Spatial distribution of intertidal sandy beach polychaeta along an estuarine and morphodynamic gradient in an eutrophic tropical bay

The spatial distribution of polychaeta along pollution gradients often reflects different degrees of disturbance. In order to evaluate polychaeta fauna of an organically polluted tropical bay, 20 sandy beaches distributed in five areas were sampled. The relationship between community structure, slope, beach index, exposure, sediment and water quality parameters were analysed. Multivariate analysis of variance (PERMANOVA) showed differences among areas and beaches. Scolelepis chilensis dominated at mouth of bay beaches whereas Streblospio gynobranchiata and Capitella capitata complex, at inner beaches. Highest polychaete density was recorded at areas 3 and 5 with the dominance of Saccocirrus sp. and the organic indicator species C. capitata complex and Polydora sp. The most important factors obtained from canonical analysis were sorting, slope, mud and organic matter percentage. Marine biotic index (AMBI) showed that areas 3 and 5 were highly affected by anthropogenic factors, given that a poor polychaeta fauna, dominated by opportunistic species, were found. Polychaete assemblages were affected by eutrophication along an estuarine gradient as well as by morphodynamic condition of the beaches.     

Landuse/land cover change in Mumbai-Navi Mumbai cities and its effects on the drainage basins and channels — A study using GIS

The Mumbai-Navi Mumbai cities (Bombay and New Bombay) are among the highest populated cities in the country. The population pressure has caused drastic landuse change in the last seventy years. Multi-date data from SOI topographical maps and Landsat TM digital data have been used to study the landuse change. The change has been quantified using A GIS It was observed that 55% reduction in forest/agricultural land, while a 300% increase in built-up land has taken place in the last seventy years. This has affected the natural drainage system of the cities, causing flooding during monsoons. The quantum of draînage basin area and stream length, in the ten basins which drain the area, under influence of built-up land was found by using a map overlay of the drainage network map and landuse map of 1994. The results shed light on the extent of drainage network disruption within these two neighbouring cities.     

RETRIEVAL OF HORIZONTAL WIND PERTURBATION FIELDS FROM SIMULATED SINGLE DOPPLER RADAR OBSERVATIONS

The application of the single Doppler radar dataset analysis is usually confined to the assumption that the actualwind is linearly distributed or uniform locally.Following some dynamic features of convective weather,a conceptualmodel of moderate complexity is constructed,wherewith a horizontal wind perturbation field is retrieved directly fromthe single Doppler radar measurements.The numerical experiments are based on a 3-D cloud model-generatedconvective cell,whose radial velocity component is taken as the radar observations that are put into the closed equationsbased on the conceptual model to retrieve the horizontal wind perturbation field.After the initial field is properlytreated,the retrieval equation is solved in terms of the 2-D FFT technique and the sensitivity to noise is examined.Finally,contrast analysis is done of the retrieved and the cloud model output wind fields,indicating the usefulness of theapproach proposed in this paper.