USGS Publication For Vertical Control Interagency Datum Establishment

§ USGS Publication For Vertical Control § Inter-agency Datum Establishment And Conversion Collaboration In Missouri Height Modernization Coordination Meeting Paul H. Rydlund Jr. PLS U. S. Geological Survey Missouri Water Science Center U. S. Department of the Interior U. S. Geological Survey

USGS GNSS T&M – Why? “RTK c an only b when s etting u e used p over a benchm directly ark “ • Technique and Approach Guidance For USGS • Accuracy and Precision etwork N e m i T “Real much y t t e r p • Metadata surveys ertical v e e t n • Example Campaigns and Decision Trees gaucacruaracies withine 2 edcma never n u o y d n a • Future Direction ation “ base st • Consistent and Referable Glob a Sate l Naviga llite S tio yste n m The Black Box g GPS n i s s e c st pro ensure 6 o p l l “A must llection at s y e v o sur data c f o s r hou um“ m i n i am “Wi t R 8 h the n s get ystem ew Tr imb t with ing ve s, we rtica are le i n in th 7 m m a l accu ed ra s ata coll stated cies ecto r“

USGS GNSS T&M - Introduction • Historic USGS Datum Establishment • Evolution • GPS Modernization • GNSS GLONASS, Galileo, Compass • Geodesy Background

GNSS T&M - Equipment

USGS GNSS T&M - Mission Planning Ionosp here Tropos phere • PDOP • Multipath < 10 km • Ionosphere & Troposphere • Satellite Availability (Notice Advisory To Navstar Users) • Space Weather (Space Weather Prediction Center) • Resolution and Accuracy of Local Geoid OR F UT KO O LO ESE TH > 10 km

GNSS T&M – Real Time (RT) Surveys • Single Base RT • Network Base RT

GNSS T&M – Real Time (RT) Surveys • Quality Assurances Blunder Check 1. 2. 3. Multipath and General Height Reinitialization Blunder Check Let’s sum it up! Collectively, the GNSS user observes 180 epochs or 3 minutes of data, walks away from the objective point a minimum of 100 feet, inverts the rover receiver (or adjusts the elevation mask) to lose initialization, changes the rover rod height at least 0. 80 feet and corrects the rover height entered in the data collector appropriately, walks a different approach path back to the objective point, then positions the rover receiver in an upright position over the objective point for the second observation. Both observations are averaged to produce the final result. This process is hereinafter referred to as a RT blunder check and should be recorded in the field notes to document that these redundant assurances are met.

GNSS T&M – Real Time (RT) Surveys • Localizations / Realizations

USGS GNSS T&M – Post Processed • Single Base – OPUS • Traditional Static • Rapid Static The USGS GNSS T&M Manual recommends and encourages use of this online utility The experts in geodesy.

USGS GNSS T&M – Post Processed • Network Surveys Modified from NOS NGS 59 Tech Memo • Quality Assurances

USGS GNSS T&M – Quality Categorization • Level I – Static Network Survey • Control • 40 Km spacing; 4 hour; 2 nd order or better • Objective • 15 Km spacing; 1 hour; 50% double occupied • Additional benchmark checks other than primary control • Level I – Static Single Base Survey (OPUS-S) • Occupation • 2 Days, 4 hours, different times • Quality Indicators

USGS GNSS T&M – Quality Categorization • Level II – Static Network Survey • Control Points • 60 Km spacing; 4 hour; 2 nd order or better • Objective Points • 25 km spacing; 1 hour; 50% double occupied • Additional benchmark checks other than primary control • Level II – Static Single Base Survey (OPUS-S) • Occupation 1 day – 4 hours • Quality Indicators • Level II – RT Surveys • Localization – 2 nd order or better • Satellites; PDOP; baseline length • Blunder check redundancy within 0. 03 m • Objective points 10% double occupied (within 0. 05 m)

USGS GNSS T&M – Quality Categorization • Level III – Static Single Base Survey (OPUS-S) • Quality Indicators • Level III – Static Single Base Survey (OPUS-RS) • Quality Indicators • Level III – RT Surveys • Localization – 3 rd order or better • Satellites; PDOP; baseline length • Blunder check redundancy within 0. 04 m • Objective points 10% double occupied; within 0. 05 m

USGS GNSS T&M – Quality Categorization • Level IV • Generally reserved for RT topographic surveys without checks • Can be composed of static surveys without quality indicators or checks

USGS GNSS T&M – Quality “How Do We Get There? ”

USGS GNSS T&M – Metadata (documentation of the geodetic trail) • Benchmark Recovery Establishment

USGS GNSS T&M – Metadata (documentation of the geodetic trail) • Observation • Database storage lat-long and altitude metadata

USGS GNSS T&M – Example Data Set (Groundwater Well Field)

USGS GNSS T&M – Example Data Set (Flood Study)

USGS GNSS T&M – Example Data Set (Streamgage Datum)

USGS GNSS T&M – Future Direction of GNSS • Modernization programs – L 5 signal • GRAV-D • Precise Point Positioning (PPP)

