Abstract:In view of the uncertainty of water supply and demand in a water resources system and its dynamics with the passage of time, based on the data of water supply, water consumption and social economy in Heilongjiang Province over the years, the water resources parameters and economic parameters in the planning years were determined. The uncertainty in the system was reflected by using interval parameters, and the dynamics in water resources allocation was reflected by using multi-stage random planning. An interval multi-stage random planning model with multiple water sources and multi-purpose users was then established, based on which the water resources allocation in Heilongjiang Province was studied. The results show that the domestic, industrial and ecological water consumption in Heilongjiang can be met in the planning years, and the agricultural water consumption is basically met in wet years, with the water shortage of 1.532 billion to 4.94 billion m³ in dry years. Compared with the current years, the agricultural water shortage has been alleviated to some extent. In terms of water supply, the proportion of surface water supply steadily increases, which can better protect underground water sources.

Abstract:Based on the definition of the concept and connotation for happy rivers and lakes, a comprehensive evaluation index system of happy rivers and lakes was constructed including 17 indicators in the four aspects of safe rivers and lakes, healthy rivers and lakes, prosperous rivers and lakes, and cultural rivers and lakes. The BWM method and CRITIC method were used to determine the subjective and objective weights of the index, respectively, and the combined weight was obtained through the principle of minimum identification information. A comprehensive evaluation model of happy rivers and lakes was established based on the TOPSIS method to evaluate its construction level in a city of Zhejiang Province from 2015 to 2019. The results show that BWM-CRITIC-TOPSIS model can effectively evaluate the construction level of happy rivers and lakes, and the evaluation results are consistent with the actual situation. Indicators such as wetland land occupation ratio, water resources development and utilization rate restrict the improvement of happy rivers and lakes grade in the city. Suggestions to promote the harmony between human and water, make rational use of water resources, and improve the utilization efficiency of water resources were put forward.

Abstract:In order to solve the problem of low photovoltaic absorption rate after water-solar complementation, the water-solar intra-month complementary scheduling rule was proposed for the first time on the basis of the water-solar intra-day complementarity rule. The complementary characteristics of hydropower and photovoltaics were fully considered by the scheduling rule, and the adjustable performance of cascade reservoirs was adapted to the photovoltaic output curve. Based on the water-solar complementary scheduling rules, taking the cascade power station in the Tibet section of the upper reaches of the Lancang River as an example, the calculation of the output process of the cascade power station and the photovoltaic consumption rate were carried out after complementation. The analysis results show that after the water-solar complementation, the total power generation of hydropower and photovoltaics increases from 55.835 billion kW·h to 59.189 billion kW·h, and the power generation gain after complementation is 3.354 billion kW·h, indicating a 20% increase of photovoltaic absorption rate.

Abstract:A curve flume generalized model experiment was carried out to study the dike-break mechanism under frozen soil condition. Based on the three-dimensional(3-D) imaging principle of structured light, a non-interference and omnidirectional measurement method for the 3-D parameters of real time breach was developed. Combined with the temperature sensor to monitor the temperature change inside the embankment, the evolution process of the breach and the variation characteristics of water level, velocity and flow rate in the failure area of the homogeneous embankment under frozen soil condition were studied. According to the characteristics of beach erosion, the process of embankment failure is divided into four stages, including infiltration and overflow, back-embankment scour, horizontal widening and balance of erosion and siltation. For both cohesive embankment and non-cohesive embankment, scarp scour and collapse instability are the main characteristics of the second and third stages respectively, and the phenomenon of scarp merger occurs obviously for the cohesive embankment. The test results also show that, the ice crystals in adjacent soil are cemented with the soil particles after freezing, the cohesive force of soil increases, and the expansion rate of the breach and the change rate of water level and velocity in the failure area decrease. In addition, the influence of the frozen soil depth on cohesive embankment is more obvious. The connection part between the backwater side and the top of the embankment is weak and easy to breach under frozen soil condition, so the maintenance should be strengthened, and the water side dike should be sealed first once the embankment breaks.

