Floods in Nebraska

on Small Drainage Areas

Magnitude and Frequency

GEOLOGICAL SURVEY 

CIRCULAR 45S
Floods in Nebraska on Small Drainage 

Areas, Magnitude and Frequency

By Emil W. Beckman and Norman E. Hutchison

Prepared in cooperation with the Nebraska Department of Roads

GEOLOGICAL SURVEY CIRCULAR 458

Washington 7962
United States Department of the Interior

STEW ART L. UDALL, SECRETARY

Geological Survey

THOMAS B. NOLAN, DIRECTOR

Free on application to /he U.S. Geological Survey, Washington 25, D. C.
CONTENTS

Page

Abstract ____________________________ 1

Introduction _. ____ _ ___ 1

Description of area ________________ 1

Phy siography____________________ 1

Soil.__ ____________ 1

Climate __ ___________________ 2

Drainage areas __________________ 3

Causes of floods__________________ 3

Flood records available ____________ 3

Flood-frequency analysis____________ 9

Flood frequency at a gaging station _ _ 9

Value _________________ _ ____ 9

Types of series _________________ 9

Plotting position--- ____________ 10

Historical data __________________ 10

Fitting frequency curves _________ 10

Limitations of a single-station

analysis _____________________ 10

Page 

Flood-frequency analysis Cont.

Regional flood-frequency analysis___ 11 

Base period ____________________ 11

Definition of mean annual flood ___ 11 

Homogeneity of records__________ 12

Composite frequency curves ______ 12

Relations of mean annual flood____ 12

Hydrologic areas-_______________ 14

Application of regional flood-frequency

data ____________________________ 16

Tributary areas of natural runoff -__ 16 

Stage of flood discharge ____________ 16

Maximum known floods_______________ 17

Summary ___________________________ 32

Selected references __j.______________ 32

ILLUSTRATIONS

Page 

Figure 1. Generalized areas of soil sources in Nebraska_____--_____--------------_-_- 2

2. Map of Nebraska showing location of gaging stations used in flood-frequency

analysis ______________________________________________________________ 9

3. Frequency of annual floods, Plum Creek near Smithfield, Nebr._______________ 10

4. Map of Nebraska showing flood-frequency regions and hydrologic areas _______ 12

5. Composite frequency curves of annual floods, regions A and B, period 1947 59 _ 13

6. Variation of mean annual flood with contributing drainage area in hydrologic

areas 1 10____________________________________________________________ 14

7. Relation of maximum discharge to 10 and 25-year floods, region A, areas

1 and 2 ____________________________________________ 28

8. Relation of maximum discharge to 10 and 25-year floods, region A, areas

3 and 4 __________________________________________ 29

9. Relation of maximum discharge to 10 and 25-year floods, region A, areas

5 and 6 _____________________________________________ 30

10. Relation of maximum discharge to 10 and 25-year floods, region A, area 7_____ 31

11. Relation of maximum discharge to 10 and 25-year floods, region B, areas

8, 9, and 10 __________________________________________ 32

TABLES

Page 

Table 1. Period of record of annual peaks at gaging stations---------------------------- 4

2. Maximum stages and discharges at gaging stations ____________________________ 18

3. Unusual peak discharges at miscellaneous sites and at short-term gaging stations

with contributing drainage areas of 300 square miles or less _________________ 26

III
Flcxxis in Nebraska on Small Drainage Areas, 

Magnitude and Frequency

By Emil W. Beckman and Norman E. Hutchison

ABSTRACT

Flood hazard information is needed for small streams as 

well as for large ones. This report explains methods of defining the magnitude and frequency of floods in Nebraska on 

uncontrolled and unregulated streams which have about 300 

square miles or less of drainage area contributing to surface runoff. Composite frequency curves defined for two 

flood regions express a ratio of floods with recurrence intervals ranging from 1.1 to 25 years to the mean annual 

flood. Curves for 10 hydrologic areas were defined to show 

the relation of the mean annual flood to the contributing 

drainage area. A flood-frequency curve can be drawn from 

these two sets of curves for any site in the State within the 

range of drainage area and recurrence interval that is defined by the base data and not materially affected by the 

works of man. The two sets of curves are based on all 

available pertinent data from records of 5 or more years' 

duration.

This report includes a tabulation of maximum flood peaks 

at gaging stations used and at a number of miscellaneous 

sites which have less than 300 square miles of contributing 

drainage area.

INTRODUCTION

When loss of life is not a factor, it is generally not economically sound to design 

structures in or across streams for the 

maximum flood that may occur. Economic 

considerations will dictate the choice of a 

design frequency. An evaluation of these 

economic factors is beyond the scope of this 

report. It should be noted that the recurrence 

interval of a flood does not imply any regularity of occurrence. For an example, at any 

site, two 2 5-year floods may occur in consecutive weeks or such a flood may not occur in 

a period of 50 years.

The purpose of this report is to describe 

methods by which the magnitude and frequency of floods may be determined for most 

sites in Nebraska for which the drainage area 

is less than 300 square miles. The report 

was prepared in the Lincoln office of the U.S.

Geological Survey, under the direction of 

Floyd F. LeFever, district engineer, Surface 

Water Branch, in cooperation with the Nebraska Department of Roads. Financial assistance in the preparation of the report was 

given by the Bureau of Public Roads.

DESCRIPTION OF AREA

PHYSIOGRAPHY

Nebraska has an expansive, gently rolling 

to rough topography, broken in places by low 

hills, a few isolated buttes, mesas, ravines, 

and several relatively shallow, major streams 

which flow in an easterly direction.

The altitude of the State ranges from 835 

feet at the extreme southeast corner to a 

maximum of 5,340 feet at the western border. 

The land surface slopes rather consistently 

to the southeast with an average decline of 

about 9 feet per mile.

The small streams of Nebraska have a wide 

variation in slope depending on the topography 

of their drainage basins. The average fall for 

individual streams used in this report ranges 

from about 6 to about 110 feet per mile. The 

major streams fall from 4 to 8 feiet per mile.

SOIL

Most of the soil mantle of Nebraska originated from four major sources. The general 

location of these soils is shown on figure 1, 

which is based on reports by the Nebraska 

State Planning Board (1941),by Condra(l920), 

and by Jenkins and others (1946), and was 

used by Furness (1955).
FLOODS IN NEBRASKA ON SMALL DRAINAGE AREAS, MAGNITUDE AND FREQUENCY

SCALE IN MILES

20 10 0 20 40 60 

I i I____|____|____|

Figure 1. Generalized areas of soil sources in Nebraska.

Loess silt is the predominant mantle of 

Nebraska. It is wind transported from both 

glacial deposits and mountain outwash and is 

quite uniform in texture but decreases in 

grain size toward the southeast. It erodes 

readily when on a steep gradient and usually 

with a vertical cleavage line. Except for 

scattered land-locked areas in the headwaters 

of streams draining relatively level areas of 

the south-central plains, the drainage patterns are connected and runoff is prompt.

The Sand Hill region, second in areal extent of the four major soil areas, is composed 

mostly of porous dune sand formed from the 

weathering and reworking of sandy bedrock 

and early water and glacial deposits of sand 

and gravel. Except in the immediate vicinity 

of the few primary channels, there is no 

drainage pattern or surface connections to 

the streams. Rainfall readily reaches the 

high ground-water table and forms numerous 

lakes and marshes. Sand Hill streams have 

a fairly uniform flow which originates from 

the ground-water table. Flood runoff is minor and comes primarily from the narrow 

strips of land immediately adjoining the 

streams.

