SWRC Sensor to Database Documentation

 

SWRC Precipitation Data

 

Overview

An extensive precipitation database at the 149 km2 Walnut Gulch Experimental Watershed (WGEW) has been developed over the past 64 years with the first records starting in August 1953 and continuing to the present. Currently, 97 rain gauges are operational on WGEW. This constitutes one of the densest rain gauge networks in the world (0.6 gauges/km2) for watersheds greater than 10 km2. Additionally, 9 rain gauges on the Santa Rita Experimental Range (SRER) and 26 gauges in the Upper San Pedro River Basin (USP) are operated by the SWRC.

Through 1999, the network consisted of analog recording weighing rain gauges. In 2000, a newly designed digital gauge with telemetry was placed approximately 1 meter from the analog gauges. Both the analog and digital networks of gauges were in operation from 2000 to 2004 to enable a 5 year comparative analysis of the two systems. The analog data were digitized from paper charts and were stored in breakpoint format. The digital data consist of rainfall depths at 1-min intervals during periods of rainfall. These data are provided in a variety formats via a web interface at http://www.tucson.ars.ag.gov/dap/. Modified from Goodrich et al., 2008

Measured Variables

Brakensiek et al., 1979

Goodrich et al., 2008

Precipitation Depth [mm, in]

Precipitation Intensity [ mm/hr, in/hr]

Network Extent/Timeline

Brakensiek et al., 1979

Chery et al., 1971

Goodrich et al., 2008

Keefer et al., 2008

Smith et al., 2017

Belfort Weighing Rain Gauge Manual

VPG Load Cell Documentation

Through 1999, the network consisted of analog recording weighing rain gauges. In 2000, the digital gauges were placed adjacent (~1 m separation distance) to the analog gauges. Both the analog and digital network of gauges were in operation from 2000 to 2004 to enable a comparative analysis of the two systems. In regards to precipitation observations, they concluded that 1) two individual digital rain gauges recorded precipitation equivalently; 2) high errors in event intensities may be produced when analog charts are digitized at short time intervals; 3) for several different measures of precipitation, the analog and digital data were equivalent. [ Keefer et al. , 2008]

 

For the analog network record, different numbers of rain gauges were in operation during different periods of time. The most notable cases were from January 1980 to June 1991 and from October 1998 to October 2004 when the analog operational network was scaled back to nine gauges (4, 13, 42, 44, 46, 60, 68, 80, and 81) during the non-monsoon months because of financial considerations. Analysis by Osborn et al. [1979b] indicated that this number of gauges was more than adequate to characterize the variability of the winter frontal rainfall. The exact turn-on and turn-off dates for each of the gauges is part of the database and they are returned with any data query via the web database interface. Modified from Goodrich et al., 2008

 

Table 1: SWRC rain gauge locations and years of operation. Coordinates are not survey grade and are based on digital gauge locations


Site/
Gauge

WGEW

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

32

33

34

35

36

37

38

39

40

41

42

43

44

45

46

47

48

49

50

51

52

53

54

55

56

57

58

59

60

61

62

63

64

65

66

67

68

69

70

71

72

73

74

75

76

77

78

79

80

81

82

83

87

88

89

90

91

92

93

94

96

100

101

102

103

104

105

106

107

108

109

180

301?

302

307?

322

341

361

381

384

385

386

392

395

397

398

399

504

510

512

537

546

550

560

568

581

583

587

593

USP

400

401

402

403

404

405

406

407

408

409

410

411

412

413

414

415

416

417

418

419

420

421

422

423

424

425

426

427*

SRER

1

2

3

4

5

6

7

8

9

501

504

507



Easting

 

580177

581187

581204

582932

582649

583583

584459

583788

584592

584265

585909

585356

586110

585442

587458

586839

588021

586710

587845

587480

589091

588341

589101

588636

589809

588736

590419

590624

591791

591511

592402

592441

591778

590946

591655

591306

593303

594711

593470

593360

593275

592673

595343

594952

594726

595289

594270

595587

594481

596864

595610

596490

596008

598218

599918

598334

596089

597422

598307

599659

599409

600544

599477

601283

601253

602039

602523

603070

603916

604288

591791

598354

594684

590549

586662

582624

593404

595153

586527

590761

589310

600154

589697

593369

597437

596308

596547

599114

581888

*

*

*

593266

589526

589517

589814

589728

599652

599793

600177

599803

600029

*

589812

*

589530

*

*

*

*

589650

593660

589546

*

*

*

591370

589732

*

*

*

*

*

*

*

*

*

*

*

*

 

