English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Plus monthly

Global: Zendy Tools annual

Global: Zendy Tools monthly

Global: Zendy Free Plan

Flood magnitude-frequency relations applicable to streams in the St. Lawrence River basin in the United States are presented in this report. For the most part, the relations are based on flood data collected at gaging stations having 5 or more years of record unaffected by regulation. For sites on mort streams, the magnitude of a flood of a given frequency can be determined from two curves one expressing the relation between the mean annual flood and size of drainage basin and the other expressing the relation between ratio to mean annual flood and recurrence interval. In Minnesota and selected areas of Wisconsin and Michigan, the procedure is modified by an adjustment b-Msed upon the percentage of lake and pond area in a basin. Special treatment i^1 accorded the main stems of several streams where the frequency relations do not conform with those for other streams in the same general area or region. Extrapolation of the curves is not recommended because of the lack of definitive data beyond the limits shown. The report contains lists of flood stages and discharges for all gaging stations having 5 or more years of record. Included also are tables giving information for maximum known floods at these stations and for unusual floods at miscellaneous sites and short-term gaging stations. INTRODUCTION PURPOSE AND SCOPE The purpose of this report is twofold (1) to provide a means for estimating the magnitude and frequency of floods for most natural streams in the area and (2) to make basic data for floods available in a readily usable form. The relation between the magnitude and probable frequency of occurrence of floods is subject to recurrent change as additional flood data are accumulated and as new and improved methods of analysis are developed. The relations presented in this report should be exposed to periodic review incorporating new data and methods as they become available. The magnitude of floods in the frequency relations is given in terms of flood discharge or rate of flow. It is recognized that in many investigations the flood stage, or elevation of the water surface at the 2 MAGNITUDE AND FREQUENCY OF FLOODS, PART 4 flood crest, is as important as the discharge, or more so. However, acceptable methods for relating flood stages directly with frequency of occurrence have not yet been developed. An investigator interested in flood stages must convert discharge to stage by application of the appropriate stage-discharge relation for the site under consideration. In general, the flood-frequency relations given are br.sed on flood data for all gaging stations where 5 or more years cf record are available and where the flood discharges are not significantly affected by manmade changes. Lack of data and uncertainty regarding the nature of flood-frequency relations on small streams for the most part limit the use and reliability of the relations presented to streams having drainage areas greater than 20 square miles. ACKNOWLEDGMENTS Most of the peak data listed in this report have been abstracted from reports on surface-water supplies published by the U.P. Geological Survey. The records were collected by the Geological Survey with the assistance of many other Federal and State agencies, counties, municipalities, corporations, and private individuals, credit for which is given in the previously published reports. If records were completely furnished by another agency, this fact is noted in the individual station description. This report was prepared under the general direction of Tate Dalrymple, chief, Floods Section, Washington, D.C. Technical guidance and review were provided by A. Rice Green, hydraulic eng:neer, Floods Section, Washington, D.C. Special credit is due L. E. Stoimenoff and J. B. Miller, hydraulic engineers, and other personnel of the Lansing, Mich., office for much of the work in assembling the flood data and in computing the flood-frequency relations. The individual station data were compiled and prepared for publication in the various district offices of the Geological Survey under the supervision of the following district engineers: Arlington D. Ash _ __ . Landing, Mich. Donald F. Dougherty Albany, N.Y. Malcolm D. Hale Indianapolis, Ind. Charles E. Knox. Boston, Mass. William D. Mitchell Chanpaign, 111. John J. Molloy _ __   Columbus, Ohio Leon B. Sawyer succeeded by David B. Anderson. St. Prul, Minn. Robert E. Steacy _  Harrisburg, Pa. Kenneth B. Young. Madison, Wis. REPORT AREA The area covered by this report is the St. Lawrence River basin in the United States (fig. 1). It extends from the Atlantic Ocean to the middle of the North American continent. All of it is in the zone FI G U RE 1 . T h e co nt er m in ou s U ni te d S ta te s sh ow in g ar ea c ov er ed b y th is r ep or t (s ha de d) . 