Key Laboratory of Water and Sediment Science and Water Hazard Prevention of Hunan Province

Changsha, China

Key Laboratory of Water and Sediment Science and Water Hazard Prevention of Hunan Province

Changsha, China
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Chen H.,Changsha University of Science and Technology | Chen H.,Key Laboratory of Water and Sediment Science and Water Hazard Prevention of Hunan Province | Liu S.,Guangdong Jindonghai Group Co. | Chen S.,Guangdong Jindonghai Group Co. | And 5 more authors.
Advances in Science and Technology of Water Resources | Year: 2013

In order to solve the problems that a long period is needed in the free settlement of the hydraulic-dredged mud, a large quantity of silt particles is brought away during the discharge of the recession flow, and a long period is also needed for the natural consolidation of the dredged mud foundation, PAC or PAM was added into the mud mixture individually in the study. After the agitation and precipitation, the residual turbidity, the residual SS of the supernatant and the height of the interface between supernatant and sediments were measured to investigate the coagulation sedimentation property. The experimental results show that both residual turbidity and SS value decrease first and then increase, and the interface remains unchanged with an increased dosage of PAC or PAM. When a PAC dosage of 360 mg/L was added, the minimum residual turbidity and SS value were obtained with the values of 287.4 and 1.45g/L, respectively. When a PAM dosage of 2.8 mg/L was added, the minimum residual turbidity and SS value were obtained with the values of 752.7 and 2.83 g/L, respectively. The addition of coagulants could in some extent promote the settling and separation of the hydraulic-dredged mud, and enhance the water quality of the recession flow.


Jiang C.-B.,Changsha University of Science and Technology | Jiang C.-B.,Key Laboratory of Water and Sediment Science and Water Hazard Prevention of Hunan Province | Long Y.-N.,Changsha University of Science and Technology | Long Y.-N.,Key Laboratory of Water and Sediment Science and Water Hazard Prevention of Hunan Province | And 3 more authors.
Shuili Xuebao/Journal of Hydraulic Engineering | Year: 2012

Overland flow resistance (OFR) is an important parameter which reflects overland flow characteristics. Exploring OFR is critical for understanding the flow characteristics, overland flow routing, soil erosion and mechanism of sediment yield on sloping land. This paper summarizes the five aspects of recent progress in studies of overland flow resistance: (1) the relationship between overland flow resistance and Reynolds number; (2) flow resistance of plane beds; (3) flow resistance of rough beds; (4) the influence of rainfall on OFR, and (5) flow resistance modeling. It is found that (1) the relation between overland flow and Reynolds number can be a positive or negative correlation under different conditions; (2) linear superposition approach to calculate the overland flow resistance under different conditions is problematic; (3) overland flow resistance calculation model is close to the practical condition on rough mobile beds. At last, this paper points out the major problems in current studies of overland flow resistance and the hot topics in this field.

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