582124

568321

568412

568806

568636

571258

573485

601853

569578

589990

605797

588104

598812

599874

561278

556530

560085

584702

575868

568576

567959

548540

544831

547920

558346

570183

567342

568243

 

513036

512945

508238

509065

514046

513778

513158

513969

514176

*

*

*

UTM NAD83

Northing

 

3510850

3512053

3509768

3512517

3510770

3509840

3512808

3511375

3509391

3508354

3512635

3511396

3510185

3507187

3513185

3511669

3510226

3508098

3506713

3504939

3513386

3511789

3511164

3508844

3506879

3505522

3511838

3509990

3508586

3505993

3513702

3511695

3510511

3507458

3506921

3504994

3506068

3513538

3511293

3510286

3508064

3504936

3514431

3511627

3510299

3508655

3507025

3505653

3505240

3514919

3513095

3511950

3509523

3513974

3513612

3512322

3510781

3509510

3508443

3512461

3511574

3511056

3509758

3514443

3512633

3511414

3514774

3513183

3515463

3514207

3512561

3511165

3514557

3513984

3513744

3509679

3503420

595153

3509127

3511243

3508200

3511680

3512426

3512745

3513364

3513931

3513084

3513048

3511774

*

*

*

3504720

3512229

3512468

3512391

3512146

3511763

3511869

3511839

3511693

3511767

*

3512445

*

3512226

*

*

*

*

3512287

3511374

3512410

*

*

*

3511054

3510331

*

*

*

*

*

*

*

*

*

*

*

*

 

3518828

3486006

3485884

3485822

3485822

3506843

3468309

3473471

3532305

3529727

3515697

3496282

3483402

3524258

3522768

3489184

3484923

3473697

3494594

3467898

3485736

3495059

3494627

3496185

3485444

3491463

3487870

3485302

 

3524541

3524350

3524192

3523927

3519959

3519800

3524352

3520124

3520077

*

*

*



Elevation

 

1222

1254

1246

1278

1269

1314

1298

1286

1339

1376

1316

1285

1334

1390

1328

1330

1357

1365

1447

1525

1356

1343

1334

1387

1431

1486

1361

1369

1373

1447

1413

1383

1387

1420

1409

1459

1404

1452

1420

1390

1407

1423

1466

1443

1428

1445

1416

1442

1437

1487

1460

1480

1422

1523

1551

1490

1456

1423

1469

1514

1502

1504

1470

1573

1550

1527

1610

1578

1638

1630

1388

1475

1448

1382

1298

1311

*

1453

1334

1372

1406

1512

1368

1418

1501

1491

1463

1530

1244

*

*

*

1418

1365

1369

1369

1361

1523

1513

1519

1508

1515

*

1365

*

1366

*

*

*

*

1359

1417

1365

*

*

*

1379

1350

*

*

*

*

*

*

*

*

*

*

*

*

 

1258

1448

1447

1431

1437

1198

1512

1494

1097

1476

1854

1299

2171

2144

1466

2110

2299

1284

1286

2017

1409

1452

1492

1453

1409

1367

1433

1439

 

1046

1049

970

897

1163

1215

1018

1157

1211

*

*

*

Analog
Operation
Years

 

