1—
Introduction
FLOODS AS NATURAL DISASTERS
During the period from 1965 through 1985, floods were the number one cause of deaths and property damage by natural disasters in the United States (Rubin et al. 1986). Floods claimed about 1,800 lives and caused more than $1.7 billion in property damage during these two decades. The deaths and property losses from floods exceeded those caused by other natural disasters such as earthquakes, hurricanes, tornadoes, tsunamis, landslides, and volcanoes—a fact that surprises many, because floods are not usually thought of as a significant cause of death and destruction. This lack of public awareness of the potential dangers of floods is itself a problem that results in unnecessary exposure to flash flood dangers, reduced media coverage of flood events, and reduced funding for flood control projects and flood research.
EXPECTED LEVEL OF FLOOD PROTECTION
As premium building and housing sites throughout the United States become developed, encroachment occurs onto relatively inexpensive and often more flood-prone areas. Cities and counties are squeezed between the options of zoning for affordable housing and developing a viable tax base while at the same time protecting residents from natural disasters.
Citizens moving into an area are generally unaware of either the immediate potential for flood damage or the level of protection that the government has provided for them. Unless specifically forewarned as to their need to purchase flood insurance, most residents assume that the local government will provide or has provided flood control facilities to protect them from any and all possible flooding. More knowledgeable residents expect that they are at least protected from a 100-
year flood (i.e., a flood of such significance that it occurs only about once every century). However, this is not the case. The planning, design, construction, operation, and maintenance of flood control facilities providing such protection throughout the United States would require annual expenditures of billions of dollars. The successful completion of such facilities must compete with the myriad demands placed on government budgets. Current federal policies tend to place the burden of flood protection on local governments and on homeowners to obtain flood insurance.
Flood control structures, as is the case for all civil engineering projects, must pass at least five tests of feasibility: (1) Economics: Will the potential benefits exceed the costs? (2) Financial: Who will pay for the proposed facilities? (3) Social: Are the facilities socially acceptable to the adjacent residents? (4) Political: Are the facilities acceptable to the governing political bodies that control the finances? (5) Environmental: Do the facilities satisfy local environmental concerns? Without passing all of these tests, no flood control facility can be built. Therefore, the planning, design, and construction of adequate flood control facilities are difficult and slow to be achieved.