Plug for USGS – GPS Committee http: //water. usgs. gov/usgs/osw/gps/

Office of Employee Development (OED) ID 1747 Application and Practice of Survey-Grade GNSS Real-Time and Static Surveys in the USGS

Office of Employee Development (OED) ID 1747 Application and Practice of Survey-Grade GNSS Real-Time and Static Surveys in the USGS Syllabus

Office of Employee Development (OED) ID 1747 Application and Practice of Survey-Grade GNSS Real-Time and Static Surveys in the USGS

Office of Employee Development (OED) ID 1747 Application and Practice of Survey-Grade GNSS Real-Time and Static Surveys in the USGS OPUS Projects

Office of Employee Development (OED) ID 1747 Application and Practice of Survey-Grade GNSS Real-Time and Static Surveys in the USGS

Levee Breach PROJECT APPLICATION – Storm Surge Sensors The New Madrid Floodway

PROJECT APPLICATION – Storm Surge Sensors What’s up with Sandy…

Legacy Datum - Mississippi River Datum and Some Tributaries 1. 2. 3. Memphis Datum Mean Gulf Datum Fourth General Adjustment of 1912 Historic datum is considered legacy

Legacy Datum – Middle Mississippi River Datum – St. Louis Gaging Station St Louis Direatrix Cario Memphis Mean Sea Level Mean Gulf Engineers Office Middle Mississipppi River Gage Hydralic Datums Datum Conversions Zero Gage 413. 68 -33. 74 400. 23 -20. 29 387. 10 7. 16 379. 94 St Louis Gage 0 379. 80 0. 14 213. 68 166. 26 Historic datum is considered legacy

NAVD 88 Datum Conversion : Simple Height Conversion or Survey – “The USGS Missouri Model” 1. Evaluation of Source Datum genesis and condition 2. Cooperative Interest 3. Hydraulics and Stability 4. Accuracy assured with USACE ‘CEPD’ and NWS modeling interests Cooperative Interest Accuracy Gage location hydraulics or channel instability

Inter-Agency Collaboration in Missouri River Datum Discrepancy Example

Benefits of Inter-Agency Collaboration ü Enhance Resources ü Reduce Expense ü Quality Assurance ü Agency Consensus ü Public Approval

Continuing Inter-Agency Collaboration in Missouri § Datum Surveys – Moving Forward § USGS and USACE duplicative surveys at important gaging locations § Main stem Missouri and Mississippi River gages § Water resource operation project gages § Limited duplication at tributary gages § USGS / USACE surveys § Sharing of metadata and results § Overcome cost prohibitive gaging locations § Augmenting staff for local/regional GNSS campaigns § USGS Gaging Installation § Installation of an observable benchmark Datum Dissemination

Continuing Inter-Agency Collaboration in Missouri Survey assistance…. MODOT MVL USACE NWK MVS SWL MVM MDNR

Continuing Inter-Agency Collaboration in Missouri – FY 13 Single Base OPUS Level I Quality - SWL Augment Survey Gaging Station Number Gaging Statiion Description 7058000 USGS Missouri Water Science Center Observations per T&M (Level I) Observation Date Time Obsevations Used Required Amibiguities Fixed Required Solution RMS (m) Required (m) Vertical peak-topeak (m) Required (m) Orthometric Height Bryant Creek near Tecumseh, MO 10/16/2012 1137 - 1703 91% >80% 94% >80% 0. 015 <0. 030 0. 028 <0. 06 182. 006 10/17/2012 0746 - 1302 91% >80% 85% >80% 0. 017 <0. 030 0. 076 <0. 06 182. 060 7053600 Lake Taneycomo at School of the Ozarks, MO 10/16/2012 1122 - 1701 87% >80% 95% >80% 0. 015 <0. 030 0. 069 <0. 06 218. 965 10/17/2012 0725 - 1204 85% >80% 90% >80% 0. 017 <0. 030 0. 027 <0. 06 218. 971 7054080 Beaver Creek near Bradleyville, MO 10/16/2012 1123 - 1704 91% >80% 93% >80% 0. 012 <0. 030 0. 028 <0. 06 252. 800 10/17/2012 0758 - 1358 90% >80% 84% >80% 0. 013 <0. 030 0. 016 <0. 06 252. 802 7053810 Bull Creek near Walnut Shade, MO 10/16/2012 1209 - 1753 96% >80% 94% >80% 0. 012 <0. 030 0. 034 <0. 06 229. 712 10/17/2012 0716 - 1313 95% >80% 87% >80% 0. 013 <0. 030 0. 035 <0. 06 229. 704 7053820 Lake Taneycomo at School Powersite Dam, MO 10/16/2012 1226 - 1747 93% >80% 95% >80% 0. 013 <0. 030 0. 017 <0. 06 219. 420 10/17/2012 0806 - 1308 95% >80% 91% >80% 0. 013 <0. 030 0. 017 <0. 06 219. 435 USACE – SWL USGS - MOWSC USGS - ARWSC Average Ortho Height (m) 182. 03 218. 97 252. 80 229. 71 219. 43 Within 0. 05 m of each solution 0. 027 0. 003 0. 001 0. 004 0. 008 0. 007