Abstract:Quantitative assessment of the climate change and human activity to the run-off alteration is significant for the sustainable management of regional water resources. The time series of run-off from 1960 to 2015 are characterized by three periods: the baseline period(1960-1971), the changing periods Ⅰ(1972-1985)and the changing period Ⅱ(1986-2015)according to the trend analysis. The sensitivity and its spatial distribution of run-off alteration on climate changes and human activities are analyzed based on the water balance and the Budyko hypothesis. The results show that the streamflow alteration is most sensitive to human activities in the Tarim River Basin during the period of 1986-2015. An obvious increase of run-off sensitivity occurred on the precipitation, potential evapotranspiration and catchment parameter from the baseline period to the impact period Ⅱ, and sensitivity indexes are in 1. 26, -0. 26 and -1. 88 in changing period Ⅱ, respectively. Moreover, a regional difference has been observed in the elasticity coefficient and the downstream is higher than the upstream of Tarim River. In the view of the deepening and aggravating loss of run-off due to the climatic change and anthropogenic factors, it is significant for the development and management of regional water resources by taking timely measures according to the sensitivity analysis.

Abstract:Hydrological experimental areas(catchments)in plains provide a base for conducting the field experiments, exploring the formation and physical mechanism of the hydrographic phenomenon, and studying the relevant methods. Abundant achievements have been obtained and many problems arose in the construction and research during the 60-year tortuous development. This paper reviewed the development history and current situation of hydrological experimental areascatchments)in plains in China and abroad. Besides some main achievements, general historic problems during the establishment of experimental areas(catchments)in plains were revealed and a few meaningful lessons were drawn from the past. Additionally, we took the experimental research work in the plain of Taihu Lake Basin as an example and introduced the particular research goals as well as the related establishing process. We hope that it can provide a reference for the newly-building, recovering and extending of the hydrological experimental area in plains in the future.

Abstract:To explore the pollution distribution, source and degree of the Huaihe River sedimentary, 16 sections along the midstream and downstream of the Huaihe River were sampled in July 2014. Then, the total phosphorus(TP)and heavy metals(As, Cu, Pb, Cd, and Zn)in the sediments were analyzed to explore the distribution of contaminants, source and pollution status. The results showed that the average content of pollutants in the downstream sections of main cities was higher than that of the upstream. The analysis of pollutant sources showed that all pollutants were affected by the point source pollution, while TP and Cu were polluted by both the point source pollution and non-point source pollution. The standard index method of a single factor was applied to evaluate the phosphorus pollution in the sediments. The results indicated that the environmental quality of sediments in the Huaihe River was less polluted by the phosphorus. The analysis on the potential ecological risk of heavy metals showed that both the ecological risk of the single heavy metal and the comprehensive ecological risk were slight.

Abstract:The research on the vegetation phenology evolution and its driving forces are of critical importance for the eco-system, global meteorological and hydrological processes. Meanwhile, it is a highlighted topic in the meteorological hydrology and eco-hydrology community. Based on the review of the progress made on the vegetation phenology observation and phenological model research based on the in-situ observation and remote sensing, the main challenges of the remote sensing based phenological modeling research were summarized. Then, the suggestions and prospection were proposed as follows; (1)carry out the research based on both the hydrological and large scale phonological models; (2)investigate quantitative methods to evaluate the control of environmental factors; (3)develop phenology predicting models.

Abstract:In order to study the effect of influencing factors on the wave dissipation and figure out the optimized layout of wavebreak forest in the Nenjiang River mainstream, influencing factors including the arrangement mode, row spacing, stem radius, crown radius, width and rigidity were identified in this study. Then, the quantitative calculation and theoretical analysis based on the calculation formulas of wave dissipation performance were conducted for the Dongyang dike. The results indicate that the equilateral triangle is the best for the wave dissipation under the same trees; in the premise of not affecting the flood discharge, the dissipation effect is better when the forest stem radius, crown radius, and width is larger or the row spacing is smaller; the effect and duration of rigid vegetation is better than the flexible vegetation under a same width; a forest mainly consisting of the rigid vegetation and mixing with the flexible vegetation should be the optimized plan for the Dongyang dike, while the proper row spacing and width are 1. 5-2 m and 30-50 m, respectively. Besides, the flexible vegetation should be higher than the lowest top of rigid vegetation to achieve a better performance.

Abstract:In terms of the excessively designed pumping house by the method in current standard, an optimized model for the pumping house of a wet-pit type was proposed. The main dimensions of the pumping house are selected as design variables, while the minimum construction cost of the pumping house is the objective function. The stress of basement, the bearing capacity of foundation, the stability of sliding, the strength and the settlement of pumping house are the primary and constrained conditions. Then, the parameterization finite element model of the pumping house was established. An optimal scheme of the pumping house was obtained by utilizing the optimization platform of ANSYS. Compared to the original scheme, the optimized design shows a decrease of 9. 7% in the cost of the pumping house. Other results including the displacement, stress, and stability were all satisfactory. It indicates that the effect of optimization is noticeable and the economic benefits are also remarkable.

