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<br />Sediment Size and ~ <br /> <br />Small sediment sizes are more easily eroded and transported <br />than large sizes, provided that the soils are noncohesive <br />(as is the case for fans not subject to mud flows). Hence. <br />fans with predominantly small sediment sizes may experience <br />rapid erosion and deposition processes which cause unstable <br />flow paths with frequent avulsions. Sediment size and type <br />can also be an indicator of past debris flows, since such <br />flows deposit poorly sorted layers of sediment with large <br />rocks and debris mixed with clays and fine sands. <br /> <br />Rainfall Intensitv <br /> <br />The distribution, duration. and intensity of rainfall in the <br />watershed are the driving forces behind the tan flood <br />proc~ss. Hence, high rainfall intensities and lon~er <br />,rainfall durations are strongly correlated with all flood <br />hazards on fans. <br /> <br />l:1!1!. Slope <br /> <br />Physical model experiments confirm the prediction. based on <br />theory, that high slope fans tend to exhibit stable channels <br />and, often. substantial entrenchments. flow velocities and <br />sediment transport capacity are higher than for low slope <br />fans. Hence, hazards due to sediment deposition, scour, <br />high velocities. and impact damages are strongly correlated <br />with high slopes. The unpredictability of flow path is <br />relatively low on a high slope fan. resulting in a <br />concentration of flood hazards within the established path. <br /> <br />Lan Geomorphic Bias. Entrance Anale, .i!Jlll. Entrenchment <br /> <br />These characteristics <br />direction. geometry. <br /> <br />have important influences on <br />and stability of the flow path. <br /> <br />50 <br /> <br /> <br />the <br />The <br />