Overview
A 27 year (1990-Present) soil hydrology database has been developed for the Southwest Watershed Research Center (SWRC). These sites encompass Walnut Gulch Experimental Watershed (WGEW), Audubon Research Ranch (ARR), Santa Rita Experimental Range (SRER), and the Upper San Pedro (USP) basin in southeastern Arizona. Data have been acquired at 3 automated weather stations, 7 TDR soil profile trench sites, and 52 locations dispersed across the southeastern Arizona co-located with recording rain gauges. Soil hydrology properties measured at the weather stations, trench sites, and rain gauges include soil moisture, soil temperature, soil heat flux, and soil surface temperature. Data are available at http://www.tucson.ars.ag.gov/dap. Modified from Keefer et al., 2008
Measured Variables
Volumetric Water Content [%]
Soil Temperature at Depth [deg C]
Soil Surface Temperature [deg C]
Soil Heat Flux [W m-2]
Network Extent
The SWRC soil hydrology network consists of sensors associated with 3 automated weather stations (AWSs), 7 soil profile trenches, and 52 near-surface soil hydrology sensors co-located with rain gauges in southeastern Arizona.
The 7 soil profile trenches and 2 of 3 AWS sites are located at 2 intensive rangeland study areas that are representative of the 2 main vegetative covers on WGEW: the shrub dominated Lucky Hills (LH) subwatershed (LHMet, LHTrench, TDRL1, and TDRL2) and the grass dominated Kendall (KEN) subwatershed (KNMet, KNTrench, KSTrench, TDRK1, and TDRK2) [Skirvin et al., 2008]. The third soil hydrology site associated with an AWS is located at the ARR, 42 km west of WGEW. Soil hydrology sensors co-located with SWRC rain gauges span WGEW, ARR, SRER, and USP (Table 1).
Table 1: SWRC soil hydrology sensor locations. Ground cover, soil series, and soil bulk densities are provided where available.
Site
LHMet
KNMet
ARRMet
LHTrench
KNTrench
KSTrench
TDRL1
TDRL2
TDRK1
TDRK2
WGEW
RG3
RG13
RG14
RG18
RG20
RG28
RG34
RG37
RG40
RG46b,c
RG57
RG69c
RG70
RG76
RG82b
RG83b
RG89
RG92c
RG100c
SRER
RG201
RG202
RG203
RG204
RG205
RG206
RG208
USP
RG400
RG401
RG402
RG403
RG404
RG405
RG406
RG407
RG408
RG409
RG410
RG411
RG412
RG413
RG414
RG415
RG416
RG417
RG418
RG419
RG420
RG421
RG422
RG423
RG424
RG426
Easting
589773
600231
547920
589798
600009
599892
589567
589793
599927
600012
581204
586110
585442
586710
587480
590624
590946
593303
593360
595289
596089
603916
604288
582624
600154
589679
596308
581888
593266
513036
512945
508238
509065
514046
513778
513969
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
567342
UTM NAD83
Northing
3512434
3511719
3496185
3512418
3511756
3511855
3512290
3512420
3511822
3511754
3509768
3510185
3507187
3508098
3504939
3509990
3507458
3506068
3510286
3508655
3510781
3515463
3514207
3509679
3511680
3512426
3513931
3511774
3504720
3524541
3524350
3524192
3523927
3519959
3519800
3520124
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
3487870
Elevation
1370
1531
1453
1368
1515
1511
1366
1373
1504
1511
1246
1334
1390
1365
1525
1369
1420
1404
1390
1445
1446
1638
1630
1311
1530
1370
1491
1244
1418
1046
1049
970
897
1163
1215
1157
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
1433
Cover
shrub
grass
grass
shrub
grass
grass
shrub
shrub
grass
grass
shrub
shrub
shrub
shrub
shrub
shrub
shrub
shrub
shrub
grass
grass
grass
grass
shrub
grass
shrub
grass
grass
shrub
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
Soil Seriesa
Luckyhills McNeal
Elgin-Stronghold
*
Luckyhills McNeal
Elgin-Stronghold
Elgin-Stronghold
Luckyhills McNeal
Luckyhills McNeal
Elgin Stronghold
Elgin Stronghold
Luckyhills McNeal
Monterosa
Chiricahua
Shiefflin
Mabray rock outcrop
Graham
Sutherland
Monterosa
Baboquivari-Combate
Clay loam
Tombstone
Blacktail
Woodcutter
Lampshire rock outcrop
Elgin-Stronghold
Luckyhills McNeal
Stronghold-Bernadino
McAllister Stronghold
Mabray rock outcrop
Combate-diaspar
Combate-diaspar
Agustin sandy loam
Hayhook-Pajarito
Sasabe-Baboquivari
Combate-diaspar
Sasabe-Baboquivari
Dona Ana-Mohave
Carbine
Carbine
Carbine
Carbine
Major
White House
Blakeney-Luckyhills
*
Budlamp-Woodcutter
Budlamp-Woodcutter
Riveroad and Ubik
Far-Hogris
*
Yarbam-Rock outcrop
Riveroad and Ubik
Blakeney-Luckyhills
Ubik
Bella
Rock outcrop-
Lithic Haplustolls
Carbine
White House gravelly loam
White House gravelly loam
White House gravelly loam
Far-Huachuca-Hogris
Gardencan-Lanque
Bulk
Density
5 cm
(g cm-3)
1.64
1.61
*
1.61
1.55
1.50
1.65
1.65
1.77
1.77
1.81
1.61
1.81
1.59
1.63
1.69
1.52
1.71
1.81
1.65
1.67
2.02
1.80
1.79
1.61
1.65
1.82
1.59
1.91
*
*
*
*
*
*
*
1.81
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
Modified from Keefer et al., 2008 Table 1
aAdditional soil texture information can be found in Table 1 of Keefer et al., 2008.
bThis rain gauge is equipped with additional soil moisture and temperature sensors at 15 and 30 cm.
cThis rain gauge is equipped with an IRT for soil surface temperature.
