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The need for large-scale and regional probabilistic simulations means that two-dimensional (2D) inundation models are still limited by computational requirements. In addition to parallelisation and physical process simplification, attempts to reduce runtimes typically involve coarsening the computational mesh, which can smooth important topographic features and hence limit accuracy. This paper presents a new 2D flow model that uses an enhanced diffusion-wave algorithm, and incorporates sub-element topography in a computational mesh that adapts to the terrain features. The model utilises a fine topographic resolution without having to use a fine computation mesh, and so achieves fast computational runtimes. The model has been tested against the UK Environment Agency's 2D benchmarking tests, and even though the model is designed to operate at larger spatial scales than those in the benchmarking tests, it is shown to provide comparable accuracy relative to a selection of conventional 2D models, at significantly faster computational speeds. The model therefore has the potential to offer a step change in performance of large-scale probabilistic flood mapping and systems flood risk analysis modelling. [ABSTRACT FROM AUTHOR]

It is difficult to find an algorithm to distribute specific reservoir releases to the floodgates of a hydropower plant in the flood season. In this study, based on a classification of floodgate combinations and the outflow from a hydropower plant, a floodgate table has been established. In order to provide a reasonable scheme for the distribution of releases to the floodgates, this paper summarises the principle of the distribution. A multi-step progressive optimality algorithm (MSPOA) is adopted for optimal floodgate operation in cascade reservoirs and applied to calculate the outflow from each reservoir of cascade reservoirs. Subsequently, according to the summarised principle, the method of bisection is used to search floodgate combinations from the floodgate table for the distribution of releases to the floodgates. To verify its feasibility, the proposed method is applied to optimal floodgate operation in a cascade reservoir system that has four hydropower plants on the Yalong River. A comparison of the application results of the progressive optimality algorithm and MSPOA methods shows that the proposed method can provide reasonable results for flood control and can distribute specific reservoir releases to the floodgates for each reservoir in the cascade reservoir system accurately. [ABSTRACT FROM AUTHOR]

This paper demonstrates the estimation and simulation of discharge and sediment concentration for two river basins in the USA and India. The first-order Sugeno fuzzy inference system was utilised to model the stage, discharge and sediment concentration relationship. A subtractive clustering algorithm, along with a least-squares estimation, was used to generate the fuzzy rules that describe the relationship between input and output data of stage, discharge and sediment concentration, which change over time. The fuzzy rules were tuned by a back-propagation algorithm. The results are illustrated using simulation and virtual reality. A comparison was made between the estimates provided by the neuro-fuzzy model and a multi-linear regression model. Different statistical criteria were used to evaluate the performance of both models in estimating discharge and sediment concentration. Comparison of the results reveals that, in general, the neuro-fuzzy model gives better estimates than the multi-linear regression model in terms of root mean square and sum of squares errors. Furthermore, compared with the multi-linear regression model, the neuro-fuzzy model yields statistical properties of estimates that are closer to actual historical data. [ABSTRACT FROM AUTHOR]

This paper gives details of the refinement and application of a two-dimensional horizontal model for rivers. An explicit finite-difference algorithm was used for solving the governing differential equations, which includes the conservation of mass and momentum to predict hydrodynamic parameters. The model includes different turbulence closure models—that is, constant eddy viscosity, Prandtl simple mixing length and Smagorinsky methods. An experimental programme was designed and carried out in a laboratory flume to measure the length of eddy produced at the entrance of the intake. Model predictions have been compared with experimental results for a lateral intake. The effect of different hydrodynamic parameters on the results obtained from several turbulence models has also been investigated. Turbulence model parameters have been calibrated according to experimental measurements. Finally, results have been classified for application of different turbulence models in lateral intakes. [ABSTRACT FROM AUTHOR]

