Abstract:This study introduces the basic situation of China‘s small and medium-sized rivers and flood disasters, and then key difficulties as well as urgent scientific and technological problems in the flood prevention of small and medium-sized rivers were analyzed. Thereafter, the study puts forward the strategy and measures for the flood forecasting and early warning of small and medium- sized rivers. Besides, prospects for the future forecasting, risk early warning, and refined risk management concepts and practices are also proposed. It will realize the change from the hydrological element forecasting to the flood impact forecasting, from the flood threshold-based warning to the flood risk warning, from the " prediction-response" emergency disposal to the grid refinement risk management, from the monitoring data provision to the information product service, in which the development level of the hydrological modernization is continuously improved.

Abstract:To reduce the serious consequences of flood disaster events, the river discharge should be predicted timely and accurately to provide decision support for the flood forecasting. In this study, an intelligent simulation method of runoff process based on the spatiotemporal feature mining was proposed. Firstly, the topological diagram of hydrological stations was established from the spatial point of view. Then, this study proposed a novel framework that incorporated the graph convolutional networks (GCN) for mining the spatial feature. The gated recurrent unit was adopted to capture temporal features for the hydrological prediction. The experimental results show that the intelligent hydrological forecasting model based on the spatiotemporal feature mining is better than other models with single feature.

Abstract:A summary is firstly made on the research achievements of key technical issues in the flood prevention and the emergency management at home and abroad. In view of the characteristics of small and mediumsized rivers such as large quantities, frequent floods, and severe disasters in China, this study discusses the construction of high spatialtemporal resolution rainfall field and shortimpending accurate forecasting, the fine and intelligent flood forecasting, the realtime flood risk assessment and emergency disposal, the quality control of hydrometeorological data, the cloud platform construction and so on. Through the discussion of key scientific problems, a train of thought can be provided on key technologies of flood prevention and emergency management.

Abstract:The GridXin’anjiang model (GXM) is used to improve the flood forecasting accuracy for small and mediumsized rivers. The effects of the flow reallocation process, storage and discharge of small reservoirs and ponds, and channel features on the runoff generation and concentration are considered in this study. With the quantitative simulation methods, the spatial distribution of model parameters is estimated based on the quantitative relationship between model parameters and underlying surface characteristics. The GXM is applied to the Hengjiang River located in Anhui Province for verifying its finescale forecasting capability. The results indicate that the model can satisfactorily forecast not only the streamflow at the outlet, but also the flood process at any interior grid cells without model recalibration. Besides, the spatiotemporal distribution of different hydrological elements, including the discharge, soil moisture and flow velocity, can be obtained from the GXM. GXM can provide abundant forecasting products for flood control of small and mediumsized rivers.

Abstract:Firstly, this study summarized the current research status of the domain knowledge graph. Secondly, the development trend of the domain knowledge graph was introduced. Then, this study sorted out some difficulties in the construction of water conservancy knowledge graph, proposed a research framework including main modules such as knowledge representation, extraction, fusion, reasoning, and storage, and briefly summarized the research content of each module. Finally, the construction of domain knowledge graph encountered some problems, such as the single representation, the extraction sample sparse, the multisource knowledge conflict, the rule representation difficulty, and the inefficient data management. Therefore, the rationalized representation, accurate and comprehensive extraction, realtime fusion, interpretable reasoning, and highperformance storage are regarded as the next research direction of water conservancy knowledge graph.

Abstract:To improve the estimation accuracy of rainfall spatial distribution based on the gauge network, an interpolation method is proposed based on the matrix factorization. By combining the traditional interpolation methods, including the inverse distance weighting (IDW) method and the ordinary Kriging (OK) method, and the FunkSVD model, this method considered the temporal development of precipitation and the spatial distribution of gauges. The daily observation data of rainfall events from 2009 to 2012 between Xiaolangdi and Huayuankou were selected for the accuracy test. The results show that through combining with the FunkSVD model, the estimation errors of the IDW and OK can be reduced over 15% in terms of MAE and PERC, and the improvement is especially obvious when the surrounding stations are unevenly distributed, or the rainfall is heavy. The proposed method can greatly reduce the estimation error of traditional methods in the precipitation interpolation process and help improve the accuracy of spatial estimation.

