Coastal Block Research Articles

New constraints on the tectonic history of the basement of the Western Cordillera and coastal forearc of Ecuador

The Western Cordillera and forearc of the Northern Andes (north of 5° S) are constructed from allochthonous terranes floored by oceanic crust. A paucity of accurate geochronological data from the ultramafic and mafic basement sequences of the Western Cordillera and Coastal region of Ecuador has lead to distinct differences in published tectonic models, with different allochthonous units and contrasting timelines of accretion and collision. We present new zircon UPb and groundmass 40Ar/39Ar dates of the basement units, which have been combined with new whole rock geochemical and isotopic data to constrain their tectonic histories prior to and during their accretion to South America. Ultramafic and mafic rocks with oceanic plateau affinities can be divided into two plateau sequences, where an inboard, younger plateau (85–92 Ma; Pallatanga Block) is sutured against South America, and was modified by a pre-accretionary intra-oceanic arc (Pilatón-Pujilí arc) that was terminated by the accretionary process. An older, outboard oceanic plateau sequence (∼120 Ma) forms the basement to a series of coastal blocks within the present forearc (Piñon, San Lorenzo, Pedernales and probably the Esmeraldas blocks). The outer plateau also hosts a pre-accretionary intra-oceanic arc (Pascuales – San Lorenzo arc), which remained active during and post-accretion (San Lorenzo – Rio Cala arc). Coeval changes in palaeomagnetic declination, the onset of rapid exhumation (>1 km/My) of the Early Cretaecous continental margin and sedimentation within the newly formed retro-arc foreland basin and foreland region supports a model where both oceanic plateau sequences accreted to South America in a single accretion event at 75–70 Ma. Thus, it is likely that the accreted oceanic plateau was composite, and included both the younger and older plateau sequences prior to accretion. We test an alternative model where the inner (younger) and outer (older) oceanic plateaus accrete in sequence, although this fails to account for the timing of block rotations in the forearc.

IJCM_398A: A cross-sectional study on morbidity patterns and health behavior among construction workers in Mangalore

Introduction: The construction industry is one of the most stable growing industries in the developing world. In India, it is the largest economic activity after agriculture. Since it is a labor-intensive industry, it consists of organized, unorganized, skilled, and unskilled labor. Morbidity is departure from a state of physical or psychological well-being, resulting from disease, illness, injury, or sickness, especially where the affected individual is aware of his or her condition which is more common among these workers. This study aims to assess the morbidity Pattern and health behavior among construction workers in a coastal block of Karnataka state. Methodology: This community based cross-sectional study was conducted among 230 manual labor workers at different construction sites in Mangalore. Data was collected using interview schedule and analyzed using SPSS version 24. Results were expressed as proportions using appropriate tables and graphs. Chi-square test will be used and P < 0.05 was considered as statistically significant. Results: In the study majority were males aged 19-29 years, Hindu by religion 84%, and unmarried, with minimum of primary educational qualification and work experience of 1-5 years. The most prevalent morbidity was Musculo skeletal disorders which manifest as constant arthralgia, myalgia followed by ophthalmic manifestation like refractive errors. Hypertension was notable, with communicable diseases like Malaria being common morbidities. Tobacco and alcohol consumption were prevalent, but knowledge on preventive measures against mosquito bites and personal hygiene practices were limited. Safety precautions at construction sites were evident as it is mandatory. Conclusions: The study highlighted prevalent morbidity patterns among construction workers in Mangalore, which seek immediate remedial measures. Improving awareness and intervention regarding the health risks associated with tobacco and alcohol consumption pose significant challenges but are crucial for enhancing workers’ well-being aa well as hygiene practices.

Coastal groundwater quality prediction using objective-weighted WQI and machine learning approach.