Instrumentation Specifications
Table 2: SWRC soil hydrology site instrumentation specifications and periods of operation.
Site/Variable
LHMet and KenMet
ARRMet
Trench- LH, KN, KS
TDRL1
TDRL2
TDRK1
TDRK2
Rain Gauges
Instrument
Depth
(cm)
Period
Modified from Keefer et al., 2008 Table 3
*All gauges contain 5 cm soil moisture. See Network Extent for gauges containing additional 15 cm soil moisture, 30 cm soil moisture, and surface temperature. Periods of operation vary between rain gauges.
Error/Accuracy Specifications
Table 3: SWRC soil hydrology site error specifications, sampling resolution, and periods of operation.
Instrument
LHMet and KenMet
ARRMet
Trench- LH, KN, KS
TDRL1
TDRL2
TDRK1
TDRK2
Rain Gaugesb
Accuracy
Output*
(Time, min.)
Period
Modified from Keefer et al., 2008 Table 3
*Data sampling frequencies were dictated by the following ARS projects: Monsoon90 Experiment - 60 minutes, Installation of Bowen Ratio Systems - 20 minutes, and Installation of Eddy Covariance Flux Towers - 30 minutes.
aThese TDR soil moisture measurements were recorded manually using a Tektronix 1502B time-domain reflectometer. Measurement frequency varies.
bPeriods of operation vary between rain gauges.
installation and Maintenance
The installation process for each soil profile trench was similar. A trench was excavated manually or with a backhoe. A small horizontal cavity, large enough to accept the soil moisture probe body, was created in the exposed trench face at the designated installation depth. Probes were inserted horizontally into this cavity, by pushing the probe tines into the soil at the recessed end of the cavity, until the probe head was within the cavity. The cavity was repacked with the soil that had been removed. Probe lead wires were run vertically down the trench face, across the bottom of the trench and up the other side, thus preventing preferential flow paths to probe head and tines. Multiple profiles were installed in the same trench, or in side by side trenches, under representative soil surface cover.
Although every attempt was made to assure good contact between soil and tines, it was impossible to know the extent of soil cracking around the tines at time of installation. Installation of soil temperature thermocouples in the same trenches was identical. Installation in the near surface, such as at the rain gauges and AWSs, of soil moisture, temperature and heat flux sensors was similar, but these shallow trenches were manually excavated and the soil surface was stabilized when installing very near to the surface, 1 and 2 cm. Proper installation is the initial step in data quality control. Taken from Keefer et al., 2008
Data Recording
LHMet, KenMet, and ARRMet
Soil hydrology measurements at SWRC meteorological stations record data using Campbell scientific dataloggers (CR1000 currently and CR10/CR10X historically) and multiplexers (AM16/32). Dataloggers are programmed using Campbell Scientific 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. Soil moisture, temperature, and heat flux sensors, are sampled every 10 seconds and averaged over the recording period (e.g., 15, 20, 30 min).
TDR Trenches - LH, KN, KS
TDR measurements for these profile trenches were recorded manually using Tektronix 1502B time-domain reflectometer. Data were then recorded onto data sheets and archived digitally.
TDR Profile Sites - TDRL1, TDRL2, TDRK1, TDRK2
Soil hydrology measurements at SWRC TDR profile sites record data using Campbell scientific dataloggers (CR1000 currently and CR10/CR10X historically) and multiplexers (AM16/32). Dataloggers are programmed using Campbell Scientific 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. Soil moisture and temperature are sampled at the end of the recording period (e.g., 15, 20, 30 min).
HydraProbe Sites Co-located with Rain Gauges
Soil hydrology measurements at co-located with rain gauges record data using Campbell scientific dataloggers (CR1000 and CR10X). Dataloggers are programmed using Campbell Scientific 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. Soil moisture and temperature are sampled at the end of the recording period (e.g., 15, 20, 30 min).
Data Collection/archiving
Shortly after midnight on a daily basis, data from the WGEW sites are downloaded automatically via telemetry 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
Data are processed quarterly using a combination of LoggerNet and Fortran processes.
QA/QC
The initial data stream from field sites may contain missing values for any property because the station was not in operation intentionally or accidentally, the sensor was not deployed at that time, or there was data collection, communication or computer failure. Data determined to be collected during periods when a sensor was known to be inoperable (e.g., vandalism, animal or natural interference) were coded with missing values.
Incoming data, after transformation from measured value to final units, if applicable, are screened by automated and visual graphic processes for outliers beyond acceptable limits. Outliers that are physically impossible (e.g., negative soil moisture) are coded as missing. Taken from Keefer et al., 2008
Database Archiving
The raw data is archived daily in an SQLServer database once received at the SWRC Tucson office. Once the data has been processed and QA/QC'd (quarterly) 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
SWRC meteorological 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)
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
Examples of Data Use
Validation and scaling of soil moisture in a semi-arid environment: SMAP validation experiment 2015 (SMAPVEX15)
Runoff simulation sensitivity to remotely sensed initial soil water content
Partitioning evapotranspiration in semiarid grassland and shrubland ecosystems using time series of soil surface temperature
Summer soil moisture spatiotemporal variability in Southeastern Arizona
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.
Smith, J.R. (2017) Instrumentation Protocol. SWRC Internal Report
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
RF400/RF410/RF415 Spread Spectrum Radio/Modem Manual Rv. 03/2015
RF450 Spread Spectrum Radio Manual Rv. 04/2015
RavenXTV CDMA Sierra Wireless Cellular Modem Manual Rv. 03/2017