[Show abstract][Hide abstract] ABSTRACT: An X-band nautical radar system was employed to examine wave run-up during a typhoon around the research pier HORS in Hasaki, Japan. Analyses on radar echo images were done to estimate the spatio-temporal variation of water fronts by manually digitizing cross-shore time stack images. Digitized instantaneous water fronts were validated with wave gauge measurements with an acceptable agreement. Longshore distribution of mean shoreline positions and inter-tidal foreshore slopes were then estimated using time-averaged images. Run-up, the height of discrete water level maxima, was estimated from the digitized water fronts with the help of foreshore profile. Run-up variations under dissipative condition were parameterized with surf similarity parameter. Low frequency variances in the run-up motion were observed, which travelled in the longshore direction.
[Show abstract][Hide abstract] ABSTRACT: An X-band nautical radar system was employed to observe the wave field during a storm around the research pier HORS in Hasaki, Japan. The radar system provides instantaneous distributions of wave crests in the near-shore region, with image sequences comprising a clear spatial and temporal variation of the wave pattern. The spectra of radar echo signals and water surface elevations from wave gauge records were compared, and a relatively high coherence for a particular bandwidth was observed. A sequence of radar images was filtered at the dominant frequency, which was used to estimate the wavenumber distribution of the refraction field. The Fast Fourier Transform (FFT) andMaximum EntropyMethod (MEM) were used to estimate the wavenumbers. The estimated wave angles were then compared with linear refraction analyses. The water depths along the pier were also estimated using the linear dispersion relationship and compared with the surveyed depths. The linear estimates of hydrodynamic parameters during the passage of the storm are presented in this paper to demonstrate the potential of radar measurements in capturing essential characteristics of coastal dynamics.
[Show abstract][Hide abstract] ABSTRACT: Indiscriminate cutting of hills in the Sylhet region has become a major environmental issue. The nature and life style of Sylhet intimately related with the hills are thus under the threat of a drastic imbalance in its ecosystem. Due to such hill cutting the mostly affected sectors of this region will be its weather and climate, geomorphology and hydrology, and the indigenous flora and fauna. As a result the frequency of natural calamities like earthquake, flash flooding etc may increase considerably. Deforestation and resulting increased soil erosion, decreased ground water recharge and deteriorated water quality might also be as consequences of such hill cutting. This paper investigates the cause and extent of the problem along with its probable impact and finally suggests actions for conservation of hills for ecological balance of the region.
International journal of Environmental Science and Technology 01/2006; · 1.84 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Municipal solid waste becomes serious environmental hazard and social problem in Bangladesh. Currently a gigantic volume of solid waste is generated every day in the district towns of Bangladesh and unfortunately solid waste management is being deteriorated day by day due to the limited resources to handle the increasing rate of generated waste. In order to check the waste management situation, a detailed survey in different cities of Bangladesh has been done in this study. Although a significant amount of municipal waste is collected by community based organizations, conservancy wings of the cities can not dispose more than 50% of the generated wastes. This study reflects the adverse impacts of pollution through solid waste and deteriorating situation of municipal solid waste management in capital city Dhaka, divisional city Sylhet, greater district town Tangail and Rangamati and new district town Gazipur.