The outwash mantle from the mountains to 

the west and northwest is found in several 

areas along the western and northern parts 

of the State. The original high-plains surface 

remains as a variety of topographic forms 

ranging from comparatively smooth to rolling,

as deeply eroded canyons, and as rough broken 

areas. The soil varies widely intexture. The 

drainage pattern is generally well defined and 

runoff is prompt although the slope of each 

drainage basin is an influencing factor.

Residual soils, the least in areal extent 

formed in place from sedimentary rocks and 

are found primarily in several smaller areas 

of western Nebraska. The ground surface 

varies from nearly level to undulating, rolling, rough and mountainous. Sedimentary 

rocks are exposed in the rough badlands. The 

soil texture also has a wide range in the residual soil areas. The drainage pattern is 

well defined and runoff is quite prompt.

Water-laid bottomland and areas of glacial 

drift are exposed to a very limited extent in 

the State.

CLIMATE

The climate of Nebraska is typical of large 

interior continental areas in the middle latitude; it is characterized by light average 

annual precipitation, a great range of precipitation from season to season and year to 

year, and frequent and abrupt changes in 

temperature and other weather conditions.

The average annual rainfall shows a gradual progressive increase from 14 inches in 

the extreme western part of the State to 34
INTRODUCTION

inches in the southeastern corner. About 75 

percent of the annual precipitation falls during the six-month period April through September and about 42 percent of the annual 

precipitation falls in May, June, and July. A 

large part of the summer rainfall occurs 

during thunderstorms and generally falls at 

intense rates in short periods of time.

DRAINAGE AREAS

The total drainage area of streams in a 

major part of Nebraska does not contribute to 

the surface runoff; therefore, it is necessary 

to determine both the total drainage area and 

the area which contributes to the stream by 

surface runoff. Both total and contributing 

drainage areas are shown for the stations 

used; however, owing to the lack of complete 

coverage of good topographic maps of the 

State, some of the drainage area figures are 

qualified as approximate. Some of the small 

drainage areas were determined from aerialsurvey photographs obtained from the U.S. 

Department of Agriculture, Commodity Stabilization Service.

Nebraska is completely mapped by 

1:250,000-scale maps of either 50-foot or 

100-foot contour intervals. The scale and 

contour intervals do not permit reliable determination of drainage areas, especially for 

smaller, fairly level areas or, differentiation 

between contributing and noncontributing 

drainage areas.

Topographic maps, in scales varying from 

1:24,000 to 1:125,000 and with contour intervals varying from 5 to 20 feet, have been published for about two-thirds of the State.

CAUSES OF FLOODS

In Nebraska the annual floods on drainage 

areas of less than 300 square miles generally

occur during the months April through September. There are some spring breakup 

floods; they occur most frequently in the Sand 

Hill region where there is a relatively limited 

range in discharge.

Rainfall is the primary cause of floods. 

Much of the rainfall results from thunderstorms and ranges widely in amount, intensity^ 

and distribution, so that the relation of the 

actual amount of rainfall to the flood peak 

cannot be correlated. Besides the stream 

basins physiography which is fairly stable, 

the following conditions also influence the 

size of floods: (1) antecedent conditions, (2) 

direction of the storm, (3) variation of soil 

infiltration rate, and (4) land use and vegetal 

cover.

FLOOD RECORDS AVAILABLE

Records for 5 or more years in length of 

the annual floods not materially affected by 

regulation and diversion are available for 

136 stations in Nebraska which have 300 

square miles or less in contributing drainage 

area. In addition, six stations which have 

more than 300 square miles of contributing 

drainage area are included because of their 

strategic location. These six stations are: 

White River at Crawford, Ponca Creek at 

Anoka, Plum Creek near Meadville, Long Pine 

Creek near Riverview, Bazile Creek near 

Niobrara and Wood River near Riverdale. 

Table 1 gives a list, in the downstream order, 

of the stations used, their drainage area size, 

and a graphical illustration of the length of 

record of annual peaks. Of the total of 142 

stations, 83 are crest-stage gages, most of 

which are operated in cooperation with the 

Nebraska Department of Roads to define the 

annual peak discharge. Figure 2 shows the 

location of the 142 stations. The symbols on 

the map identify the type of station and the 

number shown on the map corresponds to the 

number preceding the station name in table 1.
Table 1. Period of record of annual peaks at gaging stations

[Solid bar: Peak stage and (or) discharge. Open bar: Peak stage only

No.

4432 

4437 

4440 

4448

4535

4563 

4564 

4577 

4578 

4585

4595 

4610 

4625 

4635

4665

6006 

6007 

6008 

6009 

6010

a !92

Gaging station

White River basin 

White River tributary near Glen ________________________

Soldiers Creek near Crawf ord __________________________

White River at Crawford __________________________ ___

Chadron Creek near Chadron ___________________________

Ponca Creek basin 

Ponca Creek at Anoka _________________________________

Niobrara River basin 

Pebble Creek near Dunlap- ________ ___________-_-_---_--

Cottonwood Creek near Dunlap __________________________

Antelope Creek at Gordon ______________________-----_--

Antelope Creek tributary near Gordon ____________-__---_

Bear Creek near Eli_ __________________________________

Snake River near Burge __-_-_-_ ________________________

T\/Ti nno/"»Vi o fin rf o f'l^oolf Jji* \7"jjl oirfri Kif*

Plum Creek near Meadville ____________________________

Long Pine Creek near Riverview ________________________

Bazile Creek basin 

Bazile Creek near Niobrara ____________________________

Omaha Creek basin 

South Omaha Creek tributary near Walthill__________ ___

South Omaha C reek near Walthill _______________________

South Omaha Creek tributary 2 near Walthill _____________

South Omaha Creek at Walthill______________-_------.--_-

0 (stage only)

Drainage area 

(square miles)

Total

7.97 

52.6 

313 

14.9

410

23.5 

82.2 

61.1 

26.6 

360

620 

510 

581 

390

440

2.64 

15.1 

1.51 

51.0 

170

Contributing

7.97 

52.6 

313 

14.9

410

23.5 

82.2 

61.1 

26.6 

78

100 

200 

330 

390

440

2.64 

15.1 

1.51 

51.0 

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FLOODS IN NEBRASKA ON SMALL DRAINAGE AREAS, MAGNITUDE AND FREQUENCY 

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FLOOD-FREQUENCY ANALYSIS

Continuous record station

Crest-stage station

SCALE IN MILES 

20 10 0 20 40 60

Figure 2. Map of Nebraska showing location of gaging stations used in flood -frequency analysis.

FLOOD-FREQUENCY ANALYSIS

FLOOD FREQUENCY AT A GAGING STATION

VALUE

A regional frequency curve is considered 

to be superior to an individual station frequency curve; however, an analysis must be 

made at each gaging station before a regional 

study can be started.

The flood history at a gaging station is a 

record of what has happened at that particular 

site during the specified period of observation which is relatively short, statistically 

speaking. Such a record is only a chance 

sample of the flood potential representing 

the overall flood-frequency relation and as 

such may be a poor example for predicting 

what will happen in the future, even at the 

same site.

TYPES OF SERIES

There are two methods in general use for 

studying -the frequency of floods: an annual 

flood series and a partial-duration series.

