U.S. Department of the Interior 

U.S. Geological Survey 

—Seth E. Studley 

NOT TO SCALE 

Recorder 

Gage-height (pressure) 

sensor 

Gas 

cylinder 

Manometer 

assembly 

Concrete 

footing 

Concrete pier 

Orifice Plastic tube 

Battery 

Comparison of the occurrence and causes of 

missing gage-height record in Kansas from 

1987 to 1999 with data from previous 

evaluations will help determine whether the 

occurrence of missing gage-height record in 

Kansas has changed with the use of 

advanced technology equipment such as 

electronic data recorders and pressure 

transducers. 

Collection of Streamflow and 

Lake-Level Data in Kansas 

� The USGS currently (2001) collects 

gage-height data at approximately 

160 continuous-record gaging stations in 

Kansas. 

stations generally have been equipped with 

bubbler systems for the collection of gageheight record (fig. 1). 

an orifice is attached securely below the 

water surface and connected to a pressuresensing device by a length of plastic tubing. 

Pressurized gas (usually nitrogen or air) is 

gage-height record an average of about 

15 days per year (about 4 percent of the 

time) per station during the 11-year study 

period (Livingston, 1983). 

digital recorders were the primary cause of 

missing gage-height record during this 

period, closely followed by silting and 

freezing of the orifice lines and well intakes. 

� Another evaluation of missing gageheight record (Wahl and Shields, 1989) 

analyzed data for USGS offices in Colorado, 

Iowa, Kansas, Missouri, Montana, Nebraska, 

New Mexico, North Dakota, Oklahoma, 

South Dakota, Texas, Utah, and Wyoming 

for 1982–86. This evaluation showed a 

substantial reduction from 1982 to 1983 in 

the amount of missing gage-height record 

caused by malfunctions of the digital 

recorder timers resulting from the 

replacement of the faulty timers with new 

solid-state timers beginning in 1982. The 

total amount of missing gage-height record, 

however, remained about the same as that of 

the 1971–81 evaluation (about 4 percent) due 

to increases in other problem categories. 

�An e valuation of the occurrence and 

causes of missing gage-height record from 

stream- and lake-gaging stations in Kansas 

from 1987 through 1999 shows that there has 

been a 40-percent reduction in the amount of 

missing gage-height record during the past 

13 years. ge-height and 

streamflow data are important to Kansas and 

the Nation for planning and decisions related 

to agriculture, industry, urban water 

supplies, navigation, riverine and riparian 

habitat, and flood-hazard identification. 

Long-term records from gaging stations are 

a cornerstone for national, regional, and 

local efforts to understand the Nation's water 

resources. Any gaps in those long-term 

records of streamflow and lake levels can 

mean a gap in the essential understanding 

and management of water resources. 

Reducing the amount of missing gage-height 

records, which are used to monitor and 

manage water resources in Kansas, is a 

major concern for the U.S. Geological 

Survey (USGS). 

Introduction 

�Collection of flow data for streams and 

water-level data for lakes is a principal 

component of the USGS mission in 

providing reliable, impartial, and timely 

information needed to understand the 

Nation's water resources. 

height data are used to compute daily 

streamflow and lake content, any missing 

gage-height data affects the quality of the 

computed record. As part of ongoing efforts 

to continually improve the quality and 

timeliness of streamflow and lake waterlevel data, the USGS evaluated the 

occurrence and causes of missing gageheight record in Kansas for 1987–99. This 

summary of the results of that evaluation was 

done in collaboration with the USGS Office 

of Surface Water in Reston, Virginia. 

� A previous evaluation of the occurrence 

and causes of missing gage-height record in 

Kansas for 1971–81 indicated that the 

stream- and lake-gaging stations had missing 

Evaluation of Missing Gage-Height Record for 

Streams and Lakes in Kansas 

Figure 1. Typical bubble-gage installation, circa 1980. 

USGS Fact Sheet 009–01 

March 2001 

Since the mid-1960's, gaging 

In a bubbler system, 

Faulty timers on 

Real-time ga

Because gage-
GOES 

satellite 

Earth 

receiver 

station 

Gaging 

station 

equipped 

with datacollection 

platform 

(DCP) 

U.S. Geological 

Survey office 

Other USGS 

offices 

Internet 

Cooperators and 

water-data users 

World 

Wide 

Web 

0 

100 

10 

20 

Water year 

30 

40 1981 

1982 1983 1984 1985 1986 1987 1988 1989 1990 

1991 

1992 1993 1994 1995 1996 1997 1998 1999 

50 

60 

70 

80 

90 

Percentage of gaging stations equipped 

DCP’s 

Transducers 

than for manometers, and the transducers are more reliable, 

resulting in fewer days of missing data. 