1954-1999M,D

1954-1999M,D

1954-1999M,D

1954-1999A,D

1954-1999M,D

1962-1969M,D

1954-1999M,D

1954-1999M,D

1954-1999M,D

1954-1999M,D

1954-1999M,D

1954-1999M,D

1954-1999A,D

1954-1999M,D

1956-1999M,D

1954-1999M,D

1965-1999M,D

1954-1999M,D

1954-1999M,D

1954-1999M,D

1955-1999M,D

1953-1999M,D

1954-1999M,D

1954-1999M,D

1960-1999M,D

1954-1999M,D

1954-1999M,D

1956-1999M,D

1954-1999M,D

1955-1999M,D

1955-1999M,D

1962-1999M,D

1955-1999M,D

1963-1999M,D

1959-1999M,D

1953-1999M,D

1966-1999M,D

1960-1999M,D

1955-1999M,D

1962-1999M,D

1955-1999M,D

1955-1999A,D

1955-1999M,D

1955-1999A,D

1955-1999M,D

1962-1999A,D

1955-1999M,D

1955-1999M,D

1960-1999M,D

1960-1999*M,D

1960-1999M,D

1963-1999M,D

1967-1999M,D

1955-1999M,D

1960-1999M,D

1955-1999M,D

1959-1999M,D

1962-1999M,D

1962-1999M,D

1955-1999A,D

1957-1999M,D

1960-1999M,D

1961-1999M,D

1960-1999M,D

1955-1999M,D

1955-1999M,D

1961-1999M,D

1955-1999A,D

1957-1999M,D

1955-1999M,D

1960-1999M,D

1963-1999M,D

1961-1984M,D

1961-1999M,D

1961-1984M,D

1961-1999M,D

1961-1984M,D

1961-1984M,D

1964-1999M,D

1963-1999A,D

1962-1999A,D

1963-1999M,D

1963-1999M,D

1966-1999M,D

1966-1999M,D

1966-1999M,D

1966-1999M,D

1966-1999M,D

1966-1999M,D

1967-1984M,D

1970-1979M,D

1970-1984M,D

1985-1999M,D

-

-

-

-

-

-

-

-

-

1992-?

-

1960-1964M,S

-

1960-1963M,S

1960-1963M,S

1960-1970M,S

1976-1977M,S

1964-1996M,S

1964-1977?M,S

1965-1984?M,S

1976-1979M,S

1971-1977M,S

1975-1996?M,S

1977-1996M,S

1981-1996M,S

1982-1993M,W

1983-1993M,W

1968-1993M,W

1968-1993M,W

1983-1993M,W

1983-1993M,W

1968-1993M,W

1983-1993M,W

1983-1993M,W

1983-1993M,W

1968-1993M,W

1974-1976M,W

 

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

 

1975-1999A,D

1975-1999A,D

1975-1999A,D

1975-1999A,D

1975-1999A,D

1976-1999A,D

-

1976-1999A,D

1976-1977A,D

1975-1990A,W

1977-1990A,W

1976-1990A,W

Digital
Operation
Years

 

2000-2017

2000-2017

2000-2017

2000-2017

2000-2017

-

2000-2017

2000-2017

2000-2017

2000-2017

2000-2017

2000-2017

2000-2017

2000-2017

2000-2017

2000-2017

2000-2017

2000-2017

2000-2017

2000-2017

2000-2017

2000-2017

2000-2017

2000-2017

2000-2017

2000-2017

2000-2017

2000-2017

2000-2017

2000-2017

2000-2017

2000-2017

2000-2017

2000-2017

2000-2017

2000-2017

2000-2017

2000-2017

2000-2017

2000-2017

2000-2017

2000-2017

2000-2017

2000-2017

2000-2017

2000-2017

2000-2017

2000-2017

2000-2017

2000-2017

2000-2017

2000-2017

2000-2017

2000-2017

2000-2017

2000-2017

2000-2017

2000-2017

2000-2017

2000-2017

2000-2017

2000-2017

2000-2017

2000-2017

2000-2017

2000-2017

2000-2017

2000-2017

2000-2017

2000-2017

2000-2017

2000-2017

-

2000-2017

-

2000-2017

-

-

2000-2017

2000-2017

2000-2017

2000-2017

2000-2017

2000-2017

2000-2017

2000-2017

2000-2017

2000-2017

2000-2017

-

-

-

2000-2017

2016-2017

2016-2017

2016-2017

2016-2017

2016-2017

2016-2017

2016-2017

2016-2017

2016-2017

-

-

-

-

-

-

-

-

2000-2017

-

-

-

-

-

2000-2017

2000-2016

-

-

-

-

-

-

-

-

-

-

-

-

 

2002-2017

2005-2017

2005-2017

2005-2016

2005-2017

2006-2017

2006-2017

2006-2017

2006-2017

2006-2017

2006-2017

2006-2017

2006-2017

2006-2017

2006-2017

2007-2017

2007-2008

2007-2017

2007-2017

2007-2017

2007-2017

2004-2017

2004-2017

2001-2017

2007-2017

2007-2017

2007-2017

2011-2017

 

2000-2017

2000-2017

2000-2017

2000-2017

2000-2017

2000-2017

2016-2017

2000-2017

2016-2017

-

-

-

 

AAnalog rain gauges operational year round. See DAP database for exact dates of operation.