Abstract:In order to realize the rapid and accurate inspection of aggregate particle size in hydraulic engineering construction, an automatic aggregate image segmentation algorithm based on DeepLabV3+ was proposed. 150 aggregate images under different conditions were collected, and the network was optimized based on the original DeepLabV3+ network through contrast experiment. Then the optimized network was used to train the automatic aggregate image segmentation model. The MobileNetV2 is the backbone network of the improved DeepLabV3+ network, and the Swish+BN function is the activation function.After weight optimization, the aggregate’s intersection over union (IoU) is 0.861 5, which is 0.011 8 higher than the original network training model, and 0.064 6 and 0.088 6 higher than that of U-Net and FCN training models. The automatic segmentation accuracy of aggregate image based on the improved DeepLabV3+ can basically meet the accuracy requirements.

Abstract:In order to analyze the characteristics of the ventilation system of a spillway tunnel, the balance relationship between the tunnel freeboard and the cross-sectional area of the ventilation was studied. The equilibrium relationship between the drag capacity of water, tunnel freeboard and air ducts were systematically analyzed based on a proven theoretical model for spillway tunnel with multiple air ducts. The variety of air pressure in freeboard and total ventilation was related under the conditions of fixed size of air ducts. A family of curves was plotted to reveal the equilibrium between the air duct and tunnel freeboard, in which three partitions and two extremum points were summarized. It’s suggested that the corresponding curves should be calculated and plotted when designing a spillway tunnel and its ventilation system. The design should be implemented within the range of the partition Ⅱ to optimize ventilation characteristics, which can ensure both the tunnel freeboard and the cost for air duct area.

Abstract:In view of the shortcomings of traditional random forest parameter optimization methods, the particle swarm optimization algorithm was improved by introducing equalizing inertia weight and adaptive mutation, and a dam deformation prediction model based on improved particle swarm optimization algorithm and random forest algorithm(improved PSO-RF algorithm) was proposed. The example analysis shows that in terms of computational efficiency, compared with traditional grid search method, the improved PSO-RF algorithm significantly improves the optimization speed of the model. In the aspects of prediction accuracy and stability, the dam deformation prediction model based on the improved PSO-RF algorithm is obviously better than long short-term memory, support vector machine and BP neural network.

Abstract:To study the unstable water surface near an aqueduct and to provide eliminating measures in a water conservancy project, numerical simulations on flows around circular cylinders and gate piers in various channels, including straight channels with different width values, transition channels with gradient contraction sections and curved channels were performed under the condition of high Reynolds number ( Re =5×106) through COMSOL Multiphysics software. The influences of channel layout and blunt body shape on the surrounding flow field morphology and forces acting on the structures were analyzed. The results show that, in the range of the calculation parameters, as the width of the straight channel decreases, the lift and drag coefficients of the cylinder increase with the blockage ratio. The gradient section of transition channel has little effect on flow around a cylinder. For curved channels, a deflection coefficient is adopted to indicate the asymmetry flow distribution. In flow with a greater deflection coefficient, the structure may suffer lift and drag coefficients with greater asymmetry and larger average values. The results of flow around piers show that, the flow fields and force characteristics of piers without pier tail are similar with those of a cylinder. The increase of pier length can reduce the resistance coefficient. The lift and drag coefficients are greatly reduced by the streamlined body shape of piers with tails. Adding an appropriate pier tail is an effective measure to solve the vortex shedding for flow around a gate pier.

Abstract:In order to accurately and conveniently obtain the morphological information of cracks from embankment surface with a large scale of complex backgrounds, a crack detection method based on U²-ADSNet is proposed based on the improvement of U²-Net. This method combines depthwise separable convolution and atrous convolution in U²-Net, which expands the receptive field of the original model, enhances the learning ability of detailed features, and reduces model parameters. Based on a limit number of UAV measurable image data, the open source dataset of cracks for transfer learning is applied to reduce the training cost. Crack detection on a large range of UAV imagery is achieved by slicing prediction and possible false detections are removed using connected domain search. The effectiveness of the improved model has been verified by comparing U²-ADSNet with semantic segmentation models such as FCN, SegNet, U-Net and DeepCrack on the embankment crack dataset. The model intersection of union reaches 78.55% after migration learning, and the comprehensive evaluation index is 87.87%, which can be used for embankment crack detection.

