2015 International Great Lakes Datum Height Modernization Project Dave Rigney NGS Geodetic Advisor Michigan Great Lakes Region Height Modernization Meeting September 16, 2014 ● Sparta, WI

The purpose of these surveys was to monitor elevation changes across the Great Lakes to facilitate the development of the International Great Lakes Datum (IGLD) to be released in the future. Past surveys were conducted in 1997, 2005, 2010 and another is planned for The project area encompasses the entire Great Lakes Region, from Minnesota and Lake Superior eastward to the St Lawrence Seaway in New York. These surveys are a coordinated effort between the U.S. and Canada. IGLD GPS Height Modernization projects

1997 IGLD GPS Survey

2005 IGLD HMOD Survey

2010 IGLD HMOD Survey

2010 GPS Survey Phase I June (St. Marys River MI – St. Lawrence Seaway NY) Phase II July (Lake Michigan - Lake Superior) 23 Observing days (mix of 8 hr and 24 hr sessions) 14 total observers 84 Passive stations (Bench marks) 77 Active stations (CORS) Temporary Receivers at CORS\Water Level Stations Observers performed reconnaissance on the fly

Preparing for the 2015 Great Lakes GPS HMOD Survey 1 – Reconnaissance at WL sites 2 – New marks set 3 – Leveling performed 4 – June through August project timeframe 5 – Coordination with Corbin for equipment 6 - Field and Office Personnel 7 – Should gravity measurements be observed? 8 – Observations at Seasonal Sites? 2015 survey will consist of hour sessions at all stations The effort that we put in now will benefit the 2020 GPS Campaign

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Help from States Reconnaissance of BM’s at Gauge sites and Seasonal Gauge locations Mark setting Leveling ties Partnering with NOAA CO-OPS to provide GNSS equipment for use at Water Level Stations Bluebook of leveling data

Dave Rigney NGS Advisor Michigan