1. Watch video on "Floodplain mapping".
2. Examine the map of the floodplain of a local river; familiarize yourself with
the flood hazard information on the map (work in groups of 4).
3. Calculate flood level and flood depth for the four designated sites (1,2,3,4) on
the map (one site for each member of the group) for the 20-year and 200-
year floods. Use the following procedure:
a) scale the distance from the site to the flood level isoline upstream (x)
b) scale the distance from the upstream and downstream flood isolines (y)
c) subtract the downstream flood level from the upstream level (z)
d) calculate the flood level = upstream flood level – {(x/y)z}
e) calculate the flood water depth = flood level – site elevation
20-year flood event
| Site |
Elev (m)
|
x
|
y
|
z
|
Flood
level |
Water
depth |
|
1
|
4.2
|
|||||
|
2
|
5.7
|
|||||
|
3
|
6.8
|
|||||
|
4
|
7.4
|
200-year flood event
| Site |
Elev (m)
|
x
|
y
|
z
|
Flood
level |
Water
depth |
|
1
|
4.2
|
|||||
|
2
|
5.7
|
|||||
|
3
|
6.8
|
|||||
|
4
|
7.4
|
4. Compare results between groups; recheck calculations if necessary.
Discussion
5. What is the current land use at each site? Is this the optimal land use, or would you recommend?:
a) high-density residential (apartments, townhouses)
b) low-density residential (single-family homes on standard lots)
c) light industry (e.g. warehouses)
d) recreational (e.g. park, golf course)
e) undeveloped green space
6. A land developer wishes to build a residential subdivision at site 3, and submits the following architectural sketches (A - G) for planning approval. Which house type (or mix of house types) should be approved, and why? Remember, the greater the degree of site or residential modification, the greater the cost of the completed housing.
