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Bill Thayer

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Appendix III
This webpage reproduces a section of
1895 Advisory Board Report
on the
Drainage of the City of New Orleans

Text and maps are in the public domain.


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Appendix V
This site is not affiliated with the US Military Academy.

Appendix IV
Rain-fall Gauging

For the purpose of obtaining accurate information regarding the precipitation, six "Frieze" self-registering rain gauges were purchased and placed at selected points throughout the city. These gauges automatically register the precise time and rate of precipitation, the amount being registered so as to read to hundredths of an inch. The total amounts recorded by the gauge were checked by actual measurement with a graduated stick. Plate VI shows the records of the rain storms which occurred on April 24th, July 4th, July 14th and August 13th, 1894. The locations selected for the gauges were such as to furnish the rate and intensity of precipitation in the different parts of the area now subject to drainage. One gauge was placed in Audubon Park near the river, one at the Dublin Avenue Draining Machine, one at the London Avenue Draining Machine, one at the corner of France and Levee streets, one at the City Hall, and one was located at West End, but was afterwards removed and placed at the corner of Magazine and Berlin Streets. These gauges were all installed, tested and in thorough operation by April 1st, 1894.

The necessity of having several gauges for the purpose of obtaining the average precipitation on a large area, is of paramount importance, as storms even of a general character, vary largely in precipitation, even within a small area and in New Orleans a large proportion of the storms are limited in area and do not simultaneously extend over the whole city. The records of precipitation at different points in any territory enable the direction and intensity of the storm to be observed and also indicate the sections which were visited by the greatest intensity during any one storm.

The records of rain-falls by these instruments have been carefully preserved and the volume of precipitation on the different areas calculated and tabulated.

Plate VII represents graphically the fall in inches and the duration of several storms of intense precipitation which have occurred in the City of New Orleans between April 1st and December 31st, 1894, the date of the several storms being marked on the plate.

Table I is a list of the storms which have occurred in the City of New Orleans between April 1st and December 31st, 1894, where the total precipitation did not exceed half an inch. This table also shows the maximum precipitation in five minutes, the maximum rate of precipitation per hour, the total precipitation in inches, the duration of storm, and the date.

Referring to this table it will be noted that the rate of precipitation is in many instances very great in comparison to the volume, as in the storm of April 25th when, with a total precipitation of 0.33 of an inch, the rate was 2.4 inches per hour; and five of these storms having a total precipitation of less than 0.5 of an inch had a rate of 1.8 inches per hour and upwards.

Table II is a list of the storms which have occurred in the City of New Orleans between April 1st and December 31st, 1894, having total precipitations p62exceeding 0.5 of an inch and shows the date of maximum intensity in five minutes, maximum rate per hour, maximum precipitation per hour, total precipitation and duration of storms. Of the twenty-four storms referred to in this table, eleven had a rate of precipitation exceeding three inches per hour. The storm of August 13th had a rate of precipitation of 6 inches per hour, and that of April 24th a rate of 5.4 inches per hour. These tables were compiled from gaugings made at the City Hall Station.

The greatest rate of precipitation on July 4th, as registered at the Park Station, was 7.2 inches per hour. It will also be noted that the greatest precipitation in one hour occurred on August 13th, when it was 2.75 inches, but the greatest intensity of this storm was at the rate of 6 inches per hour. On April 24th, with a maximum rate of 5.4 inches, the total precipitation in one hour was 1.9 inches, and on July 14th the maximum rate was 4.8 inches, and the total precipitation in one hour was 1.82 inches.

Table III is a list of storms of great intensity which have occurred in the States of Louisiana and Mississippi between the years 1872 and 1894.

Table IV is a list of storms which have occurred in the City of New Orleans from 1871 to 1894, in which the total precipitation exceeded 2.5 inches in twenty-four hours, as gauged by the New Orleans Station of the U. S. Signal Service and Department of Agriculture, Weather Bureau.

Table V is a list of storms which have occurred in the City of New Orleans from 1871 to 1894 in which the rate of precipitation exceeded one inch per hour, as gauged by the New Orleans Station of the U. S. Signal Service and Department of Agriculture, Weather Bureau.


Thayer's Notes:

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Page updated: 15 Sep 05