MAnalog rain gauges only operational during the monsoon season. See DAP database for exact dates of operation.

DAnalog rain gauges using a daily (24-hour) clock/chart.

SAnalog rain gauges using a 6-hour clock/chart.

WAnalog rain gauges using a weekly clock/chart.

Instrumentation Specifications

Brakensiek et al., 1979

Chery and Osbourne, 1971

Goodrich et al., 2008

Keefer et al., 2008

Smith et al., 2017

Belfort Weighing Rain Gauge Manual

VPG Load Cell Documentation

Analog Gauges (1953-1999)

The analog network consisted of Belfort 0.2032 m (8 inch) unshielded weighing-recording gauges (use of trade names in this report is for information purposes only and does not constitute an endorsement by USDA-ARS). The gauges were installed so that the top edge of the gauge orifice was nominally 0.91 m (36 inches) above the ground surface. The gauges record accumulated rainfall versus time as a pen trace on a paper chart attached to the side of a rotating, clock-driven drum.

 

Digital Gauges (2000-2017)

The digital instrumentation, developed in house, and conceptually similar to the design described by Hanson et al. [2001], was placed in the same gauge housing as the analog system to minimize the differences between analog and digital gauges caused by wind effects due to the gauge profile. The digital gauges employ an electronic load cell in which the weight of precipitation in a collection bucket is converted into a voltage. A linear relationship between voltage and observed precipitation depth was defined for each gauge using a set of calibration weights in the laboratory when the gauge was fabricated. In addition to the basic measurement device, considerable effort was directed to integrating data logging and telemetry electronics, in an attempt to maximize operational reliability and enhance protection from the environment and vandalism. Modified from Goodrich et al., 2008

 

Table 2: SWRC rain gauge instrument specifications for analog and digital eras.



Instrument

Analog-recording Mechanical Weighing-bucket Raingage

Digital-recording Electronic Weighing-bucket Raingage


Weighing Mechanism

Belfort Spring
Scale

VPG Load Cell
 

Orifice
Height
(in/m)

36/0.91
 

36/0.91
 

Orifice
Diameter
(in/m)

8/0.2032
 

8/0.2032
 



Period

1953-1999
 

2000-2017

 

 

Error/Accuracy Specifications

Brakensiek et al., 1979

Chery and Osbourne, 1971

Goodrich et al., 2008

Keefer et al., 2008

Smith et al., 2017

Belfort Weighing Rain Gauge Manual

VPG Load Cell Documentation

Analog Gauges (1953-1999)

For data reduction and QA/QC procedures the following definition of an event was adopted for the network of gauges. An event begins when any one of the gauges in the network detects measurable rainfall. As long as there is not a hiatus of more then 60 min between breakpoints on any of the gauges in the network the event continues until the last breakpoint on any gauge prior to a 60 min hiatus of no measurable rainfall. If rainfall is measured in any of the gauges after a 60 min hiatus over the entire network, it is considered the start of a new event.

The digitizing resolution for analog gauge charts has always been 0.01 in for depth and whole minutes for time, with break points identified by visual inspection. Thus breakpoints consist of time, accumulated rain depth pairs, with nonuniform time intervals and depths that are multiples of 0.01 in. Modified from Goodrich et al., 2008

 

Digital Gauges (2000-2017)

The event definition for digital gauges differs from that of the analog gauges. An event begins for an individual gauge once 0.01 in of precipitation is detected in the course of an hour for that particular gauge. The event will continue until a 60 minute hiatus in precipitation is detected. The event definition for each gauge is independent of the other gauges in the network.

Voltages from a load cell are sampled every second and averaged over the course of a minute. A threshold of 0.01 in of precipitation accumulated in within 60 minutes is required for data to be recorded as a breakpoint on the datalogger.

 

Table 3: SWRC rain gauge error specifications and data recording resolutions for analog and digital eras.



Instrument

Mechanical-weighing Analog-recording
Bucket Raingage

Electronic-weighing Digital-recording
Bucket Raingage


Weighing Mechanism

Belfort Spring
Scale

VPG Load Cell
 

 
 
Error*

± 0.5%
 

± 0.02%
 

Minimum
Resolution
(Depth/Time)

0.01 in/5 min.
 

