Applied Mechanics and Materials Vols. 212-213

Abstract: The mathematical model of plane two-dimensional flow-sediment in continental sediment-laden river is established in this paper. The two-dimensional model equation is discreted with finite element method and coefficient matrix of ordinary differential equation is approximately dealt with mass-concentration principle, then solve the set of ordinary differential equations with the difference scheme which is first prediction, then correctness and iteration, the stability of this calculation process is better and the efficiency of calculation is comparatively high. The two-dimensional model is applied in numerical modeling of the flow-sediment movement of Yerqiang river middle courses, compared the numerical results with the measured data, which indicates that the numerical results are in good agreement with the measured data, which also prove the reliability and adaptability of the model and calculated method.

Abstract: Taking Nanjing macha river mouth of Yangtze river for example, a two-dimensional flow and sediment mathematical model was established to study flow pattern and characteristics of sediment deposition. The results of flow pattern show that there isn’t flood tidal current in the Nanjing baguazhou reach, but with tidal level alternating between flood tide and ebb tide, there is flood tidal current inside the river mouth under the condition of flood water. The calculation results of sediment deposition show that the sediment deposition is connected with the flow character and the incoming water and sediment condition. The deposition thickness at macha river mouth is much more than that of inside the macha river, and the sediment deposition in 1998 is much more than that of in 2006. With the increasing of calculational time, the deposition thickness per year decreases.

Abstract: By reviewing the application of stochastic hydrological models in flood control safety design, risk analysis, water conservancy project planning and scheduling in recent years in China, it is presented that stochastic hydrological models are good tools for optimizing decisions in planning, design and operation of water resources development and utilization. Also, it deals with the problems which are difficult to solve in traditional hydrological calculation method. Besides, it is focused on some work which should be improvedand popularized about stochastic hydrological models in the future.

Abstract: Groundwater is one of main water supply sources of Jiaodong Peninsula. The groundwater withdrawal accounts for more than 50% of the allowable. With the thorough analysis of groundwater resources quantity and their distribution rule, we make comprehensive analysis and evaluation on the development potential of groundwater of Jiaodong Peninsula. And combined with the actual situation of Jiaodong Peninsula, we discuss four supplement measures to improve groundwater resources.

Abstract: The mechanism of flow turbulence, sediment concentration and sediment grain size that effect the adsorption of phosphorus (P) onto sediment particles in natural waters are experimentally studied both in batch reactors and in an oscillating grid turbulence simulation device. In batch reactor experiments, both of phosphorus sorption isotherms and phosphorus sorption kinetics were studied, and the experimental data was fitted by Langmuir sorption model. The results indicated that both of the phosphorus sorption capacity and phosphorus sorption efficiency are closely related to sediment concentration and sediment grain size. In the oscillating grid turbulence simulation device, it is possible to control the turbulence intensity in two ways, by changing the frequency of the grid and controlling the oscillating stroke. According to this characteristic, the effect of flow turbulence on the adsorption of phosphorus onto sediment particles was experimentally simulated. Then a 1DV model is introduced in this paper to simulate sediment transport and phosphate sorption kinetics process.

Abstract: Urban roofwater harvesting and reuse plays a more and more important role in alleviating the pressure of urban flood control and water shortage. Roofwater was injected into aquifers after initial removal and pre-treatment to add groundwater supply, this methodology was tested in the roof of NO.1 teaching building on the west campus of University of Jinan, where the recharge system was designed and the device of initial rainwater removal was developed. The identification of rainfall intensity and hydraulic calculation of recharge system were carried out. In view of the characteristics of roofwater pollutants, the media, particular size, thickness and rate of filter material were determined by laboratory tests. It is an auto-recharge and gravity-driven system, which was proved to be feasible by the recharge test at the end of flood seasons in 2011.

Abstract: The humid region in south China has abundant rainfall. In order to make effective use of rainfall and save irrigation water, we collected the historical precipitation data of Gaoyou Irrigation District for the past fifty years and used the Geordie Coefficient model of precipitation time evenness index to calculate the precipitation concentration index in different growth stages of rice. The results showed that the precipitation concentration index was low in the early stages of rice; while it gradually increased in the later stages. The precipitation concentration index reached the minimum during the jointing-booting stage and the peak the maturing stage. There were also deceasing trends in precipitation concentration for the early stages. Therefore, it is possible to make better use of rainfall in the early stages of rice growth and save irrigation water. It is necessary to investigate accuracy of rainfall forecasts in future studies.

Abstract: Based on arbitrarily unstructured shallow water current model and finite volume method, a high-order non-oscillatory transport model is constructed. The stability and non-oscillatory condition of the transport model are also analyzed in theory. Usually, the maximum allowable time steps of current model and transport model are different, so an unsynchronized technique is used for the flow and the transport model computations to improve computational efficiency. In addition, the conservation of transport model during the unsynchronized computation is ensured by the time integration of currents continuity equation. Apply this model to the salinity transport simulation of Oujiang estuary, numerical results show that the water level, velocity and salinity agree well with the measured data.

Abstract: Kaifeng locates on a flat and open alluvial plain of the middle and lower reaches of the Yellow River. Owing to its complex history and long-term deposition, a silty stratum with multi-miscellaneous fill and alluvial soil interphase is gradually formed. Combing with the soil actual characteristics of Kaifeng area, which is mainly composed of “high water content”, “high water head”, “strong permeability”, “low strength”, “adequate water supply”, a optimal groundwater control scheme for deep excavation under above complicated geological conditions is proposed. Moreover, the most appropriate waterproof curtain form is recommended for the foundation pit engineering whose excavation depth is less than 10m. The findings of this investigation may offer some suggestions for the choice of groundwater control scheme for construction purpose in similar strata.

Abstract: Wind rose analysis method, two dimensional hydrodynamic model and particle tracer model are adopted to systematically study wind field features, flow field variation, and migration, spreading and accumulation processes of the internal and external cyanobacterial boom in Dianshan Lake. The results show that the wind direction in Dianshan Lake varies with seasons; the main wind direction is ESE in summer and autumn, and is NNW in winter and spring. Wind has great effects on the circulation patterns of the lake. In the case of no wind, the lake is mainly influenced by the upstream and downstream flows. River flow enters into the lake during flood tide, while the lake discharges during ebb tide, and there is no circulation occurred; the clockwise and counterclockwise circulations are generated respectively in the north and south of the lake under southeast wind, and similarly for northwest wind only the circulation directions are opposite. Upon different wind and flow fields, cyanobacterial boom is drifting to the windward lakeshore, and is prone to form the algae accumulation area.