Page 520 - Geosystems An Introduction to Physical Geography 4th Canadian Edition

484 part III The Earth–Atmosphere Interface
▶Figure 15.34 Indus River flooding, 2010. These Terra images combine visible light and infrared to enhance contrast between the flooded river and land; water appears blue and clouds blue-green. [NASA/GSFC.]
possible flood-management strategy. Restrictive zoning using these floodplain designations is an effective way of avoiding potential flood dam- age. Flood hazard mapping shows the different degrees of risk for parts of the floodplain and is used to determine costs for flood insurance (see www.fema.gov/floodplain-management).
Restrictive zoning based on flood hazard mapping is not always enforced, and the sce- nario sometimes goes like this: (1) Minimal zon- ing precautions are not carefully supervised, (2) a flooding disaster occurs, (3) the public is out- raged at being caught off guard, (4) businesses and homeowners are surprisingly resistant to stricter laws and enforcement, and (5) eventually another flood refreshes the memory and promotes more planning meetings and questions. As strange as it seems, there is little indication that human risk perception improves as the risk increases.
For information on floods worldwide, see the Dartmouth Flood Observatory at floodobservatory .colorado.edu/. For weather and flood warnings, go to www.noaawatch.gov/floods.php.
(a) July 19, 2010: The pre-flood braided river channel.
PAKISTAN Location of
images
Hyderabad
Bhuj
Multan Bahawalpur
Sukkur
0 50
INDIA
100 KILOMETRES
Jodhpur
Mehar
Dadu Johi
Manchhar Lake
0 25
50 KILOMETRES
Mehar
Dadu Johi
Manchhar Lake
(b) August 11, 2010: Heavy monsoon rains caused increased discharge; flooding was initiated by a levee breach near Sukkur on August 6th, followed by channel avulsion to the west.
Sukkur
Sukkur
0 25
50 KILOMETRES
Mehar
Dadu Johi
Manchhar Lake
(c) September 7, 2010: The growing channel avulsion forms a separate river flowing into Manchar Lake, threatening the cities of Johi and Dadu.
Sukkur
0 25
50 KILOMETRES
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