An annual flood is defined as the greatest 

momentary peak discharge in a water year 

(October 1 to September 30). In the annual 

flood array, the recurrence interval is the

average interval in which a flood of a certain 

magnitude has occurred once as an annual 

maximum. An objection to the use of annual 

flood is that the second highest flood in a 

given high year may outrank many annual 

floods.

The partial-duration series is a list of all 

floods above a selected base. The base is 

generally selected as equal to the lowest annual flood so that at least one flood in each 

year is included. In the partial-duration series the recurrence interval is the average 

interval of time between floods of a given 

magnitude. An objection to the use of the 

partial-duration series is that the floods 

listed may not be fully independent events.

A definite relation exists between values in 

the two series as shown by Langbein (1949) 

and Chow (1950). The following table shows 

comparative values of recurrence intervals 

derived by the two methods:

Recurrence intervals in years 

Annual flood series Partial-duration series

1.16

1.58

2.00

2.54

2.52

10.5

20.5

50.5

100.5

0.5

1.0

1.45

2.0

5.0

10

20

50

100
10 FLOODS IN NEBRASKA ON SMALL DRAINAGE AREAS, MAGNITUDE AND FREQUENCY

The annual flood series is used in this report. Where a frequency curve derived from 

the partial-duration series is desired, an 

annual-flood curve can be converted to the 

partial-duration series curve by the relation 

expressed in the preceding table.

erally it is confined to the maximum flood 

during the memory of one or possibly several individuals. Some of the stages noted 

are beyond the limits of the defined stage - 

discharge relation, and a discharge could not 

be estimated.

PLOTTING POSITION FITTING FREQUENCY CURVES

The analysis of flood data starts with a 

listing of all the annual peaks at a gaging 

station. These are ranked according to magnitude starting with 1 as the highest. A time 

scale must be computed, to obtain a plotting 

position for the frequency scale. There are 

several methods, but the one used by the Survey and in this report is

where

T is the recurrence interval in years, 

n is the number of years of record, 

m is the order of the mganitude of the-flood, 

the highest being 1.

In the study of historical floods, n isthe number of years in which it is known that the 

flood was of the order assigned.

After the flood discharges for each station 

have been plotted against their computed recurrence intervals, a curve is drawn on the 

basis of the plotted points. The relatively 

short length of most streamflow records and 

the probable inaccuracies of small samplings 

do not warrant analytical curve fitting. There - 

fore, a visual best fit smooth curve is used 

in this report to average the points. It is 

known that the maximum flood or floods of 

record may have a recurrence interval considerably greater than the period of record. 

Therefore, in drawing a best fit smooth - 

frequency curve, more weight is given to the 

lower floods than to the higher floods. Figure 

3 shows a plot of the frequency of annual 

floods for Plum Creek near Smithfield, Nebr.

LIMITATIONS OF A SINGLE STATION ANALYSIS

Annual floods are plotted on a special form 

devised by Powell (1943) on which the discharge is plotted on a linear scale as the 

ordinate and the recurrence interval on a 

scale graduated on the basis of the theory of 

extreme values as the abscissa.

HISTORICAL DATA

Historical floods can be used to extend the 

frequency curve of a station to cover a longer 

period. Historical data, however, are usually 

confined to stages or comparison of stages 

above a high base and it is important to define their order of magnitude with respect to 

a period of time. Historical information on 

small streams is more difficult to obtain than 

on larger streams because the duration of the 

flood is quite short and the number of people 

affected is very limited. Care must be exercised in assigning discharge values to historical stages because of possible channel 

changes.

Some information on historical floods was 

obtained, usually from local residents. GenGenerally the 2 5 -year or the 50 -year flood 

is selected as the design flood. Table 1 shows 

that there are no gaging stations in Nebraska

6000

1000

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RECURRENCE INTERVAL,IN YEARS

Figure 3. Frequency of annual floods, Plum Creek near 

Smithfield, Nebr.
FLOOD-FREQUENCY ANALYSIS 11

with less than a 300 square mile drainage 

area which have 50 years of record of annual 

peaks and that there are only 5 stations 

which have more than 25 years of record of 

annual peaks. Of the total 142 stations, 113 

have only 10 years or less of record of annual 

peaks. To define a 25-year or 50-year flood 

would require extensive extrapolation from 

the trend of the plotting position of lesser 

floods. The error of the curve could be considerable at its outer extremity.

The random manner in which flood events 

are distributed with respect to time is another limitation to frequency graphs based on 

records at a single station.

The maximum departure to be expected 

between flood magnitudes or frequencies 

computed from relatively short records and 

their true (long-term) values increases with 

the magnitude of the flood and decreases 

with the length of record {Benson, 1960). The 

following table, based on Benson's study, 

shows the length of record required at a 

single site to define the frequency of floods 

of various magnitudes with 10 and 25 percent 

of the true value 19 out of 20 times.

Magnitude of flood, in recurrence Le"$th of record> in

intervals 10 percent 25 percent

2.33-year. 

10-year.... 

25-year.... 

50-year....

40

90

105

110

12

18

31

39

Although the figures in the above table are 

based on a hypothetical study, they give an 

indication of the possible errors, from chance 

alone, in frequency graphs based on shortterm records for a single station. A comparison of the lengths of stream records 

available in Nebraska on drainage areas of 

300 square miles and less (table 1) with those 

indicated by Benson (1960) suggests that very 

few records in the State are long enough to 

define reliably the mean annual flood, and the 

floods of infrequent occurrence are less accurately defined. Analysis on a regional 

basis is used as a solution to the floodfrequency definition.

REGIONAL FLOOD-FREQUENCY ANALYSIS

A flood-frequency curve based on a number 

of stations has greater reliability than a 

curve from a single station. In order to combine the records for a number of stations, 

two requirements must be met. The first 

condition is that all the records must be reduced to a common time basis or base period, and the second is that the stations must 

have frequency graphs of the same general 

shape and slope, within limits of chance, so 

that they may be considered homogeneous.

BASE PERIOD

Table 1 shows graphically the length of 

usable records at the 142 gaging stations. 

Not all stations have records of the same 

length* If they are to be combined, records 

must be on the same time basis. The actual 

length of a short-period record of at least 5 

years' duration can be extended by correlation with the long-term record of a nearby 

station. This correlation, however, is more 

sensitive for small streams than for larger 

streams and requires a long-term station in 

the immediate vicinity. Therefore, because 

there is such meager distribution of longterm stations within the State,the base period selected is 1947 59. Inasmuch as this 

base period is so short, it was also neces - 

sary to analyze records for 33 long-term 

stations having drainage areas greater than 

300 square miles. This analysis was made 

for the period 1929 59 in order to establish 

the relation of the short base period to a 31- 

year period.

The actual record at each station either 

included or was extended to the 13-year base 

period, and for the 33 long-term stations 

mentioned above, to the 31-year period by 

computing a discharge figure for each year 

of no record. These computed discharges, 

which are based on correlation with records 

for long-term stations, are used only to assign the more nearly correct order numbers 

to annual peaks of record.

DEFINITION OF MEAN ANNUAL FLOOD

According to the theory of extreme values 

as applied to floods by Gumbel (1945), the 

arithmetic mean of the annual peak discharges in an infinitely long series is equal 

to the discharge corresponding to the 2.33- 

year recurrence interval. This definition is 

generally accepted, and the 2.33-year flood 

determined graphically is used as the mean 

annual flood for this report. Annual-flood
12 FLOODS IN NEBRASKA ON SMALL DRAINAGE AREAS, MAGNITUDE AND FREQUENCY

data for each of the individual gaging stations 

were adjusted to the 13-year base period 

(1947-59).

