Sundarban mangrove delta represents one of world’s delta where the Tidal action is extremely active. This unique tropical ecosystem has been delineated as almost vulnerable and disaster prone area in the world due to several aggressive natural hazards like sea level rise, cyclone, coastal erosion, salinization etc. Coastal erosion is the one of the most important hazards. This paper aimed to evaluate the coastal erosion in this area. It also attempted to find out the causes and consequences of coastal erosion in this area. Another objective of this study is to measure and quantify the rate and pattern of coastal erosion. Gobardhanpur and its surrounded mouzas (Mouza is the least administrative area in India. It is also called as a village) have been chosen for the study area. This village is most affected area due to coastal erosion in this region. Descriptive types of research method, literature survey, and questionnaire survey methods have been applied to this work. Questionnaire has prepared by 4 point Likart scale. Satellite data, mouza map and topographical map have been used for chronological analysis and determination of the rate of erosion. The maps and satellite images have been processed to digital images and superimposed for exploration of a pattern of coastal erosion through image processing software. The result shows that the Gobardhanpur and Plot G 6th portion are the most affected area. Another finding is that the Plot G 6th Portion almost vanished from the map. The cause of the coastal erosion of this area is mainly natural because forested areas are still extremely eroded. Man-made or anthropogenic causes are less in number. The result shows the consequences of this hazard. People lost their land which was used for agriculture, prawn culture, fishing. They have lost homestead property. They have diverted their occupation. People also migrated from this area as refugees.
Geospatial tools play significant role in forest ecology and management, where vegetation indices and transformations have been extensively used for vegetation characterization. Hence, in this study, an attempt has been made to characterize the various hydrologic regimes in Wayanad Wildlife Sanctuary, Wayanad district, Kerala using geospatial tools. The study area was focused on Muthanga , a part of the Wayanad Wildlife Sanctuary of Wayanad district, Kerala with an area of 87.13 km2, where the major vegetation types are moist deciduous with a few scattered patches of evergreen and forests plantation. Out of the many spectral indices employed in the hydrologic studies of the forest areas, tasseled cap wetness index, Normalised Difference Vegetation Index (NDVI) and Normalised Difference Water Index NDWI were used in this study. Since topography also affects the hydrological processes by controlling the spatial distribution of soil moisture in a realistic way, some of the terrain indices, e.g., topographic wetness index (TWI) were also employed in the present study. Statistical analysis was conducted in order to unravel the relationship between vegetation types and hydrology. The results of the analysis suggest that geospatial tools are efficient in hydrological characterization of forested vegetation of the region, which compared the wetness of the region using a variety of parameters with their corresponding vegetation.
Flood is one of the most important natural disasters that cause huge loss of life and properties every year around the world. Moreover, the International Federation of the Red Cross and Red Crescent Societies pointed out that floods were by far the greatest cause of homelessness. In West Africa, many countries are damaged from flooding almost every season. Thus, this study aimed to set a seasonal flood forecast model and carried out an evaluation of the level of risk associated with each seasonal forecast. HEC-RAS (Hydrologic Engineering Centers River Analysis System) was used to develop a hydro-dynamical model of Niger river on a 160km reach (80km upstream to 80kmdownstream of Niamey), then a simple risk measure was used to calculate the probability of overtopping the flood protection dykes in Niamey. Results show that the hydro-dynamical model reproduced well the rating curve over the period 2009-2014. A subsequent copula analysis demonstrated a dependency between flow on the Niger river and flow on the Sirba River, the main tributary contributing to the seasonal flood at Niamey. The Gumbel copula was found to be the best among the tested 5 copulas to represent the dependency between peak flow on the main channel of the Niger River and concomitant flow on the Sirba river. It is found that for the six dykes the probabilities of being overtopped by the flood range from very high (100%) to relatively low (16.67 %) over the 34 years of simulation.
Dry wind is a widespread dangerous phenomenon, which reduces the yield of crops in Ukraine.
The aim of this study is to determine the conditions of the atmospheric circulation leading to the formation of dry winds in August 2010 and to determine the effect of these conditions on the distribution of dry winds in Ukraine during this period. Daily observations at 24 meteorological stations for the period from 31 July to 31 August 2010 were used, as the initial dataset. To define the location where the formation of initial dry wind air mass begins, backward trajectories for the previous movement patterns of air particles were constructed for period of a 120 hours (5 days) for the following heights: earth surface (0 m nominal), 1500 m and 3000 m for stations where the phenomenon was observed. During this period dry winds were observed in different parts of Ukraine, and the longest multi-day dry wind in period from 1995-2015 was observed at Mariupol station, from 31July 2010 to 20 August 2010, lasting 21 days. In first half of August 2010, air masses came from regions of northwestern Kazakhstan, the Ural Mountains, and the east and northeast of European Russia. After a blocking anticyclone over European Russia was dissipated, the baric field was reorganized, and territory of Ukraine was under the influence of the western air masses. After the development of an anticyclone over Central Europe at each heights, air masses came from the west from Central and Western European regions, and the North Atlantic.
The spread of dry winds over Ukraine occurred against the backdrop of the formation in the European sector of meridional of atmospheric circulation, with the development of a blocking process over European Russia. The development of dry conditions was facilitated by the stable, clear weather, without precipitation for a long time, as well as the descent of air masses in an anticyclone system, leading to their adiabatic heating.
Delineating mineralisation zones within Keffi- Abuja North Central, Nigeria was carried out to identify structures and to suggest the viability of the basin for Mineralization Zone potentials in the survey area. Aeromagnetic data over the study area bounded by latitudes N8o50’N to 10o00’N and longitudes 7o00’E to 8o00’E was carried out using First Vertical Derivative, Horizontal Derivative, Second Vertical Derivative and Analytical Signal. The First Vertical Derivative, map shows a dominant NE trend of the structures within the study area, The Horizontal Derivative reveals those anomalies that are trending in the horizontal (x-direction) clearly, Second Vertical Derivative map identify regions around central to west part of the study area which correspond to Kagarko, Kafin and Abuja to be areas with high mineralization zone, smaller mineralisation zones are also identified to NW region around Bishini, SW within Kwali and Keffi in SE region. Analytical signal identify areas with high amplitude ranges from -0.010m to 0.141m within the study area. The high amplitude structures are to the central and western portion around the Kagarko, Kafin and Abuja axis. This made it possible to delineate the various mineralisation zones around the study area. Map shows that central to western portions around the Kagarko, Kafin and Abuja are particularly promising for mineralization.