Automation of Streamflow 

Records

GEOLOGICAL SURVEY 

CIRCULAR 474
Automation of Streamflow Records

Prepared by a work group composed of R. W. Carter, chairman, 

W. L. Anderson, W. L. Isherwood, K. W. Rolfe, C. R. Showen,

and Winchell Smith

GEOLOGICAL SURVEY CIRCULAR 474

Washington 1963
United States Department of the Interior

STEWART L. UDALL, SECRETARY

Geological Survey

THOMAS B. NOLAN, DIRECTOR

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

Page

Summary. _ __________________________ 1

Introduction _________________________ 2

History of automation program ________ 3

Recorder development ______________ 4

System development ________________ 5

Evaluation of system _______________ 5

Recommended automation system ______ 5

Special systems and computations ______ 9

Expansion of automation system _______ 9

Recorder aquisition and distribution__ 9

Procurement policy ________________ 10

Expansion of central processing

system_ _ ________________________ 10

Computer facilities required ________ 10

Page 

Financial aspect of automation ________ 11

Cost of manual computation ________ 11

Cost of machine computation _______ 12

Comparison of manual and machine

costs __________________________ 13

Effect of automation on personnel _____ 13

Effect of automation on reports ______ 14

Timing of annual reports___________ 14

Timing of current reports __________ 14

Publication techniques _____________ 15

Supporting studies___________________ 15

Significance of recording frequency _ 15 

Comparison of automated and

manual computation accuracy......... 16

ILLUSTRATIONS

Page 

Figure 1. Fischer and Porter digital recorder _________________________________________ 3

2. Facsimile of data tape from digital recorder _________________________________ 4

3. Comparison of computations based on 96,48, and 24 readings per day for

stations along the Atlantic seaboard______________________-_--_------------ 16

4. Comparison of computations based on 96,48, and 24 readings per day for

stations in Kansas _______________________________________--__---------_- 17

Table 1.

2.

3.

TABLES

Page 

Primary computation of gage height and discharge _____________________________ 7

Print -out of daily discharge _________________________________---__-_----_---- 8

Summary of cost for manual computation _____________________---___---------_ 11

4. Summary of man hours required for manual computation _______________________ 14

III
Automation of Streamflow Records

Prepared by a work group composed of R. W. Carter, chairman, W. L. Anderson, 

W. L. Isherwood, K. W. Rolfc, C. R. Showen, and Winchell Smith

SUMMARY

A system for automatic computation of 

daily discharge records has been developed 

by the U.S. Geological Survey as a result'of 

continuing studies since 1952. Basic components of the system, which is now in pilot 

operation at 268 streamflow stations, are a 

digital-stage recorder, a paper-tape translator, and a general-purpose digital computer.

The digital-stage recorder is a batteryoperated slow-speed paper-tape punch which 

records a four digit number on a 16-channel 

paper tape at preselected time intervals. 

The recorder is basically a device for coding 

and recording the position of an input shaft, 

but it can be adapted to accept a voltage input, to record several variables in sequence, 

or to transmit data by wire or radio. The 

paper-tape format is a unique configuration 

which requires rearrangement before input 

to any present high-speed digital computer. 

Because input requirements for different 

computers vary considerably, this seemingly 

redundant translation step actually precludes 

obsolescene of the field recorder. The translation permits adaptation of the basic record 

to the input form required by any present or 

future computer.

A complete data-processing system, which 

utilizes specially designed translators and a 

standard Burroughs 220 computer, is now in 

pilot operation. The computation of 268 

streamflow records for water year 1961 has 

provided experience for a critical analysis 

of this initial processing system and for developing the improved system proposed in 

this report.

A work group was activated in April 1962 

to evaluate the pilot operation and to consider

the expansion of the system to the streamflow 

network, which presently consists of 7,200 

gaging stations. This report summarizes the 

studies and recommendations of the work 

group.

Streamflow records of most gaging stations 

are presently computed by manual methods 

from stage records on strip charts and from 

stage-discharge relations that are empirically defined by streamflow measurements. 

This data-reduction process is tedious and 

time consuming. Studies on automation indicate that much of the data reduction can be 

done efficiently on a digital computer. A digital system is also more adaptable to automated systems of publication and to rapid 

storage and retrieval of information. It should 

speed up the publication process.

The digital recorder was field tested and 

modified during a 3-year period. Results of 

intensive tests during the winter of 1961 62 

on a modified production model established 

the recorder as an operational instrument 

equal in reliability to strip-chart recorders.

The presently used type of translator can 

be used for the full program recommended, 

and its use in an expanded system is economically feasible. The state of the art in this 

field, however, is advancing so rapidly that 

the development of a more efficient system of 

translation within the next 5 years appears 

certain.

The efficiency of the computer program 

used in the pilot operation was greatly improved through studies made by the work 

group. The new program, which is now ready 

for operation, is ideally suited to current 

computation of streamflow records. It incorporates several new concepts in data
AUTOMATION OF STREAMFLOW RECORDS

preparation and computation and provides for 

efficient storage and printout of information. 

The format of the daily discharge (or daily 

gage height) tabulation, which is the final output from this system, is suitable as photooffset copy for inclusion in the annual basicdata reports and is ideal for preliminary 

distribution by ozalid or xerox duplication.

The expansion rate of the automated system will be limited by financial considerations and the need for training in new techniques. In view of these problems, the work 

group recommends an expansion rate of 1,000 

stations per year. Plans have been formulated within the Water Resources Division for 

approaching this magnitude beginning in fiscal year 1964. Acquisition of recorders will 

be financed by Federal funds, and the instruments will be issued to the field offices on a 

rental basis.

Detailed analysis of the costs of manual 

and automatic computation indicates that 

overall savings of about 10 percent can be 

achieved when 2,000 stations are included in 

the program. Realization of these savings is 

tied in with a reduction in personnel assigned 

to the manual computation phase of the data 

collection program. The relatively slow rate 

of expansion, on a nationwide basis, will preclude need for reduction-in-force actions. 

The normal attrition rate is many times the 

displacement involved. District programs 

will need to be diversified, however, to retain enough man-power for field work during 

flood periods.

Efforts to date have been directed toward 

automation of routine streamflow computation 

procedures, but automation also offers great 

flexibility in special computations, and its 

application will streamline procedures presently used in manual computations. The advantages of the digital system will doubtlessly 

increase with advances in computer technology, and utilization of the digital recorder to 

record other hydrologic parameters will permit automation of many complex computation 

problems.

