. Experts differed on their opinions on how the plankton, fish, seagrass and critically endangered Irrawaddy Dolphin would respond to the salinity changes in the lake aftermath of the cyclone. Some of the impacts of ‘Fani’ on the lake shoreline and ecosystem were imminent, such as the opening of tidal inlets and spot death of three Irrawaddy dolphins; whereas, long-term impacts such as changes in the biomass and composition of plankton communities, fish and bird population in the lake are primarily unknown and warrants further detailed investigation. Nevertheless, the study asserts that cyclone driven shoreline damage can impact lagoon ecosystem by bringing in a rapid change in the salinity field

Comment on ‘Is ‘re-mobilisation’ nature restoration or nature destruction? A commentary’ by I. Delgado-Fernandez, R.G.D. Davidson-Arnott & P.A. Hesp

Abstract: In their recently published paper, Delgado-Fernandez et al. (2019) critically review the limitations and dangers of the relatively recent shift towards dune rejuvenation management in North-western Europe. We would like to comment on the paper from the Dutch perspective.

A comment on some of the conclusions made by Delgado-Fernandez et al. (2019). “Is ‘re-mobilisation’ nature conservation or nature destruction? A commentary”.

Abstract: This reply is primarily from Natural Resources Wales (NRW) and Natural England (NE) in response to several references in Delgado-Fernandez et al. (2019) to the management undertaken by NRW in the past on Welsh sand dunes and future management planned under two EU funded LIFE projects for sand dune conservation in England and Wales. Both NRWand NE are statutory nature conservation bodies and as such have specific purposes:

Assessment of groundwater quality based on GIS and geochemical methods: coastal aquifer of Bouficha (North-Eastern Tunisia)

Abstract: In Tunisia, Groundwater is an important water source for domestic, agricultural and industrial uses, but the deterioration of its quality, under the influence of anthropogenic activities and natural factors, limits its suitability for human consumption and irrigation. The present study was carried out to assess groundwater quality in Bouficha aquifer in north-eastern Tunisia using geochemical, geospatial and statistical techniques. The relationship between groundwater quality and Land Use Land Cover (LULC) patterns were also explored using remote sensing, geographic information system (GIS) and Landsat satellite images. Groundwater samples were collected from sixteen wells in April 2015 and analyzed for their physical and chemical characteristics. Concentrations of major cations and anions in the groundwater vary spatially. The dominant water types in the investigation area are Na-Cl and Ca–SO4. A basic statistical study, applying hierarchical classification analysis confirms the existence of two groundwater types. To evaluate the suitability of groundwater for irrigation, chemical data were assessed using methods such as Electrical Conductivity, Kelley’s ratio, Sodium Absorption Ratio, Magnesium Hazards, as well as Residual Sodium Carbonate. Regarding drinking groundwater assessment, the World Health Organization (WHO) standards were applied to define sites with drinking water permissible levels. Information was loaded in an ArcGIS software and analyzed with a Spatial Analyst extension using Inverse Spline interpolation methods. Fluoride content in most samples has values as high as 1.97 mg/L, with 53% of the samples showing fluoride concentration higher than the level suggested by the WHO for drinking water of 1.5 mg/L and ratified by the National Society of Exploitation and Drinking Potable Water of Tunisia. Additionally, reported nitrate concentrations are higher than the expected groundwater background level of 10 mg/L; indeed, values are up to 286 mg/L, being hazardous for domestic use and suggesting the presence of anthropogenic sources of water contamination. The Land Use and Land Cover (LULCC) of Bouficha aquifer were changed over seventeen years. The Landsat satellite images have shown that the built-up area increased from 2001 to 2018 to the detriment of water and crop vegetation. The overuse of fertilizers on a total agricultural area of Bouficha aquifer (60%) led to significant pollutants, including nitrate and a deterioration in its water quality. Regarding the WHO and the Tunisian drinking water guidelines, this work provides substantial evidence that groundwater quality is posing a significant health threat for residents. Similarly, results show groundwater’s chemical content is also unsuitable for economic activities in the Bouficha region, mainly hazardous for irrigation purposes.

