Book Description

The floods that struck Southern California in January and February 1969 were among the greatest floods of record in Southern California, and were the first great floods to occur since construction of the complex systems of flood-control improvements by the Corps of Engineers. Although all Corps flood-control projects provided the protection for which they were designed and prevented damages estimated at more than $1-1/2 billion, damage was widespread in the overflow areas of unimproved or partly improved streams. More than 100 persons lost their lives, and property damage totaled more than $213 million. The decision to evaluate the performance of Corps of Engineers projects was made soon after the onslaught of the floods. Corps planners and designers were provided with a rare opportunity to weigh the actual performance of flood-control projects against the theoretical performance assumed in the design of the projects. Where deficiencies were noted in the projects, detailed analyses were made of the data collected to determine whether modifications in present design criteria might be indicated. This report presents available information on each project sustaining flood damage or encountering problems not foreseen in design, on flood magnitudes, and on flood-damage data to permit future reevaluation of design practices and design criteria on the basis of the findings presented in this report.