INTRODUCTION

Streamflow records are presently computed from a record of stage, recorded in 

analog form on a strip-chart recorder and 

from stage-discharge relation that is defined 

empirically by current-meter measurements.

Many of the steps in the data reduction process require tedious and time consuming 

manual work that could be accomplished 

more efficiently by digital computers. Records from strip-chart records, however, are 

not suitable for direct input into automatic 

computers, nor are manual computation procedures particularly efficient when transferred directly to machine processing. In 

consequence, the search for applicable automation techniques has involved changes in 

the basic method of recording information as 

well as changes in computation procedures.

Studies during the past 10 years on the use 

of automation in computing streamflow records have lead to a system that utilizes 

digital-stage recorders in the field, translation equipment at a central unit, and a general-purpose digital computer. Pilot tests of 

the system during the 18 months ending in 

May 1962 included the installation of digitalstage recorders at 268 streamflow stations 

and the automatic computation of discharge 

records for these stations for water year 

1961. These tests have established the feasibility of the digital recorder approach to 

automation.

A work group composed of personnel of the 

Water Resources and Administrative Divisions of the Geological Survey was established in April 1962 to study the feasibility of 

extending this pilot automation system to as 

much of the whole network of streamflow 

stations as practical.

The studies and recommendations of the 

work group are summarized in this report. 

Attention was given to the following aspects 

of the program: (1) evaluation of the existing 

pilot operation, (2) development of a more 

efficient data-processing and computation 

system for large scale application, (3) adaptation of the basic program to include current computation of daily discharge and to 

include provision for computing discharge 

for shorter time intervals during flood 

events, (4) evaluation of the cost of producing 

final discharge records by manual computation and by automation, (5) feasible rate of 

extension of the automation program, and (6) 

the impact of automation on field operations 

and personnel.

The group confined its study to the computation of streamflow records, because these 

computations represent a major part of the
HISTORY OF AUTOMATION PROGRAM

standard data-collection and computation 

program of the Water Resources Division. A 

broader study of the application of automation in other phases of the program would be 

a logical sequel to this report.

HISTORY OF AUTOMATION PROGRAM

Automation efforts within the Geological 

Survey began in 1952. Initial steps were toward the development of a device that could 

automatically read graphic strip charts and 

convert the position of an inked line representing gage height into a discharge record 

by means of a special-purpose computer that 

was partly analog and partly digital. This effort was not successful, primarily because of

the variable quality of the graphic records 

and because of the maintenance problems associated with a one-of-a-kind computer. In 

1958 the conclusion was reached that successful automation would require the development of a recorder that would produce a 

digital record of stage so that processing 

could be done on a general-purpose digital 

computer.

RECORDER DEVELOPMENT

An automatic digital recorder was developed under contract with the Fischer and 

Porter Company to record river stage at 

gaging stations. The instrument, shown in 

figure 1, is a slow-speed paper-tape punch

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Figure 1. Fischer and Porter Digital Recorder.
AUTOMATION OF STREAMELOW RECORDS

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Figure 2.-«Fac$imile of data tape record from Digital Recorder.

that records a four digit gage height on a 

punched tape in configuration of holes in a 

single transverse row across a tape 2-1/8 

inches wide. (See fig. 2.)

The tape is punched in binary-decimal code. 

In this code, each binary digit is related to 

the other by powers of 2, rather than 10 as 

in the conventional decimal system. The four 

binary digits, one, two, four, and eight, are 

combined in various ways to form a single 

decimal digit. The digital recorder tape is 

preprinted with the decimal values of the 16 

binary digits (the equivalent of 4 decimal digits). Note in figure 2 the preprinted figures: 

0.01,0.02,0.04,0.08,0.1, 0.2, 0.4, 0.8; and 1, 

2,4,8; and 10,20,40,80. Hence, the decimal 

range of gage readings on this particular tape 

is 00.00 to 99.99 feet. Each readout is on a 

separate line, therefore a value of gage height 

is read by adding the total of the punched 

positions on a given line. The large holes 

down the middle of the tape are for the feed 

mechanism on the recorder. The holes in the 

center strips are for the feed mechanism of 

the tape reader on the translator. One-tenth 

inch of paper tape is required for each reading and a roll of tape is 500 feet long, so at 

15-minute readings, the tape will last for 1

year. The punch is triggered by a timer at 

preset intervals.

The paper tape format described above is a 

parallel-by-character arrangement, an arrangement that requires a minimum of recording equipment and battery power in the 

field installation, whereas present digital 

computers require serial-by-character coding in paper tape for direct input. No coding 

system is universally acceptable, however, 

because each manufacturer's computer has 

its own unique requirements for character 

coding and digit arrangement. The system 

developed for use in the Survey uses the 

compact form of basic recording by interposing a translator equipped with pinboards 

to produce serial-by-character tape in any 

5-to 8-channel character coding and any digit arrangement required. This will preclude 

the obsolescence of thousands of field recorders Whenever it is necessary or desirable to change computers. The rapid advance 

in computer technology indicates that changes 

in computer equipment will be inevitable 

within the next few years, probably before the 

proposed streamflow automation system is 

fully installed.

The prototype of the digital recorder, delivered in December 1958, was subjected to 

extensive tests in an environmental chamber 

to determine its performance under extremes 

of temperature and humidity. After slight 

modification in design, 100 production models 

were procured and distributed for trial in 

actual field installations. The first deliveries to the field were made in February 

1960. Later 400 slightly modified instruments were procured, 200 of which were delivered to the field in October 1960, the other 

200 held in reserve.

Field trials of the production models revealed only minor problems with the recorder itself but immediately pointed up the 

need for additional work in design of the 

timer unit. Three different types of timers 

were employed during the first 18 months,, 

none of which gave satisfactory preformance. 

Finally in May 1961, Fischer and Porter 

Company supplied 50 Ergas timers that performed so well that 150 more were procured 

and installed in the field in November 1961. 

In June 1961, a contract was let for 100 battery-wound, spring-driven Chelsea timers. 

These also were delivered and installed in 

November 1961.

