Wang Guangqian

Daily optimized model for long-term operation of the Three Gorges-Gezhouba Cascade Power Stations

This paper presents the step-by-step genetic algorithm based on artificial intelligence guidance and builds a long-term daily optimized operating model for the Three Gorges-Gezhouba Hydropower Complex with single generating set as the based operating unit. Actual operating data from 2004 to 2006 are used to verify the model, and results show that the simulation accuracy determined by measuring the total amount of cascade power generation reaches 99.66%. Statistic hydrological data of normal years and actual data of three years of 2004–2006 are respectively used to perform an optimized prediction of the power generation process and benefits in future when the water stored in the TGP Reservoir reaches 175 m level and power generation benefits under different operation modes, such as delayed subsiding water level, advance water storage, and adopting of different flood-limited water levels, are forecasted. In the case of years with normal inflows, the total amount of cascade power generation running on current specifications reaches 107500 GWh per year. If the commencement of water storage after the flood season is moved forward by 20 days, the amount of power generation can be increased by 3400 GWh per year. If the limited water level in the flood season is raised by three to five meters, the amount of power generation can be increased by 1600 to 3200 GWh per year. If the commencement of water storage is moved forward while the maximum water level allowed in the flood season is raised, the amount of power generation can be increased by 6400 GWh per year.

Research on underground water pollution caused by geological fault through radioactive stratum

The earthquakes cause appearance of new geological fault and dislocation of rock stratum; the original permeable rock breaks, then the fault can conduct water under the effect of pressure; the stratum with radionuclide is dislocated and connected to the water-conducting fault under the effect of the fault. Under the effect of water the stratum with seepage and the one with radionuclide link up. It causes radioactive pollution on underground water, based on which this paper does a research and makes an analysis of the radioactive pollutant concentration that diffuses along the top and bottom section and centre line of the fault following the seepage. It turns out that in the rock stratum with seepage suffering rupture, the radioactive pollutant effects an elliptical spherical diffusion. In the turning point of the fault, the elliptical sphere makes a turn following the seepage.

Two-dimensional numerical modeling of the longitudinal and lateral channel deformations in alluvial rivers

Two kinds of bank erosion mechanisms were analyzed, including fluvial and non-fluvial controlled mechanisms, and mechanical methods of simulating the erosion processes of cohesive, non-cohesive and composite riverbanks were improved. Then a two-dimensional numerical model of the channel deformation was developed, consisting of a 2D flow and sediment transport submodel and bank-erosion submodels of different soil riverbanks. In the model, a new technique for up dating the bank geometry during the bed evolution was presented, which combines closely two kinds of submodels. The proposed model is capable of not only predicting the processes of flood routing and longitudinal channel deformation in natural rivers, but also simulating the processes of lateral channel deformation, especially the processes of lateral erosion and failure of cohesive, non-cohesive and composite river banks.

Numerical simulation of ae- olian sediment transport

A discrete element model (DEM) is developed for aeolian sediment transport in the scope of investigation of the dynamic behavior of grains, in which the motion of individual grain is considered while velocity distribution of wind is given according to bed forms. The above model has been used for simulating the phenomenon of 4000 grains blown by wind, resulting in ripples and saltating paths, which shows good agreements with experimental observations. The result is helpful for revealing the intrinsic mechanism of sand flow.

Simulation of fan formation using a debris mass model

Based on the particle-in-cell computing method, a debris mass model has been established to simulate debris flow fan formation over large downstream areas. Under the assumption that the debris medium is an assembly of many small, identical debris particle masses, the overall flow behavior is obtained by averaging the flow parameters of neighboring debris masses at fixed grid points. The equation of motion for each debris mass is based on the depthaveraged Navier-Stokes equation in two horizontal dimensions. The friction slope of debris flow is modeled by combining the effects of both the liquid phase (slurry composed of water and fine particles) modeled as a Bingham fluid and solid phase (coarse particles) in the debris mixture. The rheological parameters are evaluated according to the density and particle size distribution of the debris material. Convergence of the method is demonstrated by repeatedly doubling the number of debris masses employed in the computation until insignificant change is observed. The debris mass model is demonstrated through a prototype application to a documented 1991 debris flow deposited in the lower reach of the Shawan Ravine in Yunnan Province. China. The final alluvial fan was formed by eight consecutive debris flow events, each lasting about 2000 seconds with a discharge rate of 250 m3/s. The simulation results are in good agreement with field observations. The general features of debris fan development and configuration are well predicted.