0.01 in/1 min.
 



Period

1953-1999
 

2000-2017

 

*Error specifications are provided by the manufacturers of the weighing mechanisms of the rain gauges. These values do not include other sources of error from digitization, wind, etc.

installation and Maintenance

Brakensiek et al., 1979

Chery and Kagen, 1975

Chery and Osbourne, 1971

Goodrich et al., 2008

Smith et al., 2017

The first SWRC network gauges were installed on WGEW in the early 1950s. These gauges provided sparse coverage of WGEW in a pseudo-grid format. Gauge installation followed recommended protocols as defined in Brackensiek et al. (1979). Gauges were installed on level concrete slabs in regions unobscured by tall vegetation or man-made structures. As the network expanded more complete and dense spatial coverage of WGEW was achieved.

 

Analog Gauges (1953-1999)

Prior to 1968 there was not a regular schedule of in-field rain gauge calibration. Occasional field checks were made by measuring the amount of rainfall accumulated in the collection bucket with a standard volumetric tube measurement. If differences existed between the measurements, a correction factor was developed from the tube measurement and applied. As of 1968, each gauge was checked and adjusted annually, usually prior to the summer monsoon, with a set of standard weights through the full range of a pen sweep on the analog gauges "with the following sequence of calibrated weights - 0.05, 0.10, 0.15, 0.20, 0.25, 0.30, 0.40, 0.50, 0.75, 1.00, 1.25, 1.50, 2.00, 2.50, 3.00, 3.50, etc., to the maximum" [ Chery and Osborn , 1971, p. 5].

Chart on and off times were set and compared respectively, to the wristwatches of field technicians whose watches were set to a broadcast standard time. If clocks stopped or gained/lost more than 15 min over the course of a 7-d period (weekly gauge visits), the clocks were replaced with spares and the malfunctioning clocks were serviced in Tombstone. In these cases the event start times would be adjusted to account for the fast/slow clock using a linear correction. In the case where a clock stopped, start times from the nearest operating gauge were used. However, because of the daily time resolution of the analog charts and the use of a wrist watch, "time at one gauge at any instance will be, at best, within ±5 minutes with any other gauge in the network" [Chery and Kagan, 1975, p. 49]. Modified from Goodrich et al., 2008

Digital Gauges (2000-2017)

The voltage to depth relationship of each digital gauge is also verified annually using the calibration weights in the field. At this time the gauge is cleaned and inspected by a hydrological technician. Each data logger clock time is checked daily via telemetry and periodically reset to National Institute of Standards and Technology (NIST) standard time. The time kept by the base station computer is manually set to NIST standard time once per month and then all data logger clocks are updated via telemetry to match the base. Though the base station computer may deviate from NIST time by about ±2 min per month, the network of 88 data logger clocks stay within less than one minute of each other and standard time [Keefer et al., 2008]. Modified from Goodrich et al., 2008

Daily maintenance procedures include checking battery voltages and water depths in buckets from daily maintenance reports. Daily precipitation depths are evaluated for each gauge and compared with surrounding gauges and meteorological data to screen for potential problems. Collection buckets are emptied when water depth reached a threshold of 3-4 inches. During these maintenance visits buckets are inspected for leaks and gauges are inspected for damage and repaired as needed. Additionally, gauges are checked if data communication via telemetry is not received at the Tombstone field office. All maintenance procedures, problems, and repairs are logged by technicians for future reference.

Data Recording

Brakensiek et al., 1979

Goodrich et al., 2008

Keefer et al., 2008

CR10X Manual

CR1000 Manual

LoggerNet Manual

Belfort Weighing Rain Guage Manual

Belfort Chart Drives Manual

Analog Gauges (1953-1999)

The analog gauges produced an ink line on a paper chart to record accumulated rainfall versus time. The vast majority of analog gauges were fitted with clock gears and charts such that one revolution of the drum is equivalent to a 24-h period. A smaller number of gauges were set up with weekly clocks and charts, to aid in interpreting the storm event timing of the daily gauges. Several gauges were also equipped with 6-h clocks and charts to provide finer time resolution for several nested WGEW source area catchments. Modified from Goodrich et al., 2008


Digital Gauges (2000-2017)

The digital rain gauge network was outfitted with Campbell scientific dataloggers to record voltages from the load cell. The network is currently comprised mainly of CR10X and some CR1000 dataloggers. Data is only recorded if a precipitation event is initiated, i.e., 0.01 in of rain is detected. Data continues to be recorded until a 60 min hiatus in rainfall is reached. In addition to recording accumulated precipitation, various diagnostic measures, as well as hourly and daily summaries, are recorded for maintenance purposes.