Abundance, type, and origin of litter on No. 1 Bathing Beach of Qingdao, China

Abstract: Detection of litter along beaches in many countries indicates an anthropoginic source of marine pollution. The abundance and composition of litter were measured for the first time along the No.1 Bathing Beach, Qingdao, China. Surveys were conducted during May to July, 2018 in order to estimate the occurrence and abundance of nine litter types. In total, 4476 litter items were collected with a corresponding weight of 330.2 kg. The most prominent litter was plastic followed by paper, wood, and (cloth and ropes) with corresponding percentages of 49.91, 10.30 and 9.76% of the total litter items. Plastics were the most abundant litter type (38.81%) in term of weight, followed by paper (12.11%) and food items (9.07%). The main sources of litter included human recreational activities, e.g. tourism, fisheries and cafes. Statistically significant differences (p < 0.05) were found between the number/weight of different items during the three months of study. The results of the present study will help to administer effective beach litter management programs.

Historical coastal maps: importance and challenges in their use in studying coastal geomorphology

Abstract: Historical maritime maps such as navigation charts, bird’s-eye view maps and plan maps preserve useful coastal information of the time. Through the archival survey of such documents, a large number of charts and maps (particularly of large and medium scale) have been found that were published from sixteenth-century CE onwards. These maps– depict manmade structures such as forts and other buildings visible to sailors approaching the coast; and mark geomorphic features such as spit, bar, shoal, delta; with appropriate shape, relative position and size. Understanding the geomorphic features present in these maps and analyzing them using remote sensing imagery, historical text and recent studies can immensely enhance knowledge of coastal geomorphic changes in the interim period. However, there are challenges in analyzing these maps, such as scale variability within or across the maps, date of publication versus survey, originality of map content (copied versus original), the importance of the place to the cartographer, the purpose of making the map, cartographic skills, style and methods, etc. The present study discusses the untapped potential of historical maritime maps and charts to understand coastal geomorphology along with the challenges one can confront while studying them and suggests ways to overcome them.

Role of mangroves in wind-wave climate modeling – A review

Abstract: Globally, there has been dedicated research on mangrove ecosystems, however, the modeling of wave-mangrove interaction is seldom considered in the operational wave prediction for vegetated coastlines. This review work apprises on the significant impact of mangroves on surface gravity wave characteristics. Prediction and quantification of wave attenuation characteristics by mangroves is an essential pre-requisite for coastal zone management activities along a mangrove dominated shoreline. Nevertheless, the dynamic impact of waves on mangroves is missing in the current regional wave forecasting systems. In this review article, the scientific advancements in wave-mangrove interaction studies are elucidated and focus on its significance in an operational wave modeling scheme for the Indian coast. The relevant studies on wave dissipation by mangroves and other vegetation; its nonlinear interaction in the presence of currents and extreme waves, and the need for improving its parameterization are considered distinctly. The study also highlights the importance to predict the futuristic scenarios of wave attenuation characteristics in mangrove dominated regions which are highly sensitive to effects from climate change. The authors believe that the research on dynamics of wave-mangrove interaction in India has an extensive scope, and possible future endeavors towards a realistic nearshore wave modeling along mangrove dominant coasts are presented in the concluding remarks.

Investigating the performance of sentinel-2A and Landsat 8 imagery in mapping shoreline changes

Abstract: Regular detection and timely monitoring of shoreline evolution are essentially needed in order to identify areas that require further investigation and protection. Possibilities for regular monitoring of shoreline changes are better facilitated now with high-frequency revisit times of Landsat-Sentinel-2 virtual constellation. Accordingly, this study aimed at investigating the performance of Landsat 8 and Sentinel-2A satellite imagery in mapping shoreline changes. The specific objectives were to 1) create reference data of shoreline erosion, accretion and seafilling using very high spatial resolution data, 2) compare the results of shoreline changes by using Landsat 8 and Sentinel-2A imagery respectively, and 3) complete the inventory of shoreline changes between 1962 and 2016. A Quickbird panchromatic imagery (0.6 m) of 2010 was employed in combination with aerial photography (0.5 m) from 1962 for the generation of reference data using a traditional photo-interpretation method. Then, geographic object-based image analysis (GEOBIA) was employed to map changes in the shoreline between 1962 (i.e., reference shoreline) and 2016 using Sentinel-2A (10 m) and Landsat 8 panchromatic band (15 m) imagery, consecutively. The use of Sentinel-2A image provided slightly better accuracy results when compared with those from the Landsat 8 image. Accordingly, an inventory of Lebanese shoreline evolution between 1962 and 2016 was completed using the Sentinel-2A classification results. The combined use of Landsat-Sentinel-2 imagery is expected to generate reliable data records for continuous monitoring of shoreline changes.