Due to a simpler calculation process and better precision, the rotating-angle softened-truss model is often used to predict behaviours of reinforced concrete shell or panel structures. In the current algorithm of the rotating-angle softened-truss model, the calculation process is from strains to stresses, which needs a trial and error procedure. A new algorithm of the rotating-angle softened-truss model is proposed in this paper. The Poisson effect is included in the new algorithm. Its calculation process is from stresses to strains. The trial and error procedure is avoided, which simplifies the calculation process significantly. The reliability of the new algorithm is verified by test data of six panels. [ABSTRACT FROM AUTHOR]

A series of algorithms is proposed for calculating the flow depth ratio and surge wave velocity for positive surge waves in open channels of rectangular and trapezoidal sections and for circular sections running part full. These algorithms make use of the standard formulations for the solution of problems of this kind and propose some iterative protocols (Newton-Raphson, numerical interpolation) for finding the desired result. The algorithms may be incorporated into a spreadsheet or a similar software package for use by hydraulic design engineers. Some results for a few selected cases are presented and show a dependence of depth ratio and surge wave velocity on flow ratio and on Froude number prior to the arrival of the surge wave. There is also a dependence on flow and channel scale in all cases, except that for rectangular flows; the depth ratio is independent of scale for the conditions investigated. There is also evidence of a minimum surge wave velocity for surge waves moving downstream at a specific Froude number for rectangular and circular sections, although not for trapezoidal sections. The algorithms generally give good agreement with the literature, although it is noted that in real situations an undular wave front is generally observed, and that most of the experiments cited have hitherto only been carried out in rectangular channels. Given the effect of friction on moderating the passage of the surge wave, the idealised assumption of a frictionless channel is clearly of importance. [ABSTRACT FROM AUTHOR]

In this paper, an efficient and accurate method for the extended period simulation of pipe networks under dynamic loading is proposed. The method uses the modified Euler method to discretise the ordinary differential equation governing the variation of water level in the reservoirs to yield a non-linear algebraic equation in terms of the reservoir head and inflow. These equations are then embedded into the non-linear system of equations describing the steady-state flow in the pipe network to obtain the final system of equations. A Newton-Raphson method of linearisation is used for the equation governing the tank water level variation along with a gradient formulation of the pipe networks. The solution of the resulting system of equations automatically yields the distribution of nodal heads along with the reservoir head at the end of each period. The method uses only one steady-state simulation per period to predict accurately and efficiently the reservoir water elevation. Application of the proposed method does not require special coding and can be easily embedded into the existing pipe network simulation codes. The method is applied to four test problems and the results are presented and compared with those of a conventional extended period simulation method and some other existing methods. The results show that the proposed method is considerably more accurate than the conventional algorithm and more efficient than existing improved methods of dynamic simulation. [ABSTRACT FROM AUTHOR]

A concise algorithm is introduced to perform slope stability analysis to determine the geometry of the critical slip circle and the corresponding factor of safety without the need for iterative calculations. An optimisation process is performed using the developed algorithm for various soil properties and slope geometries to determine the critical slip circle within all possible slip circles and obtain the factor of safety. The performance of the algorithm is compared with three-dimensional finite-element analysis using the strength reduction method and benchmark studies conducted previously. It is found that the developed algorithm shows good agreement with the previous studies and three-dimensional finite-element analysis. The factors of safety are calculated for a wide range of parameters and variations in these factors are expressed using linear and quadratic equations to establish a correlation between factor of safety and five parameters: cohesion, friction angle and unit weight of soil, as well as slope height and slope angle. The correlation coefficients introduced in this study provide a convenient way for practising engineers to estimate factors of safety that are applicable to uniform slopes. [ABSTRACT FROM AUTHOR]

An algorithm is presented for representing irregular particles as clusters of overlapping spheres, for use within discrete element method (DEM) simulations of particulates. The algorithm is sufficiently fast to be implemented on desktop computers. Although volume and moment of inertia comparisons of resulting clusters with prototypical geometric data show that in the region of 50 to 100 spheres may be needed to represent a particle, actual DEM simulations of an unstable pile of simulated particles show that only 10 or so spheres may be sufficient to capture the mechanics of the system. [ABSTRACT FROM AUTHOR]