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<br />I <br /> <br />I <br /> <br />I <br /> <br />I <br /> <br />I <br /> <br />I <br /> <br />I <br /> <br />I <br /> <br />I <br /> <br />I <br /> <br />I <br /> <br />I <br /> <br />I <br /> <br />I <br /> <br />I <br /> <br />I <br /> <br />I <br /> <br />I <br /> <br />I <br /> <br />13 <br /> <br />07/16/99 <br /> <br />Table 1. Methods for defining the IOO-year flood within areas defined in Stage 2. <br /> <br />METHOD ASSUMPTIONS LIMITATIONS RECOMMENDED <br />APPLICATIONS <br />Risk-Based Refer to "Guidelines for Risk and Uncertainty <br />Analysis Analysis in Water Resources Planning" <br />(USACE,1992). <br />FAN Program flooding in rectangular channel, critical depth, fluvial (as opposed to highly active conical fans <br /> erosion ofrectangular channel banks until the debris flow) formed <br /> change in width per the change in depth equals - fan, unstable flow <br /> 200, the probability density function of a paths <br /> discharge occurring at the apex is log-Pearson <br /> Type III, the frequency of flood events for <br /> various recurrence intervals, Le., 2-year through <br /> SOO-year, can be adequately defined, equal <br /> probability along contour arcs (random flow <br /> paths), (also provides for multiple channels at <br /> normal depth assuming total width is 3.8 times <br /> the single channel width) <br />Sheetflow broad, unconfined, shallow flooding not for use in areas of shallow flooding across <br /> undulating terrain uniformly sloping <br /> surfaces <br />Hydraulic stable flow path, uncertainty is to a degree that not for use with active entrenched stable <br />Analytical may be disregarded alluvial fan flooding chaJUlel networks, <br />Methods constructed channels, <br /> urbanized areas <br />Geomorphic Data, relies primarily on qualitative information, post- approximate method alluvial fans with little or <br />Post-Flood Hazard flood verification, historical data, and no urbanization <br />Verification, and interpretive studies <br />Historical <br />lnfonnation <br />Composite as identified in the sections referring to the must integrate multiple floodprone areas that <br />Methods methods being applied methods into one contain unique physical <br /> result features in some <br /> locations or ha ve areas <br /> varying in levels of <br /> erosion and migration <br /> activity <br />