Abstract:During the different stages of anti-seepage engineering using geomembrane, the defect is almost inevitable. According to many related literatures at home and abroad, the paper introduced some detecting methods of geomembrane defect including the examining and monitoring. In particular, the advantages and disadvantages of various detecting methods and their application scope were analyzed and evaluated in detail. After summarizing the applicability of various detecting methods, the paper lists the various repair technologies of geomembrane defects during the different stages of anti-seepage engineering. The study indicates that, compared with other detecting methods, the electrical method has strong applicability, high accuracy, and easy operation, which will attract more attention and development in the future. The combination of the electrical detecting method and the relevant defect repairing will be helpful for the forming of an effective prevention system of the geomembrane defect and the integrity improvement of geomembrane impervious system.

Abstract:In order to improve the theory and technology of the flowing field method that is used to detect the entrance of dam leakage, this work started from the numerical modelling of a quasi-flowing field. The physical quantities of the quasi-flowing field for a typical dam are calculated by the finite element method and main distributing features of variables for the quasi-flowing field have been obtained. Result shows that intensities of the electric field, electric potential and current near the source had a peak distribution, and it decreased dramatically to a stable level at the far field. Due to the existence of leakage, an abnormal distribution of the current intensity and electric filed appeared near the entrance of leakage in the water area. This abnormal can help detect the leakage entrance and the detecting device requires a smaller division value and high anti-interference ability.

Abstract:Along with the exploitation of underground space approaching to the deep constantly, the high external water pressure is posing a big threat to the safety of lining structure. Drainage holes are often used to release the pressure in the engineering practice. An optimization analysis of the drainage hole layout based on the stress target of lining was carried out in this study. The effect of the drain hole diameter, spacing and entry depth in rock on the water pressure was studied by orthogonal numerical tests. The results showed that influencing factors can be ordered as entry depth, diameter and spacing, from a high influence to a low influence, and with the pore pressure increasing, the influence of different layout decreased. A week after lining installation, the influence of different layouts reached 0. 3 MPa. Therefore, to reduce the water pressure on lining and ensure the safety of the lining, it’s preferred to increase the entry depth. Through the range analysis, influences of factors on the lining security were obtained, and the optimal drainage holes arrangement scheme was determined as 2. 86 m in spacing, 0. 2 m in diameter and 0. 2 m in entry depth, which means a great significance for the drainage hole design of hydraulic tunnels.

Abstract:The hydrodynamic conditions near a floating structure are complex during its operation in the flowing water. The floating structure is easy to overturn if it gets improper handling. The overturning moment is an important factor that affects the stability of floating structure. Based on a CFD method, the overturning moment and its variation rules with different length-height ratios, different heights from the bottom and different water heads in the flowing water were explored in this paper using an appropriate grid scale. The results show that the overturning moment of floating structure decreases after the first increasing with the growth of height from the bottom; also, the overturning moment of floating structure has a tendency of growth with the increase of length-height ratio and the water head. This study can offer reference for the understanding of overturning mechanism and stability design of floating structure in flowing water.

Abstract:Tensile stress is prone to be developed within the dam heel during the operation period of the concrete gravity dam, thereby leading to a weak area. To address the problem of hydraulic fracture in the weak area, experiments are conducted to simulate the hydraulic fracturing process of dam heel under tensile stress, in which a combined loading mode including four-point bending moment and high hydraulic pressure is used. The hydraulic fracturing problem due to initial cracks during construction is explored using different loading combinations. The experimental results show that the variation of the concrete strain is composed of linear and exponential stages during cracking process, and a fracture failure is prone to be developed when the exponential stage is reached. In this case, a small load increment applied will break the steady state with crack failure being extended. It is found that superposed effect is developed due to the splitting water pressure and the tensile stress. When the maximum values of the two stresses are applied at the same place, significant stress concentration at crack tip is developed, which would contribute to hydraulic fracture failure. In contrast, if the two maximum stresses act at different places, the strain distribution on the tensile section of the concrete would be more uniform with its tensile strength being largely mobilized, thereby reducing the hydraulic fracturing effect.

Abstract:In order to study the hydrodynamic characteristics of shallow submerged jet with depression angle, detailed flowing field of plunge pool was obtained by the Particle Image Velocimetry(PIV)technology, and the law of the two-dimensional longitudinal velocity distribution was analyzed systematically. Formulas of the velocity attenuation along the flow-path and the velocity distribution of cross section perpendicular to the primary flow in the submerged plunged jet region and wall attached jet region have been obtained from the study. The results showed that the shallow submerged jet issued into the plunge pool by a incidence angle and the depression angle of dived jet was larger than the incidence angle. Attenuation ratio of velocity in the submerged plunged jet region was greater than that in the wall attached jet region. Besides, the velocity distribution of the cross section perpendicular to the primary flow had similarity or self-holding.

Abstract:In this paper, the current status of cement-based materials with limestone powder at home and abroad is reviewed from the aspect of the mechanism, material properties, technical standards and its engineering application. Problems about the mechanism, time varying behavior and performance controlling methods that are needed to be further studied have been proposed.

Abstract:A temperature influence coefficient for the rutting evaluation model of steel bridge deck pavement based on the double-Gaussian distribution was developed to reduce the error of the rut depth evaluation of the Forth Nanjing Yangtze Bridge. First, the double-Gaussian distribution was employed to analyze the monitoring temperature of the Forth Nanjing Yangtze Bridge. Then, the formula of the temperature influence coefficient for the rutting evaluation model was modified, and the calculated value of rutting evaluation model was compared with the measured one. The results show that the temperature of the asphalt pavement of a steel box girder can be described by the double-Gaussian distribution. The difference is very small between the rutting prediction value considering the temperature influence coefficient and the monitoring rutting data, while the relative error is 15. 2%.