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I I I I I I I I I I I I I I I I I I I H. Non-structural methods such as flash-flood warning, flood insurance, evacuation plans, etc. Y. Relocation of the channel to routes other than the historic channel. J. Other Plans as suggested by participating entities. K. Combinations of the preceding. Each of the alternatives except A can be implemented for any design frequency. For the purpose of analyzing alternatives for DFA, the channel has been broken down into the following reaches: Reach I Reach 2 Reach 3 Reach 4 Confluence to Riverdale Road Riverdale Road to Holly Street Holly Street to 112th Avenue 112th Avenue to upstream study limit Because each channel reach presents a unique problem, alternative flood control plans have been considered on a reach by reach basis. Alternative flood control plans are identified by reach in an alternative matrix, Figure V-I. Preliminary examination of each alternative plan led to the elimination of those shown in the shaded sectors of the matrix as being infeasible for practical application. Discussion of the feasibility of each of the alternatives follows. A cursory review of the matrix in Figure V-I indicates that it is possible to separate the possible alternatives into two basic categories: non-structural and structural. Alternatives A, G, and H will fall into the non-structural category. Column J represents a means by which any or all of the other columns may be combined. Since this section is a general discussion of alternatives, it will not be necessary to examine Columns J and K. Alternatives J and K will be addressed in the discussions of the individual reaches. Non-Structural Alternatives Alternative A: Maintain Existing' Config'uration This is the simplest and most basic of all alternatives. All other alternatives are born from this alternative and are evaluated by comparison with it. By proposing to maintain the floodplain exactly as it exists at the present, future flood damage can be reasonably predicted in the existing developed areas of the floodplain. Further flood damage potential to future development would be controlled under this alternative by floodplain zoning, however, no improvement to existing structures or channel sections would occur. Flood control benefits attributed to other alternatives are reductions in the flood damages from those calculated for the existing condition. Although no flood damage reductions are attributed to this alternative in this analysis, outside of continued erosion and low flow problems, future flood damages would gradually decline with the enforcement of floodplSlin rpg:J11Sltions. In addition, the enforce- ment of floodplain regulation is required for local participation in the Federally subsidized flood insurance program and considered as part of this alternative. Channel maintenance would be required to remove flood debris from culverts, irrigation ditches, and streets and to repair erosion damage. Because this is the baseline condition, the benefit/cost methodology assumes that there are no damage reduction benefits associated with this alternative. V-2