The water quality index (WQI) is a globally accepted guideline to indicate the water quality standard of any groundwater resource. Water levels in existing groundwater sources are declining in several coastal zones. Therefore, for monitoring water quality and improving water management, the prediction and identification of groundwater status by an effective technique with higher accuracy is urgently needed. Therefore, this research aims to find an effective model for WQI prediction by comparing entropy and critic weight-based WQI (ENW-WQI and CRITIC-WQI) with multi-layer perceptron artificial neural network (MLP-ANN) technique and also to identify contaminated zones using GIS. Initially, 1000 water sampling datasets with concentrations of several water quality parameters of different coastal blocks of eastern India during 2018 to 2022 are considered for the estimation of ENW-WQI and CRITIC-WQI. It shows 65% and 67% of the samples are excellent to good for drinking. ENW-WQI and CRITIC-WQI-based MLP-ANN models have been established considering different data portioning and hidden neuron numbers. Input variables and appropriate dataset partitioning with hidden neurons for models obtained from correlation and trial-error analysis. Spatial distribution maps are also produced for calculated WQIs using inverse distance weighted interpolation approaches. Three fitting models are obtained: ENW-WQI-MLP-ANN, CRITIC-WQI-MLP-ANN-I and CRITIC-WQI-MLP-ANN-II. CRITIC-WQI-MLP-ANN-II model (data ratio 85:15, network structure 6-12-1, R2 = 0.986, NSE = 0.98, and error rate 0.49%) provides the best accuracy in WQI prediction. The GIS-based WQI maps record several areas related to drinking water quality. The results of this research can help in planning the provision of safe drinking water in the future.

Evaluating rural poverty and livelihood diversification in the context of climate-induced extreme events in coastal area: Insights from Indian Sundarban

Agriculture has traditionally been the backbone of the Indian economy, accounting for a large portion of our country’s gross domestic product. Climate change scenarios, rising sea surface temperatures, and other environmental concerns have had a significant impact on agricultural production, making this situation more vulnerable and forcing rural communities to seek alternative forms of income. To better grasp the genuine status of livelihood diversification, researchers looked at some of the most vulnerable cyclone-affected villages in the Indian Sundarban’s southwest coastal districts. For this exploratory work based on geomorphological units, 850 households from fifteen different places were surveyed. However, 15 FGDs were performed to get specific information from the community. Using Alkire and Foster technique with Simpson Index, this study seeks to estimate multidimensional poverty index for village households in coastal blocks of West Bengal. The multiple linear regression model (MLRM) subtraction of predictor variables using the T-test uses stepwise regression. Results reveal livelihood diversification as way-out to poverty due to climatic extreme events. Coastal and riverine villages decomposed of roughly 80% of deprivation with 48% intense poverty. Livelihoods in island, coastal and riverine locations heavily transformed during last 10-12 years. In MLRM model food security alone explains (81.7%) the regional livelihood diversification. The majority of rural communities primarily from island, coastal, and riverine areas, have diversified their livelihoods from agriculture and fishing. Multiple factors, both positive and negative, lead to the reduction of livelihood diversification. Extreme occurrences have a substantial impact on livelihood diversification, as do the number of migrants, household assets, education of the head of family, dependence ratio, and amount of savings. In order to address such problems, households in most villages aim to diversify their income opportunities from nature-based (farm-related) to non-formal (non-farm) activities, as shown by the findings of this assessment.

A cyclone preparedness plan for the coastal blocks of the Indian Sundarban

A cyclone preparedness plan for the coastal blocks of the Indian Sundarban

The Variscan belts of North-West Africa: An African legacy to the Wilson Cycle concept

The concept of cyclic closure and opening of oceans along the same crustal scar was introduced by J.T. Wilson (1966) based on the example of the Atlantic Ocean and its continental borders. At that time, the only Variscan orogen cited south of Europe along the Atlantic coast of Africa was the Mauritanides of Mauritania. Here we report on the recent achievements in the Mauritanides from Mauritania to Morocco, and on the Moroccan Meseta orogen, which also records the Variscan orogeny. The Southern and Central Mauritanides are a poly-orogenic, Pan-African and Variscan orogen characterized by a thin-skinned tectonic style that mirrors the structure of the southern Appalachians, but with a different tectonic history. The Northern Mauritanides crops out in the Moroccan Oulad Dlim massif, northwest of the Reguibat Rise. This part of the belt compares with the southern part, but additionally exhibits in the west a Silurian-Devonian sector that shows possible affinities with Gondwana-derived Appalachian terranes. The Western Meseta is only affected by Variscan events, which were mild in the westernmost Meseta Coastal Block, while the Eastern Meseta was also affected by Eo-Variscan events. The along-strike change from the Mauritanides to the Meseta orogen is interpreted as a transition from a head-on collision south of the South Meseta transform fault (SMF, precursor of the South Atlas Fault, SAF) to a dextral, transpressional collision north of the SMF. South of the SAF, the Anti-Atlas and the Dhlou-Zemmour expose the foreland foldbelts of the Meseta and northernmost Mauritanides. The Coastal Block was likely displaced from the south-westernmost Anti-Atlas during the Early Carboniferous.The Wilson Cycle concept mostly applied in that the Atlantic Ocean opened where the prior Rheic Ocean had closed. Possible exceptions are the Sehoul Block north of Western Meseta and the Silurian-Devonian Sector of the Oulad Dlim massif, which may have separated from NW-Africa and re-amalgamated to it during the Variscan orogeny. Likewise, a NW-African fragment from the Anti-Atlas may have stranded in offshore Massachusetts in eastern North America. An early Ediacaran-Cambrian Wilson cycle nested in the classic cycle introduced by Wilson (1966) occurred along the margin of NW-Africa, where Cadomian terranes rifted off Africa, and some were transferred to Europe and some accreted back to NW-Africa. This early cycle likely controlled the localization of the subsequent Rheic rift, and that of the Atlantic rift along the Mauritanides after the Variscan collision.

