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Inter-Agency Datum Establishment and Conversion Collaboration in Missouri. 2013 National Height Modernization Partner Meeting Western States Regional Webinar. Paul H. Rydlund Jr. PLS U.S. Geological Survey Missouri Water Science Center. What’s the problem?.
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Inter-Agency Datum Establishment and Conversion Collaboration in Missouri. 2013 National Height Modernization Partner Meeting Western States Regional Webinar Paul H. Rydlund Jr. PLS U.S. Geological Survey Missouri Water Science Center
What’s the problem? • Reporting vertical datum differences generates confusion and depreciates public confidence.
What’s the problem? • Reporting vertical datum differences generates confusion and depreciates public confidence. For example…. River Forecasting
What’s the problem? • Public welfare regarding impacts
What’s the problem? • Cooperative agencies all disseminate vertical datum for reference of hydrologic products. Consistency (and accuracy) is needed.
What’s the problem? • Levee overtopping concerns exist where USGS streamgage datum and datum for levee surveys differ. For example…. Public Protection Level
What’s the problem? • Inundation mapping, whether agency function or private sector, is dependent upon datum representing consistency and quality.
USGS Policy Guidance NAVD88 is the recommended datum established in the Federal Geographic Data framework (USGS - Office of Water Information Technical memorandum 2002.01).
USGS Database Statistics • 84,944 Surface-Water sites • 62,032 determined elevation from maps • 7,737 from levels • 8,023 unknown source • 1,269 from a GPS • 4,771 already reported to NAVD88
NGS-USGS-NWS-USACE Streamgage Datum Workgroup • Workgroup interaction and support for datum conversion of USGS streamgages to NAVD 88 • Driven by “unfunded mandate” to update gage datums • Pilot states of Missouri, North Carolina, and Michigan • Goals • Establish decision model: • How to prioritize gages to update? • How to determine accuracy needed? • What method to measure/compute/derived updated height • Create guidelines that other regions/districts can use
NGS-USGS-NWS-USACE Streamgage Datum Workgroup • Site Priority – driven by need and resources • Cooperative Interest – needed by multiple agencies • Location, e.g. high population areas subject to flooding • Accuracy Requirement – dictate method for conversion • Method for conversion – driven by accuracy requirements and resources • Rename datum • Simplistic Height Conversion Tool: VERTCON, CORPSCON • GNSS Survey • Leveling • Roadblocks • Lack of resources regarding personnel, expertise, and funding
NAVD 88 Datum Conversion : Simple Height Conversion or Survey – “The USGS Missouri Model” 1. Evaluation of Source Datum 2. Cooperative Interest 3. Hydraulics and Stability 4. Accuracy assured with USACE ‘CEPD’ and NWS modeling interests Source Datum genesis and condition Cooperative Interest Cooperative Interest Accuracy Gage location hydraulics or channel instability
Inter-Agency Collaboration in Missouri MODOT MVL USACE NWK MVS SWL MVM MDNR
Inter-Agency Collaboration in Missouri Missouri River Datum Discrepancy Example
Continuing Inter-Agency Collaboration in Missouri – FY 13 USACE – SWL USGS - MOWSC USGS - ARWSC
Inter-Agency Collaboration • 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 Dissemination of NGVD 29 and NAVD 88 datum Dissemination of NGVD 29 and NAVD 88 datum
Inter-Agency Collaboration Datum Surveys – Assistance and Collaboration http://www.ngs.noaa.gov/ADVISORS/AdvisorsIndex.shtml
Inter-Agency Collaboration Datum Surveys – Assistance and Collaboration Mark.W.Huber@usace.army.mil
Benefits of Inter-Agency Collaboration • Enhance Resources • Reduce Expense • Quality Assurance • Agency Consensus • Public Approval
USGS Resources – Questions? USGS Global Positioning System Web Committee http://water.usgs.gov/usgs/osw/gps/