FLOOD02408

• County: Statewide
• Community: Nationwide
• Basin: Statewide
• Title: Design Hydrographs for Very Small Wathersheds from Rainfall
• Date: 7/1/1962
• Prepared By: USDA Hydrograph Laboratory, Civil Engineering Section Colorado State University
• Floodplain - Doc Type: Educational/Technical/Reference Information

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ABSTRACT

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Individual flood hydrographs observed on
agricultural and range land throughout the United
States of America were described bya three-para-
meter mathematical model. The values of the three
hydrograph parameters were related to topography,
land use and rainfall associated with each flood event.

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Three separate multiple regressions were
developed, each for predicting one of the hydrograph
parameters from three independent variables.
Thirty~six independent variables were tested including
many which have been suggested by previous workers
and which- are incorporated in current design methods.

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Multiple linear regression, with three inde-

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pendent variables, accounts for 80 percent and 61
percent of the variance in the volume and peak rate
of runoff respectively. The third parameter a time
variable, which also defines the hydrograph recession,
can be predicted by a logarithmic relationship in-
volving only soils, land use and topography so that
about 60 percent of its variance is explained.

Due to the sample size being limited to forty-
seven flood events, the developed regressions do not
provide a rigorous formula for design. They are
presented rather to show that this approach prOvides
a simple method by which hydrographs could be
synthesized. The discussion suggests that a large-
scale study could provide the desired accuracy, and
indicates ways of achieving this.

ACKNOWLEDGEMENTS

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The author wishes to acknowledge the guidance
of Dr. V. M. Yevdjevich in conducting this research
and his advice on "!he preparation of this dissertation.
Thanks are also due to the other members of the
author's research and dissertation committee for
reviewing the manuscript and for earlier discussions.
Dr. F. A. Graybill, Mr. W. S. Devenney and other
members of the Computing Service gave valuable help
in processing the data.

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Thanks are due to the AgricultW'al Research
Service of the United States Department of Agricul-
ture for providing the funds with which the research
leading to the dissertation was carried out. Parti-
cular thanks is due to Mr. H. N. Holtan. Director
of the U. S. Hydrograph Laboratory of the Soil and
Water Conservation Research Division of the above
service.

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The Department of Agricultural Technical
Services of the Republic of South Africa kindly afford-
ed the author leave to study in the United States of
America. The interest of Mr. E. D. Adler, Director
of its Natal Region. where the author will undertake
hydrological research, has been a great encourage-
ment. Thanks are also due to the innumerable per-
sonnel in bureaus of the United States for the courte-
ous and generous manner in which they provided
technical information and counsel. Special thanks is
due to Mr. H. O. Ogrosky, Chief of the Hydrology
Branch of the Engineering Division, of the U. S. Soil
Conservation Service, and to other engineers of the
Branch for valuable discussions and correspondence.

The author is most grateful to his wife and
family for the sacrifices they have made to enable
him to complete his studies.

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