The role of structural inheritance in the tectonic configuration of the Moroccan Meseta Coastal Block: Insights from morpho-structural and aeromagnetic data

The Coastal Block (CB) of the Western Meseta (Morocco) is located between the Atlantic passive margin and the Middle and High Atlas Mountains. In this contribution, a morpho-structural analysis using topographic data and an aeromagnetic data interpretation have been integrated to map tectonically related structures and to unravel the surface-subsurface faults interaction and their geodynamic implications in the CB. The morpho-structural analysis allowed the structural lineaments mapping through the processing of the topographic and hydrographic data. The application of derivatives operators on the magnetic anomaly map reduced to the pole allowed the assessment of the tectonic framework. The visual integrated analysis of surface and subsurface structures allowed to establish a synthetic structural map of the CB. Several N–S to NNE-SSW, NW-SE and NE-SW oriented fault systems were identified, some of which were confirmed and others were newly outlined. Four geometrically horst and graben type blocks were well distinguished, including the Triassic Basins of Berrechid to the north and of Doukkala to the south separated by the Casablanca Paleozoic block. Meanwhile, the Sahel represents an uplifted zone separating the Doukkala Basin from the continental shelf to the west. Rooted faults bounding these blocks, which are heavily inherited from the pre-Mesozoic tectonic events, record variable reactivation indicators related to the Neogene-Quaternary Atlasic shortening.

Mapping the multi-hazards risk index for coastal block of Sundarban, India using AHP and machine learning algorithms

Global climate change, climate extremes, and overuse of natural resources are all major contributors to the risk brought on by cyclones. In I West Bengal state of India, the Pathar Pratima Block frequently experiences a variety of risks that result in significant loss of life and livelihood. In order to govern coastal society, it is crucial to measure and map the multi-hazards risk status. To depict the multi-hazards vulnerability and risk status, no cutting-edge models are currently being applied. Predicting distinct physical vulnerabilities is possible using a variety of cutting-edge machine learning techniques. This study set out to precisely describe multi-hazard risk using powerful machine learning methods. This study involved the use of Analytic Hierarchical Analysis and two cutting-edge machine-learning algorithms - Random Forest and Artificial Neural Network, which are yet underutilized in this area. The multi-hazards risk was determined by taking into account six criteria. The southern and eastern regions of the research area are clearly identified by the multi-hazards risk maps as having high to extremely high hazards risk levels. Cyclonic hazards and embankment breaching are the main dominant factors among the multi-hazards. The machine learning approach is the most accurate model for mapping the multi-hazards risk where the ROC result of Random forest and artificial neural network is more than the conventional method AHP. Here RF is the most validated model than the other two. The effectiveness, root mean square error, true skill statistics, Friedman and Wilcoxon rank test, and area under the curve of receiver operating characteristic tests were used to evaluate the prediction capacity of newly constructed models. The RMSE values of 0.24 and 0.26, TSS values of 0.82 and 0.73, and AUC values of 88.20% and 89.10% as produced by RF and ANN models, respectively, were all excellent.