Abstract:An autonomous underwater robot path planning algorithm for underwater dam surface apparent crack detection was designed based on bio-inspired neural network in order to acquire continuous local images of long cracks on underwater dam surface. The algorithm identifies the crack orientation and calculates the raster it points to, and then applies the pointing result to the path decision by means of an activity gain. It is confirmed by simulation tests that the algorithm can continuously acquire local images of long cracks with a greater degree of continuity than the paths planned by the cow plowing method, while ensuring full coverage of the detection object.

Abstract:A seepage slope stability analysis model for an ancient city wall for flood protection in Lanxi was constructed based on the finite element software ABAQUS. A seepage-stress coupling calculation method was used to simulate the variation process of pore water pressure in the soil behind the ancient city wall under the condition of rainfall infiltration, and the seepage and deformation characteristics of the ancient city wall with anti-seepage facilities, drainage facilities and no drainage facilities were compared and analyzed.The study results show that under the condition of rainfall infiltration, the pore water pressure and overturning moment of the soil slope of the ancient city wall with anti-seepage facilities or no drainage facilities can be increased, which is not conducive to the stability of the ancient city wall. The pore water pressure of the soil slope inside the ancient city wall with drainage facilities is greatly decreased through the drainage channel, and the overturning moment is also reduced, which is more conducive to the stability of the ancient city wall.

Abstract:By analyzing the effects of different utilization schemes of soft rock and dam zoning forms on the mechanical properties of a high concrete-faced rock fill dam(CFRD), the characteristics about the stress and deformation of the dam were obtained. The proportion of soft rock in the downstream rock-fill zone, the geometric characteristics of the downstream rock-fill zone and the zoning form of the main rock-fill body can affect the mechanical properties of the high CFRD. With the increase of strength and stiffness of the secondary rock-fill zone in the downstream dam body, the deformation coordination between the primary rock-fill zone and the secondary rock-fill zone becomes better, and the deformation and stress of the concrete face slab are reduced. The dam deformation and face slab stress can be effectively reduced by improving the bearing capacity of the rock-fill body located at the dam axis. To control the deformation and stress of the high CFRD, the rock-fill zone at the lower part of dam body near the dam axis should be filled with the rocks of high bearing capacity, and the proportion of soft rock in the downstream rock-fill zone should not exceed 30%.

Abstract:In order to explore the mechanism of measurement error reduction for a double tipping bucket rain gauge(DTBR),and to further improve its measurement accuracy, a method of combining experiments and numerical simulation was proposed. A high-speed camera was used to get the tipping characteristics during the movement and a dynamic grid and the volume of fluid (VOF) model were used to simulate the overturning process for the upper tipping bucket of the DTBR. The structure design of DTBR was further optimized.The results show that the DTBR relies on the upper bucket to smooth the discharge under natural precipitation intensity at a steady rate of 1.01 g/s injecting into the lower bucket through the middle funnel, which can significantly reduce the influence of precipitation intensity on the measurement error of the rain gauge, and the effect is more obvious under high precipitation intensity. The discharge of the middle funnel under different precipitation intensity remained at a steady rate of 1 g/s (corresponding to precipitation intensity of 1.91mm/min), and as a result, for the future DTBR calibration, the 1.91mm/min precipitation intensity calibration can be considered for the lower tipping bucket, which can meet the error requirements of DTBR. There is an oscillating outflow process of the middle funnel, which can reach a maximum of about 2.g/s. Reducing the central shaft height of the upper bucket can stabilize the outflow of the middle funnel to a certain extent.

Abstract:A centrifuge model test was conducted on the deformation and failure of a cohesive soil steep slope under the water-level rising conditions. The failure mechanism was analyzed based on integrated analysis scheme of deformation and failure processes using measured displacement of the slope. The test results showed that the water-level rising resulted in a progressive slippage failure of the slope which started at the toe and gradually developed upwards to form an integral slip surface with the tensile cracks on the top. The water-level rising process induced significant deformation and concentrated within a limited zone. The development of deformation localization resulted in the local failure of the slope and the coupling development of both was essential to the full slip surface of the steep slope. Significant deformation occurred after the full slip surface appeared and the deformation characteristics of each point were related to its location.