Coastline changes and their effects on land use and cover in Subang, Indonesia

Abstract: Indonesia is at high risk of coastal erosion. Therefore, is important to understand the current status over a large area in order to devise protection strategies. This study measured the coastline changes and examined the land use and cover affected by coastal changes in Subang, Indonesia, using Landsat images from 1990 and 2018. The modified normalized difference water index (MNDWI) was used to separate the water and non-water features of the images, and land use and cover were classified using object-based image analysis based on the red, green, and blue bands and normalized difference vegetation index (NDVI). The results revealed considerable coastal erosion in Legonkulon. In the most extreme case, the coastline had moved 2361.46 m inland, and the total area lost to erosion was 1012.25 ha. This area was mostly covered by fishponds (983.34 ha) in 1990. Given that the fishery sector is the main livelihood of communities in the study area, the disappearance of fishponds might have affected their income and worsened their poverty. We found marked coastal accretion in Blanakan. In the most extreme case, the coastline had moved 1695.61 m seaward from 1990 to 2018, adding a total area of 1856.62 ha. The new areas were used as fishponds (1738.95 ha) in 2018. Although the accretion exceeded the erosion, the distributions differed regionally. Therefore, a regional protection strategy is necessary.

Blue carbon conservation in West Africa: a first assessment of feasibility

Abstract: The loss of blue carbon ecosystems results in significant levels of carbon emissions and decreased supply of other ecosystem services. West Africa contains approximately 14% of the world’s mangrove area but despite 25% of coverage loss between 1980 and 2006, the region’s mangroves have not been well studied. This study aims to provide a first step toward increasing the knowledge of the region’s blue carbon stocks, with a focus on mangroves, and of their financial value based on their carbon storage benefit alone. The best available data suggest that the region contains 1.97 million hectares of mangroves storing 854 million metric tons of carbon in above- and below-ground biomass and the top meter of soil; 4.8 million hectares of seagrass storing 673 million metric tons of carbon; and 1.2 million hectares of salt marshes storing 303 million metric tons of carbon. Even without including values for other benefits of intact mangroves, the conservation of mangroves in the region appears viable. Specifically, the discounted value of 20-year emission reductions under a conservation scenario is estimated to be between $341.2–569.0 million at an 8% discount rate and carbon prices of $3 and $5 per metric ton respectively.

Selection of mangrove species for shrimp based silvo-aquaculture in the coastal areas of Bangladesh

Abstract: The purpose of this work was to assemble information with which to help identify and select mangrove species most likely to be useful and locally acceptable for use in transforming the dominant current non-mangrove shrimp culture practice in Bangladesh towards more sustainable shrimp silvo-aquaculture in the coastal regions of the country. We reviewed current mangrove use in the extensive aquaculture setting, compiled published evidence on mangrove properties and characteristics that influence their suitability for such use and assessed farmer preferences of the various species. Thirteen mangrove species (all of which are available in Bangladesh) were documented as being used in silvo-aquaculture system in the tropics. Followed by these already “established” mangrove species, Aegialitis rotundifolia, Heritiera fomes and Lumnitzera racemosa could be enlisted as additional “optional” mangrove species to consider, while Ceriops decandra, Excocaria agallocha and Phoenix paludosa were found to be unsuitable for silvo-aquaculture. Based on their experience and indigenous knowledge on mangroves, shrimp farmers ranked (in declining order of preference) Sonneratia apetala, S. caseolaris, Avicennia officinalis, Nypa fruticans, Bruguiera sexangula, Heritiera fomes, and also, the mangrove-associate wild rice species Oryza coarctata as the most suitable species to be used for promoting silvo-aquaculture in the coastal areas of Bangladesh. Thus, the focus group interviews with the farmers not only identified which mangroves enjoy most local support for use in transforming current shrimp culture towards more sustainable shrimp silvo-aquaculture but also provided additional leads for species interesting to further investigation into their suitability for silvo-aquaculture.

