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<br />program. Additional clllllputer runs NY be made to improve the accepta- <br />bility of the floodway. The computerized procedure is discussed here <br />and illustrated in the example proble111. <br />The cClllputer procedure is based on calculating a natural pro- <br />file as the first profile in a ~ultiple profile run. Other profiles <br />in the run can be calculated using various encroachment options as <br />desired. The fhe encroachnent methods available are described in <br />Exhibit 9A of the Users Manual. The input requirements and associated <br />output statements are also presented. The HEC-2 Standard Test T. <br />shown in Exhibit 8 of the Users Manual. provides an example of ap- <br />plication of Methods 2. 3, and 4 of the encroachment options. The <br />procedure described herein is based on the use of Method 4. which <br />provides the most direct means for delineating a floodNaY. <br />Method 4 establishes encroachment limits at a cross section on <br />tne basis of natural (i.e.. prior to encroachment) flow conditions. <br />As part of program input. the user specifies a target incremental <br />increase in Nater surface elevation (nonnally one foot). The program <br />increases the computer "natural" Nater surface elevation by the incremen- <br />tal amount and computes the corresponding increase in the computer con- <br />veyancel over the natural conveyance for each cross section. The pro- <br />gram then sets encroacn.ent limits at each cross section by eliminat- <br />ing the increased conveyance from the extremities of the overbank <br />areas. The program removes an equal percent of conveyance from each <br /> <br />lconveyance is defined as K. 1.~9 AR2/3 where: n. Manning's rough- <br />ness coefficient. A . Flow area, and R z Hydraulic radius. <br /> <br />5 <br />