The city of New Owerri Nigeria is situated on a flat terrain and rainfall pattern is tropical high. The area is the seat of Government of Imo state and is crisscrossed by network of dual carriage roads adjoining exclu...The city of New Owerri Nigeria is situated on a flat terrain and rainfall pattern is tropical high. The area is the seat of Government of Imo state and is crisscrossed by network of dual carriage roads adjoining exclusive housing complexes. The road drainage system comprises open concrete drains on both sides of the cambered asphalt pavement. Much of the area is often flooded after a torrential rainfall and the flood water remains in the drains as long as evaporation permits. A study shows that the scenario is due to a number of factors, amongst which siltation and vegetal growth in the drains, poor drainage outlets are, very gentle terrain and poor maintenance culture. The standing pools of water in the drains sustain massive breeding of mosquitoes which constitute health hazard. Replacement of open concrete drains with properly designed trenches backfilled with permeable earth materials, sand, and overlay of grasses does not only reduce standing time of flood water but completely eliminates stagnant water. The method makes use of enlarged surface area of infiltration provided by the trenchless drain and millions of infiltration channels provided by the grass rootlets.展开更多
This paper proposes an equation to calculate breaking wave induced wave set-up and set-down along reef flat. The mathematical equation was derived based on the theory of radiation stress and the conservation of wave e...This paper proposes an equation to calculate breaking wave induced wave set-up and set-down along reef flat. The mathematical equation was derived based on the theory of radiation stress and the conservation of wave energy. The equation is primarily determined by several physical variables including the breaking wave index, the stable wave index, the attenuation coefficient of wave energy flux, and the flow velocity in the re-stabilization zone. A series of laboratory experiments were carried out to calibrate the theoretical equations. Specifically, the breaking wave index,the stable wave index, and the velocity over the reef flat were measured in the laboratory. The attenuation coefficient of wave energy flux in our theoretical equation was determined by calibration by comparing with the laboratory measured wave height. Furthermore, it has been put forward that the velocity based on cnoidal wave theory could be used to determine the velocity over the reef flat if there is no velocity measurement available. Overall, the proposed equation can provide satisfactory prediction of wave set-up and set-down along the reef flat.展开更多
文摘The city of New Owerri Nigeria is situated on a flat terrain and rainfall pattern is tropical high. The area is the seat of Government of Imo state and is crisscrossed by network of dual carriage roads adjoining exclusive housing complexes. The road drainage system comprises open concrete drains on both sides of the cambered asphalt pavement. Much of the area is often flooded after a torrential rainfall and the flood water remains in the drains as long as evaporation permits. A study shows that the scenario is due to a number of factors, amongst which siltation and vegetal growth in the drains, poor drainage outlets are, very gentle terrain and poor maintenance culture. The standing pools of water in the drains sustain massive breeding of mosquitoes which constitute health hazard. Replacement of open concrete drains with properly designed trenches backfilled with permeable earth materials, sand, and overlay of grasses does not only reduce standing time of flood water but completely eliminates stagnant water. The method makes use of enlarged surface area of infiltration provided by the trenchless drain and millions of infiltration channels provided by the grass rootlets.
基金jointly supported by the National Key R&D Program of China (Grant No. 2018YFC0407503)the National Natural Science Foundation of China (Grant No. 51779149)+2 种基金the Scientific Research Project of Yangtze-to-Huaihe Water Diversion Project (Grant No. YJJHYJJC-ZX-20191106220)the Nanjing Hydraulic Research Institute Special Fund for Basic Scientific Research of Central Public Research Institutes(Grant Nos. Y220002, Y219012 and Y220013)the Water Conservancy Science and Technology Project of Jiangsu Province (Grant No. 2019009)。
文摘This paper proposes an equation to calculate breaking wave induced wave set-up and set-down along reef flat. The mathematical equation was derived based on the theory of radiation stress and the conservation of wave energy. The equation is primarily determined by several physical variables including the breaking wave index, the stable wave index, the attenuation coefficient of wave energy flux, and the flow velocity in the re-stabilization zone. A series of laboratory experiments were carried out to calibrate the theoretical equations. Specifically, the breaking wave index,the stable wave index, and the velocity over the reef flat were measured in the laboratory. The attenuation coefficient of wave energy flux in our theoretical equation was determined by calibration by comparing with the laboratory measured wave height. Furthermore, it has been put forward that the velocity based on cnoidal wave theory could be used to determine the velocity over the reef flat if there is no velocity measurement available. Overall, the proposed equation can provide satisfactory prediction of wave set-up and set-down along the reef flat.
