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Development of a new bedform predictor

Hölscher, R. (2016) Development of a new bedform predictor.

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Abstract:To maintain the function of rivers such as irrigation, drinking water supply, navigation and to protect against flooding, it is of great importance to gain more insights in the behaviour of rivers. An element of central interest in the behaviour of rivers are bedforms, especially dunes on the bottom of these rivers. The flow in rivers which generally flows in one direction, results in an asymmetrical dune with a stoss and lee side. Due to flow separation and associated energy dissipation, dunes form the main source for hydraulic roughness on the riverbed. The roughness in turn, is a key element in predicting flow conditions and corresponding water levels. The generally non-uniform unsteady flow in rivers causes occurrence of different types of bedforms with varying hydraulic roughness. This research only considered ripples, dunes, washed-out dunes and upper stage plane bed bedform types. In particular, water levels may increase due to increasing hydraulic roughness associated with rapid growth of dunes during high river discharge. However, due to increasing flow intensities, dunes may also evolve towards upper stage plane beds. In this case, water levels will decrease due to a decrease in hydraulic roughness associated with the transition of dunes to upper stage plane beds (Naqshband, 2014). Previous studies from Karim (1999), Paarlberg et al. (2007), Van der Mark (2009), Van Rijn (1984) and Yalin (1964) demonstrated the direct relationship between the hydraulic roughness due to the presence of bedforms and the bedform height
Item Type:Essay (Master)
Faculty:ET: Engineering Technology
Subject:56 civil engineering
Programme:Civil Engineering and Management MSc (60026)
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