� A few gaging stations currently (2001) are equipped with a 

new, compact, air compressor-bubbler system that replaces the 

compressed-gas cylinder and conoflow (a mechanical device that 

regulates the orifice-line pressure and bubble rate). This new 

device also has the advantage of a programmable orifice-line 

purge that can periodically clear the orifice at gaging stations that 

have a persistent problem with the blocking of an orifice with silt 

or organic growth. The purging of the orifice line at these stations 

can greatly improve the accuracy of the gage-height data. 

� The advances in gaging-station equipment technology have 

helped to decrease the occurrence of missing gage-height record 

by reducing the amount of equipment that can malfunction and by 

allowing a quicker response time in repairing or replacing 

equipment. 

tasks to perform during visits to the station, and the maintenance 

of the equipment is less time consuming. Technicians no longer 

need to retrieve and process digital punch tapes and graphic strip 

charts. , all of the gage-height record is sent directly to USGS 

offices by satellite or downloaded onsite to a laptop computer, thus 

reducing the opportunity for mechanical malfunctions or human 

error that can lead to missing gage-height record. 

Evaluation of Missing Gage-Height Record, 

1987–99 

�Station analyses written by the USGS at the end of the water 

year for each gaging station include information for determining 

the occurrence and causes of missing gage-height record for each 

year of operation. Any day having less than 12 hours of gageheight data that cannot be reasonably recovered was considered a 

day of missing gage-height record. The causes of missing gageheight record were divided into six problem categories: 

� Orifice—included problems associated with the orifice line or 

well-intake systems, including silted or frozen orifice lines and 

intakes. 

� Gage-Height Sensor—included manometer problems and 

pressure transducer problems excluding battery problems. 

leaks were included in this category. 

� Power—included problems due to a weak or dead battery or 

power outage. 

forced through the tubing and out the orifice. 

pressure in the tubing is a function of the depth of water above the 

orifice, a change in the water level of a stream or lake produces a 

corresponding change in the pressure in the tubing. 

sensors, such as mechanical manometers or electronic pressure 

transducers, convert the pressure in the tubing into height of water 

above a set datum level referred to as gage height. 

recorders, digital punch-tape recorders, or electronic data loggers 

record the gage height either continuously or at preset time 

intervals, usually 15 minutes. -recharged batteries power the 

electrical equipment. 

cause missing gage-height record. 

�Gaging-station operation changed significantly in 1982 with 

the introduction of data-collection platforms (DCP's). The DCP 

collects gage-height data and transmits it to the Geostationary 

Operational Environmental Satellite (GOES) that relays the data to 

a ground station and then to USGS offices for dissemination 

(fig. 2). The data enters the computer system within a few seconds 

after satellite transmission. This information then is made 

available to the public on the USGS "Current Gage-Height and 

Streamflow Conditions" Internet site at URL: 

http://ks.water.usgs.gov 

�Station descriptions, updated each year for each gaging station, 

include installation dates for new equipment. 

half of the gaging stations in Kansas were equipped with DCP's 

and by 1997, all of the gaging stations had DCP's (fig. 3). The 

new technology permits USGS offices to monitor the operation of 

the gaging stations continuously and allows them to time visits to 

gaging stations to coincide with those times when the need for data 

is greatest, such as during floods and to repair or service 

equipment at the gaging stations. 

� The introduction of the electronic pressure transducer also has 

reduced the gaps in gage-height data. 

pressure transducer replaced the mechanical manometer as the 

primary gage-height sensor (figs. 3 and 4). 

maintenance of the electronic pressure transducer takes less time 

Figure 3. Cumulative percentage of data-collection platforms (DCP's) 

and electronic pressure transducers installed in U.S. Geological 

Survey gaging stations in Kansas, 1981–99. ater year is the 

12-month period beginning October 1 and ending September 30. 

water year is designated by the calendar year in which it ends. 

example, the period beginning October 1, 1998, and ending 

September 30, 1999, is called the 1999 water year.) 

