Abstract:Based on the definition and connotation of water environmental capacity, the shortcomings of currently prevalent zero-dimensional and one-dimensional methods for estimating the water environmental capacity of medium- and small-sized rivers are pointed out. According to these shortcomings, a new method considering the variation of water environmental capacity along a river is put forward. This method eliminates the exaggerated part of the environmental capacity estimation generated with the previous methods, and it is more practical. Moreover, the critical judgment criteria for estimating the existence of water environmental capacity are derived, including the maximum allowable concentrations of discharged pollutants and the maximum ratio of the length of the river reach with water quality indicators exceeding the standards to the total length of the river. Finally, practical cases are provided in order to compare the proposed method with previous methods.

Abstract:An optimal operation model based on the evenshortage water supply hedging rules can be used to solve the timehistory allocation problem in irrigation water quantity because the water demand process is uneven and highly correlated with timehistories. The objective function of the minimum square sum of the water deficit ratio was analyzed based on the meaning of an evenshortage water supply object. The results show that the objective function cannot obtain a water supply process with an even water deficit ratio, and the water deficit ratio is proportional to water demand. Based on the fundamental form of the objective function of the minimum square sum of the water deficit ratio, and considering the constraint of the water balance, the Lagrangian function was built and a new objective function with an even water deficit ratio was derived. Considering the sensitivity extent of crops in different growth stages, the weighting objective function with an even water deficit ratio was constructed by introducing the water sensitivity coefficient. The improved objective function was validated by analyzing a variety of water process examples.

Abstract:In order to study the spatial and temporal dynamic changes of water salinity at a large scale in coastal reservoirs, the source and sink terms in the salinity transport equations of the hydrodynamics and water environment numerical simulation model, i.e., the Delft3D model, were improved, and the improved Delft3D model was validated by comparing the simulation values with theoretical values. The results show that the improved Delft3D model can be applied to the simulation of water salinity change in a proposed coastal reservoir, and quantitatively predict the salinity change processes of the reservoir caused by the sediment salt release under different scenarios.

Abstract:Using the Dongsha offshore radial sand ridges as a study area, the layout design for the offshore sand ridge artificial island was studied under the condition of insufficient basic hydrologic, sediment, and terrain data. With longterm remote sensing data under ebb tide conditions from 1973 to 2014, stability analysis of tidal flats was carried out based on the repetition rate of the exposure area, and the most stable and appropriate dike outlines for sand ridge reclamation were identified based on the distribution characteristics of the repetition rate and the spectral distribution of the grid number. According to the characteristic lines of geomorphological evolution, including the water parting line of the sand ridges and that of the main tide intake subbasin, the internal contours for the water parting lines in the reclamation area and of the main tide intake subbasin were designed.

Abstract:Tidal flats, which represent a wide landsea interaction zone, are difficult to measure. The lack of historical topographic data has seriously affected the development and utilization of tidal flats. Using a tidal flat of radial sand ridges as an example, waterlines under different tide conditions were extracted from TM and MSS remote sensing images from around 1987, and sea surface heights were simulated with a Mike21 hydrodynamic model. Elevations were assigned to the waterlines. The digital elevation model was obtained through the terrain iteration process. The results show that, in the tidal flat of radial sand ridges, there is a strong correlation between the topographic results obtained from the waterline method and the measured data from the nautical chart, with a coefficient of determination (R2) of 0.864, a mean absolute error of 0.37m, and a root mean square error of 0.41m, indicating that the topographic results can be further used to analyze the morphologic evolution of the tidal flats.

Abstract:In order to reduce the siltation downstream of tide gates constructed in a seaward channel that has a significant impact on the efficiency of the drainage culvert and navigation capability of the seaward channel, the CST module in the MIKE11 model was used to study the water requirement for silt scouring in the seaward channel at the Xinyang Port in Yancheng City. The CST module was developed by coupling a hydrodynamic model and sediment transport model, with the model parameters calibrated using the measured data of water level, flow rate, and siltation height at three sections, located, respectively, 60 m, 970 m and 3 030 m downstream of the gate. The calculated ecological flow rate for silt scouring and port protection with the MIKE11 CST model was 80 m³/s under a siltation height of no more than 0. 1 m. This value was close to the flow rate of 85 m³/s obtained from experiments on silt scouring by water diversion from the Yangtze River at the Xinyang Port in December 2006, under the conditions of no silting and no scouring.

Abstract:Using the Tiaozini reclamation project as a case study, the offshore phytoplankton, zooplankton, macrobenthos, and intertidal benthos before and after reclamation were surveyed, and the variations of ecological characteristics were analyzed. The results show that phytoplankton species and biological density increased and species composition changed after reclamation; the number of zooplankton species near the reclamation area increased, and the dominant species changed; the number of benthic species decreased, with crustaceans being the main species, uniformly distributed at all monitoring stations before reclamation but only at some stations after reclamation; the number of intertidal benthos species decreased, but the dominant species were still shellfish with economic value, such as Mactra veneriformis; and the variations of biological density and biomass were small. It is concluded that reclamation changes a variety of environmental factors in the habitat, such as hydrodynamic conditions, suspended solids, and sediment characteristics, resulting in variations in biodiversity and community structure of aquatic organisms.

Abstract:A field survey and quadrat sampling methods were used to investigate vegetation during different reclamation periods in Jianggang Town, Dongtai City, Jiangsu Province. The communitys dominant species, species richness, Simpson index, and Shannon index were used to analyze the characteristics of the plant community. Soil samples were taken to determine the pH value, conductivity, and salinity. The results show that the soil salinity and conductivity are the two most important factors affecting the distribution of plants in the tidal flats; and the reclamation of tidal flats influences community types, species richness, and, especially, the characteristics and distribution of the plant community.