Assessment of Soil Fertility and Creation of Thematic Mapping in the Coastal Soils of Ramanathapuram Block, Ramanathapuram District in Tamil Nadu, India

Aims: A view of the current analysis used GPS and GIS techniques to evaluate and map the soil fertility status of the Ramanathapuram block in the Ramanathapuram district of Tamil Nadu, India.
 Study Design: In this study, a systematic set of 100 georeferenced soil samples were collected from 100 selected villages and analyzed for 10 chemical parameters and the data along with GPS readings were used for the preparation of soil fertility maps using GIS.
 Methodology: Hundred soil samples were collected from the sixteen revenue villages of Ramanathapuram block, Ramanathapuram district, Tamil Nadu during the pre-monsoon season with lat-long coordinates by using GPS to evaluate the soil fertility. Ramanathapuram block is the middle- coastal block of Ramanathapuram district of Tamil Nadu. 
 Results: In the present study, the mean soil values of pH (8.16), EC (0.74 dSm-1), organic carbon content (2.52 g/kg), Available N (159.36kgha-1), Available P (30.83 kgha-1), Available K (355.39kgha-1) and (Di- Ethylene Triamine Penta Acidic Acid DTPA) extractable micronutrients viz., Fe (7.21), Zn (0.16), Mn (6.46) and Cu (1.36) ppm were recorded respectively in Ramanathapuram block of Ramanathapuram district. Thematic maps pertaining to soil fertility were prepared using Arc GIS software 10.1.
 Conclusion: The georeferenced sampling sites can be revisited with the help of GPS, which helps in monitoring the soil fertility changes over long run. Further, it will be useful to the researchers, planners, policymakers, extension workers of the State Department of Agriculture, fertilizer industries, and farmers.

Delineation and Mapping of Groundwater Quality in Coastal Blocks of Tiruvallur District of Tamil Nadu Using GIS

An investigation was carried out to assess the quality of groundwater in coastal blocks of Tiruvallur district, Tamil Nadu. Approximately fifty groundwater samples were obtained from the coastline blocks in May 2022, particularly Minjur (25 Nos), Puzhal (7 Nos,) and Gummidipoondi (18 Nos). The groundwater samples were tested for physio-chemical (pH and EC) and chemical characteristics like cations-Ca2+, Mg2+, Na+, K+ and anions- CO32-, HCO3-, Cl-, and SO42- ; and the resultant properties were computed (SAR and RSC). The pH of Minjur, Puzhal, Gummidipoondi blocks ranged from 7.66 to 8.78, 7.77 to 8.36 and 7.35 to 8.76 respectively.The EC of Minjur ,Puzhal,Gummidipoondi were 0.3 to 3.56 dS m-1,0.76 to 2.91 dS m-1 and 0.2 to 2.07 dS m-1 respectively. The SAR of Minjur, Puzhal, and Gummidipoondi ranged from 1.60 to 11.73 ,1.67-10.01, 0.6 to 6.87 respectively. . The RSC of Minjur ,Puzhal, Gummidipoondi ranged from -4 to 8.4 meq l -1 ,-0.8 to 3.4 meq l -1, -4.4 to 4.8 meq l -1 respectively. In the Minjur block, the majority quality of groundwater was characterized as good quality water (32 per cent), salty water (24 per cent), and alkali water (36 per cent). While in the Puzhal block, the majority quality of groundwater was characterized as good quality water (28.57 per cent), saline water (14.28 per cent), and alkali water (57.14 per cent). In the Gummidipoondi block, the majority quality of groundwater was assessed as good quality water (38.8 percent), and alkali water (50 per cent).

Delineation and Mapping of Groundwater Quality in Chengalpattu District of Tamil Nadu, India

Groundwater is a major natural source of water supply all around the world. It's utilised for irrigation, industry, and even household purposes. The quality of groundwater is important for irrigation. Irrigation water quality plays a critical role in long-term soil productivity. To assess the quality of the groundwater, 149 samples were taken in May 2022 from the coastal blocks of the Chengalpattu district: Chithamur (42), Lathur (37), Thirukalukundram (31), and Thiruporur (39). The samples were analysed in accordance with the appropriate protocol. The study revealed that the coastline blocks pH ranges from 8.92 to 7.52 and their EC ranges from 11.50 to 0.13 dS m-1. The Sodium Absorption Ratio (SAR) ranges from 20.00 to -6.80, while the Residual Sodium Carbonate (RSC) ranges from 14.77 to 0.26 meq/L. The Chengalpattu district has a high concentration of alkali water, according to CSSRI, Karnal classification. Among the coastal blocks, the Thiruporur block contains more alkali water compared to other coastal blocks (46%).