Is ‘re-mobilisation’ nature restoration or nature destruction? A commentary. Discussion

Abstract: Delgado-Fernandez et al. (2019) have recently questioned whether remobilisation of coastal sand dunes through direct management interventions, such as turf stripping and frontal dune notching, constitutes nature restoration or nature destruction. They argue such interventions are misplaced because they act against natural processes and in most cases are likely to be unsustainable. Their comments potentially have wide application but are focussed on England andWales where trial interventions to counteract dune stabilization have been undertaken since 2012. Specifically, Delgado-Fernandez et al. maintain that: (1) interfering with the evolution of coastal dunes to maintain artificial levels of bare sand leads to systems that are ‘not natural’ and ‘fights against natural evolutionary processes’; (2) the dunes of the British coast can be expected to be characterised by low mobility because cool temperatures and high precipitation promote dense vegetation cover; (3) dunes such as those on the east coast of North America and the coast of Europe enclosing the Wadden Sea are likely to be more dynamic compared tomany British dunes because of the absence of stability provided by bedrock substrate and headlands, and the relatively regular occurrence of hurricanes and significant storm surges; (4) there is little evidence to suggest that the trend towards vegetation colonization and dune stabilization is not natural; (5) there is no evidence that humaninduced climate changes are playing a primary role at the regional or local scale; (6) indirect human-induced factors such as enhanced atmospheric nitrogen deposition could be aiding dune stabilization, but the significance of their role remains to be established; (7) under the present climatic conditions in England andWales it is likely that dune stabilization will continue, and there will be an ongoing requirement for human intervention to maintain bare sand and dynamic dunes; (8) manipulating a dune system to favour a few chosen species runs the risk of endangering the system as a whole; (9) little consideration is being given to the possibility that dune rejuvenation will lead to increased coastal erosion; (10) artificial enhancement of inland sand transfer may leave foredunes more vulnerable to scarping and/ or overwash, and thus to destruction of inland habitats; (11) the best route to nature restoration is the removal of stressors that cause artificial system changes and the implementation of actions that prevent other stressors from operating, including unnecessary landscape interventions, and by promoting ‘correct public attitudes’ and ‘sustainable recreation’. The following discussion examines some of these arguments, principally from a UK geomorphological perspective. No major British dune system can be regarded as truly natural, having been influenced by human activities over hundreds of years. While the observed reduction in bare sand and mobile dune extent over the past century is undoubtedly due to a combination of factors, the effects of direct human actions such as sand fencing, surface mulching, marram planting and tree planting on a large scale are well documented (e.g. Ranwell and Boar 1986; Doody 1989). Interventions to counteract the effects of these practices can therefore be legitimately considered as ‘restoration’. However, an exact return to a previous condition is likely to be unachievable, and is not the main objective of dune rejuvenation interventions which are concerned mainly with conserving, and where possible enhancing, notified features of ecological interest. Bedrock substrate and the presence of headlands provide only weak constraints on the scale of dune building and mobility in the UK. In fact, headlands are often important in intercepting alongshore sand transport and encouraging large-scale dune development behind a ‘receptive shore’. At several locations (e.g. Llangennith Burrows, Merthyr Mawr Warren, Broomhill Burrows, Newborough, Penhale Dunes) transgressive dunes have climbed bedrock escarpments and crossed headlands. The ‘cool temperatures’ and ‘high precipitation’ currently experienced in Britain are not in themselves * Kenneth Pye k.pye@kpal.co.uk

Habitat mapping of Cabo Girão Marine Park (Madeira island): a tool for conservation and management

Abstract: At the time Cabo Girao natural marine park was proposed (2016) and later when it was established, (2017), its effective conservation and marine spatial planning goals were hampered by the scarce knowledge on the sea floor habitats and biotic patterns inside the area. In the present work, a combination of different datasets and underwater surveys was used to produce the first habitat map of the Natural Marine Park of Cabo Girao, which is also the first habitat map for Madeira island. Five major habitats were identified, including two previously unknown for Madeira — Avrainvillea canariensis meadows and maerl beds. 132 marine taxa (macroflora, macrofauna and fishes) were identified, including 18 commercially important species and three vulnerable fish species. The results show that the methods used are useful to produce reliable information with limited resources. The information obtained is a tool for conservation and marine spatial planning, which allows for improved policy-making and better management. This study provides a baseline for the benthic habitats of this MPA against which future marine biodiversity changes can be recognised.

