1
Introduction to
Environmental Geology, 5e
Chapter 9
Rivers and Flooding
–
Chapter 9: Overview
•Understand basic river processes.
•Understand the nature of the flood hazard.
•Understand the effects of urbanization on
flooding in small drainage basins.
•Know the major adjustments to flooding and
which are environmentally preferable.
•Know the potential adverse environmental
effects of channelization and the benefits of
channel restoration.
Case History: Pakistan Floods of 2010
•The number of people killed or affected, along with
economic loss, is the greatest in Asia
• A monsoon refers to a seasonal shift in air pressure
and precipitation patterns (dry winter to wet summer)
•August of 2010, the greatest monsoon rains in
decades, caused catastrophic flooding in Pakistan
•July 29th, 12 inches of rain fell in the Upper Indus
•Killed about 1,600 people, 20 mill ion people were
affected, 1.4 million acres were flooded
Case History: Implications
•The population of Pakistan has grown from about 34 million
in 1951 to 170 million in 2010
•Most people in Pakistan live close to the river
•About 20 percent of Pakistan was flooded in 2010
How to compare this catastrophe with the US:
•Rethink our philosophy of how we adjust to the flood
hazard in the United States as population grows
•Plans for future flood hazard reduction that do not require
massive evacuation from flood prone areas
–Avoid the hazard through land use instead of evacuation
Case History
Figure 9.2a/b
Rivers: Historical Use
•For more than 200 years, Americans have lived
and worked on floodplains, depending on soil,
water supply, ease of waste disposal, and the
commerce
•If the floodplain and its relation to the river are
not recognized, flood control and drainage of
wetlands become prime concerns
•The pioneers moved west modifying the land:
cutting and burning the trees, and then modifying
the natural drainage
Docsity.com
