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<br />,. The effect of fan characteristics such as <br />slope. watershed conditions. and morphology <br />should be incorporated into the method through <br />the use of empirical equations (see Part II. <br />Section 3) for depth and velocity. <br /> <br /> <br />5) Permanent entrenchments. topographic biases. <br /> <br />and other morphologic features which may modify <br /> <br /> <br />flood hydraulics are either absent or have a <br /> <br /> <br />minor influence. <br /> <br />, <br /> <br />The fIA methodology was developed. for application on <br /> <br /> <br />unentrenched. smoothly sloped (active) alluvial fans with <br /> <br /> <br />little or no man-made obstructions. As such. it represented <br /> <br /> <br />a substantial improvement over the use of standard riverine <br /> <br /> <br />approaches (HEC-2. etc.) or the reliance on "eyeball <br /> <br /> <br />guestimates". It provided an easily applied. simple <br /> <br /> <br />technique which. given suitable fan conditions. predicted <br /> <br /> <br />the approximate depths and velocities of flooding. <br /> <br />The data and insights gained in the present study through <br />field investigations and physical model experiments provide <br />the basis for substantial improvements to the methodology. <br />The most important attributes of a widely applicable <br />alluvial fan methodology are as follows. <br /> <br />2. The observed pattern of three hydraulic zones. <br /> <br /> <br />channelized. braided. and sheet flow. should be <br /> <br /> <br />considered in the predictions. since each zone <br /> <br /> <br />has different flood hazard severity and flood <br /> <br /> <br />behavior. <br /> <br />3. The froude number and channel geometry should <br /> <br /> <br />vary with fan conditions such as slope and <br /> <br />sediment size. <br /> <br />54 <br />