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<br />. <br /> <br />uniformly; and <br />human time, which <br /> <br />encompasses <br /> <br />the tYPlcal <br /> <br />planning horizon (100 years). <br /> <br />fan flood behavior will be unstable over geologic time, but <br />may be consistent over human time due to channel <br />entrenchments or other restrictions on flood pathways. <br />Planners must, during the course of a flood investigation, <br />determine whether existing flood channels are stable over <br />human time. <br /> <br />4. flood dynamics are strongly influenced by fan and <br /> <br /> <br />watershed characterics. watershed characteristics affect <br /> <br /> <br />the duration, intensity, and total volume of water and <br /> <br /> <br />sediment that enters the fan at the apex. fan <br /> <br /> <br />characteristics influence the directlon, hydraulic behavior, <br /> <br /> <br />amo~~t of sediment scour .or deposition, depth, and velocity <br /> <br /> <br />of the flow. <br /> <br />5. Any analysis of flood behavior on fans must identify and <br />consider fan and watershed characteristics. <br /> <br />2.3 Flood Hazards ~ Fans <br /> <br />1. The following types of flood hazards are common on fans: <br /> <br />. inundation; <br />. sediment deposition; <br />. scour and undermining; <br />. impact forces; <br />. hydrostatic and buoyant forces; <br />. high velocities; and <br />. unpredictable flow paths. <br /> <br />2. The severity of each hazard varles with location on the <br /> <br />16 <br />