This report contains flood information for the Rock River basin in Iowa, it updates and supersedes the 1967 report "Floods in Rock River basin, Iowa" by P. J. Carpenter.
The occurrence of an outstanding flood in 1969 and the acquisition of additional flood data in the basin prompted the preparation of this report. The 1969 flood, the greatest flood on the Rock River in at least 45 years, is nearly equivalent to a flood of a 50-year recurrence interval. The 1953 flood was the greatest recorded on Otter Creek. This flood was 1.8 times the 50-year recurrence interval discharge at the gaging station near Ashton.
Flood information is reported for 49.8 miles (80.1 kilometers) on the main stem, 49.6 miles (79.8 kilometers) on the Little Rock River, and 33.0 miles (53.1 kilometers) on Otter Creek. This information is useful to those concerned with the design of bridges and other structures and those involved in regulatory or planning activities on the flood plains of the streams. Included in the report are flood-peak records, frequency curves, water-surface profiles, and bench mark data.
Flood profiles for the Rock River include those for the 1962, 1964, 1965, 1969, and the computed 25- and 50-year floods. On the Little Rock River and Otter Creek, profiles include those for the 1969 flood and the computed 25- and 50-year floods. Low-water profiles are shown for all reaches.