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<br /> <br /> A FLOOD- PlAIN FI& I <br />14. Determine type of flood plain, and estimate conditions at time of <br /> flow event; compare the flood plain with photograf*1s and descriptions <br /> of the other flood plains. <br />15. Determine method to be used in assigning n to flood plain, whether <br /> vegetation-density method will be used with boundary roughness <br /> factors, or boundary roughness factors only. <br />16. Determine if roughness is uniform throughout flood plain, or whether <br /> flood plain needs to be subdivided. (Fbllowing steps apply to each <br /> subdivision. ) <br />17. Determine the factors that cause roughness and how each is to be <br /> accounted for. <br />18. Assign a base nb from tables and comparison with other flood plains <br /> and verification photographs. <br />19. Determine adjustment factors from tables. <br /> I <br /> I 1 <br />Ebundary roughness methodl Boundary roughness method with <br /> vegetation density method. <br /> I <br /> 20. Determine no value from tables and <br /> formulas. <br /> 2l. Determine vegetation density of repre- <br /> sentative sample area of flood plain. <br /> I <br /> I <br />22. Determine n for flood plain by using formulas. <br />23. Canpare value determined with that for other flood plains and <br /> verification photographs to test for reasonableness. <br /> <br />Figure 21. --Flow chart of procedures for assigning n values--Continued. <br /> <br />41 <br />