Sand dunes are topographical height in the low-lying coastal plain of west Bengal. They protect wave attack in the low-lying areas, shelter land ward communities and assist in the retention of fresh water tables against salt water intrusion. Sand dunes are developed along the coast belt with three basic processes: Supply of sand to the beach plain, aeolian sand transport from the beach to the backshore region, and interaction between sand transport by the wind and vegetative growth or distribution. It is useful to regard a dune like a savings account of a bank. At present, of the entire coastal ecosystem, sand dunes have suffered greatest degree of human processes. Many dune systems have been irreversible altered through the activities of man, both by accident and design. Ecosystem components of the sand dunes are affected by the intensive use of dunes in the coast. Artificial structures like houses; hotels, fishery etc are disturbing the normal growth of the dunes. Removal of sands by road cutting, grazing the dune in Shankarpur, Mandarmoni areas. The level of grazing pressure is instrumental in determining species composition. Dune plants are destroyed by growth of urbanisation, agriculture and costal defence programme. We observed and measuring the rate of coastal erosion, it has been remarkable increasing in last decade. The dunes are totally destroyed by increasing wave action at many places. Accelerated dune erosion by the cyclonic storm, tidal bore and wave action. It has been observed that the front dunes are eroded and also shifted landward at the rate of 6 m to 12 m/year of this area. Certain conservation measures have been recommended including mechanism of dune maintenance by artificial simulation, dune creation and control of coastal water pollution from hotel sewage and fisheries waste water.
Urban expansion is a universal trend primarily determined by the over population growth, particularly in developing countries like Egypt. Pattern and boundary of urban expansion could be observed and modeled on a spatial and temporal dimension. In the present study, GIS and remote sensing data along with other thematic maps were used to analyze the urban expansion and directions in the past 25 years for 6th October city which is one of the biggest new cities in Egypt. Five Landsat images, acquired in 1990, 2000, 2005, 2010 and 2015 were calibrated, classified and compared using ENVI 5.1. and Arc GIS 10.2. software. The classified images were analyzed to locate the directions of urban expansion in 6th October City during four periods 1990-2000, 2000-2005, 2005-2010 and 2010-2015. Change detection results showed the areas and directions of urban expansion. Results indicated that the southern direction of the urban expansion was predominant during the period 1990-2000 (2.31 km2), while the northern direction was predominant during 2000-2005 (1.42 km2). However, the eastern direction of the urban increase was predominant in two sequent periods; 2005-2010 and 2010-2015 recording 1.2 km2 and 2.22 km2, respectively. This study supports the future urban planning strategies through assessing the spatiotemporal changes and directions of urban expansion.
This study reports the ambient concentrations of total suspended particulate matter (TSP: both respirable and non-respirable) measured in Yenagoa and its environs as means of determining the distribution of particulate matter to assess the ambient air quality of a fast growing urban town in Southern Nigeria. Particulate matter was collected at five stations (Berger junction, Onopa government house, Tombia Roundabout, Gbaran Ubie and Ogbogoro Village), using a high volume portable SKC air check MTX Sidekick air sampler (Model: 224-52MTX). The mean TSP Matter measured at each of the five locations are 1189.857
This study on Qualitative Interpretation of recently acquired aeromagnetic data of Naraguta, sheet 168 was aimed at analysing and interpreting the data, identifying the subsurface structures and the mineralized zones. Using some software packages, the data was analysed using the following processes; Total Magnetic Intensity (TMI), Reduced-To-Equator (RTE), Upward Continuation and First Vertical Derivative (FVD). Results from the analysis show that the magnetic intensity range for TMI map varies from -696.9 to 599.2 nT/m, RTE varies from -430.1 to 346.4 nT/m both showing anomalies in circular to near circular closures which could be associated with granitic intrusions, long narrow features which could be dykes or long ore bodies and dislocations which could be due to subsurface fractures. Upward continuation map at 3 km deep revealed a basement trending mostly in the NE-SW and ENE-WSW directions with the latter being the major trend direction. The first vertical derivative sharpened the anomaly edges which were extracted to produce the lineament map and to obtain the rose plot. The rose plot shows the dominant lineament trend to be in the NE-SW direction. Finally, the analytic signal maxima may represent the edges of circular, elliptical or polygonal porphyritic ring dykes that characterize many of the complexes in the study area. Comparison of this study with previous research done using an old data of Naraguta sheet 168, shows similarities with few differences noticed especially in the TMI map which may be attributed to sophistication in equipment used or the effects of temporal variation on the geomagnetic field of the earth which helped in making visible anomalies that were hidden in the former data of Naraguta sheet 168.
A study of variability of latent heating rate over West Africa has been done. Results were divided into three categories: mean latent heating rate profiles, monthly time series of mean latent heating rate at four different vertical layers in the atmosphere, and the latitudinal cross section of the mean 4 – 11 km diurnal latent heat distribution.
The data was analysed using seventeen (17) years Tropical Rainfall measurement mission (TRMM) Precipitation Radar (PR) data, of total (convective + stratiform) latent heating, over West Africa.
Strong latent heating rate was observed in the Savannah zone than Guinea and Sahel zones during MAM season, whereas in the JJAS season, latent heating rate was much weaker when compared to MAM season. In JJAS season, the Sahel zone indicated stronger latent heating rate than the other two zones. Sahel had the weakest latent heating rate in MAM, whereas Guinea had the weakest latent heating rate in JJAS.
The first vertical layer (0.5 – 3 km) indicated that latent heating rate dropped sharply in April and August, and there are also bi – modal peak in June and September. With altitude, the bi – modal distribution is sustained in the Savannah zone, but Guinea and Sahel zones gradually change to one – mode. At higher layers, results indicated that Guinea and Sahel are always showing contrasting modes, especially around August.
The 4- 11 km diurnal pattern showed that, during MAM, peak occurrence of latent heating rate is mostly observed during 16 – 23 hours, that is, late in the evening hours. In the case of JJAS, these observed strong latent heating rate are now located above latitude 80N, but occurrence of peak values are sustained at evening hours.