HOMOGENEITY OF RECORDS

The test for homogeneity of records involves determining whether differences in 

slopes of individual frequency curves are 

greater than might occur by chance in random sampling. This statistical test has a 

95-percent confidence level,that is, one station in 20 may plot outside the limits of the 

test graph. The slope of each individual station frequency curve is expressed by the 

ratio of the 10-year flood to the mean annual 

flood. The average ratio derived from the 

group was multiplied by the mean annual 

flood for each individual station and the cor - 

responding recurrence interval was determined from the station frequency graph. The 

recurrence interval thus obtained was then 

plotted against the effective length of record 

in years on the specially designed test graph. 

The effective length of record is the number 

of annual floods of record plus one-half the 

number of estimated annual floods used to 

complete the base period.

The test applied to the 142 gaging stations 

used in this report indicates two homogeneous 

flood regions in Nebraska which are designated as regions A and B. The regional 

boundaries are shown in figure 4. Region B

is the Sand Hills, and region A consists of 

the remaining part of the State. There are 

132 stations in region A and 10 stations in 

region B.

COMPOSITE FREQUENCY CURVES

In order to compare flood records at different gaging stations and combine them to 

define composite flood relations,it is necessary to convert the floods to a dimensionless 

basis. This was done by computing the ratio 

of floods of selected recurrence intervals to 

the mean annual flood for each gaging station 

in a homogeneous region. The median ratio 

of each selected recurrence interval was 

then plotted against the corresponding recurrence interval to give the composite frequency curve for each homogeneous region 

(fig. 5).

RELATIONS OF MEAN ANNUAL FLOOD

The composite frequency curves as derived in the preceding section define dimensionless ratios of the mean annual flood to 

floods of other recurrence intervals. In order to define the flood-frequency curve in 

terms of discharge for a specific site, the 

magnitude of the mean annual flood is required. The magnitude of the mean annual 

flood is obtained by relating it to measurable 

characteristics of the drainage basin.

SCALE IN MILES

20 10 0 20 40 60 

I i I____I____I

Figure 4. Map of Nebraska showing flood-frequency regions and hydrologic areas.
FLOOD-FREQUENCY ANALYSIS 13

1.01 10 20 30 40 50

RECURRENCE INTERVAL, IN YEARS

Figure 5. Composite frequency curves of annual floods, regions A and S, period 1947-59.

The physiographic factors which may influence the mean annual flood at a given point 

are size of the drainage basin, shape of the 

basin, alinement of the basin with the prevailing direction of storm travel, channel 

storage, artificial or natural storage in lakes 

or ponds, slope of stream, land slope, stream 

density, stream pattern, altitude, depth and 

porosity of soil mantle, vegetal cover and 

land use. Some of these factors are difficult 

to evaluate and therefore cannot be used in a 

correlation.

The mean flow of a stream is a hydrologic 

measure that integrates all factors of runoff 

and thus includes an indication of flood potential. Because the majority of the station 

records used in this report are from creststage gages at which total runoff is not measured, the mean flow had to be determined 

from streams which have larger drainage 

areas and which are not always strategically 

located.

The mean annual flood was correlated 

graphically with contributing drainage area, 

mean flow, stream slope, and shape of basin 

factor. The drainage area size, the mean 

flow, and stream slope are all significant 

factors, drainage area and mean flow being 

the most significant. The correlations, however, do not give consistent results and inasmuch as mean flow was inadequately defined, 

the contributing drainage area alone was

used to define a relation with the mean annual 

flood. Along with variations in mean flow, 

other factors or combination of factors that 

influence floods are not reflected in the size 

of the basin, but their effect is related in 

areas having somewhat similar physical features. Accordingly, the State was subdivided 

into 10 hydrologic areas shown in figure 4. 

Except for the boundaries of the regions A 

and B which are also boundaries of hydrologic 

areas, the boundaries of the hydrologic areas 

follow the drainage divides or major streams.

Records for the 33 long-term stations mentioned under "Base Period" above were used 

in order to define mean annual flood relations 

with respect to time. The graphical definition 

of the mean annual flood for the 31-year (1929 

59) base period was compared to the mean 

annual flood defined by the 13-year (1947-59) 

base period at each of the 33 individual stations which are distributed around and within 

the State. This study revealed that the average correction factor required to adjust the 

mean annual flood from the 13-year period to 

the 31-year period in the 10 hydrologic areas 

is as follows:

Area

1 and 2............

3 and 4............

5, 8, 9, and 10. 

6 and 7............

Correction factor

0.816

.925

1.00

1.08
14 FLOODS IN NEBRASKA ON SMALL DRAINAGE AREAS, MAGNITUDE AND FREQUENCY

The above adjustments are reasonably well 

established in all areas except in area 7 

where there is considerable spread in results 

for individual stations used to define the 

average correction.

The mean annual flood for each station determined from the 13-year period was corrected by the average correction factor for 

the hydrologic area in which the station was 

located. For each of the 10 hydrologic areas, 

the corrected mean annual flood for each 

station in that area was plotted against the 

contributing drainage area for the station. 

Curves were drawn to average all the data in 

each area. The variation of mean annual

10,000

5000

flood with contributing drainage area for each 

of the 10 hydrologic areas is shown in figure 6.

HYDROLOGIC AREAS

Area 1, as shown in figure 4, is the northeast corner of the State. It includes all the 

smaller streams downstream from the Niobrara River and upstream from the Platte 

River which are direct tributaries of the 

Missouri River. It also includes the left 

bank tributaries of the Elkhorn River which 

are downstream from the Sand Hill area. The 

area is generally quite hilly. The variation 

of the mean annual flood with drainage area 

is defined by 15 stations.

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2000

1000

500

200

I 00

0.3 0.5 12 5 10 20 50 100 200 

CONTRIBUTING DRAINAGE AREA, IN SQUARE MILES

Figure 6. Variation of mean annual Hood with contributing drainage area in hydrologic areas 1-10.

500
FLOOD-FREQUENCY ANALYSIS 15

Area 2 is the southeast corner of the State. 

It includes Salt Creek, a tributary of the 

Platte River, and all direct tributaries of the 

Missouri River in the State downstream from 

the Platte River. This area is also quite hilly 

except for a flat area in Saunders County 

which probably is the remains of an old 

Platte River channel. The five Silver Creek 

stations included in this report are in this 

flat area and their drainage areas include 

many depressions which trap water and prevent it from reaching the stream. Available 

topographic maps for this flat area do not 

distinguish between the contributing and the 

noncontributing area. Twenty-five stations 

are in area 2, but because the contributing 

drainage of the five Silver Creek stations is 

not defined, the curve of variation of mean 

annual flood with drainage area is drawn on 

the basis of the data from the 20 remaining 

stations. The mean annual floods are higher 

than those in area 1 because of the greater 

mean annual rainfall and resulting greater 

mean flow.

Area 3 (fig. 4) consists of the south-central 

plains of the State. It contains the Big Blue 

River, the Little Blue River, and the tributaries of the Republican River downstream 

from Harlan County Dam. The headwaters of 

these streams drain gentle sloping land, and 

there are some depressions which trap runoff and prevent it from reaching the streams. 

