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<br />. <br /> <br />27 <br /> <br />. <br /> <br />Resistance to flow is relatively low with the Manning's n varying from <br /> <br />0.014 to 0.022. <br /> <br />. <br /> <br />2.4.2.5 Antidunes <br />When the shear stress of the stream power is further increased, sand <br /> <br />and water waves gradually build up from a plane bed and from a plane water <br /> <br />surface. The waves may grow in height until they become unstable and break <br /> <br />like the sea surf, or they may gradually subside and subsequently reform. <br /> <br />The former have been called breaking antidunes, or antidunes, and the latter <br /> <br />standing waves. <br /> <br />With antidune flow, the water and bed surface waves are in phase. This <br /> <br /> <br />is a positive indication that the local flow is rapid (Froude number> 1.0). <br /> <br /> <br />Resistance to flow with antidunes depends on how often the antidunes form, <br /> <br /> <br />the area of the reach they occupy, and the violence and frequency of their <br /> <br />breaking. If the antidunes do not break, resistance to flow is about the <br /> <br />same as for a plane bed with sediment movement. The Manning's n value <br /> <br />varies from 0.012 to 0.028. <br /> <br />. <br /> <br />. <br /> <br />. <br /> <br />. <br /> <br />. <br /> <br />2.4.2.6 Chutes and Pools <br />At very steep slopes, sand-bed channel flow changes to chutes and pools. <br />This type of flow consists of a long chute in which the flow accelerates <br />rapidly, a hydraulic jump at the end of the chute, and then a long pool in <br />which the flow is tranquil, but accelerating. Resistance to flow is large. <br /> <br />Manning's n varies from 0.015 to 0.031. <br /> <br />. <br /> <br />. <br /> <br />2.4.2.7 Recommended Values of Manning's n <br /> <br />Floodplain study and sediment transport analysis are two completely <br /> <br />different analyses. For conservative estimation, it is recommended, within <br /> <br />. <br />