Coincident with the procurement of the 

Ergas and Chelsea timtrs, and as a final 

phase of field testing, all recorders were returned to Fischer and Porter Co. in the fall of 

1961 for slight modification and adaptation to
RECOMMENDED AUTOMATION SYSTEM

the new timers. This was followed in November 1961 by a well-documented field test program to determine the performance of the 

new timers and the modified recorders. By 

mid-January 1962 it was apparent that the 

only significant cause of malfunction was the 

drive motor of the recorder. This problem 

was easily resolved by substituting a new 

type motor, which has given excellent service. Performance of the Chelsea timers 

was significantly better than that of theErgas 

timers, although the latter were also considered acceptable. This test program firmly 

established the Fischer and Porter Digital 

Recorder, equipped with the Chelsea timer, 

as a reliable operational instrument. Continuation of the testing program through May 

1962 has shown a loss of less than 3 percent 

of record during the period since modifications were completed, a loss ratio which 

compares very favorably with the performance of strip chart recorders.

The digital recorder can be used for recording a variety of data. It is basically a 

device for coding and recording the position 

of an input shaft and consequently can be used 

to record any event that can be expressed in 

terms of shaft position. It can be adapted to 

record rainfall, temperature, wind-speed, or 

other hydrologic parameters. Equipped with 

a multiplex input system, it can record several variables in sequence. Fitted with contact points in the punch assembly and suitable 

transmission equipment it serves as a telemetering device to transmit data by wire 

or radio to a remote location. The digital 

recorder is thus a versatile instrument which 

can be used to record hydrologic events in 

remote locations in a form that permits rapid 

and economical machine analysis of the data.

SYSTEM DEVELOPMENT

Other components of the automation system have been developed to utilize the record 

from the digital recorder. A data processing 

unit was activated and a program for computation of daily discharge was written for 

the Burroughs 220 computer. Equipment at 

the processing center consists of translation 

units, add-punch machines, and other equipment required for mass-handling of punched 

paper tape.

The computer program used for processing of 1961 water-year records is patterned rather closely after manual computations procedures. Principal output forms are 

machine adaptations of manual computations 

forms. A significant block of gage-height 

data (6 months or 1 year) is translated, edited, 

listed, and stored on magnetic tape during 

one or more computer passes. After the 

ratings have been supplied by the field office 

the computer computes the daily discharge 

using the stored gage-height data and lists 

daily mean gage heights, shift corrections, 

and discharges on a special form. It also 

stores daily mean discharges on magnetic 

tape and lists all peak flow figures above a 

given base. After quality control checks are 

performed by personnel at district level, a 

list of needed corrections are fed into the 

computer to update the magnetic tape record 

for the stations, and a final output is produced 

listing all daily mean discharges on a form 

suitable for offset reproduction.

EVALUATION OF SYSTEM

Evaluation of this system by the work 

group revealed several areas where improvements could be made in the interest of 

overall economy and usefulness. For instance, the storage of all basic data on magnetic tape was originally considered necessary because discharge values were not computed until the end of the water year. Reevaluation of the entire system in the light of 

almost 2 years of experience led to the development of a new system which requires a 

minimum of data storage and computes daily 

discharge on the first pass through the computer. This makes the system more economical as well as more useful in meeting the 

need for current reports.

RECOMMENDED AUTOMATION SYSTEM

The computation system recommended by 

the work group is described in the following 

paragraphs. The computations have been 

programmed for the Burroughs 220 computer 

and the system is ready for operation, in an 

Automatic Data Processing Unit located in 

Washington, D.C. Several of the new features in the computer program that deserve 

special mention are as follows: Final discharge records are computed on the first 

pass through the computer, up-to-date tabulation of daily discharge may be produced at 

the end of any computation period to satisfy 

the need for current records, discharges can 

be recomputed or revised on a second pass 

through the computer without recourse to the
AUTOMATION OF STREAMFLOW RECORDS

instantaneous gage readings, the input for the 

stage-discharge relation may be a set of 

points picked from a conventional rating 

table at the ends of tangents (or as an alter - 

native as much smaller set of points selected 

from a graphical log-log plot), for all discharges above a preselected base, gage 

heights are printed out for 2-hour intervals, 

and automatic editing features are incorporated in the program. The system is described in sequence of operation:

1. River stage is punched on 16-channel tape 

bythe digital recorder in the gage house.

2. Tape is removed by field personnel at intervals of 30 to 60 days. Upon removal 

the tape is checked for continuity and 

quality of record, and appropriate notes 

concerning identity of the station and 

quality of the record are made on the 

tape.

3. The tape, rating table, datum correction, 

and table of shifts is forwarded from the 

field office to the Automatic Data Processing Unit. Ratings may be submitted 

in one of three alternate forms. Discharge may be tabulated for each 0.01 

foot of gage height for the part where 

curvilinear expansion between tenths of 

feet is necessary, it may be tabulated for 

each 0.1 foot, or it may be defined by a 

series of coordinate values at the ends of 

straight-line segments on log-log plot of 

the rating curve. The entry of ratings 

directly from the log-log plot would 

eliminate the preparation of a rating 

table in the usual form. Shift adjustments will be prorated with time to give 

a shift for each day between the days for 

which values of shift are submitted. A 

new rating may be put in use at any time 

during a day, and any shift applicable to 

the old rating on the same day will be 

dropped when the new rating takes effect.

The refinement considered in ratings for 

the initial run through the computer de - 

pends upon the complexity of the rating 

problem and the completeness of the 

data available. Sometimes final ratings 

can be prepared at the outset, at other 

times the output from the first run will 

be needed to complete the analysis. In 

the.latter situation only base ratings and 

approximate shift corrections are supplied.

Data from the 16-channel tape are translated by the central processing unit onto 

7-channel paper tape suitable for input 

into the digital computer. The information on ratings, shifts, and datum corrections are manually punched on paper 

tape with an add-punch machine. These 

two tapes comprise the input data to the 

computer.

4. The computer converts each instantaneous 

reading of river stage into a discharge 

value by a table look-up routine. Discharge application is made to each 0.01 

foot in stage up to 20.00 feet. Beyond this 

limit, application is made to the nearest 

0.1 foot. Both daily mean discharge and 

daily mean gage height are computed as 

an average of instantaneous values. An 

equivalent daily mean gage height (the 

gage height corresponding to the mean 

daily discharge) is computed for each 

day so that recomputation, if necessary, 

can be made at a later date without reference to the individual items of the 

original base data. Daily mean values of 

gage height, discharge, and equivalent 

gage height are stored on magnetic tape. 