Seventeen stations are used to define the 

variation of the mean annual flood with drainage area.

Area 4 (fig. 4) includes Ponca Creek, the 

tributaries of the lower part of the Niobrara 

River, the upper part of the Elkhorn River 

and all its right-bank tributaries, the Loup 

River basin downstream from the Sand Hills, 

and the left-bank tributaries of the Platte 

River between the Loup River and the Elkhorn 

River. This area has a wide variety of topography and soils. Flood flow at some of the 

stations is materially affected by the proximity of the porous Sand Hills. Generally, it 

is possible to determine the contributing 

drainage area if good topographic maps are 

available. Good topographic maps have not 

been made for this area; therefore, some of 

the drainage areas are listed as approximate. 

Twenty-eight stations are used to define the 

variation of the mean annual flood with the 

contributing drainage area. The resulting 

curve is so similar to that for area 3 that one 

curve is shown on figure 6 as representative 

of both hydrologic areas.

Area 5 (fig. 4) includes the small tributaries 

of the Platte River in the central part of the 

State. The area contains some low rolling 

hills at the headwaters of the streams and at 

the perimeter of the area but toward the interior the land and stream slopes become 

less. As the drainage area increases, channel storage becomes a factor in reduction of 

the mean annual flood. Twenty-one stations 

are used to define the variation of the mean 

annual flood with drainage area.

Area 6 (fig. 4) includes the Medicine Creek 

basin and all left-bank tributaries of the 

Republican River between Medicine Creek 

and Harlan County Dam. This area is very 

hilly and contributes to surface runoff, except 

for the upper reaches of the Medicine Creek 

basin where part of the Sand Hills is located. 

Thirteen stations are used for defining the 

variation of the mean annual flood with the 

drainage area.

Area 7 (fig. 4) is the western part of the 

State that includes drainage basins of the 

Republican, South Platte, North Platte, Niobrara, and White Rivers. This area has a 

wide variety of topography and soils. Some 

parts of the Republican River basin have depressions and sandy areas which do not contribute to surface runoff. Thirteen stations 

are used to define the relation of the mean 

annual flood to the contributing drainage 

area. The definition in area 7 is considered 

to be the poorest in the State.

Area 8 is the southwestern part of the Sand 

Hills as shown in figure 4; it is defined on 

the 'basis of only one station record. The 

station frequency curve indicates that mean 

annual floods are considerably lower than 

those defined in area 10. The relation of the 

mean annual flood to contributing drainage 

area is defined by the one station and the 

slope of the relationship curve defined in 

area 10.

Area 9 (fig. 4) is the part of the Sand Hills 

north of the Niobrara River. As in area 8, 

only one station record is available. The 

station frequency curve indicates that mean 

annual floods are considerably lower than 

those in area 10. The relationship curve, as 

shown in figure 6, is based on the one station 

record and the slope of the relationship curve 

defined for area 10.

Area 10 (fig. 4) contains the greater part of 

the Sand Hills which generally drain to the
16 FLOODS IN NEBRASKA ON SMALL DRAINAGE AREAS, MAGNITUDE AND FREQUENCY

south and east. Only the area immediately 

adjacent to the streams contributes to surface 

runoff; the high base flow comes from ground 

water. The contributing drainage areas of the 

eight stations in this area are not very well 

defined and are listed as approximate. The 

range in size of the contributing drainage 

area is from 50 to 140 square miles.

The definition of the mean annual flood with 

respect to contributing drainage area covers 

the range of drainage area from 1 to 300 

square miles in hydrologic areas 1 7. The 

range of drainage area defined in areas 8 10 

is from 50 to 200 square miles.

APPLICATION OF REGIONAL FLOOD-FREQUENCY 

DATA

TRIBUTARY AREAS OF NATURAL RUNOFF

This section gives step-by-step procedures 

for determining the magnitudes of floods in 

Nebraska having any recurrence interval up 

to 25 years at any site not subject to manmade regulation or control that has a contributing drainage area between 1 and 300 square 

miles in region A and between 50 and 200 

square miles in region B (fig. 4).

1. Determine the total and contributing 

drainage areas at the site. The contributing 

drainage area is that part of the total basin 

area that contributes directly to surface runoff.

2. From figure 4, obtain the number of the 

hydrologic area and the flood region in which 

the site is located.

3. With the contributing drainage area (step

1) and the number of the hydrologic area (step

2), determine the mean annual flood for the 

site from figure 6.

4. With the flood region (step 3) determine 

the ratio to the mean annual flood for the flood 

of the selected frequency of recurrence from 

figure 5.

5. Multiply the ratio of the selected flood 

to the mean annual flood (step 4) by the mean 

annual flood determined in step 3 to obtain 

the flood magnitude at the site. If a complete 

frequency graph is desired, repeat steps 4 

and 5 for a number of recurrence intervals.

It must be emphasized that the curves cannot be extrapolated with confidence beyond 

the limits of the base data from which the 

curves were derived.

STAGE OF FLOOD DISCHARGE

This report deals specifically with the fre - 

quency of flood discharges. Flood stage corresponding to these discharges may also be 

of primary concern in the design of certain 

structures and in other related studies. For 

rock-lined or firm-bedded streams at sites 

not subject to variable backwater from downstream inflow or structures, a stage-discharge 

relation provides a ready solution to the problem. For shifting-channel streams of Nebraska and where variable backwater may exist, 

the stage corresponding to the selected discharge may be approximated only after extensive research. If the stage is to be investigated, the engineer will find the site in question to be in one of two" categories:

1. Site at or near an established gaging 

station. Gaging stations have been maintained 

at several hundred sites in Nebraska. Locations of those established prior to September 

30, 1950, are described in reports of the 

Geological Survey (Water-Supply Papers 1309 

and 1310). Stations established since 1950 

are described in the annual series of watersupply papers entitled "Surface Water Supply 

of the United States." A reasonable stagedischarge relation has been established at 

each of the small-area stations used for this 

report, and may be examined in the Lincoln 

office of the Geological Survey. For sites at 

or near gaging stations, it is usually possible 

to obtain stage data that are adequate for 

most purposes.

2. Site not near an established gaging station. The stage corresponding to a discharge 

of selected recurrence interval must generally be obtained through the medium of a 

stage-discharge relation. The extent of the 

investigation required to establish such a 

relation will depend upon the accuracy requirements. The following methods of deriving a stage-discharge relation are noted 

in decreasing order of reliability, (a) If the 

need for data can be anticipated far enough in 

advance, discharge measurements may be 

obtained to define the relation up to the maximum discharge observed in the period. The
MAXIMUM KNOWN FLOODS 17

relation may be extended by the application 

of measured channel characteristics to appropriate hydraulic formulas. Shifting-channel characteristics may be investigated by 

studies of bed material and some long-term 

changes may be obtained from local residents.

(b) If the need for data is immediate,the discharge for a past flood may be computed by 

hydraulic formulas if adequate floodmarks 

can be recovered and one point on the stagedischarge relation curve thereby established. 

A direct measurement of discharge at the 

time of the visit will provide one other point.

(c) A method has been used to develop ratings 

for stable channels from the product of the 

stream slope at zero flow or low flow and 

characteristics of conveyance at a typical 

cross section. This method is unsuited to 

streams with unstable channel beds.

MAXIMUM KNOWN FLOODS

The design of major hydraulic^ structures 

whose failure may cause loss of life should 

consider the maximum probable flood rather 

than one that may be expected to occur in a 

defined period of years. A prerequisite to 

such an analysis is the record of maximum 

known floods.

