FLOOD08495

• County: Statewide
• Community: Statewide
• Basin: Statewide
• Title: Methodology for Evaluation of Feasibility: Multijurisdictional Urban Drainage and Flood Control Projects
• Date: 2/1/1977
• Prepared By: UDFCD
• Floodplain - Doc Type: Educational/Technical/Reference Information

I
I
II
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I

15

1. Decomposition into Decision Units. The Little Dry Creek
Basin contains some logical points for decomposition since there
are five local governments involved, The area breaks down neatly
into subcatchments and reaches, Table 11-1 shows the decomposition
of the basin into subcatchments, giving the stream mileage within
each subcatchment by jurisdiction, To further summarize the de-
composition by jurisdiction, Table 11-2 gives the subareas of the
basin by jurisdiction. Figure 11-3 shows the subdivision of the
basin into reaches in the form of a line diagram, The average
length of the reaches is on the order of 0.75 miles. Each reach can
now be referred to as Little Dry Creek, 109-111, for example.
2. Development of Damage Reduction Data. The procedure is to
build up relationships within each reach for damage versus depth of
flooding, Appendix A demonstrates how this is done. The result
should be curve(s) for reaches where damage can be reduced or miti-
gated by implementing flood control measures. Figure 11-4 shows
typical curve development.
3. Formulation of Alternatives. Alternatives are formulated
for each Decision Unit or combination thereof, The Decision Units
correspond to the reaches show~ on Figure 11-2. The existence of
zoning over the 100-year floodplain is assumed for each alternative,
Because of the special conditions in the basin, combination of
the fol16wing classes of alternatives are considered:
1, Improvement of existing dams or construction of new dams
2. Natural channels with necessary improvements
3, Improvement of existing conduits