Abstract. The advent of low-cost pressure transducers capable of directly measuring water surface elevation enables continuous measurements of dynamic water surface slopes. This opens up a new possibility of dynamically monitoring unsteady flows (i.e., hysteresis) during the course of flood wave propagation. Hysteresis in this context refers to a looped stage–discharge rating caused by unsteadiness of flows. Hysteresis is monitored in this study using a continuous slope area (CSA) method, which uses Manning's equation to calculate unsteady discharges based on continuously measured water surface slopes. In the rising stage, water surface slopes become steeper than a steady water surface slope, resulting in higher discharges than steady-based discharges, while the trends are reversed in the falling stage. The CSA method applied to Clear Creek near Oxford (Iowa, USA) estimates the maximum differences of peak discharges by 30–40 %, while it shows sound agreements for a low to medium range of discharges against USGS steady-based records. The primary cause of these differences is the use of a single channel bed slope in deriving Manning's roughness coefficients. The use of a single channel bed slope (conceptually equal to the water surface slopes at every stage in uniform flow conditions) causes substantial errors in estimating the channel roughness, specifically at high stages, because non-uniformities of natural channels result in varying (non-uniform) steady water surface slopes at each stage. While the CSA method is promising for dynamically tracking unsteady water surface slopes and flows in natural streams, more studies are still needed to increase the accuracy of the CSA method in future research.
Utilisation of submerged vanes in front of intake ports is an effective approach to address sedimentation in lateral intakes from rivers. Strategically installed, these flow-training structures could increase the mid-depth and near surface flows into the intake, and simultaneously prevent bed-load transport from entering the intake channels. The effectiveness of submerged vanes depends on their number, shape, dimensions and configuration. Determination of optimum values for dimensions or configuration of the vanes is very challenging as the effect of many parameters, which are effective in sedimentation in the intake zone, must be investigated. In this study, effort has been made to determine appropriate dimensions of submerged vanes that are installed in front of a 908 intake from a straight channel. Fuzzy TOPSIS, a multi-objective optimisation method, has been utilised for the optimisation process by considering ten parameters. The simulations have been conducted for three discharge ratios of 0 . 11, 0 . 16 and 0 . 21.The results show that a height of 0 . 2 times the flow depth, and a length of four times the vane height are the appropriate dimensions for utilisation of submerged vanes in front of the lateral intakes from straight channels.
Abstract. Despite the emergence of a large number of specialized decision-support systems (DSS) in the last decades, currently there are fewer efforts made for integrating the flood risk management relevant sciences with information and communication technologies into generalized DSS. Such systems are expected to formulate decision options for prevention, mitigation, preparation, response, and recovery from flood impacts with consideration of climate change, socio-HFRQRPLF HYROXWLRQ DQG VWDNHKROGHUV ¶ LQSXW &XUUHQWO\ WKHUH LV QR XQLILHG YLVLRQ RQ WKH DUFKLWHFWXUH components, and the needed computer and communications technologies for attaining generic DSS for flood mitigation and resilience. Moreover, there is no guidance of what components should be developed first and in what order and how to efficiently include human-computer interfaces for efficient stakeholder engagement and consensus. This paper calls for the formation of a strategic global partnership for framing and subsequently assisting in the development of a generalized flood DSS (FLOODSS) that can overcome the current flood DSS limitations. The call is preceded by a review of the flood decision-support terminology and context. Subsequently, an initial vision on the FLOODSS is outlined and the steps for transitioning such a system from vision to practice are proposed.
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