EXPERIMENTAL INVESTIGATION ON BEACH MORPHODYNAMICAL PROCESS NEAR RIVER MOUTH

Physical model study on wave influences on river-mouth depositional process ispresented. Experiments were performed in a wave basin in order to determine erosionand accretion area due to the combined wave – current flows. An inflow glass channelwas designed to reproduce a river mouth model in a 3D wave basin made with a sandbottom. The tests were carried out under three different conditions: river current,waves, wave –current interaction. Measurements of wave heights, beach profiles andbathymetric profiles were made. The results show that in the presence of combinedwave-current flows, erosion areas are more evident in vicinity of a mouth with depthand width values greater than depth and width values of inflow channel.

Conservation Design and Scenario for Flood Mitigation on Arui Watershed, Indonesia

Flooding has been natural disaster in Indonesia and elsewhere. This research is designed to create scenarios and designs conservation to mitigate flooding disaster. Data potential ,vulnerability, and duplicated river covering 0.25% of the targeted flooding area were collected and analysed. Five disain of conservation, natural river as control, river normalization, normalization with gabion stone, river straigtening, and straigtening with gabion stone, are proposed, and main targeted responses of these five scenarios are river current velocity. Effectiveness scenarios were analysed using Anova and Tukey test. The results showed that alignment with gabion stone was the most effective scenario for flooding mitigation since this was the most effective in increasing river current velocity. This could prevent riverbank occurrence of avalanche, accelerate river current, overcome flooding, and prevent future flooding. Other scenarios likes dead clicth ended-hallway, canalization, and riparian reclamation are also possible implemented.

Development and Numerical Performance Analysis of a Pump Directly Driven by a Hydrokinetic Turbine

Marine and hydrokinetics (MHK) represent an emerging industry with hundreds of potentially viable technologies, such as potential extractable energy from plain area rivers where the water level differences are very small and the traditional water turbine pump (WTP) cannot be used. A suitable WTP, composed of a tubular turbine directly driving a centrifugal pump, was designed and developed based on computational fluid dynamics (CFD) and model tests. Two general design schemes of such river-current (RC)-driven WTP are presented here, obtaining the desired operating parameters of discharge and pump head. A CFD analysis of Scheme B, which employs a radial outlet, allowing additional degrees of freedom for the dimensions of the centrifugal pump, was carried out and verified experimentally by model tests. The minimum deviation of pump head is within ±5%, and the trend of other working conditions is consistent, so the results of the numerical simulation and model tests show good agreement, demonstrating the feasibility of the CFD method for practical applications. Then, using the CFD method, the optimum rotational speed for the turbine was determined, and the turbine draft tube was improved further. With a turbine runner diameter of 0.5 m, the results show best performance at n = 350 r/min. The straight conical draft tube was changed to an elbow draft tube with multiple exits. Additionally, four different cross-sectional shapes were designed for the pump volute, and their effects on the performance of the WTP were analyzed. Finally, the round shape was selected, because of its best performance. The turbine unit has the highest efficiency of 81.2%, at an inlet velocity v = 2.4 m/s, while the pump exhibits the best efficiency of 90.2% at the design discharge and head of 30 l/s and 4.45 m respectively. Overall, the RC-driven WTP makes good use of the kinetic energy of the river current as a power source, solving the inapplicability of traditional WTP in plain areas.

River and Estuary Current Power Overview

This paper presents a review of the stream current power sector, with a distinction made between the marine (MCP) and the river/estuary current power (RECP). Although scientific literature about MCP is actually well defined, that about RECP seems small, though this domain has some research interest. This paper has thus a special emphasis on this latter, with comparative studies done between these domains. The assessment of the academic and industrial interests for the RECP is first addressed, based on two main scientific resources and a qualitative highlight of its potential. Then, a review of actual constraints restricting its development is introduced, followed by a non-exhaustive presentation of industrial projects. Finally, some development prospects allowing constraints to be mitigated are proposed. Globally, MCP and RECP are treated unconcernedly, with a primary interest on the mechanical converter study and the location energy potential estimation. It has been highlighted that countries with RECP potential are more plentiful, and that undertaken projects can be classified mainly into two categories following the nominal power of the production unit. Furthermore, the river current power growth has been confirmed in recent years, with a majority part of patented hydrokinetic technologies, although commercial deployments are still scarce.

Mathematical Modeling of Ice Dynamics as a Decision Support Tool in River Engineering

The prediction of winter flooding is a complicated task since it is affected by many meteorological and hydraulic factors. Typically, information on river ice conditions is based on historical observations, which are usually incomplete. Recently, data have been supplemented by information extracted from satellite images. All the above mentioned factors provide a good background of the characteristics of ice processes, but are not sufficient for a detailed analysis of river ice, which is highly dynamic and has a local extent. The main aim of this paper is to show the possibility of the prediction of ice jams in a river using a mathematical model. The case of the Odra River was used here. Within the Lower and Middle Odra River, the most significant flood risk, in winter conditions, is posed by ice jams created when movable ice is stopped by existing obstacles such as shallow areas in the riverbed, the narrowing of the riverbed, and other obstacles caused as a result of sudden changes of the river current, backwater from sea waters, and north winds, which contribute to the creation of ice jams. This in turn causes the damming of water and flooding of adjacent areas. The DynaRICE model was implemented at two locations along the Odra River, previously selected as ice-prone areas. Also, a thermal simulation of ice cover formation on Lake Dąbie was shown with variable discharge. The results of numerical simulations showed a high risk of ice jamming on the Odra River, created within one day of ice moving downstream. The prediction of the place and timing, as well as the extent, of the ice jam is impossible without the application of a robust mathematical model.