The potential of Tidal River Management for flood alleviation in South Western Bangladesh.

Reduced sediment deposition, land subsidence, channel siltation, and salinity intrusion has been an unintended consequence of the construction of polders in the south western delta of Bangladesh in the 1960s. Tidal River Management (TRM) is a process that is intended to temporarily reverse these processes and restore sediment deposition and land elevation at the low-lying sites, known as 'beels', where TRM is carried out. However, there is limited evidence to prioritise sites for TRM on the basis of its potential effectiveness at alleviating flooding. In this study, the south western delta of Bangladesh was classified according to different flood susceptible zones. In south western Bangladesh, the major portion of agricultural and aquaculture land is located within flood susceptible zones (65% and 81%, respectively). 44.5% of the total population in embanked regions live in areas classified as being flood susceptible. This study identified 106 'beels' suitable for TRM. Modelling of potential sediment deposition predicted that the consequent increase in land elevation could be up to 1.4 m in five years, which would alleviate land subsidence and modify several geomorphological factors such as aspect, slope, curvature, and Stream Power Index (SPI). Implementation of TRM at these sites could potentially reduce the probability of annual flooding from 0.86 (on average) to 0.57 (on average). Therefore, TRM could lower the flood susceptible area by 35% in suitable 'beels'. Whilst during the implementation of TRM agriculture has to cease for a few years, a systematic programme of TRM could result in a long-term increase in agricultural production by reducing flood susceptibility of agricultural lands in delta regions.

Recent sediment flux to the Ganges-Brahmaputra-Meghna delta system.

The physical sustainability of deltaic environments is very much dependent on the volume of water and sediment coming from upstream and the way these fluxes recirculate within the delta system. Based on several past studies, the combined mean annual sediment load of the Ganges-Brahmaputra-Meghna (GBM) systems has previously been estimated to vary from 1.0 to 2.4 BT/year which can be separated into components flowing from the Ganges (260 to 680 MT/year) and Brahmaputra (390 to 1160 MT/year). Due to very limited data and small contribution of the Meghna system (6-12 MT/year) to the total sediment flux of the GBM system, the data of the Meghna is not considered in the analysis assuming the sediment flux from GB system as the sediment flux of GBM. However, in this paper our analysis of sediment concentration data (1960-2008) collected by Bangladesh Water Development Board shows that the sediment flux is much lower: 150 to 590 MT/year for the Ganges versus 135 to 615 MT/year for the Brahmaputra, with an average total flux around 500 MT/year. Moreover, the new analysis provides a clear indication that the combined sediment flux delivered through these two major river systems is following a declining trend. In most of the planning documents in Bangladesh, the total sediment flux is assumed as a constant value of around 1 billion tons, while the present study indicates that the true value may be around 50% lower than this (with an average decreasing trend of around 10 MT/year).

A Case of Infantile Large Parapharyngeal Rhabdomyosarcoma Followed Up for More Than 20 Years.

Rhabdomyosarcomas in the parapharyngeal space are quite rare. We report herein on the case of a 14-month-old boy who was hospitalized with a 2-month history of stridor. On admission, right peritonsillar swelling was noted. CT demonstrated the presence of a large tumor in the right parapharyngeal space. MRI findings showed a right parapharyngeal tumor, 6-cm in diameter. Histopathologic evaluation of the tumor revealed embryonal rhabdomyosarcoma. The clinical staging of the Intergroup Rhabdomyosarcoma Study Group (IRSG) was classified as group III. According to regimen 35 of the IRSG III treatment protocol, radiochemotherapy was started, comprising combination therapy with vincristine, actinomycinD, cyclophosphamide, adriamycin, and carboplatin. The patient tolerated the therapy, but with severe pancytopenia and fever. His sedation during irradiation was difficult. After he received a total dose of 10 Gy and had undergone 9 cycles of chemotherapy, an operation for the rhabdomyosarcoma was performed, resulting in successful removal of the tumor. Doses of 20 Gy were intraoperatively administered. After surgery, residual chemotherapy and irradiation was resumed. The evaluation of the response to therapy was complete remission. After 4 years from the start of therapy, all chemotherapy was halted. At present there is no evidence of recurrence or metastasis, and the patient is a well-developed college student. His sequela following therapy consisted of facial asymmetry, dental abnormalities, and pigmentation of the neck. No adriamycin cardiomyopathy was found.