FLOOD02527

• County: Otero
• Community: La Junta
• Basin: Arkansas
• Title: FIS - La Junta
• Date: 6/1/1982
• Prepared For: La Junta
• Prepared By: FEMA
• Floodplain - Doc Type: Current FEMA Regulatory Floodplain Information

Horizontal control is based on Colorado State Plane Coorninate
System South Zone 1929 USC & GS Seal Level Datum. Elpvation
reference marks used in this study are shown on the maps.

4.0 FLOOD PLAIN MANAGEMENT APPLICATIONS

The Na ti ona1 Flood I nsurance Program encourages sta te and local
governments to adopt sound flood p1 a in management programs. Therefore,
each Flood Insurance Study includes a flood boundary map designed to
assist communities in developing sound flood plain management measures.

4.1 Flood Boundaries

In order to provide a national standard without regional
discrimination, the laO-year flood has been adopted by FEMA as the
base fl ood for purposes of fl ood p1 ain management measures. The
500-year flood is employed to indicate additional areas of flood
ri sk in the commun i ty. For each stream studi ed in deta il, the
boundaries for the 100- and 500-year floods have been delineated
using the flood elevations detennined at each cross section;
between cross sections, the boundaries were interpolated using
aerial topographic maps at scale of 1:2400, with a contour interval
of 2 feet, (Reference 81. In cases where the 100-and 50D-year
flood boundaries are close together, only the lOa-year flood
boundary has been shown.

Flood boundaries for the 100- and 500-year fl oods are shown on the
Flood Boundary and Floodway Map, Small areas within the flood
boundaries may lie above the flood elevations and, therefore, not
be subject to flooding; owing to limitations of the map scale, such
areas are not shown.

4.2 F100dways

Encroachment on flood plains, such as artificial fill, reduces the
flood-carrying capacity and increases flood heights, thus
increasing flood hazards in areas beyond the encroachment itsel f.
One aspect of flood plain management involves balancing the
economic gain from fl ood pl ain development against the resulti ng
increase in flood hazard. For purposes of the National Flood
Insurance Program, the concept of a floodway is used as a tool to
assist local communites in this aspect of flood plain management.
Under thi s concept, the area of the 100-year fl ood is divided into
a f10adway and a f100dway fri nge. The f10adway is the channel of a
stream, p1 us any adjacent flood plain areas, that must be kept free
of encroachment in order that the 100-year flood may be carried
without substantial increase in flood heights. Minimum standards
of the FIA 1 imit such increases in flood heights to 1.0 foot,
provided that hazardous velocities are not produced. The floodways
in this report are presented to local agencies as minimum standards
that can be adopted or that can be used as a basis for additional
studies.

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