Transport Model of Underground Sediment in Soils

Studies about sediment erosion were mainly concentrated on the river channel sediment, the terrestrial sediment, and the underground sediment. The transport process of underground sediment is studied in the paper. The concept of the flush potential sediment is founded. The transport equation with stable saturated seepage is set up, and the relations between the flush potential sediment and water sediment are discussed. Flushing of underground sediment begins with small particles, and large particles will be taken away later. The pore ratio of the soil increases gradually. The flow ultimately becomes direct water seepage, and the sediment concentration at the same position in the water decreases over time. The concentration of maximal flushing potential sediment decreases along the path. The underground sediment flushing model reflects the flushing mechanism of underground sediment.

Spatial integrated analysis on water erosion of Yellow River China

Using remote sensing technology applied to research water erosion introduced firstly, and then choosing such data mining approaches as spatial statistical analysis and spatial cluster analysis to discuss the relationship between water erosion and geologic environment and other factors of Yellow River. The results show in two aspects below. (1) The character of spatial distribution was compared under the condition of different grade elevation, average temperature per year, rainfall and other geographic environment factors. The percentage of water erosion area above heavy under the condition of six-grade elevation (elevation between 1501 and 20000), eight-grade average temperature per year (between 8.1 and 10 centigrade) and five-grade rainfall (between 400.1 and 500 mm) is more than any other geographic environment. (2) On the basis of geographic environment factors, the discrepancy of the region of water erosion of Yellow River was analyzed using spatial cluster analysis, and the water erosion percentage of the fifth type account for most of all these ten regions.

Sky River: Discovery, concept, and implicationsfor future research

Presented in this paper is a brief introduction to our recent discovery and definition of Sky River, as well as its implications for future research. Based on meteorological reanalysis data, we found that there exist highly structured water vapor conveyance systems in the troposphere of the atmosphere. The water vapor conveyance systems have higher vertically integrated flux than their immediate environments, consisting the dominant channels from local scale to global scale for atmospheric water vapor transfer. The water vapor transfer systems in the troposphere share the similarity of having high water (vapor) conveyance with land surface rivers and thus can be referred to as “River in the Sky”, or simply “Sky River”. Sky River is different from “atmospheric river” essentially in that it is a global system where water vapor concentrated and conveyed by atmospheric circulations, rather than the transient and local high flux belts found in previous studies. Studies on the Sky Rivers will help us to have a new vision about global atmospheric water vapor transfer and a better understanding of global water cycle.

Study on the Evaluation Method of Groundwater Vulnerability to Pollution from Informal Landfills in Regional Scale

Aimed at the increasing severe domestic wastes pollution, evaluation model of groundwater vulnerability to pollution from informal landfills in regional scale has been proposed. It is based on the DRASTIC model and LeGrand model, considering the characteristics of regional geology and hydrogeology, as well as pollution that landfills do to groundwater. Then the actual and potential risks in groundwater environment that are caused by informal landfills have been quantified. Take the Beijing Plain as example, which shows the method is feasible and the result is reliable.

A conditional value-at risk-based two-stage stochastic programming model for grassland ecosystem restoration—A case study for the three-river source

Taking three-river source grassland ecosystem as an example, a conditional value-at risk-based two-stage stochastic programming model was proposed for grassland ecosystem restoration. Overload area and restoration area of grassland ecosystem in the three-river source region can be optimized with consideration of environmental requirements, soil erosion and restoration cost. Loss of overload, increased ecological benefit and additional cost of restoration can be evaluated, which will provide theoretical basis for grassland ecosystem restoration and management in three-river source region. Results indicate that overload area and loss of overload will decrease with the stochastic level increase. The total ecological benefit of grass ecosystem will decrease with risk level decrease, indicating that risk attitudes of decision-makers play a decisive role in developing sustainable ecological management schemes. The obtained results can be helpful for decision makers to balance the conflicts between ecological benefit and system risk. Reducing the total amount of livestock should be taken as the main goal of grassland ecosystem restoration and management, while ecological stockbreeding should be developed to promote sustainable development of grassland ecosystem and livestock. Besides, compensation mechanism in related areas should be refined to coordination the relationships between economic development and ecosystem conservation.