Impact of urbanization on creeks of Mumbai, India: a geospatial assessment approach

Abstract: Creeks are the inherent coastline feature that connects rivers to the sea and plays an important role in the ecological processes and the material transfer. In the present study, an impact of urbanisation on the creeks of Mumbai, India namely Thane, Malad and Manori creeks, has been addressed. Multi-temporal satellite images of Landsat for the years 1972, 1994 and 2016 are considered to perform the changes in the mudflat and growth of the mangrove, as well as the changes in creeks width apart from the Land use Land cover (LULC). Object-based image analysis using multi-spectral resolution confirmed that there is an overall increase in the spatial extent of mangroves and reduction in the width of all the creeks. Mangroves around Thane creek and Manori creek have increased from 50.7 km2 to 57.6 km2 and 8.4 km2 to 25.2 km2respectively. However, there is a decrease in mangroves around Malad Creek from13.3 km2 to 9.7 km2during 1972 to 2016. The relationship between the creek geometry and LULC was also explored, and it has been revealed that the creek width has reduced due to urbanisation. Life expectancy analysis projected a further reduction in the width of the creeks for the years 2025 and 2050. The study suggests that there must be stringent bye-laws for disposal of sewage into the creeks and development activity near the creek areas. Further, upper stretches of the creeks require cleaning and dredging so that the tidal water will be approached up to the upper portion to maintain the creek ecosystem.

Geomorphological and ecological change in a coastal foreland dune system, Sandscale haws, Cumbria, UK: the management challenges posed by climate change

Abstract: Many coastal sand dune systems in the UK and other parts of the world have experienced a decline in bare sand extent and dune mobility over the past 70 years, accompanied by increased coverage of coarse grass, scrub and woodland vegetation. This has raised concerns amongst nature conservationists about the survival of dune specialist species. Opinions are divided, however, regarding what management interventions should be made to counteract these trends. This paper reviews the factors which have contributed to progressive dune system stabilization at Sandscale Haws, located on the Irish Sea coast in Northwest England, considers the implications for the site of UKCP18 future climate change projections, and discusses the options and plans for future adaptive management. Analaysis of aerial photographs indicated a large reduction in bare sand area between 1946 and 1988 (from >34% to 9% of the dune system), since when there has been a further decline to 1.7%. Consideration of the evidence suggests that a trend towards a warmer, slightly wetter and less windy climate has been the main driver of stabilization, although atmospheric nitrogen deposition, increasing atmospheric CO2 concentrations, reduced grazing intensity, reduced human disturbance from the mid-1980s onwards and a tendency for shoreline progradation on the west-facing coast have played contributing roles. Some species characteristic of open habitats can still be found in good numbers in parts of the dune system, but without increased management it is likely they will decline further and some may become locally extinct. Since the site is of national and international importance for a number of nationally scarce plant and animal species it is considered that there is both a legal and an ethical duty to attempt to maintain suitable habitat for their survival. As a National Nature Reserve Sandscale Haws provides a suitable ‘natural laboratory’ within which to research the effectiveness of different intervention methods. A number of small-scale dune rejuvenation methods have been trialled since 2015, and options for larger scale interventions, including turf stripping and possible dune notching, are currently being evaluated as part of the nation-wide Dynamic Dunescapes project.

Assessing coastal vulnerability of Chittagong District, Bangladesh using geospatial techniques