Maximum known stages and discharges at 

the 142 gaging stations used in the floodfrequency analyses are shown in table 2. The 

stations are listed in downstream order and 

the number preceding the station name corresponds with the numbers shown in table 1 

and figure 2. The flood region and hydrologic 

area in which the station is located is shown 

as well as the total and contributing drainage 

area. The contributing drainage area is used 

to compute the peak discharge in cubic feet 

per second per square mile. The period of 

known floods is that for which the stage or 

discharge is known to be the greatest. The 

stage is given for each maximum discharge 

except for stations 7730 and 7829. The discharge at these two stations had been determined from an indirect measurement prior to 

the establishment of the gage and there is no 

datum tie between the survey and the gage. 

Where the maximum stage and the maximum 

discharge are not concurrent, a change in the

stage-discharge relation is indicated, and no 

discharge figure is shown for the maximum 

stage. Some periods of known floods for the 

maximum stage are extended on the basis of 

recovered floodmarks beyond the period of 

known floods for the maximum defined discharge. For such periods, a leader line has 

been placed in the discharge column to indicate that the discharge for this known stage 

could not be defined within allowable limits 

of accuracy. A leader line in other columns 

is also used to indicate that the information 

could not be determined.

Twenty-five unusual peak discharges have 

been collected at miscellaneous sites or at 

short-term gaging stations which have 300 

square miles or less contributing drainage 

area. These data are shown in table 3. The 

sites are listed in downstream order. Gaging 

stations having records of insufficient length 

to be included in the flood-frequency analysis 

have been operated or are being operated at 

numbered sites. Unnumbered sites are miscellaneous sites where only one observation 

has been made.

As shown in figure 5, there is a great difference in the composite frequency curve for 

region A and for region B, and the curves of 

figure 6 show that the mean annual flood for 

a given drainage area can vary considerably 

between hydrologic areas. A separate illustration was developed, therefore, for each of 

the 10 hydrologic areas on which the 10- and 

2 5-year recurrence interval floods are shown 

as a curve to compare with the maximum 

discharge at the stations and miscellaneous 

sites in that hydrologic area. The maximum 

discharge at the 142 stations used in this frequency analysis are shown as open circles, 

and the maximum discharge at the miscellaneous sites and short-term gaging stations 

which are listed in table 3 are shown as 

closed circles. The gaging stations are identified by the last four or five digits of the 

index number, in order to correspond with 

those shown in tables 2 and 3.

The relation of the maximum discharge to 

the 10- and 25-year floods in the 10 hydrologic regions are shown in figures 7 11.
18 FLOODS USLNEBRASKA ON SMALL DRAINAGE AREAS. MAGNITUDE AND FREQUENCY

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286

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1950-59

1950-59 

1951 59

1920-59

1946-59

1950-59

1950-59

1950-59

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1952 59

1951-59

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1951-59

June 16, 1957

June 21, 1954 

June 20, 1954

June 13, 1957 

June 4, 1940

July 2, 1958

July 15, 1950 

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Apr. 21, 1954

July 15, 1950 

Aug. 13, 1958

June 15, 1957 

June 21, 1957

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July 2, 1951 

June 11, 1944

July 15, 1950 

May 10, 1942

July 3, 1956 

May 20, 1938 

Dec. 21, 1945

Dec. 15, 1940

Apr. 1, 1949 

June 8, 1951

June 22, 1948

June 8, 1951

14.57

18.71 

12.90

24.92 

a 32.5

23.62

21.3 

19.3

20.17

14.26 

15.10

16.19 

17.80

23.40

24.14 

e 20.8

e !9.5 

7.8

7.33 

f4.46 

*4.93

5.12

4.35 

13.88

^18.8

13.36

See footnotes at end of table.
20 FLOCDDS IN NEBRASKA ON SMALL DRAINAGE AREAS, MAGNITUDE AND FREQUENCY

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Wood River near River dale______

Dry Creek at Cairo ___ __________

Middle Loup River near Seneca __

Middle Loup River at Dunning ___ 

Dismal River at Dunning ________

Lillian Creek near Broken Bow __

Lillian Creek tributary 2 near 

Walworth.

South Branch Mud Creek

tributary near Broken Bow. 

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Broken Bow.

North Branch Mud Creek at

Broken Bow.

Mud Creek tributary near 

Broken Bow.

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Oak Creek near Loup City _______

Oak Creek near Dannebrog ______

Turkey Creek near Farwell _____

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North Loup. 

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Davis Creek southwest of North

T .r\tnr\

A5

A5

BIO

BIO 

BIO

A4

A4

A4

A4

A4

A4 

A4

A4

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BIO

A4 

A4

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379

22.2

1,140

1,760 

1,780

4.77

2.04

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400

15.5

5.98 

440

41.9

122

27.2

1,890 

2,210

1,260

2.29 

6.79

21.1 

41.6

379 

22.2

60

80

50

4.77 

2.04

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45.9 

10.8

5.98

81.1 

41.9 

122

27.2

140

180

110

2.29 

6.79 

21.1

41.6

1946-59 

1949-53

1950 53

1948-53

1946 59

1946-59

1932, 

1946-59

1947-59 

1951-59

1951-59 

1948-59 

1951-59

1945,

1951-59 

1951-59

1949-56 

1950-59

1950-57 

1950, 

1953-59

1946-51

1937-59

1941 59

1951-59 

1951-59 

1951-59

1951-59

June 22, 1947 

June 6, 1949

May 27, 1953

Jan. 7, 1949

Aug. 8, 1950 

Mar. 31, 1949

Sept. 13, 1958 

Jan. 19, 1947

May 26, 1952

June 22, 1947 

Aug. 12, 1951

July 18, 1958 

June 17, 1956 

__ do _____ .

May 27, 1945

July 21, 1951

June 17, 1956 

July 3, 1951

June 17, 1954 

July 9, 1950

Feb. 2 5,2 6, 1950

June 14, 1951 

_._do _____ .

Feb. 25, 1957

Mar. 19, 1950

May 16, 1951 

July 3, 1951

July 14, 1957 

__ do _____ .

June 16, 1957

19.75

7.64

2.61

2.09 

7.02

3.90 

5.21

3.18

e !2.2 

e !2.4

12.43 

16.41 

16.16

e !4.80

9.48 

e !5.50 

e !9.0

17.23 

e !7.50

4.20

b 3.40 

6.50

e 9.5

5.19

3.76 

17.74

16.82 

15.6

e 21.5

19.35

See footnotes at end of table.
22 FLOODS IN NEBRASKA ON SMALL DRAINAGE AREAS, MAGNITUDE AND FREQUENCY

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8041

8042

8043

8044

8045

8064 

8064.2

8064.4

8064.6

8064.7 

8065

8101 

8102

8103

8104

8105

8155

8230 

8235

8240

8360

Silver Creek near Cedar Bluffs __

Silver Creek near Colon ________

Silver Creek tributary near

Colon. 

Silver Creek tributary at Colon __

Silver Creek at Ithaca. __________

Weeping Water Creek basin

Weeping Water Creek at Elmwood 

Stove Creek near Elmwood ______

Stove Creek at Elmwood ________

Weeping Water Creek at Weeping

Water. 

Weeping Water Creek tributary 

near Weeping Water. 

