G51C-0360 Advancing Water Level Measurements through GNSS Interferometry:Experiences, Challenges, and Innovations (7 MB)
By Nathan Wardwell, Drew Lindow, & James Mitchell
In December of 2023 Drew Lindow of JOA participated in the American Geophysical Union poster session on the topic of “Incorporating GNSS into Water Level Monitoring Networks: Key Focuses, Advancements, and Advantages”. Over the past three years JOA has deployed over a dozen temporary and permanent GNSS-R sites. The poster showcases JOA’s effective implementation of the GNSS-IR method for measuring water levels at three sites in Alaska, highlighting the success and practical applications of this technique.
Use of Gps For Tidal Measurements (8 MB)
By Drew Lindow, Jim Mitchell, & Nathan Wardwell.
The Alaska National Water Level Observing Network faces significant gaps, especially along the rugged coastlines of Western and Northern Alaska where stable surfaces are scarce. How might GNSS-R technology help address these data deficiencies? JOA has been deploying GNSS-R alongside traditional tide stations in various locations for comparative analysis. Jim Mitchell of JOA Surveys, presented at the Alaska Society of Professional Land Surveyors conference on unique methods of measuring water levels with GPS, highlighting our findings and GNSS-R plans for 2024.
NTDE Update – Tides Workshop presentation by Nathan Wardwell
Nathan Wardwell, Managing Partner of JOA Surveys, presented at the Tidal & Water Level Datums Workshop on industry’s perspective of the tidal datum epoch. This presentation was part of a four person panel on Using the Datum. Nathan was joined by Dave Doyle of Base 9 Geodetic Consulting, Denis Riordan of NGS and Mark Huber retired from the USACE.
2023 Pacific Rim Geospatial Conference GNSS presentation by Jim Mitchell
At the 2023 Pacific Rim Geospatial Conference Jim Mitchell of JOA Surveys presented on the technical aspects of Global Navigation Satellite Systems Reflectometry (GNSS-R) and its applications in tide measurement, including the basic principles, limitations, and challenges. He showcased recent GNSS-R acquisition and processing case studies from JOA Surveys, highlighting the practical implementation of GNSS-R for tide measurement.
He then went into the potential of GNSS-R for tide measurement in Alaska, where the challenging environmental conditions and limited infrastructure pose challenges for conventional tide gauges. The discussion provided insights into how GNSS-R can provide more accurate and reliable tidal information in these conditions.
Tidal Coordination for Data Acquisition
In November of 2022 JOA presented at the Alaska Coastal & Ocean Mapping Summit on considerations when performing tidal coordinated mapping in Alaska.
GNSS Water Level Measurement Systems for Tidal Datums
In December of 2020 JOA presented at the 3rd Alaska Coastal Mapping Summit on the use of Global Navigation Satellite Systems (GNSS) for establishing tidal datums. The presentation includes an overview of GNSS Tide Buoy and GNSS-Reflectometry (GNSS-R) water level measurement systems in addition to a few examples from recent field deployments along Alaska’s Coast.
Online Tide Datum Computations Presentation
Presentation outlining JOA Surveys’ online tidal datum computation tool.
Rapid Deployment Storm Surge Gauge
A lack of coastal infrastructure in western Alaska poses a challenge to efforts directed at collecting water levels referenced to tidal datums for storm surge analysis. The two primary challenges are sensor stability and the level of effort required for sensor installation. JOA Surveys, LLC (JOA) developed a system to measure storm surge in low areas with existing deep rod style tidal benchmarks that can be deployed with no tools and the installation time is less than 10 minutes. JOA tested this system in Kinak Bay and successfully measured storm surge during a September 2016 storm. Follow link above to download pdf in a new window.
Tides Under the Ice
NOAA’s Center for Operational Oceanographic Products and Services (CO-OPS) has developed an innovative system design to collect water level data in remote cold climate regions where winter sea ice precludes traditional tide station installations. Barrow Alaska 2008-2010.
Gauging the Tide
A Point of Beginning (POB) article my Mike Zieserl about tertiary tide stations in Kenai Fjords Alaska – May, 2001.
Evaluating VDatum in Chesapeake Bay with a GPS Buoy
In August and September of 2009, David Evans & Associates (DEA) deployed a GPS buoy in Chesapeake Bay. JOA Surveys, LLC (JOA) used the 1Hz RT and PPK solutions to compute tidal datums for comparison with VDATUM through water level transfers from Lewisetta to the Buoy and a similar transfer from Windmill Point resulting in final datums within 2cm of the VDATUM determination at the location of the GPS buoy.
Tidal Datum Determination and VDatum Evaluation with a GNSS Buoy
Under a charting contract with the National Oceanic and Atmospheric Administration (NOAA), David Evans and Associates, Inc. (DEA) was tasked to evaluate the VDatum model in addition to mapping large portions of Chesapeake Bay. Using a buoy outfitted with GNSS and a tilt sensor, tidal datums were computed at three locations bounding the project area in 2009 and 2010. Final results were compared with existing shore-based tide stations, GNSS water levels computed on two survey vessels and the VDatum model.
Water Level Adjustments for NOAA Hydrographic Surveys in Cook Inlet
In 2008 a combination of National Water Level Observation Network (NWLON) tide stations, tertiary tide stations, submersible pressure sensors, and hydrographic vessels were used to measure and zone water levels in Alaska’s Cook Inlet. The goal during the 2008 field season was to apply the experience gained from surveys during the past decade to derive MLLW to NAD83 transformation parameters that can be used in future surveys.
Datum Determination and VDatum Model Validation with a GPS Buoy
Under a charting contract with the National Oceanic and Atmospheric Administration (NOAA), David Evans and Associates, Inc. (DEA) was tasked to evaluate the VDatum model in addition to mapping large portions of Chesapeake Bay. Using a buoy outfitted with GPS and a tilt sensor, tidal datums were computed at six locations distributed throughout the 2009 and 2010 project areas. JOA Surveys, LLC (JOA) computed tidal datums from the ellipsoid referenced water levels using the Tide-by-Tide (TBYT) method of simultaneous comparisons with NOAA’s permanent tide stations.