 

Dataloggers are programmed using Campbell Scientific's LoggerNet. CR10X dataloggers are programmed using EdLog and CR1000 dataloggers use CRBasic. While the programming languages differ in syntax, the logic and recording functions where shown to be interchangeable through thorough testing of the programs.

Data Collection/archiving

Brakensiek et al., 1979

Goodrich et al., 2008

Keefer et al., 2008

Nichols and Anson, 2008

CR10X Manual

CR1000 Manual

LoggerNet Manual

Spread Spectrum Radio (RF400/RF450/451)

RavenXTV Cellular Modem

RF 310 VHF Radio and Modem

Analog Gauges (1953-1999)

Accumulated precipitation charts were collected from the gauges weekly by technicians. The charts were logged in at the Tombstone field office shortly after they are retrieved from the gauges and notes were compiled from the charts to aid in data processing. The charts are then sent to the SWRC in Tucson and inspected for continuity and completeness and queued for coding. Modified from Goodrich et al., 2008


Digital Gauges (2000-2017)

Shortly after midnight on a daily basis, data from the WGEW sites are downloaded automatically via radio and are transmitted to a computer at the SWRC Tombstone field office. VHF, spread spectrum, and cellular modems are used depending on the geographic location of the gauge. Raw data are archived in the Tombstone office and a series of batch processes are executed using LoggerNet to parse out relevant data to be processed in Tucson and to generate daily maintenance reports. The daily data are then transfered to a SWRC server residing in Tucson. Modified from Nichols and Anson., 2008

Data Processing

Anson and Wong, 2005a

Brakensiek et al., 1979

Chery and Kagen, 1975

Chery and Osbourne, 1971

Goodrich et al., 2008

Keefer et al., 2008

Analog Gauges (1953-1999)

Charts were coded by a technician in Tucson. In coding the charts, a technician ascertains the date, beginning time and classification codes of each precipitation event. Precipitation events are classified as significant or nonsignificant. A significant event causes runoff through any of the flow-measuring structures or has total rainfall of 0.25 inch with intensities greater than 0.50 inch per hour at any gage. This determination requires that all the records of a single event be examined as a group and the runoff records be consulted. The coded precipitation charts were digitized by an analog-to- digital converter coupled with a card punch. The operator entered coded information (date, begin time of event, type of precipitation, significance of event) and then separated the pen traces into appropriate line segments that accurately describe the event [Chery and Kagan , 1975]. Estimation of the digitization error can be found in work by Chery and Beaver [1976], Freimund [1992], and Keefer et al. [2008]. It should be noted that analog to digital conversion has evolved as technology has advanced (from manual reading, done prior to 1960, to an electromechanical analog to digital converter coupled with a card punch until the mid-1980s, through several solid state electronic digitizing tablets [ Osborn, 1963; Chery and Kagan, 1975; Keefer et al. , 2008]. Modified from Goodrich et al., 2008

 

Digital Gauges (2000-2017)

A scheduled Visual Basic script is executed every morning at the Tucson SWRC office after the raw data has been received. This program gathers the raw rain gauge data from the previous day and calculates precipitation depths, in breakpoint format, based on calibration records. These calibration coefficients allow voltages to be converted to precipitation depths. This processed precipitation data is then archived into an SQL database where it is queued for QA/QC procedure and made available for visual inspection on an internal maintenance website.

