Kansas Water Science Center
Water-Supply Paper 2502
Summary of Significant Floods in the United States, Puerto Rico, and the Virgin Islands, 1970 Through 1989
Summary of Significant Floods, 1970 Through 1989, by State or Territory
In addition to the specific flood data, this section provides a description of the hydroclimatology and a summary of significant floods for each State or territory in the United States. The summary of significant floods includes those with loss of life or excessive damage during the period 1970 through 1989. The floods that were in the top 5 percent of each streamflow-gaging station's record during this period are tabulated, and an estimated recurrence interval is provided along with other pertinent data. A map of each State or territory is supplied to locate the streamflow-gaging stations.
Indiana's location in the midcontinent interior allows several different sources of moisture to affect the climate. These sources originate from the Pacific Ocean, Lake Michigan, the Gulf of Mexico, and the subtropical Atlantic Ocean. Tropical airmasses dominate the climate in the late spring, summer, and early fall. These airmasses originate in the Gulf of Mexico and the subtropical Atlantic. Polar continental airmasses control the late fall, winter, and early spring climate. These typically dry airmasses carry frontal systems that form over Alberta, Canada, and move southeastward. However, lake-effect moisture from Lake Michigan combines with the polar airmasses to cause greater precipitation in northern and northwestern Indiana. A well-defined, north-south climatic gradient across the State results in a cool, temperate, continental climate in the north and a warm, temperate, continental climate in the south. Mean annual precipitation ranges from 37 in. in the northwestern and north-central parts of the State to 44 in. in the south-central part (Paulson and others, 1991).
Flooding in Indiana is most widespread in late winter when excessive rainfall caused by frontal systems is combined with snowmelt. Frozen or saturated soil can result in an increase in runoff. Indiana also receives flooding due to the remnants of hurricanes tracking across the State. Summer floods typically are caused by thunderstorms and affect a smaller area than the floods associated with the remnants of hurricanes.
On the basis of regionalization procedures that relate flood characteristics to watershed and climatic characteristics, factors affecting the magnitude of maximum discharges for streams in Indiana are contributing drainage area of the basin; storage, which is the percentage of the contributing drainage area covered by lakes, ponds, and wetlands; runoff coefficient, which relates storm runoff to soil permeability; main-channel slope; precipitation, using 2-year, 24-hour measurements; and main-channel length (Jennings and others, 1994).
Moderate rainfall combined with a melting snowpack produced the floods of March 1982. Northern Indiana was most affected by the floods. Thirteen percent of the streamflow-gaging stations in the State recorded significant discharges. Flooding on the Kankakee River and its tributaries caused extensive damage in three counties in northwestern Indiana.
The summer of 1979 was plagued by flooding. The first storm arrived in June, and an excess of 10 in. of rain fell in parts of southwestern Indiana. Remnants of Hurricane Bob caused the second major storm. Rainfall lasting all day caused local flooding in areas of southwestern, central, and eastern Indiana. The third and largest storm of the summer was caused when remnants of Tropical Storm Claudette combined with a stationary weather front. Intense rains caused flash flooding, and a total of 9 in. of rain was recorded in some areas. The recurrence intervals of the floods on some smaller creeks were greater than 100 years (Paulson and others, 1991).
The location of streamflow-gaging stations in Indiana that had significant floods for 1970-89 is shown figure 36 by station number. The specific data for each significant flood are listed in table 15. A significant flood is one that ranks in the top 5 percent of all annual maximum discharges for that station's period of record.
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