Abstract:To reveal the temporal and spatial distribution of nonpoint source nitrogen and phosphorus loss in the Luanhe River Basin above the Panjiakou reservoir, this study selected the Panjiakou Reservoir basin as the research watershed, adopted the SWAT model and SUFI2 algorithm, and simulated the change of nonpoint source nitrogen and phosphorus loss in different hydrological years, based on the measured hydrological and water quality data. The results show that the total nitrogen load in a wet year is 1.68 times of that in a normal year, and 2.12 times of that in a dry year. Meanwhile, the total phosphorus load in a wet year is 1.52 times of that in a normal water year and 2.21 times of that in a dry year. In spatial distribution, the descending order of total nitrogen and phosphorus emissions is cultivated land, forest land, grassland, and wasteland. Further analysis of the correlation reveals that the sediment production is an important driving factor of the spatial distribution of pollution load for the nonpoint source pollution.

Abstract:Low resolution satellite imageries are mostly used in the mass concentration inversion analysis of chlorophyll a in Taihu Lake, with insufficient high resolution satellite images. Based on the GF6 satellite data, this study quantitatively retrieved the mass concentration of chlorophyll a in Taihu Lake with the band ratio (TBR) model, the normalized difference index of chlorophyll (NDCI) model and the threeband semianalysis(TBS) model. The inversion accuracy of the three models was verified by using the GF6 satellite image data on October 28, 2018, April 6, 2019, and June 3, 2019. The results show that the average relative error, root mean square error and mean absolute error of the NDCI model are the minimum. Therefore, the NDCI model has better accuracy and stability, and is more suitable for the application of GF6 satellite in the inversion of chlorophyll a mass concentration in Taihu Lake.

Abstract:To quantitatively evaluate the influence factors of regional runoff, a field base was constructed, and field data about the rainfall, evapotranspiration, soil moisture, groundwater table, and surface water dynamics were collected in two different experimental sites of the Taihu Basin, China. Through the analysis of water balance in different rainfall runoff processes, it was found that the Dunne overland flow was the dominant mechanism responsible for the rapid runoff generation. The total rainfall and runoff expressed a good linear relationship with an R2 of 0.95 in the Hongqiwei test site. In addition, the initial groundwater depth was considered as the indicator of the antecedent soil moisture estimation for the close linear relationship that indicated the strong interaction between shallow groundwater and soil moisture. The depression storage was recommended in a range from 4.72 to 8.03 mm according to an estimation based on the water balance analysis for each rainfall event，which proves that the depression storage should not be neglected when calculating the runoff generation process in plain areas.

Abstract:To gain a deeper understanding of the deformation trend of No. 1 toppling deformed slope in the Huangdeng Hydropower Station, the LMBP neural network and the SVR were used to conduct the deformation prediction. Based on the practical deformation monitoring data of the toppling deformed slope in the Huangdeng Hydropower Station, this study analyzed the data of displacement, rainfall, reservoir water level, temperature, etc. Then the reservoir water level, rainfall, temperature, and time were taken as input parameters and the displacement was used as the output parameter to construct the LMBP neural network model and the SVR model. Two models were trained by a part of the monitoring data, and the subsequent monitoring data was used for verification and forecasting, which predicted the deformation of the measuring point in advance. The results show that the accuracy of the two models is higher, the maximum error of the LMBP neural network model is 2.53% and the maximum error of the SVR model is 4.35%, which demonstrate that two prediction methods are both effective.