Abstract: Bangladesh is one of the most vulnerable countries exposed to natural disasters. This paper attempts to analyze the vulnerability of coastal areas of the Chittagong District in the southeastern coast of Bangladesh. This study explores the spatial variations of coastal vulnerability of the study area using three physical variables and four social variables with a spatial analytical method. In this regard, a Physical Vulnerability Index (PVI), and a Social Vulnerability Index (SVI) have been prepared for the research area. Finally, a Coastal Vulnerability Index (CVI) was constructed within a geographic information system combining both PVI and CVI. The vulnerability indices reveal that the rural areas are more vulnerable to disaster than the urban areas. According to the PVI, SVI, and CVI about 66%, 48%, and 43% areas are highly vulnerable respectively. Despite of data limitations in constructing the PVI and SVI, this research is the first endeavor to apply a composite CVI based on geospatial techniques in the southeastern coast of Bangladesh. The CVI results illustrate that the coasts are the most vulnerable to flooding, storm surges and cyclones. In this study, CVI is presented as a tool to identify areas of vulnerability in the zones of the coastal district Chittagong. The CVI will serve as a practical guideline for policy makers to introduce policies and plans to mitigate the natural hazard-induced disaster impacts on the coastal Bangladesh.

Groundwater potentiality mapping of tertiary volcanic aquifer in IBB basin, Yemen by using remote sensing and GIS tools

Abstract: Groundwater (GW) is the primary source of water for local inhabitants in the Yemen Republic. The Yemen Republic is dominated by an arid and semi-arid climate and suffers from a scarcity of natural resources and a soaring population growth rate. The IBB basin is one of the areas of main concern in Yemen, as the ascending local inhabitant’s activities have led to an increase in the water demand throughout the IBB City (The major City of IBB basin area). The area is mainly covered by stratified volcanic rocks of Tertiary age. The current research aims to delineate, identify, integrate, assess and map the groundwater potentiality (GWP) zones in the Tertiary volcanic aquifer of the IBB basin, Yemen utilizing space-borne data and weighted overlay method in GIS tools. Thematic layers such as lithology, slope, plain curvature, structural lineaments density, geomorphology, land use/land cover, drainage density, and rainfall intensity were used as factors in the geo-database building of the GW potentiality map. To each class of the factor layers, a fixed score was assigned. The scores were ranked, and the weighted sum for all layers was calculated. Finally, a GW potentiality map of the IBB basin area was constructed by integrating the weighted thematic digital maps. The integrated model’s results were classified into three main categories; low, moderate, and high GWP. The model validity was tested by considering the geospatial relationship between the resulted recharge productive zones and the distribution of the real-life productive wells and springs of IBB basin area. The integrated results successively delineate the GW potential zones in the IBB basin and raise awareness to methods useful for the management of GW resources and water recovery plans.

Sea cliff instability hazard assessment for coastal management in Chabahar, Iran

Abstract: Hazards from sea cliff instabilities are increasing because of the growing human occupation in coastal areas. Assessment of cliff hazards is very important in order to develop appropriate coastal management plans. In this study, a semi-quantitative heuristic method was developed to assess instability hazard for rocky coasts at Chabahar (Iran) along the northern coastline of the Gulf of Oman. In this method, seven factors affecting cliff instability, including: wave exposure, cliff height, cliff slope, rock resistance, lithology, bathymetry and beach width, were used to calculate an instability hazard index, from which a hazard map was constructed for the study area. Results were validated by statistical analysis of the previous instabilities detected by comparing old and new satellite images. According to the instability hazard class and cliff height, a hazard zone from the top of cliffs was determined within which development is not recommended.

The impact of flash-floods on the adjacent marine environment: the case of Mandra and Nea Peramos (November 2017), Greece

Abstract: The extreme flash-flood of November 2017 in Western Attica, Greece, caused severe damages not only in the landward area, but also in the adjacent marine environment. The study of a number of data, such as visual observations immediately after the catastrophic event, a series of satellite images that demonstrate the movement of the flood-related suspended material, and comparative elemental and hydrocarbon geochemical analyses between the fresh, recently deposited sediments, and the older ones, have shown that an extended part of the Elefsis Bay, particularly the northeastern sector, has experienced a severe modification in its sedimentary and geochemical status, that may have irreversibly affected the already environmentally degraded marine ecosystem of the area.