Figure 2. Transmission of gage-height or lake-level data from the gaging 

station to the data users. 

In addition, hydrologic technicians have fewer routine 

Now

Gas 

Because the 

Pressure 

Graphic 

Solar

Failure of any one of these components can 

In 1987, nearly oneBeginning in 1993, the 

Installation and 

W

(The 

For 
B. 

Data-collection 

platform (DCP) 

antenna 

Battery 

Data-collection 

platform (DCP) 

Pressure 

transducer 

Air compressor

bubbler system 

Rain gage 

A. 

Recorder 

Gas 

cylinder 

Manometer 

assembly 

Battery 

30 

0 

2 

4 

6 

8 

10 

12 

14 

16 

18 

20 

22 

24 

26 

28 

Number of days of missing gage-height records per year per station 

1971 to 1986 average number

of days of missing record per

year is about 15 days per station 

9.8 

8.6 

10.4 

17.9 

6.5 

12.4 

17.3 

23.8 

26.1 

15.5 

10.8 

14.1 

14.8 

19.5 

16.1 

13.3 

12.8 

7.7 

8.4 

7.7 

11.0 

4.7 

8.8 

9.9 

8.4 

13.9 

12.4 

5.1 

5.8 

1987 to 1999 average number

of days of missing record per

year is about 9 days per station 

Water year 

1971 

1980 1990 1999 

� Recorder—included graphic, digital, 

electronic data recorder, and timer problems. 

DCP problems also were included in this 

category. 

� Vandalism and Animal Damage— 

included human destruction and animal 

damage. 

� Oversight—included technician errors 

such as leaving a graphic recorder pen off 

the chart, leaving a timer unplugged, leaving 

intake or gas valves closed, permitting a strip 

chart or digital tape to run out, or incorrectly 

programming electronic equipment. 

� These categories are slightly different 

from those used by Wahl and Shields 

(Sensor, Manometer, Timer, Power, 

Recorder, Vandalism, Oversight, and Other) 

in their 1989 report. –99 

evaluation, 

sensor category of Wahl and Shields (1989), 

the gage-height sensor category replaced the 

manometer category, and the timer category 

was included in the recorder category. The 

vandalism and animal damage category 

included the "Other" category of Wahl and 

Shields (1989) because most of the other 

reasons for missing gage-height record for 

1987–99 involved either human vandalism 

or animal damage of gaging equipment. 

� A comparison of the average number of 

days of missing gage height record for 

1971–86 with the average number of days of 

missing record for 1987–99 shows an overall 

decrease of 40 percent. An average of about 

15 days (about 4.1 percent) per year per 

station for 1971–86 was reduced to an 

average of about 9 days (about 2.5 percent) 

per year per station for 1987–99 (fig. 5). 

The average yearly number of days of 

missing gage-height record ranged from 

6.5 to 26.1 days per station for 1971–81 and 

from 4.7 to 13.9 days per station for 

1987–99. 

� The orifice system used by the USGS 

has not changed significantly since the 

1960's, and orifice problems continue to be 

the major cause (46 percent) of missing 

gage-height record for 1987–99 (fig. 6). 

1999 alone, orifice problems were the cause 

of nearly 80 percent of the missing gageheight data in Kansas (fig. 7). The gageheight sensor caused 29 percent of the 

missing gage-height record for 1987–99 but 

was responsible for only 4 percent of the 

missing gage-height record in 1999 (fig. 8), 

mainly due to the replacement of 

manometers with electronic pressure 

transducers. 

� An increase in the number of DCP's 

located at gaging stations across the State 

from 1982 to 1999 most likely was 

responsible for most of the 40-percent 

decrease in missing gage-height record from 

1987 to 1999. 

decreasing the duration of problems that 

caused missing gage-height record. 

Problems were detected and corrected more 

quickly because of immediate access to realtime data from the gaging stations. 

� There was an increasing trend in missing 

gage-height record caused by the gage-height 

sensor from 1991 to 1994 (fig. 8). The 

manometer had been the preferred gageheight sensing instrument used by the USGS 

in Kansas since its introduction to streamgaging stations in the early 1960's. 

these units still had their original parts, and 

by the early to mid-1990's, they began 

failing. The replacement of manometers 

with electronic pressure transducers, 

beginning in 1993, greatly reduced the 

number of days of missing gage-height 

record due to problems with the gage-height 

sensor. 