Coastal vulnerability assessment of India's Purba Medinipur-Balasore coastal stretch: A comparative study using empirical models

The 90.20 km coastal stretch extending from India's Subarnarekha estuary (Balasore District, Odisha) to the mouth of the Haldi River (Purba Medinipur, West Bengal) was evaluated. The evaluation was for vulnerability to climate extremes and variabilities (e.g. tropical cyclones, storm surges, and eustatic sea-level rise) resulting in coastal erosion, inundation, salinization and increased biophysical and socio-economic impacts. Coastal vulnerability mapping with respect to coastal hazards was applied to identify and implement risk reduction policies. In order to understand the spatial distribution of physical vulnerability along this coastal stretch, the Coastal Vulnerability Index (CVI) using Gornitz's CVI model and the Analytical Hierarchy Process (AHP) method were applied. These models were run in ArcGIS ver. 10.5 using six geological parameters viz., elevation, slope, bathymetry, coastal geomorphology, shoreline change, and coastal land use and four physical process variables viz. Mean sea level (MSL), mean tidal range, significant wave height, and storm surge height. Both of the models produced very good results. Based on Gornitz's CVI model, it was found that 13.56% of the coastline is highly vulnerable to these hazards, while the AHP model indicated 11.29% of the coast was at high vulnerability. When both models were simulated the same probable inundation extent of two different storm surge scenarios of wave height, viz. ≤ 3 m and≤5 m, the areas estimated to be affected by the surge were 255.22 and 779.59 sq. km, respectively. The coastal blocks of Nandigram-I, Contai-I, Deshopran, and Bhograi were identified as highly vulnerable due to landward erosion and inundation. The study inferred that the combined effect of cyclonic activities and storm surge along with high tide made the coast highly susceptible. This study could help coastal planners, decision-makers, and administrators to prepare a risk management plan for long-term coastal conservation and management.

INVESTIGATION OF HYDROCHEMICAL DYNAMICS OF GROUNDWATER IN COASTAL BLOCKS OF TIRUVALLUR DISTRICT, TAMILNADU, INDIA

This paper presents the behaviour of cation and anion in samples of water collected from the coastal blocks of Tiruvallur District, Tamilnadu, India. 13 physiochemical parameters are investigated on the uniformly collected groundwater samples. It is revealed that fifty percentage of groundwater samples surpassed water quality levels pertaining to drinking and irrigation. In this investigation, descriptive statistical analysis is performed to understand groundwater characteristics. The hydro-chemical dynamics of groundwater are evaluated using graphical plots Piper, Wilcox, and Gibbs. Through the Piper plot, it is concluded that high concentrations of sodium would induce cation exchange between Ca2+ and Mg2+ from the soil. This may lead to the acceleration of air and water circulation through the soil in wet conditions. The inference of the Piper plot is supported by end result of Gibbs plot. Gibbs plot indicates evaporation dominance of anthropogenic activities, while Wilcox plot clearly indicates groundwater’s suitability for irrigation purposes. Moreover, the cation concentration is seen to be high on the eastern portion of the chosen area. The level of groundwater treatment should be adequately determined for potable purposes and for agricultural purposes as the study concludes the intrusion of saline water, rock water interaction and irrigation flows.

Vulnerability assessment of coastal fishing communities for building resilience and adaptation: Evidences from Tamil Nadu, India