The printed output from the first computer pass consists of two items; a primary computation sheet, which is standard, and a daily discharge sheet, which 

is optional.

The primary computation sheet, table 1, 

gives for each day the maximum, minimum, and mean gage heights, equivalent 

mean gage height, the datum and shift 

corrections applied, and the daily mean 

discharge. In addition, bi-hourly gage 

heights and the time when maximums occurred are printed out whenever any discharge during the day exceeds a given 

base figure, or when the difference between successive gage heights is greater 

than a specified control value.

The print-out of daily discharge, table 2, 

which is suitable for outside distribution, 

lists daily mean discharges for the period from the beginning of the water year 

to the end of the record being computed.

5. The field offices will use the primary 

computation sheet in quality checks of 

the original and computed data, in further
-RECOMMENDED AUTOMATION SYSTEM

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AUTOMATION OF STREAMFLOW RECORDS

Table 2. Print-out of daily discharge

Discharge, in cubic feet per second, water year October 1959 to September 1960

(Station no. 1-4780.00)

Day

1.....

2.-__.

3.....

4_._._

5_____

6_....

7 __ ..

8

9._...

10.....

11....

12....

13....

14....

15___.

16....

17____

18....

19....

20....

21....

22....

23....

24____

25....

26....

27....

28____

29....

30....

31....

Total

Mean

CFSM

Inches

AC-FT

October

11

12

6.6

2.3

7.5

5.4

4.9

4.8

35

11

5.0

9.4

5.2

21

16

8.6

6.4

5.7

9.8

6.6

6.7

6.1

7.6

22

15

11

8.6

7.9

8.2

7.6

6.4

301.3

9.72

.474

.55

November

8.6

11

7.0

9.0

6.4

8.0

140

31

15

12

10

9.4

10

7.5

7.6

10

11

11

9.5

8.8

8.3

6.2

8.6

40

62

16

14

13

15

13

538.9

18.0

.878

.98

December

11

8.8

8.7

10

8.4

12

222

41

24

19

15

291

168

33

22

20

17

22

22

16

16

17

14

12

15

17

17

28

207

49

25

1,407.9

45.4

2.21

2.55

January

20

18

264

49

29

22

20

19

16

16

16

16

43

31

136

48

23

27

49

24

19

15

15

15

14

14

17

59

31

21

18

1,124

36.3

1.77

2.04

February

18

16

14

15

15

124

34

21

17

16

183

34

18

16

15

17

33

132

372

37

23

24

20

18

32

200

34

23

23

1,544

53.2

2.60

2.80

March

21

18

15

14

14

14

14

14

14

15

14

14

14

14

15

23

98

70

44

28

24

23

21

19

17

14

16

16

15

17

60

729

23.5

1.15

1.32

April

27

17

150

473

640

82

48

34

30

26

23

24

22

21

20

18

18

23

22

18

17

17

15

16

15

17

18

16

16

15

1,898

63.3

3.09

3.44

May

25

18

15

15

14

14

12

14

103

33

20

28

33

19

17

16

15

20

15

14

14

20

94

28

19

36

18

15

69

29

22

824

26.6

1.30

1.49

June

16

14

13

13

14

12

12

13

11

12

10

112

67

16

40

July August September
EXPANSION OF AUTOMATION SYSTEM 9

analysis of the computer stage-discharge relation, and in selecting instantaneous peak discharges to be published. 

Daily discharges from this sheet can be 

plotted for comparison with adjacent 

streams, and the usual studies can be 

made for periods of ice effect, no gage 

height record, or backwater from various 

sources. Estimates can be made for all 

anomalous periods, and ratings can be 

revised, if necessary, so that daily discharge can be recomputed from the effective mean gage heights on the second 

pass through the computer. The information necessary for revision or recomputation is forwarded to the Automatic 

Data Processing Unit.

6. The final tabulation is the same as table 2 

except that it is complete for the year 

and is produced on the second pass 

through the computer. Where rating 

changes have been made as a result of 

the quality control analysis or where individual discharge figures have been estimated, the recomputation will involve 

substituting the estimated figures on the 

magnetic storage record, recomputing 

other discharge figures from revised 

ratings and the equivalent daily mean 

gage height, and printing out of the final 

discharge figures. The print-out from 

this final computer pass will be for the 

complete year. The format of the output 

is suitable for direct offset reproduction. 

The data on this form will be also be 

stored on magnetic tape for permanent 

storage.

7. A tabulation of daily mean gage heights 

may also be printed out during the second computer pass for stations designated by the field offices. The tabulation 

will be prepared only for those stations 

for which there is a specific need.

8. The documentation file in the field offices 

will consist of the original measurement 

notes, the 16-channel tapes, a station 

analysis, a list of discharge measurements^ rating curve, the primary computation sheet,a table of daily mean discharges from the final computer run, and 

possibly a rating table.

SPECIAL SYSTEMS AND COMPUTATIONS

The availability of data in digital form will 

permit great flexibility in meeting special 

problems, and auxiliary programs are being 

planned to take advantage of this potentiality.

Programs now being considered include the 

following:

1. Computation of instantaneous discharge for unit hydrograph studies.

2. Computation of daily discharge where 

water slope is a rating factor.

3. Computation of daily discharge where 

rate of change of stage is a factor.

4. Computation of daily discharge in tidal 

reaches.

5. Development of the basic computation 

routine to include shifts that vary 

with gage height.

6. Computation of discharge, both instantaneous inflow and daily mean 

inflow where the gage is located in a 

pond.

7. Computation of discharge from sonic 

observations of velocity.

8. Automatic plotting systems.

9. Automatic quality control of data.

In addition to these surface-water items, serious consideration could be given to developing a program for computation of sediment 

and chemical load from the discharge records 

and samples of concentration.

EXPANSION OF AUTOMATION SYSTEM

RECORDER ACQUISITION AND DISTRIBUTION

The Geological Survey and its cooperating 

agencies presently operate about 7,200 

streamflow stations at which the installation 

of digital recorders might be considered. 