Abstract:Focusing on the stability problem of floating wind turbine subjected to various complex loads, by equipping a tuned mass damper(TMD) on the nacelle of the 5MW Barge wind turbine and using FAST to simulate the dynamic performance of the structure, this paper is to investigate the control effect of TMD on the motion characteristics, tower top displacement and tower root load of floating wind turbines. In addition, the TMD structure parameters were optimized based on the Genetic Algorithm. Meanwhile, motion responses of floating wind turbines without the control, with the nonoptimized TMD control and with the optimized TMD control were compared. Based on the measured sea state data, the rationality and reliability of optimized TMD were verified. The results show that compared with the nonoptimized TMD, the optimized TMD is more effective in controlling the roll, the sidetoside displacement at the tower top and the sidetoside load at the tower root. The optimized TMD can be applied to most sea states and can well control the amplitude of motion response in the high frequency interval of sea state. Besides, with the improvement of sea state level, the control effect of motion response for the floating wind turbine becomes more obvious. The results show the reliability and superiority of TMD control method and optimization algorithm.

Abstract:In order to obtain the dynamic characteristics of the overall structure of aqueduct, the modal tests of ambient excitation were conducted by the oneway SIMO method and the twoway MIMO method. Longitudinal, transverse, vertical and transversevertical bidirectional modal parameters were identified by the enhanced frequency domain decomposition. The results show that most spectrum peaks have been obviously identified by two methods with satisfactory dentification results of modal parameters. The longitudinal modes and first four transverse modes of aqueduct structure are dominated by the vibration of the bent structure, and the aqueduct body is the translation or rotation or motionless. After the fifth transverse modes, most of them are dominated by the aqueduct body, and the bent structure is barely moving or vibrates very little. The vertical modes are dominated by the vibration of aqueduct body. In addition, the bidirectional modes identified by the MIMO method include both the transverse and vertical components, and the errors of modal frequency identified by both the SIMO and MIMO methods are small. According to the identification accuracy and comprehensive information of modal tests, the twoway MIMO method is better than the oneway SIMO method for the overall structure of aqueduct.

Abstract:In order to solve the surface cracking, peeling and spalling of airport concrete pavement under the longterm freezethaw cycle in cold areas, this study added the basalt fiber mesh and alkaliresistant glass fiber mesh in the mortar layer to enhance the frost resistance of the airport pavement. Effects of three environmental factors, which are the tail flame erosion (ablative), the chloride salt erosion (chloride corrosion) and the ultraviolet radiation (ultraviolet), on the frost resistance of fiber mesh reinforced concrete were studied, by applying factors by separate and combined means. Singleside freezethaw tests were carried out on different kinds of fiber mesh reinforced concrete under different environmental factors, and the test results are quantitatively analyzed by SPSS. The result shows that the fiber mesh can effectively enhance the frost resistance of concrete under the effect of composite factors, and the basalt fiber mesh is better. The case in which three factors are applied simultaneously has the greatest effect on the concrete frost resistance, while the case that simultaneously applied of two factors has different effects on the frost resistance of different concretes. The degree of effect for basalt fiber mesh reinforced concrete can be listed in descending order as: ablation and chloride corrosion, ultraviolet and chloride corrosion, ablation and ultraviolet. For the alkaliresistant glass fiber mesh reinforced concrete, it is ablation and chloride corrosion, ablation and ultraviolet, ultraviolet and chloride corrosion. Finally, the degree of effect for single factor is chloride corrosion, ablation and ultraviolet, in descending order.

Abstract:In this study, according to the seepage characteristics of backfill behind a quay wall on the highly permeable foundation soil, a differential program for the onedimension transient seepage was built based on the seepage theory of saturated and unsaturated soil under the condition of waterlevel rapid drawdown. The reliability of the program was verified by the model test and the numerical simulation. Then the program was used to study the influences of the drawdown speed, the permeability coefficient and the water content of saturated soil on the change of water pressure during the seepage. The results show that the drawdown speed and permeability coefficient have a great influence on the change of water pressure during the rapid drawdown of water level, while the water content of saturated soil has negligible influence.