Darrell D. Carlson | USGS Science

USGS2007

Justification for a reduction in the crest-stage gage program in Louisiana

The crest-stage gage program in Louisiana was evaluated to determine if the data were adequate for use in developing regional flood-frequency equations and to determine if any crest-stage gage stations could be discontinued. An abundance of data at many crest-stage gage stations and a lack of data for urban areas and flat-slope areas indicated a need for a shift in the number, type, and locations of gages. Correlations and comparisons of annual peak discharges and watershed characteristics of 96 existing stations resulted in the elimination of 72 stations and the addition of one new station, reducing the total network to 25 stations that could be used for future flood-frequency analyses. The adequacy of the reduced network for development and verification of regional flood-frequency equations was tested by comparing a set of regional flood-frequency equations developed using data from the full network with a set developed using data from the reduced network. The results indicate that the crest-stage gage network can be reduced to 25 stations and still provide adequate information for future flood-frequency analyses.

Louisiana↗

USGS1983

Floods of April 1983 in southern Mississippi and southeastern Louisiana

Extreme flooding occurred in April 1983 in southern Mississippi and southeastern Louisiana. The floods resulted from a near-stationary cold front, which moved slowly across Louisiana and Mississippi. Flood heights and discharges of many streams exceeded previously known maximums of record, and for many the recurrence interval of peak discharge exceeded 100 years. On Black Creek, near Brooklyn, Miss., the previous maximum stage (since 1961) was exceeded by 4.26 ft, and the April 7 peak discharge of 42,500 cu ft/sec was about two times the previous maximum discharge. This flood exceeded the 100-yr event. In southeastern Louisiana, the area with the most severe flooding was in the Bogue Chitto basin. At the Franklinton, LA, Station, the April 7 peak discharge of 125,000 cu ft/sec was more than two times the previous maximum discharge. In April 1900 the stage at this site was 29.6 ft, 4.9 ft higher than the April 1981 peak. An extreme event also occurred on the Tchefuncta River near Franklinton, LA. The previous maximum stage (since 1949) was exceeded by 3.75 ft, and the April 6 discharge of 26 ,900 cu ft/sec is more than three times the previous maximum. This discharge also exceeded the 100-yr event. Combined flood damages for both States totaled in the hundred of millions of dollars. (Lantz-PTT)

Open-File Report↗