The rate of expansion from +he present pilot 

operation to such a large scale program will 

be regulated by several factors. Limitations 

are imposed by available money, by the plant 

capacity of the instrument manufacturers, 

and by the ability of our own organization to 

install the new units and to become familiar 

with the new procedures involved. Operational problems inherent in the switchover 

from a manual to an automated system may 

actually control the expansion rate. ^Training 

is thus a dominant factor in the expansion 

process and is an item that needs to be given 

a high priority. District personnel must learn 

to operate with digital recorders and to efficiently utilize the records obtained. Development of efficient data handling methods in 

the Automatic Data Processing Unit will also 

require time. In light of these factors it is 

recommended that the installation of digital 

recorders be limited to a rate of about 1,000 

per year.
10 AUTOMATION OF STREAMFLOW RECORDS

It is estimated that the automation system 

can be profitably applied to 5,000 streamflow 

stations now operated by the Geological Survey. Additional installations will be feasible 

when programs are developed for stations 

where discharge is not a function of stage 

only, and when more elaborate instrumentation systems are developed to record simultaneously several variables. Dual operation 

of the strip chart and digital recorders will 

be desirable at some sites, such as key sites 

use.d in computation of ice-affected records.

The most profitable expansion scheme is 

to equip one or more moderate-sized districts and subsequently to distribute other 

recorders in blocks of about 50 each to other 

districts. Other installations would of course 

be permitted at new stations or where special 

applications of the recorders are involved. 

In succeeding years, efforts would be made to 

complete the coverage in selected districts 

in preference to obtaining partial coverage on 

a country-wide basis. The recommended pattern of distribution should contribute to the 

solution of operational problems and provide 

the experience needed to refine processing 

techniques.

In line with this philosophy, arrangements 

have been made to install a digital recorder 

at each gaging station in the Boston district, 

which cover the states of Massachusetts, New 

Hampshire, and Vermont. This district has 

had experience in the pilot operation and is 

interested in further development of the program. Also, a block of 50 instruments will be 

installed on the Gila River research project 

in Arizona to record rainfall, river stage, and 

ground-water levels. This is a new application of the digital recorder.

PROCUREMENT POLICY

The following plan for procurement and financing has been developed jointly by the 

Water Resources and Administration Divisions.

1. Initial procurement of digital recorders by advance budgeting of Federally appropriated funds will start in 

fiscal year 1964 and continue in 196 5 

and 1966 at a rate of 1,000 recorders 

per year for each of the 3 years.

2. Recorders will be rented to the district and project offices at a uniform 

rate. The rental rate, which is based 

on an estimate of the probable useful

life of the recorders and other considerations, has been set at $40 per 

year. The rental rate in future years 

will be governed by actual experience on the life span of the recorder.

3. The instrument maintenance costs will 

be borne by the using office or 

project.

4. The rental system will become effective July 1, 1963.

5. Field off ice swill be permitted to make 

advance payment of rental charges 

to help even out fluctuations in other 

operating costs.

EXPANSION OF CENTRAL PROCESSING SYSTEM

Increase in the number of digital recorders 

will require proportional increase sin personnel and equipment in the Automatic Data Processing Unit. Present translation equipment is 

adequate for processing the output from about 

1,000 digital recorders, and the system can 

be expanded gradually as the load increases. 

About 8 high-speed translators will be needed 

to handle data from 5,000 digital recorders. 

There is little likelihood, however, that the 

ultimate data processing equipment will consist of modules of the equipment now used. 

Within the next few years equipment may be 

available at reasonable cost to translate the 

16-channel recorder tape directly onto magnetic tape in a format suitable for high-speed 

input to the computer. Such equipment will 

make obsolete the present translation equipment and will speed up processing rates. Economic expansion of the program, however, 

does not hinge upon development of highspeed translation equipment, because extention of the present system to meet the ultimate needs is economically feasible.

COMPUTER FACILITIES REQUIRED

A general-purpose digital computer is an 

integral part of the automation system. The 

proposed system is based on the use of the 

Burroughs 220 computer, which is currently 

maintained and operated in Washington, D.C. 

by the Geological Survey. This computer is 

currently operated for one 8-hour shift per 

day.

Computation of 5,000 records will require 

about 4 hours time each day on the present 

computer, and thus a two-shift operation will 

be required. However, expansion of other 

programs within the agency will very likely 

require an increase in computer capacity
FINANCIAL ASPECTS OF AUTOMATION 11

either at a central location or at regional 

centers. Decentralization of computer facilities would facilitate the computation of 

streamflow records as the work load approaches its ultimate level.

FINANCIAL ASPECTS OF AUTOMATION

To evaluate the economic aspects of shifting from manual computation techniques to 

an automated system, cost studies were made 

on each system, and the costs involved were 

compared.

COST OF MANUAL COMPUTATION

In June of 1959, ten districts were asked to 

keep detailed records of the time spent in 

various phases of manual records computation. A breakdown was requested showing 

costs in each of six major computation steps, 

gage-height analysis, rating analysis, discharge computation, special computations 

such as those for ice effect and periods of no 

gage-height record, preparation of the table 

of daily discharges, and preparation of the 

station description. This cost study covered 

a full year, and represents documentation of

work done in preparation of a total of 1,146 

station years of record. Results of the study 

are shown in table 3. The costs shown are 

computed on the basis of salary charges at 

each grade level increased by 33 percent to 

account for retirement, leave, health insurance, and cost of direct supervision. The 

figures do not include overhead items such 

as traveling expenses, rent, or other significant non-salary items pertaining to overall 

operations, because the shift from manual to 

automated procedures may not effect such 

items. Comparable factors in the study are 

salary charges for manual computation steps 

which can be compared with the machine 

costs for the same operations. Shift from 

manual to automated computation procedures 

will eliminate 90 percent of the work in gage 

height analysis, 10 percent of the work in 

rating analysis, all of the discharge application work 80 percent of the work preparing 

the daily discharge table. Additional saving 

in manuscript preparation is possible if the 

machine-produced daily discharge table is 

used as the offset copy for publication. The 

dollar value of work shifted to the automated 

program is computed on page 12.

Table 3. Summary of cost for manual 'computation

[Cost in dollars per station-year of record]

District

A .....

