A topographic map of development along State Hwy 100 crossing the Floodwood Rive
ID: 283992 • Letter: A
Question
A topographic map of development along State Hwy 100 crossing the Floodwood River has been developed from surveys. The contour interval is 2 feet, and the map scale is 1" equals 500 ft. A flood frequency analysis of records from a nearby gaging station has produced the 10 yr and 100 yr flood discharges. These peak discharges have then been used by an engineering firm in the program HEC II (Hydrologic Engineering Center of Corps of Engineers program that produces flood profiles along a river for a given discharge) to determine the flood levels at intervals along the river. The following table gives the elevations in feet for the 10 and 100 year floods for stations along the river.
Station or location 10 year flood level 100 year flood level
50 ft. DS Centerline Town Rd "A" 204.00 206.00
50 ft. US " 205.20 207.20
500' above Rd "A" 205.50 207.50
2000' " 206.40 208.10
50 ft. DS of Hwy 100 208.00 209.60
50 ft. US of Hwy 100 209.30 211.00
4000' above Rd "A" 209.50 211.30
5000' " 210.00 211.70
50 ft DS of Town Rd "B" 211.50 213.20
Plot the boundaries of the 10 yr and 100 yr floods along the river on the topographic map. Use different colored pencils (not ink, so you can erase) or other means to differentiate the two floods.
PROCEDURE:
1. Plot the profiles (Elevation vs Distance) of the river bottom and the flood levels on graph paper. Use the first station (50 ft DS of Town Rd "A") as the reference point (Distance = 0) for distance along the river channel. The top of Town Rd "A" has an elevation of 208.00, and the top of Highway 100 has a minimum elevation of 212.00. Town Rd. "B" is at the ground surface.
2. For each station for which a flood elevation is given above, determine the position of the station on the river channel by measuring upstream along the river channel. Determine the extent of the floodplain for each flood by extending the cross section out from the channel on both sides until the flood elevation reaches the ground surface. Interpolate between contours. Plot the points at cross sections that are perpendicular to the flow direction in the river or floodplain.
3. Connect your plotted points on the map to determine the flood boundary. NOTE: The flood boundary will cross the contour lines as it moves up or down stream at a very small angle. The flood boundary can only cross each contour 1 time on each side of the river.
Answer the following:
the map with the delineated floodplains for the 10 and 100 year floods,
the profile of the river showing the two flood levels as well as elevation of bottom of river,
Number of houses in the Riverview and Edgewater subdivisions (shown as black squares) that are flooded by each of the floods?
River ViewDrive mm HIGHWAY /00Explanation / Answer
Three houses are affected by the flood water where as in the Edge water only one house is affected by the flood.
The various measure that can be employed in the modifying the flood or in the control are-
1. Dams and reservoirs
2. Dikes, levees, flood-walls
3 Channel alterations
4. High-flow diversions and spillways
5. Land treatment
6. Shoreline protection measures
Most of the stated measures are old method that can be employed in the volume of water for runoff this can help a lot in the damage that can be caused by the water along with the sediments that the river will deposited during the flooding.
Channel alternation is also an good way to alter the direction of the flow of the river water this is an expensive method that can be employed to minimize the damage that can be caused by the flooding well this requires an huge investment along with it’ll be going to disturb the natural ecosystem that is being existing now in the current flow of the channel.
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