4 MAGNITUDE AND FEEQTJENCY OF FLOODS, PART 4 once covered by the glaciers that invaded the continent. It thus contains a great variety of surface formations and landforms, typical of glaciated areas. Transitions from one type of surface formation to another can be very abrupt. For example, lake plains composed of tight impervious clays may adjoin highly porous and absorptive outwash deposits. Land altitudes range from near sea level to more than 5,000 feet above mean sea level. The climate is also diverse, though modified by the presence of the Great Lakes. The Great Lakes basin lies in the path of the cyclonic storms that travel generally eastward across the continent at more or less regular intervals. In addition, the southern part can be frequented by storms originating in the Gulf of Mexico and traveling north and east up the Mississippi and Ohio valleys and the eastern part can be affected by the coastal hurricane 'Storms. Mean annual precipitation ranges 'between 24 and 50 inches. The heaviest snow belts east of the Rocky Mountains lie on the uplands along the leeward sides of the Great Lakes, notably in the Upper Peninsula of Michigan near Lake Superior, in the northern part of the Lower Peninsula of Michigan near Lake Michigan, and in western New York. Seasonal snowfalls in excess of 200 inches are not uncommon. The five Great Lakes provide a unique hydrologic setting for the area. These lakes, representing a total water surface area of about 95,000 square miles, have a dominant influence upon the hydrology of the region. Because the local drainage is into one of the Great Lakes, this major drainage basin is characterized by a proliferation of small streams. The largest tributary stream in the basin in terms of drainage area is the Eichelieu River which drains an area of about 9,000 square miles. PBEVIOUS STUDIES Reports on the magnitude and frequency of floods covering parts of this report area have been published for all the States except Michigan (Benson, 1962; Busch and Shaw, 1960; Cross and Webber, 1959; Ericson, 1961; Green and Hoggatt, 1960; Mitchell, 1954; Prior and Hess, 1961; and Robison, 1961). Except for Benson's report which covered all New England, each of these reports covered a single State. The treatment of the flood data and consequently the application of the relations defined differed considerably among these reports. In this report, an attempt has been made to use a single, simple method of flood-data analysis for the entire area. A few modifications were necessary, however. Wherever possible, an effort was made to incorporate the previous analyses into those of this report sp that there might be more consistency in the results reported by these overlapping studies. Prior's curves for the Minnesota part of the area and Robison's curves for the New York part were extracted, virtually FLOOD-FREQUENCY ANALYSIS 5 unchanged, from their respective reports for inclusion in this report. More divergence in results may be expected in those States Ohio, Vermont, and Wisconsin where somewhat different methods of analysis were used. It should not be construed that the methods used and the results obtained in this study are better or more precise than thase of the previous studies. The differences that exist are probably well within the expected range of variability of flood-frequency data. The need for consistency of approach to avoid a multiplicity of methods of analysis in a single river basin, and simplicity of application prompted the treatment described in this report. FLOOD-FREQUENCY ANALYSIS Floods are caused by runoff from rainfall and snowmelt, dam failures, and channel obstructions such as ice and debris jams. In this report, only the rainfall and snowmelt floods are considered. Floods resulting from the other causes are so capricious as to defy rational analysis. Many methods have been suggested for determining flood frequency by using statistical analysis. The methods used in this report, described by Dalrymple (1960), have been developed largely in the Water Resources Division of the Geological Survey. Th^y involve the definition of individual flood-frequency relations at specific points and the combination of a number of these to derive relations applicable over relatively broad areas. They permit determinatioE of floodfrequency estimates for ungaged as well as for gaged siter. The following sections of this report describe the analyses and methods used to derive the flood-frequency relations. Readers interested primarily in the application of the relations contained herein may refer directly to the sections headed, "Special treatment for selected areas and streams" (p. 13) and "Application of methods used" (p. 19). FLOOD FREQUENCY AT A GAGING STATION In this report, flood data at a gaging station were analyzed as an annual flood series in which the highest momentary peak discharge for each water year (October 1 to September 30) was used. For some stations the annual maximum daily disc

Magnitude and frequency of floods in the United States; part 4. St. Lawrence River basin