QA/QC

Anson and Wong, 2005a

Brakensiek et al., 1979

Chery and Kagen, 1975

Chery and Osbourne, 1971

Goodrich et al., 2008

Keefer et al., 2008

Nichols and Anson, 2008

Analog Gauges (1953-1999)

Once chart digitizing is completed, event rainfall totals are plotted by gauge location and isohyetal maps are visually examined for missing data or spurious totals. On the basis of this examination, charts may be reexamined, recoded, and/or redigitized. For spurious or missing data, nearby gauges may be used to provide estimates, which are tagged as such in the database. Chery and Kagan [1975] reported on the amount of estimated analog data for the 6-year period from 1967 to 1972. On an annual basis, the percentage of rainfall duration that was estimated ranged from 3.4 to 12.6 percent. For the same period, the percentage of total rainfall event depth that was estimated ranged from 3.1 to 5.6 percent. It was also found that because of rain gauge accuracy and the processing resolution of the analog gauges, many small events (typically less than 1.27 mm or 0.05 inches) are not measured. Modified from Goodrich et al., 2008


Digital Gauges (2000-2017)

The precipitation events are then quality checked by visual inspection. A Windows-based visualization tool was developed using Borland Delphi. This program queries the database for "unchecked" events and displays them graphically for the user. In addition to displaying a graph of the time series of an event for a particular instrument, it also displays a color coded map which represents daily summary precipitation over the watershed. If the time series graph looks typical and the magnitude and duration of the event are judged to be within the range of expected values on the basis of the daily summaries across the watershed, the event is marked as "verified." Otherwise the event is marked as "not good." The program also provides methods for correcting common problems. Modified from Nichols and Anson., 2008

Database Archiving

The raw precipitation data is archived daily in an SQLServer database once received at the SWRC Tucson office. This provisional data for rain gauges co-located with meteorological stations is pushed to an SWRC FTP site, from which the data is ingested and served by the Long Term Agroecosystem Research Network (LTAR) daily. The precipitation data is then queued for the QA/QC application. Once the precipitation data has been QA/QC'd (yearly) it is archived locally and served from the SWRC FTP site, accessible from the SWRC Online Data Access Project Site (DAP) in csv format.

Data Access

Goodrich et al., 2008

Nichols and Anson, 2008

DAP Flowchart

SWRC precipitation data can be accessed at the following websites:

SWRC Online Data Access (DAP) - QA/QC'd data updated approximately every 90 days

USDA Long-Term Agroecosystem Research Network - 15-min data updated daily (provisional data at select gauges)

USDA National Agricultural Library Ag Data Commons - DAP mirror

 

Data Use Agreement

All data available through the SWRC data access website are in the public domain, and are not restricted by copyright.

 

The SWRC will review the research results to ensure sound scientific data interpretation in the context of our historical results and our in situ experience with these data. We expect that our support will be acknowledged through co-authorship and formal acknowledgment of field and/or data support in the manuscripts (see example below).

 

Datasets were provided by the USDA-ARS Southwest Watershed Research Center. Funding for these datasets was provided by the United States Department of Agriculture, Agricultural Research Service.

 

Please send 1 copy of the published manuscript to:

Southwest Watershed Research Center

2000 E. Allen Rd.

Tucson, AZ 85719

Known Data Issues

  • The definition for a precipitation event differs between analog and digital rain gauges.
  • Zeros are used as a placeholder for missing values when multiple gauges are queried though DAP.
  • No estimation of missing digital gauge data for known false negatives or methodology for tagging these data points exists.
  • No standard approach for fixing errors in DAP exists.
  • Inconsistent analog estimation of missing gauge data may provide erroneous estimated analog data.
  • On/off dates may be estimated for monsoon only gauges. NoData values do not exist for off dates resulting in potential erroneous interpretation of aggregate data.
  • Several gauges within DAP have unknown coordinates or unknown genesis/usage.
  • Examples of Data Use

    Mendez et al., 2003

    Nichols et al., 2002

    Goodrich et al., 2008b

    Nichols et al., 1993

    Syed et al., 2002

    Rainfall point intensities in an air mass thunderstorm environment: Walnut Gulch, Arizona

    Precipitation changes from 1956-1996 on the Walnut Gulch Experimental Watershed

    Event to multidecadal persistence in rainfall and runoff in southeast Arizona

    Analysis of spatial and temporal precipitation data over a densely gaged experimental watershed

    Spatial characteristics of thunderstorm rainfall fields and their relation to runoff

    References and KEY Literature

    Anson, E. and Wong, J. (2005a). Process DAP Documentation. SWRC Internal Report.

     

    Anson, E. and Wong, J. (2005b). DAP Access Database Description. SWRC Internal Report.

     

    Armendariz, G., ??? (2016). DAP QA/QC processes followed at Walnut Gulch Experimental Watershed.