Marine Zoning and Landscape Management on Crete Island, Greece

Abstract: The present paper deals with landscape management issues, not only of terrestrial landscape but also of coastal and marine landscape This paper also proposes a methodology to introduce the landscape dimension in marine zoning and underline the need to include marine landscape as a discrete unit in Greek marine spatial planning More specifically, this work presents key issues and basic axes related to marine zoning implementation by identifying marine landscape typologies that have emerged based on the visibility of the marine space in structures with negative visual impact that are placed in the terrestrial space For the empirical part of the study, Crete island is chosen where the coastal and marine exploitation is significant and continues to increase The methodological approach for the quantitative rendering of visibility is based on viewshed analysis

Retrospective study on changes in Dondra lagoon (2006–2017) resulting from tsunami impact and post-tsunami development

Abstract: Spatio-temporal changes during the last twelve year period (2006–2017) and their impacts on ecological and socio-economic status of Dondra lagoon, southern coast of Sri Lanka were studied as many lagoons in southern Sri Lanka are being seriously affected due to anthropogenic pressure in the recent past. The changes of Dondra lagoon and its immediate surroundings were studied in conjunction with a GIS-coupled ecological survey and a questionnaire survey. The lagoon water surface area has decreased by about 0.92 ha (~8%) and the mangrove cover has increased by about 1.38 ha (~11%) over this period. The salinity of the lagoon has also reduced, forming a ‘low saline’ (3 psu) regime. About 40% of the lost water surface has scarified for a newly formed land mass (~0.4 ha) within the proximal part of the lagoon. The bridge, broken by the tsunami of 2004, has newly been constructed twice during the reporting period. The construction most likely led to impair the inflow and outflow through the lagoon mouth. Several development projects were launched in the immediate periphery of the lagoon stimulated soil erosion causing heavy siltation in the lagoon. The above changes in the morphometry of the lagoon is a cumulative effect of two factors; impaired inflow and outflow through the lagoon mouth, and the increase of the sediment input to the lagoon. If the ongoing processes are sustained, the lagoon will change into a different landscape. Therefore, early intervention to restore the lagoon hydrology is highly recommended if the lagoon ecosystem is to be protected.

Seafloor mapping to support conservation planning in an ecologically unique fjord in Newfoundland and Labrador, Canada

Abstract: As human impacts continue to threaten coastal habitats and ecosystems, marine benthic habitat and substrate mapping has become a key component of many conservation and management initiatives. Understanding the composition and extent of marine habitats can inform marine protected area (MPA) planning and monitoring, help identify vulnerable or rare habitats and support fisheries management. To support conservation planning in Eastern Canada, we mapped the seafloor of Newman Sound, identifying the benthoscape classes (i.e. discrete biophysical seafloor classes) of this ecologically diverse and unique fjord in Newfoundland and Labrador (NL). Mapping was achieved using multibeam echosounder (MBES) data collected using multiple platforms, seafloor videos and an unsupervised pixel-based classification method. Seven benthoscape classes were identified within the extent of the MBES coverages. Multivariate statistical analyses indicate that two benthoscape classes - mixed boulder and mud - support distinct epifaunal communities, and also capture the changes in benthic community composition between hard/shallow substrates and soft/deep substrates. Our results illustrate how benthoscape maps can inform marine spatial planning and conservation in the Newman Sound region, support monitoring and also calls for adaptive management of the adjacent Eastport MPA.

An assessment of geomorphic evolution and some erosion affected areas of Digha-Sankarpur coastal tract, West Bengal, India

Abstract: The coastal sites of Ramnagar-I and Ramnagar-II Administrative Blocks (Kanthi Coastal Plain), Purba Medinipur District, West Bengal, India, reveal various morphological features, which are represented by four categories of surface formation under different processes in the present study through a contour plan with 50 cm contour interval. The first category of landform being some isolated ridges with above 10 m elevation, which are stretched out in a linear pattern parallel to the modern shoreline behind Ramnagar-Deuli beach ridge section. The second set of landforms of the area which ranges from 7 m to 10 m elevation from the MSL is extended in the form of sandy terrace and continuous sand ridge surface along the sides of the first category landform. The third category of landform is visible along the edges of the second category of continuous sand ridge topography in the form of an extensive sandy tract with the reactivated sand surface.Last category of the ancient surface with an elevation of 2.5 m to 5.0 m above MSL is also clearly visible from the wide valley flat surface depressions in between the Contai-Paniparul beach ridge section and Ramnagar-Deuli beach ridge section at present. Some crenulated ridges of sandy sediments observed in the the present contour plan, particularly along the bank of abandoned channels. These are most probably evolved in the ancient period by natural levee depositions from various fluvio-tidal channels of the coastal plain. They are also categorized into older natural levees and younger natural levees delineated from the tonal contrasts of images and field verification of lose sediments. The older natural levees represent oxidized soils and the younger one represents the grey white color of sediments. Tidal prisms are the result of spring time tidal waves, keeping pressure on the seaward sides and spill over the backshore area by entering into the tidal channels at the time of high tide in the coastal belt. The study reveal the effects of significant increase of tidal prism estimated from 1990 to 2017.

