River dynamics play the most vital role in the socio-economic of the country. These rivers are highly dynamic in nature which causes extensive riverbank erosion. Active river bank erosion and bed scouring, is apprehen...River dynamics play the most vital role in the socio-economic of the country. These rivers are highly dynamic in nature which causes extensive riverbank erosion. Active river bank erosion and bed scouring, is apprehended to change the scenario, leading to loss of limited valuable land of Bangladesh. River training is being practiced in Bangladesh since 1960s but the process is very expensive especially in the Ganges and the Jamuna Rivers. Five types of river training works were selected at different reaches. Hydro-morphological characteristics of the major rivers are being evaluated not only in engineering concepts but also in socio-economic and environmental aspects. PRA （participatory rural appraisal） tools were applied to evaluate protection safety, hydraulic and hydrological connectivity, ecological and environmental characteristics, causes of failure and social acceptability. This comparative study is being carried out for closing the gap between the modem river training works and in country experience through adaptation of research findings with a view to effectively arresting river bank erosion. Sirajganj Hardpoint, Chandpur Town Protection work and Nakalia Revetment are found to be suitable and effective. A technically suitable structure may not have good social acceptance without IWRM （integrated water resource management）.展开更多
Rock-fill dykes are often damaged caused by rapid flow currents in a mountainriver. Based on the relationship between the rock size on cover layer and its incipient velocity,it is found that rock weight is directly pr...Rock-fill dykes are often damaged caused by rapid flow currents in a mountainriver. Based on the relationship between the rock size on cover layer and its incipient velocity,it is found that rock weight is directly proportional to the 6th-9th power of incipient velocity,and 50% increase of the velocity may result in about 40 times increase of the rock weight.Therefore, it is inappropriate to improve the stability of rock-fill dykes by simply increasing therock weight. Some new measures should be used to reach this purpose.展开更多
文摘River dynamics play the most vital role in the socio-economic of the country. These rivers are highly dynamic in nature which causes extensive riverbank erosion. Active river bank erosion and bed scouring, is apprehended to change the scenario, leading to loss of limited valuable land of Bangladesh. River training is being practiced in Bangladesh since 1960s but the process is very expensive especially in the Ganges and the Jamuna Rivers. Five types of river training works were selected at different reaches. Hydro-morphological characteristics of the major rivers are being evaluated not only in engineering concepts but also in socio-economic and environmental aspects. PRA （participatory rural appraisal） tools were applied to evaluate protection safety, hydraulic and hydrological connectivity, ecological and environmental characteristics, causes of failure and social acceptability. This comparative study is being carried out for closing the gap between the modem river training works and in country experience through adaptation of research findings with a view to effectively arresting river bank erosion. Sirajganj Hardpoint, Chandpur Town Protection work and Nakalia Revetment are found to be suitable and effective. A technically suitable structure may not have good social acceptance without IWRM （integrated water resource management）.
文摘Rock-fill dykes are often damaged caused by rapid flow currents in a mountainriver. Based on the relationship between the rock size on cover layer and its incipient velocity,it is found that rock weight is directly proportional to the 6th-9th power of incipient velocity,and 50% increase of the velocity may result in about 40 times increase of the rock weight.Therefore, it is inappropriate to improve the stability of rock-fill dykes by simply increasing therock weight. Some new measures should be used to reach this purpose.