B_____

C__ __

D_____

E_____

F___._

G__ __

H_____

I _____

J _____

Average

of 8

central

values

Recorder 

chart 

analysis

109

112

131

105

77

86

68

52

73

27

85

Rating 

analysis

211

99

143

109

64

86

79

92

125

45

100

Discharge 

application

137

83

55

99

73

65

77

52

58

36

70

Special 

computations

43

11

18

73

29

14

24

28

25

13

24

Preparation of 

daily 

table

16

17

11

22

14

9

11

11

10

6

12

Manuscript 

preparation

38

74

43

40

27

18

29

26

14

15

30

Total cost 

of office 

computation

554

396

401

448

284

278

288

261

305

142

321

Field 

operations

342

306

293

240

307

290

260

294

196

272

Total of 

office 

and field 

costs

896

702

694

688

591

568

548

555

501

594
12 AUTOMATION OF STREAMFLOW RECORDS

Computation step

Gage height analysis. ______ ___

Rating analysis ______________

Discharge application _________

Special computations _________

Preparation of table and daily 

discharge _________________

Preparation of station

H^Qr*T*i Til"! on

Field operations _____________

Total ____________---___--_

Cost by manual 

techniques 

(dollars per 

station year)

85

100

70

24

12

30

272

Percent of work 

done by 

automation

90

10

100

0

80

0

0

Value of work done 

by automation 

(dollars per 

station year)

76

10

70

0

10

0

0

166

COST OF MACHINE COMPUTATION

Machine computation costs consist of instrumentation costs, data preparation costs, 

and computer costs. Instrumentation costs 

include the rental and maintenance costs of 

the digital recorder. Data preparation costs 

are those required for equipment, salaries, 

and supplies necessary for operation of the 

Automatic Data Processing Unit. Computer 

costs are charges for time on the computer 

and include related supplies and salaries as 

well as the larger item of computer rental.

The rental fee for the digital recorder has 

been set at $40 per year. Batteries and maintenance costs will add about $10 per year to 

make the total cost to the districts $50 per 

year.

Data preparation and computer cost are 

related to the number of recorders in operation and the amount of data collected at the 

individual site, A record of 24 readings per 

day will pass through the translator in onefourth the time required for a record of 96

readings per day, and input of this same 

record into the digital computer is also proportionally faster. The difference in total 

cost, however, is not in direct proportion to 

the number of gage readings on the data tape 

because handling costs and the cost of preparing supplementary data are not reduced, 

and also because the same amount of computation time is required for the final pass 

through the computer. A conservative estimate is that overall costs for data preparation and computer processing can be reduced 

by at least 10 percent by changing the recording frequency from 96 to 24 readings each day. 

More experience in the data processing pnase 

is needed before accurate figures of relative 

cost can be determined. For this study of 

comparative costs, the processing costs are 

based upon the capabilities of translating 

equipment now in use and on digital recorder 

records containing 96 readings per day.

Estimates of computations cost for the 

automated process are summarized below. 

Costs shown for data preparation are the 

overhead and materials cost of the Automatic

Estimated cost of automated computations system 

[Cost in dollars per station-year of record]

Number of digital 

recorders in 

operation

250 ___ __ __ _____

500_______________

1,000 __ ___ __ _

2,000 _____________

Data preparation

80

50

35

30

Computer 

charges

40

40

40

35

Recorder 

rental and 

operation

50

50

50

50

Total annual 

cost

170

140

1 9^

115

Net savings*

26

41

51

^Computed using $166 as the comparative cost of manual computation.
EFFECT OF AUTOMATION ON PERSONNEL 13

Data Processing Unit divided by the number 

of records indicated. The unit costs for these 

items decreases as the number of digital recorders is increased. Other unit charges are 

more nearly fixed and do not vary significantly with increase in the size of the operation.

COMPARISON OF MANUAL AND MACHINE COSTS

Direct comparison of overall costs for 

manual and machine methods indicates that 

operation with about 250 digital recorders is 

near the break-even point. The use of digital 

recorders in numbers less than this wduld 

not be economical; however, significant savings can be achieved with 500 or more recorders in service.

The use of digital recorders during the 

high-cost period before significant numbers 

are in service can be justified by placing 

them at sites that are more difficult than 

average to handle by manual methods, such 

as streams that are subject to power regulation or frequent flood peaks and that require 

relatively large expenditures for manual 

analysis. Savings of significant magnitude 

can be obtained by the use of digital recorders 

on such streams even though the unit cost of 

mechanical computation is high.

It should be emphasized that figures for 

this comparison are based upon the configuration of equipment now available and on a system involving 96 gage readings each day. 

Additional savings can be achieved immediately by recording only 48 or 24 readings a 

day for those stations for which this is sufficient refinement. At some future time savings may be possible by use of improved 

translation equipment. Other savings will accrue through the use of discharge tabulations 

produced by the computer as photocopy for 

reproduction of annual basic-data reports and 

for reproduction in the Water-Supply Paper 

Series.

EFFECT OF AUTOMATION ON PERSONNEL

Present staffing practice centers around 

use of one crew for performance of both field 

and office phases of the data collection program. This practice provides a cadre of 

trained personnel for use during flood periods 

and permits considerable flexibility in the 

number of men assigned to field duty. As the 

shift of computations from manual to machine

methods will eliminate over 50 percent of the 

office computations, a reduction in personnel 

will be required to finance automation costs 

if monetary savings are to be realized. This 

reduction in personnel may be realized within a district either by an actual reduction in 

force or by a seasonal shift or personnel 

from the basic data collection program to 

some oth«r type of assignment. The increasing diversification of the Water Resources 

program in the Geological Survey may fit in 

well with this change in computation method.

Magnitude of the personnel shifts involved 

canbe estimated from the cost studies. Table 

4 shows the time spent in man-hours per 

station-year of record for each of the data 

collection steps. Figures shown are overall 

averages without segregation by grade. Arithmetic manipulation of these man-hour figures 

along the same pattern as was applied to the 

dollar cost figures shows a reduction of 45 

hours in the time spent on the computation 

steps listed. Manual computation requires 83 

man-hours per station-year; with automation, 

only 38man-hours will be required. Conversion of these figures into terms of operating 

load per man gives a more graphic picture of 

the significance of the shift. There are approximately 1800 man-hours in a man-year. 

(260 days less 33 for leave and holidays equals 

226 days or 1808 man-hours.) On the basis 

of 160 man-hours now required per stationyear for both field and office work, the present 

work load is at a rate of 1800/160 or 11.3 

gaging stations per man. If personnel is reduced in direct ratio to figures shown, the 

work load after automation would be 1800/115 

or 15.7 gaging stations per man. If the amount 

of fieldwork is held constant, this would imply 

almost a 40 percent increase in the field 

duties of each man. At the present time the 

average ratio of field to office hours for each 

man is 48:52. The projected ratio would be 

67:33.