How bottom-up and top-down controls shape dune topographic variability along the U.S. Virginia barrier island coast and the inference of dune dynamical properties

Abstract: When topography is incorporated into models of barrier dune dynamical states, how it is represented determines the dynamical properties inferred. Bottom-up representations rely on elevation and localized biogeomorphic modification. Top-down representations incorporate constraints imposed by the spatial patterns of topography. These spatial patterns emerge from island morphological context and the extent localized biogeomorphic processes can expand and structure the larger landscape. We compared topographies across 30 sites among seven barrier islands of the Virginia (U.S.A) coast to gauge the importance of elevation, the bottom-up variable often weighted most in dune biogeomorphic models, relative to top-down patch and continuous surface landscape representations of topography. LiDAR-derived digital elevation models of each site were characterized with non-metric multidimensional scaling to assess how these bottom-up and top-down metrics structured dune topographic variability. Multiple response permutation procedures gauged the strength of topographic differences among sites grouped according to island morphology versus groupings defined by clustering of topographic metrics. Elevation was the dominant metric structuring topography for these low relief islands. Spatial structure was weakly developed. Topographic differences were more robust when based on clusters defined largely by elevational properties rather than by island or island morphological type. For the Virginia barrier islands, storm inputs may more directly shape topography and override landscape-extent top-down spatial structure. The dominance of elevation suggests that resistance may be the more relevant dynamical property for this coast. Properties like resilience may be greater on higher islands with longer storm-free intervals in which biogeomorphic elements can configure relief and act as recursive top-down controls.

High nitrogen to phosphorus ratio in a Texas coastal river: origins and implications for nutrient pollution sources and exports

Abstract: Inorganic forms of nitrogen and phosphorus, oxygen levels, suspended solids, and planktonic primary productivity were monitored in Guadalupe River, a major waterway in southeast Texas. Our measurements have shown elevated levels of inorganic nutrients, with soluble reactive phosphorus reaching into 30 μg/L. Curiously, those elevated levels of nutrients combined with unexpectedly high nitrogen to phosphorus (N:P) ratio and low planktonic primary productivity. We attribute those phenomena to suspended solids acting as a selective sink for phosphorus while preventing effective photosynthesis in planktonic algae. At the same time, the potential for nitrogen removal is limited by abundant oxygen present in the water. This combination of low light, selective phosphorus removal, and high oxygen levels suggest that the Guadalupe River is likely to effectively export nitrogen, but not phosphorus into the estuary.

Seawall effects in a coastal wetland landscape: spatial changes in soil carbon and nitrogen pools

Abstract: Seawalls are common features in coastal landscapes. They can alter ecological processes in coastal wetland ecosystems at multiple scales. Evaluation those ecological effects requires consideration of spatial characteristics of variables. We used a scaling method, quadrat variance analysis, to quantify the patterns and scale characteristics of soil organic carbon (SOC) and total nitrogen (TN) in a wetland reclaimed by a 30-year-old seawall and a natural wetland in the Yellow River Delta, China, and then analyzed their spatial relationships with different plant and soil variables. The results revealed that spatial variances in SOC and TN in the seawall-reclaimed wetland had two scales. The smaller scale (40 m) was the distance between soil salinity patches, reflecting the influences of soil salinity on SOC and TN. The larger one (130 m) was the distance between shrub communities and the grass patches beneath them, reflecting the influences of shrubs on SOC and TN. However, in the natural wetland, both SOC and TN had only one scale of variance (90 m), which reflected the influences of soil salinity. Soil salinity determined the spatial patterns of dominant grass patches, and thus SOC and TN. Seawall altered plant distributions and shrub–grass interactions, thereby affected the patterns of SOC and TN. Scaling method can help us to efficiently evaluate the landscape impacts of seawalls on coastal wetlands.