Abstract:In view of the permeability coefficient prediction for gravel soil of a core wall only considering material sources parameters, while a few prediction methods only considering construction quality having the problems of large error and incomplete data characteristics, a combined permeability coefficient predicting model BPNN-WOA-SVM considering both construction quality and material sources parameters was proposed. Whales optimization algorithm (WOA) was introduced to solve the difficult problem of SVM parameter selection, and the maximum information entropy principle was adopted to synthesize the strong adaptive ability of BPNN, good regression performance of whale optimized support vector machine (WOA-SVM) algorithm, and the advantages of small sample size.Engineering application results show that compared with the single prediction method, the combined prediction method reduces the mean square error, mean absolute error and relative analysis error, improves the prediction accuracy and convergence rate, and has a strong advantage in predicting the permeability coefficient for gravel soil of a core wall.

Abstract:Based on the three-dimensional numerical model of drainage system, the influences of different upstream and downstream pipe diameter ratios and relative heights, chamber and shaft parameters on geyser pressure and intensity were analyzed. The results show that smaller relative height of the upstream and downstream pipes can cause the flow regime in the upstream pipe to be full pipe flow, and the rapid increase in upstream flow can induce greater geyser pressure. Reducing the diameter of the downstream pipe can reduce the transport capacity, resulting in more severe geyser. When the chamber volume is constant, increasing the chamber height can alleviate the maximum geyser pressure. Increasing the shaft length has little effect on the geyser pressure, but it can reduce the volume of water ejected. Increasing the shaft diameter makes the geyser pressure to increase first and then decrease.

Abstract:In order to describe the nonlinear relationship between the cavity backwater depth, cavity length and many influencing factors in aeration erosion reduction projects, and to achieve the accurate calculation of backwater and cavity length, a support vector machine regression model (GS-SVR) by means of machine learning was established based on the collection of 162 sets of model experimental data. Through the method of grid search and cross-validation, the relationship between the hyperparameters ( C and γ) in the support vector machine model and its influence mechanism on the accuracy of the model’s prediction were studied. On this basis, the model performance of six different input combinations (a total of twelve groups) was analyzed. The results show that the region with the best model performance can be found through grid search. In this region, C and γ show the opposite growth trend. Based on the above method, the optimal variable combination can be found ( i 1, i 2, Fr , Δ/h ) and the accurate prediction of the cavity length and the backwater depth is realized.

Abstract:In order to understand the effect of the ring clearance size on the internal flow characteristics of a high speed multistage deep well pump, based on SST k-ω turbulence model and refined mesh, the influence of the ring clearance on the internal flow field of the pump was studied. Based on the entropy generation theory, the characteristics of leakage flow loss in the pump under different ring clearance were analyzed in detail. The results show that with the increase of the ring clearance size, the total head and efficiency of the multistage pump show decreasing trends. The increase of leakage makes the flow pattern at the inlet of the impeller worsen. However, when the ring clearance size increases to a certain range, the increase of the leakage can slow down. Turbulent dissipative entropy production is the main part of the flow loss, and the cavity and impeller inlet are the major loss zones. The ring clearance size has little effect on the vortex characteristics in the cavity, but has an obvious effect on the vortex strength in the impeller inlet and impeller channel.

Abstract:Aiming at the problems of strong subjectivity in risk grade judgment, fuzziness and randomness of risk index in levee risk evaluation, a risk evaluation model based on two-dimensional cloud model with combination weighting was proposed by using improved analytic hierarchy process (AHP) and entropy weight method. On the basis of the existing levee safety evaluation criterion, the risk evaluation index system of levee engineering was constructed by considering six aspects, including operation management, levee foundation quality, levee body quality, flood control ability, seepage safety and structural safety. On this basis, the two-dimensional cloud model parameters of each evaluation index belonging to different risk levels were calculated, and the results were output in the form of risk cloud map, which could intuitively judge the risk of caution. Finally, the model was applied to a levee project in the lower Yellow River, and the results were consistent with the actual situation, indicating the reasonability and feasibility of the proposed method.