Abstract:Based on landuse maps and soil distribution maps of three years (1985, 1995, and 2005) and basic information, such as temperature, precipitation, and runoff, from the main hydrological stations in the Zhangweinan River Basin during the period from 1960 to 2010, this paper establishes a distributed hydrological model, soil and water assessment tool (SWAT) model, and proposes an itemized quantitative method to measure the impact of climate changes and human activities on runoff. By simulating different scenarios, the contribution rates of different humanactivity driving factors, such as water and soil conservation, urbanization, hydraulic engineering, and social economy water consumption, to runoff in different eras were quantitatively calculated based on the quantitative analysis of the impact of climate changes and human activities on runoff in the Zhangweinan River Basin. The results show that there are different impact degrees of climate changes and human activities on runoff in different eras. Compared with the baseline period from 1960 to 1978, the contribution rates of climate changes and human activities to runoff of the changing period from 1979 to 2010 are 29.39％ and 70.61％, respectively. All driving factors of human activities caused runoff to decrease, except for urbanization. The impact of social economy water consumption is greatest, accounting for more than 50％ of the total runoff reduction caused by human activities.

Abstract:An iterative model was proposed to approximate the Richards' equation by coupling the soil water budget method and the analytical solution of steadystate transpiration flux, and was used to analyze the variation of soil water storage with groundwater table and its influences on soil water evaporation and groundwater evaporation. The coupled model was verified against the Hydrus-1D model. Then, the model was applied to simulation of the variation of soil water storage and transpiration flux at the groundwater depths of 0.4 m, 0.6 m, and 1.5 m at the Wudaogou Hydrological Experimental Station in Anhui Province, and the results were compared with observations from three lysimeters. The results indicate that the coupled model can effectively simulate the effects of the groundwater table on soil water storage and evaporation flux under capillary forces, and conduct a reasonable inversion of the hydraulic conductivity and pore size distribution index at different groundwater depths.

Abstract:In order to improve the method for bioremediation of soil contaminated by heavy metals, ironbased complexes produced by the metabolism of iron bacteria A were used to remediate soil contaminated by Pb2+or Cu2+. The effects of bioremediation through different grouting methods were investigated. Methods including scanning electron microscopy (SEM), Xray diffraction (XRD), and Fourier transform infrared spectroscopy (FTIR) were used to identify the composition and structure of ironbased complexes and to analyze the deposition mechanism of heavy metals. Results showed that the concentrations of available Pb2+ and Cu2+ in soil decreased by 64.6％ to 70.4％ and 47.6％ to 49.2％, respectively, after one round of biogrouting, and decreased by 75.1％ to 85.5％ and 73.3％ to 78.9％, respectively, after two rounds of biogrouting. Microscopy analyses showed that the ironbased complexes, which contained schwertmannite and Ferrum oxydatum phosphate, as well as other substances with excellent flocculation efficiency and large specific surface area, had poor crystalline form, but could fix heavy metals in a contaminated environment through adsorption and coprecipitation.

Abstract:The electric topological structure of a hybrid offshore renewable energy generation system, including offshore wind, wave, and tidal power generations, is described. Using this system as an example, a detailed model and phasor model based on the Matlab/Simulink platform were built. On the basis of a qualitative analysis of the differences in these two models, simulations were carried out with different wind speeds and power grid disturbance faults. Timedomain simulation results show that the tendency of steady and dynamic responses of the detailed model and phasor model are similar; the simulation time is longer when using the detailed model, and the simulation curves contain highfrequency components; and, with the phasor model, the simulation time is shorter, and the simulation curves are relatively smooth.

Abstract:In order to effectively restrain the harm caused by harmonics injected by an ultrahighvoltage direct current (UHVDC) converter station to an alternating current (AC) system, according to the basic principles of the design of AC filters, a set of AC filter design software for UHVDC projects was developed. The software has various functions, including inputting, modification, saving, and batch generation of relevant parameter files; configuration of AC filters; analysis of harmonics; calculation of filter performance and steadystate rating; importing of result data into the database; and generation of word report forms. The software was used to design AC filters for a UHVDC project. The results show that the proposed software is flexible, accurate, convenient, and universal.

Abstract:In order to handle the uncertainty of data used in quality of service (QoS) prediction, increase the confidence value of prediction results, and make the QoS prediction more reliable, a probability model for quantifying the confidence in QoS prediction was built. In the process of building the model, the number of QoS data items used in prediction, the data fluctuation (data deviation), and the data decay over time were considered. The results show that the number of data reflects the impact of the number of QoS data used in prediction on the reliability of the prediction result, the data deviation reflects the consistency degree of the actual value and predicted value of QoS in service, and the data decay reflects the impact of data on the prediction result over time. The simulated test indicates that the confidence model can help consumers effectively select services based on their requirements.

Abstract:In order to improve the performance of the inversion algorithm for travel time tomography, a simple iterative algorithm based on the precise integration method was used. The improved algorithm could be considered a simple iterative process. The precise integration method was used to solve the inverse matrix to ensure convergence and obtain the true solution to the equation at a higher speed of iteration. The checkerboard model recovery test and real data inversion results show that the calculation process of the improved algorithm is simple, and the algorithm can obtain the velocity profile with higher resolution and fewer iterations. Compared with some commonly used methods, this algorithm has higher image resolution and greater iteration efficiency.