The coastal communities are the most vulnerable to climate vagaries, which affect their habitat and livelihood alike. Vulnerability assessments undertaken using quantitative or qualitative methods at macro- or micro-level need to capture the location and context so as to be able to use them towards improving mitigation and resilience strategies at the community level, where the impact is felt. The characteristics of the marine fishing villages differ from those of other villages in any coastal block / district in a State, making a strong case for a marine village-specific vulnerability assessment as well as intervention planning. This work, capturing this grassroots reality and deriving vulnerability indicators that affect fisheries and coastal households, pilots a novel socio-economic vulnerability (SEVIPH) and cumulative vulnerability (CVIPH) framework in marine fishing villages of Thoothukudi, a coastal district of Tamil Nadu in India, and compares it with an existing framework (SEVISV) that relies on secondary data. A set of 54 indicators reflecting vulnerability components such as exposure, sensitivity (fishery and social) and adaptive capacity (economic, development drivers and alternate livelihood activity) has been developed. Primary data were collected from 1741 households residing in all the 24 marine fishing villages in Thoothukudi district to estimate various sub-indices and indices of SEVIPH, SEVISV and CVIPH. Significant differences (p < 0.01) in sensitivity index (SI) and adaptive capacity index (ACI) were observed among the fishing villages, which however, got masked at taluk and district level due to aggregation, underscoring the importance of household based village level assessment of vulnerability. Overall, 42 % of the fishing villages were socio-economically highly vulnerable, while about 71 % of the villages had high cumulative vulnerability index. While the overall social and economic status of fishing households were lower compared to non-fishing population, it could be ascertained that there was relatively less inequity among them. The study also found significant disparities and differences (p < 0.05) across the villages/taluks in terms of exposure, sensitivity as well as socio-economic capabilities to respond, adapt and develop resilience. The two dimensional decision matrix plotted against SI and ACI median threshold values presented a greater contrast and helped in identifying the key drivers (or contributing factors) and buffers (or ameliorating factors) for coastal vulnerability of marine fishing villages to aid in location-specific intervention planning. The study also highlighted the need for imparting need-based location-specific training programmes at the village and taluk level for vulnerability reduction.

A Predictive Human Health Risk Assessment of Non-Choleraic Vibrio spp. during Hurricane-Driven Flooding Events in Coastal South Carolina, USA

Densely populated, low-lying coastal areas are most at-risk for negative impacts from increasing intensity of storm-induced flooding. Due to the effects of global warming and subsequent climate change, coastal temperatures and the magnitude of storm-induced flooding are projected to increase, creating a hospitable environment for the aquatic Vibrio spp. bacteria. A relative risk model analysis was used to determine which census block groups in coastal South Carolina have the highest risk of Vibrio spp. exposure using storm surge flooding as a proxy. Coastal block groups with dense vulnerable sub-populations exposed to storm surge have the highest relative risk, while inland block groups away from riverine-mediated storm surge have the lowest relative risk. As Vibriosis infections may be extremely severe or even deadly, the best methods of infection control will be regular standardized coastal and estuarine water monitoring for Vibrio spp. to enable more informed and timely public health advisories and help prevent future exposure.

Brittleness modeling selects optimum stimulation zone in shaly source rocks in the Whangai Formation, New Zealand

Within New Zealand, the East Coast Basin represents the primary shale oil and gas play in which the Whangai Formation is widespread. This formation is oil and gas prone and prevalent throughout a large area of the East Coast Basin and is typically composed of the Upper Calcareous, Porangahau, and Rakauroa Members. The primary goal of this study was to develop an integrated methodology to define the best stimulation intervals in the formation. To do this, we evaluated four different definitions of the brittleness index for the Rakauroa Member, the only member drilled in the three study wells. A Python-based automated process was specifically developed for this purpose and uses four indexes: elastic parameters, internal friction coefficient, mineralogy, and total organic carbon content. Through this process, these four indexes were analytically combined to select intervals with the highest brittleness values and identify the optimum stimulation interval and most desirable perforation intervals in the pay zone. Our results show that the Whangai Formation contains 25% clay (and reaching up to 70% clay content in some intervals) and a maximum organic matter content of 2.54%. The geomechanical model indicates a uniform distribution of high pore pressure across the entire reservoir section. The interval between 1497 and 1750 m in the Opoutama-1 well located in the Coastal block presents high combined brittleness indexes, indicating excellent characteristics from a stimulation standpoint.

Micro-level Assessment of Rural Societal Vulnerability of Coastal Regions: An Insight into Sagar Island, West Bengal, India

Most of the villages in coastal blocks of West Bengal, India, are prone to both cyclones and coastal and river flooding. Very severe cyclones in recent time (e.g., Sidr, Aila, Fani, Bulbul, and Amphan) exposed the coastal population livelihood at stake. Displacement and migration are very much evident due to such extreme events. However, the existing study examines the nature of societal vulnerability mainly for the coastal villages that focus on the biophysical components. An ‘integrated approach’ was adopted to assess the societal vulnerability which is viewed as a function of exposure, sensitivity and adaptive capacity. A number of proxy indicators were considered to represent these components and a normalisation procedure was adopted in order to aggregate them into a single value. Three key observations emerged. First, components such as sensitivity and adaptive capacity were found to act as the major determinants of vulnerability. Second, eight mouzas were found to have a higher vulnerability score, and surprisingly, some of the mouzas are non-coastal. Third, factors such as demography, agriculture and economic capacity emerged as the major cause for increasing vulnerability. These results have policy implications in the context of prioritising limited resources among the vulnerable villages and determinants through the disaster risk management programme at the district and block levels.

