Environmental Engineering Reference
In-Depth Information
FIGURE 3.2
National Inventory of Dams database, Available at http://crunch.tec.army.mil/nidpublic/
webpages/nid.cfm.
the country have modiied at least 600,000 miles, or about 17% of American rivers. Virtually all large
rivers (and most small rivers) in the United States are modiied and fragmented by dams.
3.2.1.2 What Are They for (and How Are They Operated)?
Dams are typically designed and constructed for designated uses such as (the number of dams
with their use is given in parentheses taken from NIDs) lood control and stormwater management
(15,769), irrigation (9,405), water supply (7,430), navigation (693), recreation (33,934), and hydro-
power (2,551). By far the majority of dams are privately owned, as illustrated in Figure 3.3, with
only 4% of U.S. dams being federally owned.
The purpose, function, and manner of a dam's operation will vary with its designated use. For
example, some of the typical purposes and functions along with design considerations are:
•
Municipal and industrial (M&I) water supply: Provide water of a satisfactory quality to
meet the demand with adequate pressure at all times in all parts of the system.
•
Estimate the demand and supply based on historical data and expected trends.
•
Locate water sources as close to the demand as possible.
•
Design surface storage to retain wet season lows to bridge dry periods; keep reservoirs as
full as possible.
•
Design a distribution system to supply time-varying demand with adequate pressure.
•
Maintain source quality and treat as needed.
•
Treat waste lows.
Federal
Local government
Private
Public utility
State
Not listed
FIGURE 3.3
Dam ownership. (Based on data from the National Inventory of Dams.)
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