A comparison may also be made between 

the normal separation rate within the Survey's 

Surface Water Branch and the displacement 

rate that will result. Installation of digital 

recorders at the rate of 1,000 per year would 

cause a displacement of about 25 people each 

year as compared with a total of 161 personnel separated from the Branch during 1961.

Although these figures are only approximate, they do indicate the degree of readjustment involved. As the conversion will be
14 AUTOMATION OF STREAMFLOW RECORDS

Table 4. Summary of man-hours required for manual computation 

[Figures shown are man-hours per station-year of record]

District

A_____ 

B_____ 

C_____ 

D_____ 

E_.___

F__-__ 

G--___

H_____ 

I _____

J _____

Average 

of 8 

central 

values

Recorder 

chart 

analysis

30 

30 

39 

28 

23

25 

18

16 

19

6

24

Rating 

analysis

57 

23 

38 

26 

16

24 

20

22 

31

9

25

Discharge 

application

34 

22 

16 

27 

21

17 

19

15 

16

8

19

Special 

computations

10 

3 

5 

16 

7

3 

5

6 

6

2

6

Preparation of 

daily 

table

4 

4 

3 

5 

4

3 

3

3 

2

1

3

Manuscript 

preparation

8 

19 

10 

8 

6

4 

7

6 

3

3

6

Total cost 

of office 

computation

143 

101 

111 

110 

77

76 

72

68

77

29

83

Field 

operations

88 

88 

92 

63 

86

88 

69

80 

55

77

Total of 

office 

and field 

costs

231 

189 

203 

173 

163

164 

141

148 

132

160

gradual, no reduction-in-force actions or 

large scale dislocations are anticipated. 

However, the present balance of field and 

office work will be significantly changed and 

the type of personnel hired may gradually 

change. In many districts expansion of diversified activities, which have been held up 

for lack of qualified personnel, will be made 

possible by the relief from a significant part 

of the computation load.

EFFECT OF AUTOMATION ON REPORTS

TIMING OF ANNUAL REPORTS

One of the objectives of this automation 

program is to reduce the delay in publishing 

annual reports of daily discharge. Egonomic 

considerations dictate that the capacity of the 

Automatic Data Processing Unit be geared to 

the total volume of records processed each 

year so that working at a uniform rate it 

could process 1 year's output from all the 

digital recorders within 1 year. Therefore, 

if records are submitted currently the Unit 

can operate on a current basis, but if records 

are held back and submitted annually there 

will be a year's delay in production. The 

computation system permits efficient processing of relatively short periods of record, 

the optimum period being about 3 months. 

Submission of records on a quarterly basis 

would permit records for the water year

ending September 30 to be computed by about 

January 1.

TIMING OF CURRENT REPORTS

Success of the automation program will 

depend largely on how well the program 

meets the need for currently computed records. For some gaging stations records of 

discharge are needed soon after the end of 

each month, while for other stations an unexpected need may arise for several months 

of discharge records to be made available in 

a few days. The computation system is well 

adapted to the former condition. The limiting 

factor is the capacity of translation equipment, which now has a peak capacity of 7-| 

station-years (90 station-months) per day. 

Although this rate cannot be maintained for 

any extended period, several hundred monthly 

records can be handled in a few days. Development of methods for handling emergency 

requests for quick computation of a large 

amount of record requires additional study. 

It may be desirable to place a premium on 

such requests that would permit financing 

overtime operation of the translating equipment so as to minimize delays and avoid disruption of the normal flow of data. If the volume of such requests becomes significant, a 

subunit should be set up to handle them. In 

any event a system should be devised within 

the framework of the automation scheme to
SUPPORTING STUDIES 15

permit rapid computation when needed. 

Elapsed time between the receipt of the 16- 

channel tapes and the mailing of primary 

computations sheets can be reduced to less 

than 48 hours under optimum conditions.

PUBLICATIONS TECHNIQUES

The automation system is well suited to the 

monthly distribution of current reports where 

required and to the preparation of the annual 

basic-data reports at District level. Current 

records distribution can be made by means 

of ozalidor xerox copy of provisional figures 

on the daily discharge table (form 9-211M). 

The final discharge figures, produced on this 

same form, can be assembled with the station 

description and used as photo-off set copy for 

the annual basic-data reports.

Further study of printing techniques is required to adapt the output of the automation 

system to the publication of the daily discharge in Water-Supply Papers. Present editorial standard and the diversity of copy 

material, some produced manually and some 

produced by machine, make automation of 

publication phases of the 5-year Water-Supply 

Paper series a more complicated process. 

One feasible system would be the production 

of all daily discharge or daily gage height 

tables on form 9-211M by the computer, using 

the records from automatic computations 

directly and hand-punched entry of manual 

computed data. These tables could then be 

assembled with the manually typed station 

descriptions for photo-off set copy.

SUPPORTING STUDIES

SIGNIFICANCE OF RECORDING FREQUENCY

Computations based on a series of discrete 

observations taken at uniform time intervals 

are subject to errors that depend upon the 

complexity of the hydrograph and on the time 

interval used. If the recording interval is 

reduced sufficiently, these errors can be 

.eliminated, but because computation costs 

are directly related to the number of gage 

readings used, a moderate amount of error 

must be permitted. Errors in the mean discharge and errors in instantaneous discharge 

must both be considered.

Recording error's are of two basic types 

random errors due to surge, and definition 

errors caused by undefined stage changes

between gage readings. Errors due to surge 

may have a significant effect on instantaneous 

values, but because they are random in character they will not seriously affect daily 

means. Decrease in time interval will not 

reduce surge errors in recorded maxima, 

and acceptance of small errors from this 

source will be necessary where surge cannot be eliminated.

In contrast to problems with surge, which 

are minor in most instances, the size of the 

definition errors is directly related to the 

recording interval and to the rate at which 

stage can change. A decision on the recording interval will have to be made for each 

station on the basis of an allowable error in 

daily means. It should be pointed out that the 

maximum stage, between visits, can be recorded independently of the digital recorder 

by crest-stage gages or by very simple devices clipped to the float tape. Therefore, 

the allowable error in definition of the maximum stage for major peaks need not be the 

controlling criterion for selecting the recording interval.

