Performance polygons enable easy comparison with any relevant data set and are a visual tool that potentially has wider applications in healthcare quality improvement.
The attraction efficiency of a by-pass fishway installed at Gangjeong-Goryeong Weir on the Nakdong River in South Korea was evaluated according to flow rate variation of the main channel. Optimal flow rate that achieved the maximum value of attraction efficiency at the fishway entrance was also determined. The weir can adjust the flow rate of the main channel and the fishway by operating sluice gates. The weighted usable area (WUA) calculated on the basis of habitat suitability criteria (HSC) for target species using River2D (a two-dimensional physical habitat model) was regarded as an indicator of attraction efficiency. The simulated velocity field by River2D was validated by virtue of measured data acquired from GPS drifter field experiments. Additionally, monthly fish monitoring data obtained with a fish trap served as supporting data to confirm the validity of the estimated attraction efficiency. The monitoring results revealed that the fishway attraction efficiency was the highest during the spawning season (from April to June). The target fish used the fishway most frequently in April. However, many other fish species used the fishway in June. Simulation results revealed that the flow rate of the main channel at the weir should be maintained at 190 m3/s in order to most effectively attract the target fish species into the fishway entrance. Managing the optimal flow rate by operating the sluice gate is especially important during the spawning season of the target fish to facilitate upstream and downstream migration.
The abrupt rises of water level in rivers by torrential rain or storm repeatedly cause inundation damage, such as erosion and deposition in floodplains. However, studies on identifying the abrasion of waterfront facilities or the accumulation of sediment near rivers under extreme flow conditions are seldom found because floodplains are utilized in various ways in each country. In this study, novel floodplain sustainability indices by spatial classification of erosion and deposition were developed for sustainable waterfront development. The indices can provide the relative spatial distribution of erosion and deposition in a floodplain by using only kinematic flow information, such as flow depth and velocity obtained by 2D numerical analysis. Accordingly, applying a complex sediment transport model that involves numerous assumptions and parameters can be moderately replaced with the present approach. The suitability of developed indices was tested in several flow problems by comparing the predicted erosional or depositional region with measured data. In addition, the developed indices were applied to a floodplain in a natural river to examine the relative spatial distribution of the erosion and deposition for a typhoon event, and the results were compared with field monitoring data. It was found that deposition was more likely to occur than erosion in most floodplains, and the developed floodplain sustainability indices accurately quantified the erosion and deposition phenomena.
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