Weeping Water Creek at Union. __

Little Nemaha River basin

Hooper Creek tributary near 

Palmyra. 

Hooper Creek near Palmyra. ____

Owl Creek near Syracuse _______

Little Nemaha River tributary

near Syracuse. 

Little Nemaha River near

Syracuse.

Nemaha River basin 

Muddy Creek at Verdon _________

Kansas River basin 

North Fork Republican River at 

Colo. Nebr. State line. 

Buffalo Creek near Haigler ______

Rock Creek at Parks ___________

Blackwood Creek near Culbertson

A2

A2

A2

A2

A2

A2 

A2

A2

A2

A2 

A2

A2 

A2

A2

A2

A2

A2

A7 

A7

A7

A 7

10.9

29.9

14.3

22.4

72

21.4 

4.94

10.0

75.5

1.07 

238

7.81 

57.5

25.4

.76

218

188

320 

180

180

290

21.4 

4.94

10.0

75.5

1.07 

238

7.81 

57.5

25.4

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218

188

130 

21

14

290

1894-

1959 

1894-

1959 

1894-

1959 

1894-

1959 

1894

1959

1950-59 

1950-59

1950-59

1882-

1959 

1950-59

1947-59

1950-59 

1950 59

1950 59

1950-59

1950-59

1953-59

1931-59 

1941-59

1941-59

1946-59

___do ______

__ do ______

__ do__ __ ___

__ do ________

May 9, 1950 

__ do ___ __

__ do__ ___ _

__ do__ ______

May 15, 1954 

May 9, 1950

June 1, 1951 

May 9, 1950

do

do _ _ _ _

July 10, 1958

Apr. 28, 1947 

June 27, 1948

Mar. 25, 1957 

Sept. 3, 1951

Jan. 26, 1949 

June 17, 1955

15.02

19.22

17.32

19.29

16.92

e24.6 

e !8.2

e23.0

e !8.5

18.02 

J26.80

16.55

e23.0 

e 30.6

e !6.6

e 36.7

31.50

5.92

4.37 

5.36

3.80 

3.92

( 14.64

See footnotes at end of table.
24 FLOODS IN NEBRASKA ON SMALL DRAINAGE AREAS, MAGNITUDE AND FREQUENCY

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8520

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8807.2

8807.3

8807.4 

8836

8837

8838 

8839

Thompson Creek at Riverton_____ 

Elm Creek at Amboy__ __________ «/

School Creek tributary near 

Harvard. 

School Creek near Harvard _____

School Creek tributary 2 near

Harvard. 

School Creek near Saronville ____ 

South Fork Big Sandy Creek 

near Edgar. 

South Fork Big Sandy Creek

TI &z\ T* yinfr-^TTT-OYH"

South Fork Big Sandy Creek 

near Carleton. 

South Fork Big Sandy Creek 

near Hebron.

A3 

A3

A3 

A3

A3

A3 

A3

A3

A3 

A3

223 

39.2

13.1 

55.1

14.0

89.4 

15.2

32.0

49.4 

81.9

223 

39.2

13.1 

55.1

14.0

89.4 

15.2

32.0

49.4 

81.9

1948-56 

1948-53

1952-59 

1953-59

1953-59

1952-59 

1953-59

1950, 

1952-59

1952-59 

1952-59

July 9, 1950 

Sept. 20, 1950

Sept. 6, 1958 

July 10, 1958

___do _____ _

July 14, 1952 

Aug. 16, 1957

July 9, 1950

July 14, 1952 

June 27, 1952

13.22 

9.45

12.14 

16.74

16.17

e !7.6 

13.56

h !7.3

e !6.4 

e21.8

a App r oximat e. 

b Maximum observed. 

cApproximate natural peak. 

dRegulated peak; affected by backwater. 

eFrom floodmark. 

Datum then in use. 

sAdjusted for diversion.

From information by local reside

^ Present site and datum. 

k Exceeded by flood of Apr. 24, 19

mAt site 2-3/4 miles upstream, fr

n One of the greatest floods known 

stage and discharge unknown.
26 FLOODS IN NEBRASKA ON SMALL DRAINAGE AREAS, MAGNITUDE AND FREQUENCY

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8375 

8398

Union Creek at Madison, sec. 

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Middle Logan Creek near 

Laurel, sec. 32, T. 29 N., 

R. 3 E. 

East Fork Maple Creek near 

Howells, sec. 21, T. 20 N., 

R. 4 E. 

Olive Branch above Sprague, 

NWi sec. 5, T. 7 N., R. 6 E.

Olive Branch below Sprague, 

SWi sec. 23, T. 8 N.,R.6 E.

Middle Creek at Emerald, 

SEi sec. 23, T. 10 N.,R. 5 E. 

Antelope Creek at 48th St., 

Lincoln, SWi sec. 32, 

T. 10 N., R. 7 E. 

Antelope Creek at 27th St., 

Lincoln, SE^ sec. 25, 

T. 10 N., R. 6 E.

Antelope Creek at Lincoln, 

NWi sec. 24 T. 10N.,R.6 E. 

North Fork Cottonwood Creek 

near Prague between sec. 26 

and 35, T. 16 N., R. 5E.

Kansas Fiver basin 

Red Willow Creek near

Mr>r'nnk 1XTW- «3pr> fi T 4 1ST

R. 29 W. 

Brushy Creek near Maywood, 

sec. 34, T.8 N., R.29 W.

Medicine Creek near Curtis, 

sec. 35, T.8 N.,R.28 W.

Fox Creek tributary near 

Curtis, NEi sec. 9, T. ION., 

R. 28 W. 

Unnamed Creek at McCool 

Junction, NE^ sec. 13, 

T. 9 N., R. 3 W. 

Unnamed Creek near York, 

center sec. 6,T. 9N.,R.2 W.

__ do___ _____

Logan Creek ___ 

Maple Creek ___ 

Salt Creek_____

___do __ ____ _

__ do___ __ _ __

__ do __ _____

__ do_ ___ __..

___do__ __ __ _

Cottonwood 

Creek.

Republican 

River.

Medicine CreekRepublican 

River. 

Medicine 

Creek.

West Fork Big 

Blue River.

___do_ ___ ___

A4 

Al

A4

A2 

A2 

A2 

A2

A2

A2 

A2

A7

A6 

A6 

A6

A3 

A3

167.0 

37.5

67.1

43 

81 

88 

6.82

10.4

12.5 

5.2

600

163 

358 

6.97

17.2 

6.9

167.0 

37.5

67.1

43 

81 

88 

6.82

10.4

12.5 

5.2

300

105 

290 

6.97

17.2 

6.9

1877- 

1950

1956-59 

1956-59 

1909-53

1951, 

1958-59

1957-59

1958-59 

1909-59

1935, 

1941_47

1958-59 

1874- 

1959

1952-59

June 

May 1

June 1

Aug. 1

July 1

June 

June 1

July 1

__ do _

Aug. 