Identification of Suitable Aquaculture Sites Using Large-Scale Land Use and Land Cover Maps Factoring the Prevailing Regulatory Frameworks: A Case Study from India

Identification of a suitable site is a crucial step for the sustainability of an aquaculture venture. This study shows a framework for identifying areas suitable for freshwater and brackishwater aquaculture in India while integrating the governing regulations. Land use and land cover (LULC) maps at 1:10,000 scale derived from high-resolution imagery were used as base maps, along with allied layers. Site selection criteria were identified through review. Multi-criteria evaluation technique was used to select the technically suitable sites. Coastal regulation zone and coastal aquaculture authority guidelines, which form the regulatory framework governing brackishwater aquaculture in India, were spatially applied on the technically suitable sites to locate sites complying with regulations. The analysis was carried out using layers in the vector geographical information system format. The study was done in one coastal block each from two coastal states along the east coast of India, viz. Odisha and Tamil Nadu. The study identified areas suitable for brackishwater aquaculture in the selected blocks of Odisha (Ersama block: 86 ha) and Tamil Nadu (Pattukottai block: 343 ha). Areas suitable for freshwater aquaculture in Ersama and Pattukottai were 4286 ha and 6265 ha, respectively, while the areas suitable for freshwater aquaculture with interventions, in the respective blocks, were 487 ha and 2467 ha. In context of scarce land availability for aquaculture and stringent laws governing it, we demonstrate utility of large-scale LULC maps for identifying sites suitable for freshwater and brackishwater aquaculture, through a multi-criteria approach.

Analyzing climate variability and its effects in Sundarban Biosphere Reserve, India: reaffirmation from local communities

Climate variability and continual occurrence of cyclones, flood and storm surge have greater implications on fragile ecosystem of Indian Sundarban Biosphere Reserve (SBR). Centurial meteorological data were used to assess the climate variability in the Reserve. Multivariate principal component analysis was performed to identify the consistency among the conditioning parameters of climate. Cyclones, severe cyclone, storm surge height, salinity intrusion, pH and surface water temperature were assessed to figure out the overall consequences of climate variability. Field investigation from 570 households from coastal and inland blocks (administrative division of the district) was carried out to reaffirm the variability in climatic conditions and its environmental, economic and social consequences in SBR. Study revealed wide spatiotemporal variation in temperature and rainfall. Rise in sea level, flood and high storm surge height and salinity intrusion were inducing vulnerability in the coastal blocks. Communities in Gosaba, Kultali, Kakdwip, Sagar, Patharpratima and Namkhana blocks largely showed high level of agreement for climate variability. Hence, the study calls for effective adaptation and mitigation strategies.

Zircon U-Pb geochronology and geochemistry of Cambrian magmatism in the Coastal Block (Oued Rhebar volcanic complex, Moroccan Meseta): Implications for the geodynamic evolutionary model of North-Gondwana

U-Pb dating (SHRIMP) of magmatic zircons from an intermediate-mafic agglomerate of the Oued Rhebar Volcanic Complex (Coastal Block, Western Meseta) yielded a weighted mean age of 507 ± 5 Ma. The obtained middle Cambrian age (Series 3, Stage 5) seems to be the best estimate for the crystallization of the ORVC volcanic rock, providing a maximum depositional age for the overlying Bouznika volcanosedimentary Formation. The ORVC rock is representative of middle Cambrian crust generation in North-Gondwana, but contains Ediacaran (ca. 546-542 Ma) and early Cambrian (ca. 536-526 Ma) inherited zircon which might be derived from recycling of older continental crust. This geochemistry study corroborates the existence of calc-alkaline rhyolites, basaltic andesites and andesites in the ORVC rocks, but also of the existence, albeit to a lesser volume, of tholeiitic basalt. The relative higher volume of calc-alkaline compared to tholeiitic signature might reflect, in some extent, contamination of depleted mantle-derived magmas by the upper continental crust, as has been proposed for the origin of the same age rift-related igneous rocks from North-Gondwana, as the Iberian correlatives.