     

    Brakensiek, D. L., Osborn, H. B., & Rawls, W. J. (1979). Field manual for research in agricultural hydrology. Field manual for research in agricultural hydrology.

     

    Chery, D.L., Jr., Kagan, R.S. 1975. An overview of the precipitation processing system at the Southwest Rangeland Watershed Research Center. Nat'l.Sym. on Precipitation Analysis for Hydrologic Modeling, Precipitation Committee of the Hydrology Section, AGU, Davis, CA, pp. 48-59.

     

    Chery, D.L., Jr., Osborn, H.B. 1971. Rain gage network reports. Chpt. (1) Location 63; Chpt. (8) Location 64. Agric. Res. Service Precipitation Res. Facilities and Related Studies, D.M. Hershfield (ed.), USDA-ARS 41-176, pp. 1-14, 57-63.

     

    Goodrich, D. C., T. O. Keefer, C. L. Unkrich, M. H. Nichols, H. B. Osborn, J. J. Stone, and J. R. Smith (2008), Long-term precipitation database, Walnut Gulch Experimental Watershed, Arizona, United States, Water Resour. Res. , 44 , W05S04, doi:10.1029/2006WR005782.

     

    Goodrich, D.C., Unkrich, C.L., Keefer, T.O., Nichols, M.H., Stone, J.J., Levick, L., Scott, R.L. ( 2008b). Event to multidecadal persistence in rainfall and runoff in southeast Arizona. Water Resour. Res., 44, W05S14.

     

    Keefer, T. O., C. L. Unkrich, J. R. Smith, D. C. Goodrich, M. S. Moran, and J. R. Simanton (2008), An event-based comparison of two types of automated-recording, weighing bucket rain gauges, Water Resour. Res. , 44 , W05S12, doi:10.1029/2006WR005841.

     

    Keefer, T. O., The role or the Walnut Gulch Experimental Watershed instrumented network in support of the SWRC research program (2014). SWRC internal report.

     

    Mendez, A., Goodrich, D.C., Osborn, H.B. 2003. Rainfall point intensities in an air mass thunderstorm environment: Walnut Gulch, Arizona. J. Am. Water Resour. Assoc. 39(3):611-621.

     

    Nichols, M.H., Lane, L.J., Manetsch, C. 1993. Analysis of spatial and temporal precipitation data over a densely gaged experimental watershed.

     

    Nichols, M.H., Renard, K.G., Osborn, H.B. 2002. Precipitation changes from 1956-1996 on the Walnut Gulch Experimental Watershed. J. Am. Water Resources Assoc. 38(1):161-172.

     

    Nichols, M. H., & Anson, E. (2008). Southwest watershed research center data access project. Water resources research, 44(5).

     

    Osborn, H.B., Lane, L.J., Hundley, J.F. 1972. Optimum gaging of thunderstorm rainfall in southeastern Arizona. Water Resour. Res., AGU 8(1):259-265.

     

    Osborn, H.B., Renard, K.G., Simanton, J.R. 1979. Dense networks to measure convective rainfall in the southwestern United States. Water Resour. Res. AGU 15(6):1701-1711.

     

    Osborn, H.B., Lane, L.J., Richardson, C.W., Molenau. M. 1982. Precipitation. Chpt. 3 In: Hydrologic Modeling of Small Watersheds, ASAE Monograph No. 5, pp. 81-118.

     

    Osborn, H.B., Renard, K.G. 1988. Rainfall intensities for southeastern Arizona. J. Irrig. and Drain. Div., ASCE 114(ID1):195-199.

     

    Smith, J.R. (2017) Instrumentation Protocol. SWRC Internal Report

     

    Syed, K., Goodrich, D.C., Myers, D., Sorooshian, S. 2002. Spatial characteristics of thunderstorm rainfall fields and their relation to runoff. J. Hydrology 271(1-4):1-21.

     

    CR10X Measurement and Control Module Operator's Manual Rv. 02/2003

     

    CR1000 Datalogger Operator's Manual Rv. 12/2016

     

    LoggerNet Version 4.4 Instruction Manual Rv. 02/2016

     

    VPGT Low Capacity Single-Point Aluminum Load Cell Specifications Rv. 10/18/2016

    USDA-ARS SWRC | Draft 4/16/2018 | Mark Kautz