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Chen G.,Hohai University | Chen G.,Yunnan Survey and Design Institute of Water Conservancy and Hydropower | Zhang Y.,Yunnan Survey and Design Institute of Water Conservancy and Hydropower | Zhou M.,Yunnan Survey and Design Institute of Water Conservancy and Hydropower | Gu S.,Yunnan Survey and Design Institute of Water Conservancy and Hydropower
Shuikexue Jinzhan/Advances in Water Science | Year: 2016

Composite roughness is a crucial parameter in determining the stage-discharge relationship using Manning's formula. Due to the increased resistance resulting from ice cover, a stage-discharge relationship developed in open water is not applicable to the ice-affected reason. This calls for the development of a new stage-discharge relationship. According to the Einstein hydraulic radius separation theory, the flow cross section of a rectangular ice-covered river may be divided into bed, ice and side-wall subsections. Based on the determination of hydraulic radius and sectional area of each flow subsection, this paper presents an analytical solution of composite roughness for flows in rectangular ice-covered rivers. Comparisons of the calculated results with measured data from literature show that the proposed formula does well in predicting the composite roughness of rectangular ice-covered rivers. Compared with Einstein formula and Sabaneev formula, the proposed formula produces more accurate results. For wide ice-covered rivers, if width-depth ratio is greater than 20, hydraulic radius may be considered approximately equivalent to flow depth as a simplification of relatively high precision. © 2016, Science Press. All right reserved.


Chen G.,Hohai University | Chen G.,Yunnan Survey and Design Institute of Water Conservancy and Hydropower | Gu S.,Yunnan Survey and Design Institute of Water Conservancy and Hydropower | Huai W.,Wuhan University | Zhang Y.,Yunnan Survey and Design Institute of Water Conservancy and Hydropower
Journal of Hydraulic Engineering | Year: 2015

This paper develops an analytical approach to evaluate the mean boundary shear stress in rectangular ice-covered channels. The flow cross section was divided into an upper ice layer and a lower bed layer at the plane of zero shear stress, determined analytically from an order of the Boussinesq approximation involving the eddy viscosity concept, together with Prandtl's mixing length theory. The conformal mapping procedure was used to obtain the functional relationships for the division curves within each flow layer. Based on the force balance in each flow subregion, an analytical model for the average bed, ice, and side-wall shear stresses was developed. The two-power law for describing vertical velocity profiles in asymmetric channels was adopted to determine the location of zero shear stress and its parameters, determined using coupled equations for the flat-bed friction factor and an empirical relationship for the bed-form friction factor. A comparison between the results of the present model and the collected data from literature shows that the proposed method does well in predicting the mean boundary shear stress in rectangular ice-covered channels. © 2015 American Society of Civil Engineers.


Gu S.,Yunnan Survey and Design Institute of Water Conservancy and Hydropower | Chen X.,Yunnan Survey and Design Institute of Water Conservancy and Hydropower | Su J.,Yunnan Survey and Design Institute of Water Conservancy and Hydropower | Xie B.,Yunnan Survey and Design Institute of Water Conservancy and Hydropower | And 2 more authors.
Advances in Science and Technology of Water Resources | Year: 2014

In order to analyze the water level of Dianchi Lake after the construction of several inter-basin water diversion projects, including the Zhangjiu River Water Diversion and Supply Project, the water supply project of the Qingshuihai Lake Water Supply and Water Sources Management Project, and the Water Diversion Project from the Niulanjiang River to Dianchi Lake, data from the investigation of current social and economic development, long-term hydrological observation data series, and water supply, utilization, consumption, and drainage data series from the Dianchi Basin and the Haikouhe-Tanglangchuan Basin were collected. Then, the runoff reduction method and a simulation method for lake runoff and flood regulation were adopted. Through comparison of multiple schemes, reasonable values of the water level of Dianchi Lake were determined as follows: the normal pool level was set to 1887.50 m, and the limiting level during the flood season was set to 1887.20 m. Unless the spillway of Dianchi Lake and the forecast and operation system are built, the limiting level during flood season should not exceed 1886.70 m during operation. The areas in the outer lakes of Dianchi Lake with a water level beneath the normal pool level were divided into the ecological water supply (utilization) area, the industrial and agricultural water supply area, and the dead storage area. The results show that Dianchi Lake has changed from a former water supply source into a water body that has to be supplemented with water for ecological rehabilitation, and that the high water consumption industry in Kunming City and areas around Dianchi Lake has to be moved to the downstream Haikou-Anning area in order to reduce the consumption of water resources in Dianchi Lake and the contaminants into the lake. Therefore, the social and economic development will be guided by the water resources situation, and the strategic adjustment of the industrial layout will be achieved.

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