June 

June 2

June 2

May 1

July 

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Furnished by Corps of Engineers. bApproximate.
28 FLOODS IN NEBRASKA ON SMALL DRAINAGE AREAS, MAGNITUDE AND FREQUENCY

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EXPLANATION 

o 

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-

-

-

50 100 200 30

CONTRIBUTING DRAINAGE AREA,IN SQUARE MILES

Figure 7. Relation of maximum discharge to 10 and 25-year floods, region A, areas 1 and 2.
MAXIMUM KNOWN FLOODS 29

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20,000

10,000

5000

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10,000

5000

2000

EXPLANATION

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Miscellaneous site or short 

term gaging station

1000

500

200

100

0.30.40.5 12 5 10 20 50 100 200 500 

CONTRIBUTING DRAINAGE AREAJN SQUARE MILES

Figure 8. Relation of maximum discharge to 10 and 25-year floods, region A, areas 3 and 4.
30 FLOODS IN NEBRASKA ON SMALL DRAINAGE AREAS, MAGNITUDE AND FREQUENCY

100

0.5

100,000 -j-j

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0

z 

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5000

2000

1000

500

300

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EXPLANATION

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Miscelkineous site or short 

term gaging station

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O 

8395

2 5 10 20 50 100 200 

CONTRIBUTING DRAINAGE AREA,IN SQUARE MILES

Figure 9. Relation of maximum discharge to 10 and 25-year floods, region A, areas 5 and 6.

400
MAXIMUM KNOWN FLOODS 31

50,000

20,000

10,000

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CONTRIBUTING DRAINAGE AREA, IN SQUARE MILES

Figure 10. Relation of maximum discharge to 10 and 25-year floods, region A, area 7.

4OO
32

1000

500

200

FLOODS IN NEBRASKA ON SMALL DRAINAGE AREAS, MAGNITUDE AND FREQUENCY

SUMMARY

-

-

-

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100

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X »4585 EXPLANATION

Goging station

0 0

AREA 9

AREA 10

CONTRIBUTING DRAINAGE AREA 

IN SQUARE MILES

Figure 11. Relation of maximum discharge to 10 and 25-year 

floods, region B, areas 8, 9 and 10.

The accuracy of flood magnitudes for selected recurrence intervals obtained by methods outlined in this report is contingent upon 

the number of stations used, and the length of 

each record. When more data are obtained 

and, perhaps, improved methods of analysis 

are developed, better definition of the flood 

regime will be possible.

The curves presented are based on all 

available annual peak data through the 1959 

water year on uncontrolled and unregulated 

streams having 300 square miles or less contributing drainage area, and 5 or more years' 

record of annual peaks. The regional frequency curves cannot be extrapolated with 

confidence beyond 25 years. The drainage 

area-mean annual flood curves should not be 

extended beyond the limits shown.

The curves presented in this report should 

not be used on controlled and regulated 

streams.

SELECTED REFERENCES

Benson, M. A., 1960, Characteristics of frequency curves based on a theoretical 1,000- 

year record,//? Dalrymple, Tate, Flood-frequency analyses: U.S. Geol. Survey WaterSupply Paper 1543-A, p. 51-74.

Berwick, V. K., 1958, Floods in eastern Montana, magnitude and frequency: U.S. Geol. 

Survey open-file report.

Bigwood, B. L., and Thomas, M. P., 1955, A 

flood-flow formula for Connecticut: U.S. 

Geol. Survey Circ. 365.

Bodhaine, G. L., and Robinson, W. H., 1952, 

Floods in western Washington, frequency 

and magnitude in relation to drainage basin 

characteristics: U.S. Geol. Survey Circ. 191.

Carter, R. W., 1951, Floods in Georgia, frequency and magnitude: U.S. Geol. Survey 

Circ. 100.

Chow, VenTe, 1950, Discussion of W. B.Langbein's paper "Annual floods and the partialduration flood series:" Am. Geophys. Union 

Trans., v. 30, p. 939-941.

Condra, G. E., 1920, The soil resources of 

Nebraska: The Nebraska Conservation and 

Soil Survey, Univ. of Nebraska, Bull. 15, 

p. 1-76.

Cragwall, J.S., Jr., 1952, Floods in Louisiana, 

magnitude and frequency: Louisiana Dept. 

of Highways.
SELECTED REFERENCES 33

Cross, W-. P., and Webber, E. E., 1959, Floods 

in Ohio, magnitude and frequency: Ohio 

Dept. of Natural Resources, Div. of Water 

Bull. 32.

Dalrymple, Tate, 1960, Flood-frequency analyses: U.S. Geol. Survey Water-Supply Paper 

154 3-A.

Darling, J. M., 1959, Floods in Maryland, mag - 

nitude and frequency: U.S. Geol. Survey 

op en-file report.

Ellis, D. W., and Edelen, G. W., Jr., 1960, 

Flood frequency, pt. 3 of Kansas stream - 

flow characteristics: Kansas Water Resources Board Tech. Rept. 3.

Furness, Li. W., 1955, Floods in Nebraska, 

magnitude and frequency: Nebraska Dept. 

of Roads and Irrigation, p. 2 3.

Green, A.R.,and Hoggatt, R.E., 1960, Floods 

in Indiana, magnitude and frequency: U.S. 

Geol. Survey open-file report.

Gumbel, E. J., 1945, Floods estimated by 

probability method: Eng. News-Rec., v. 134, 

no. 24, p. 833-837.

Jenkins, D. S., and others, 1946, The origin, 

distribution, and airphoto identification of 

United States soils: U.S. Dept. of Commerce, Civil Aeronautics Adm., Tech. 

Devel. Rept. 52, pi. 1.

Langbein, W. B., 1949, Annual floods and the 

partial-duration series: Am. Geophys. Union 

Trans., v. 30, p. 879-881.

McCabe, J.A., 1958, Floods in Kentucky, magnitude and frequency: U.S. Geol. Survey 

open-file report.

McCabe, J. A., and Crosby, O.A., 1959, Floods 

in North and South Dakota, frequency and 

magnitude: U.S. Geol. Survey open-file 

report.

Mitchell, W. D., 1954, Floods in Illinois, magnitude and frequency: Illinois Div. of Waterways, Dept. of Public Works and Buildings.

Nebraska State Planning Board, 1941, Water 

resources of Nebraska: p. 1 19.

Peirce, L.B., 1954, Magnitude and frequency 

of floods in Alabama: U.S. Geol. Survey 

Circ. 342.

Powell, R: W., 1943, A simple method of estimating flood frequencies: Civil Eng., v. 13, 

no. 2, p. 105-106.

Pride, R. W., 1958, Floods in Florida, magnitude and frequency: U.S. Geol. Survey 

open-file report.

Prior, C. H., 1949, Magnitude and frequency 

of floods in Minnesota: Minnesota Dept. 

Conserv., Div. of Waters Bull. 1.

Rantz, S.E., and Riggs,H.C., 1949, Magnitude 

and frequency of floods in the Columbia 

River basin, in Floods of May-June 1948 in 

Columbia River basin: U.S. Geol. Survey 

Water-Supply Paper 1080.

Riggs, H. C., 1955, Floods in North Carolina, 

magnitude and frequency: U.S. Geol. Survey 

open-file report.

Schwob, H. H., 1953, Iowa floods, magnitude 

and frequency: Iowa Highway Research 

Board Bull. 1.

Searcy, J.K., 1955, Floods in Missouri, magnitude and frequency: U.S. Geol. Survey 

Circ. 370.

Tice, R. H., 1958, Delaware River basin, flood 

frequency: U.S. Geol. Survey open-file 

report.

U.S. Geological. Survey, Water Resources 

Division, 1952, Floods in Youghiogheny and 

Kiskiminetas River basins, Pennsylvania 

and Maryland, frequency and magnitude: 

U.S. Geol. Survey Circ. 204.

INT.DUP..D.C.62- 3551