� The pressure transducer requires less 

maintenance than the manometer, eventually 

resulting in a reduced risk of missing gageheight record due to human oversight. 

A relatively high percentage of missing 

gage-height record due to oversight during � 

Figure 4. Typical stream-gage house installations in Kansas in (A) mid-1980's and in (B) 1999. 

Figure 5. Average number of days of missing gage-height record per station in Kansas, 1971–99. 

In the 1987

the orifice category replaced the 

In 

DCP's played a major role in 

Many of 
Orifice 

(46 percent) 

Gage-height 

sensor 

(29 percent) 

Power 

(4 percent) 

Recorder 

(9 percent) 

Vandalism 

and animal 

damage 

(6 percent) 

Oversight 

(6 percent) 

1987–99 

Orifice 

(79 percent) 

Gage-height sensor 

(4 percent) 

Power 

(8 percent) 

Recorder 

(7 percent) 

Oversight 

(0 percent) 

1999 

Vandalism 

and animal 

damage 

(6 percent) 

1987 

1988 

1989 

1990 

1991 

1992 

1993 

1994 

1995 

1996 

1997 

1998 

1999 

Water year 

0 

50 

5 

10 

15 

20 

25 

30 

35 

40 

45 

Percentage of missing gage-height record 

Average 

percentage 

for 1987–99 

Transducer 

Manometer 

0 

2 

4 

6 

8 

10 

12 

14 

16 

18 

0 

1987 

1988 

2.1 

5.4 

5.3 

3.2 

1.7 

8.4 

5.0 

5.8 

4.7 

10.1 

16 

12.8 

1989 

1990 

1991 

1992 1993 

1994 

1995 

1996 

1997 

1998 1999 

Water year 

Percentage of missing gage-height record 

the effectiveness of improved equipment 

technology. An annual evaluation of the data 

can indicate the need for operational 

changes, additional training, and research 

and development of advanced sensing and 

recording equipment for the continued 

reduction of missing gage-height record. 

The USGS will continue to evaluate its 

record of providing high-quality, impartial 

environmental data and to seek 

improvements in data-collection techniques 

and equipment for the Nation's benefit. 

References 

Livingston, R.K., 1983, Lost gage-height � 

�record in Kansas —its cause and 

�occurrence: U.S. Geological Survey 

� WRD Bulletin, May–December 1983, 

�p. 52 –56. 

� 

1996–98 (fig. 9) coincides with the period of 

the installation of electronic pressure 

transducers. , a part of the higher 

percentage of missing gage-height record 

caused by gage-height sensor problems 

during 1997–98 (fig. 9) can be attributed to 

technicians learning the operation of the 

electronic pressure transducers. 

1999, the amount of missing gage-height 

data due to oversight was reduced to 

0 percent. 

� The orifice continues to be the largest 

contributor to missing gage-height record. 

The occurrence of missing gage-height 

record could be reduced considerably with 

the development of a viable replacement for 

the bubbler system. 

development of radar, laser, and acousticdoppler devices that can sense gage height or 

measure discharge directly without direct 

contact with the water show some promise. 

� 

Conclusions 

�Continuing evaluation shows the 

importance of tracking the occurrence and 

causes of missing gage-height record to help 

minimize the loss of valuable information 

from USGS gaging stations and to evaluate 

Wahl, K.L., and Shields, R.R., 1989, Net 

�gage-height record loss in the Central 

�Region, WRD: U.S. Geological Survey 

�Hydrologic Instrumentation Facility , 

�Instrument News, December 1989, p. 12. 

Figure 6. Average percentage of missing 

gage-height record in Kansas by problem 

category, 1987–99. 

Figure 8. Percentage of missing gage-height record in Kansas due to 

problems with the gage-height sensor, 1987–99. 

Figure 9. Percentage of missing gage-height record in Kansas due to 

oversight by technicians, 1987–99. 

Figure 7. Average percentage of missing 

gage-height record in Kansas by problem 

category, 1999 water year. 

For more information contact: 

District Chief 

U.S. Geological Survey 

4821 Quail Crest Place 

Lawrence, Kansas 66049–3839 

(785) 842–9909 

email: waucott@usgs.gov 

http://ks.water.usgs.gov 

However

By 

Currently (2001), the