Statewide regression equations are defined for estimating peak discharges of floods having recurrence intervals ranging from 2 to 500 years. Contributing drainage area, main-channel slope and mean annual precipitation are the independent variables required for estimating flood discharges for rural streams. For urban streams the percentage of the basin that is impervious and served by storm sewers also is required. The regression equations are applicable for watersheds draining less than 2,500 mil (6,500 km2) that are not significantly affected by regulation. For the rural streams, the regression equations are presented in graphical form for easy application.
Annual peak data, basin and climatic characteristics, log-Pearson Type III statistics and the flood-frequency relations are presented for 188 gaging stations.