Geographical location, drainage area, and 

proximity to sources of regulation are the 

most significant factors in selecting a recording interval. To give some measure of 

the significance of these various factors, a 

comparative study of the results of computations based on 96, 48, and 24 readings per 

day has been made on the computer. The 59 

stations selected for study covered a range 

in drainage area in each of five districts; 

Boston, Massachusetts; College Park, Maryland; Tuscaloosa, Alabama; Topeka, Kansas; 

Menlo Park, California. Discharges were 

first computed by using 96 gage readings per 

day and were then independently computed 

using 24 and 48 readings per day. Daily discharges were compared using discharge 

values from the 96 per day computation as a 

base, and the standard deviations of the departures, expressed in percent of the base, 

were computed. Standard deviations for stations along the Atlantic seaboard and those 

for stations in Kansas have been plotted 

against drainage area in figures 3 and 4. The 

significance of drainage area and regional or 

climatic factors is very evident in these two 

graphs. For stations along the Atlantic seaboard the standard deviation of departures 

for computations based on hourly (24 per day) 

gage readings is less than 1 percent for 

drainage areas greater than 100 square
16

AUTOMATION OF STREAMFLOW RECORDS

 1*8 readings per day vs. 96 

readings per day

. 2k readings per day vs. 96 

readings per day

o o o o o

CVJ -* O O O 

H <M .*

Drainage Area, in Square Miles 

Figure 3. Comparison of computations based on 96, 48, and 24 readings per day for stations along the Atlantic seaboard.

miles. Computations based on 48 readings 

per day retain this same accuracy for drainage areas as small as 40 square miles. For 

drainages smaller than 40 square miles 96 

readings per day are required. In contrast, 

the same accuracies in Kansas require gage 

readings at 15 minute intervals (96 per day) 

for drainage areas of less than 300 square 

miles, and a recording frequency of at least 

48 readings per day for all drainage areas 

below 5,000 square miles. Hourly gage readings in this area can safely be used only on 

streams with very large drainage areas.

Although decision as to the timing interval 

required at a given site will depend on the 

stage characteristics of the stream, a rough 

approximation of the number of recorders 

that will eventually be operated at various 

recording intervals can be computed from an 

average curve relating drainage area and required recording frequency. Using a 1 percent standard deviation as a. criterion, average curves based on data from all 59 stations 

used in the analysis, suggest that definition 

of hydrographs at gaging stations on drainage areas of less than 200 square miles will 

require 96 readings per day; that records 

from drainage areas ranging from 200 to

2,000 square miles can be computed from 48 

readings per day, and that records from 

drainages larger than 2,000 square miles can 

be defined by 24 readings per day. Of the 

gaging stations in the national network, 50 

percent are on streams of 200 square miles 

or less drainage area, 35 percent are on 

streams ranging from 200 to 2,000 square 

miles in drainage area, and 15 percent are 

on streams whose drainage areas are over 

2,000 miles. Projecting these figures to the 

ultimate system involving 5,000 digital recorders would indicate that 2,500 will record 

at 15-minute intervals, 1,750 will record -at 

30-minute intervals, and 750 will record at 

60-minute intervals.

Operation of recorders in this general 

pattern will reduce the translation load by 

about 30 percent below the load if all stations 

used 15-minute intervals, and this will result in lower processing costs.

COMPARISON OF AUTOMATED AND MANUAL COMPUTATION ACCURACY

Consideration of the relative accuracy of 

automated and manual procedures involves 

assessment of the relative accuracy of both 

the base data involved and the actual compu-
SUPPORTING STUDIES 17

tation steps employed. Base data and analytical work in connection with the rating are 

identical in either case; thus the comparison 

reduces to the relative accuracy of the gage 

height records and of the methods employed 

in converting these records into equivalent 

discharge figures.

Digital representation of data is inherently 

more precise than graphic representation; 

hence gage height records, recorded in digital 

form, are free from many small errors that 

are involved in strip-chart recordings. Once 

a digital recorder is properly set,the relation between float position and the information recorded on the paper tape is uniquely 

fixed. There are no corrections needed for 

paper skew, paper expansion, side play in pen 

carriages, or reversal point errors, and time 

corrections are minimal because the timer 

is not linked mechanically with a paper-drive 

mechanism. Reduction of data is much more 

accurate because translating equipment is 

much less apt to err than personnel who read 

and record chart values. The only errors that 

can occur are those due to recorder or translator malfunction (errors generally large 

enough to be readily apparent) and those due 

to recording interval (previously discussed). 

Assuming a properly selected recording interval, the definition of the stage record in 

digital form should thus be superior to that 

which can be obtained from a strip chart.

Manually computed daily mean discharges 

are normally obtained by application of 

graphically determined mean gage heights to 

the rating tables except on days when the 

fluctuation in stage is large enough to introduce an error of a predetermined amount in 

the resulting discharge. This manual system 

thus permits an error, always negative, in all 

days when significant changes in discharge 

occur. The maximum error allowed ranged 

from 2 to 4 percent depending upon standards 

determined in each district. By way of contrast a daily mean discharge computed from 

a digital record is based upon individual application of each of the gage readings to the 

rating. Each day is computed in identical 

fashion so that subdivision errors are almost 

nonexistent regardless of the variability of

 kQ readings per day vs. 96 

readings per day.

, 2k readings per day vs. 96 

readings per day.

8

O Q Q Q Q 5

O O O Q Q Q

H CVJ -* \0 O O O

Drainage Area, in Square Miles 

Figure 4. Comparison of computations based on 96, 48, and 24 readings per day for stations in Kansas.
18 AUTOMATION OF STREAMELOW RECORDS

the stage. Computations of monthly summary 

figures by the automation system are also 

free from human error. Manual computations 

do permit greater flexibility in application of 

ratings by the use of variable shift corrections within a day, but provision in the automation system for a rating change at any time 

within the day allows enough freedom to meet 

all but very extreme conditions.

In summary, digital-recorder records are 

inherently more accurate except in certain 

very special circumstances, because the computational system is mathematically more 

precise and human error is eliminated from 

the routine; thus, a small but significant quality improvement in the average record is 

possible by a shift to automated procedures.

U. S. GOVERNMENT PRINTING OFFICE : 1963 O - 688066