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Frequently Asked Questions

Hohonu blends scientific rigor with community value and access


Read the most common questions in building water monitoring programs for a

single town and/or at a national scale

  • Do you use exclusively ultrasonic sensors or do you use other technologies, too?
    Hohonu uses sensors of all types, including ultrasonic and radar. It has performed testing in partnership with NOAA at multiple sites throughout the US to verify accuracy of its monitoring system. Hohonu has been built and deployed water level instruments comprised of temperature-compensated ultrasonic sensors (MaxBotix MB7388), traditional radar sensors (Hydromet OTT RLS), emerging radar sensors (Vega C22), depending on the specific site, application, and customer budget. Full technical specifications are available for each following the links provided. Hohonu adds on-board power & data management, telemetry to the cloud, automated Quality Assurance & Quality Control following NOAA QARTOD standards, public access of custom visualizations via a web data portal and iOS app, and custom, site-specific predictive analytics that outperform federal forecast models. Hohonu’s fully documented onboarding procedures for new customers is freely available here.
  • Do you only deploy sensors for tidal purposes?
    Absolutely not! We use the same technology to deploy inundation sensors that can detect flooding for low-lying infrastructure such as roads. You can learn more about our work in Boston by clicking here.
  • Why use Hohonu if I can just work with a local research group? Isn't the hardware easy to make?
    Hohonu was born out of the University of Hawai'i because there was demand it could not meet within the walls of a research lab. Its founding team all has research and academic backgrounds. When working with a local research team to deploy sensors, we believe it is prudent to ask the below questions: How will data telemetry, integration, and management be developed? How will data be visualized and accessed? Can data be easily shared and understood by the general public? Will there be API documentation? Will the resulting data management system be able to handle calculation of tidal datum's and sensor replacements? Will it adhere to NOAA standards for metadata management? What is the longevity of support? Does the team have other funded, competing projects that needs to be managed in addition to deploying these sensors? How many sensors are needed? Does the team have the capacity to meet that volume while keeping quality and consistency high?
  • In what ways can I access the data?
    Hohonu has developed multiple methods for accessing data, depending on the use-case and end-user experience level. Each method was developed with ease-of-use and accessibility in mind: For general and quick public access to real-time data: Web-Based Dashboard: TideCast iOS Mobile App : HTML Widgets 2 lines of HTML code can be copy/pasted to generate a real-time water level graph on any website For advanced public users: CSV Downloads CSV reports can be downloaded directly from the web-based dashboard API Access Fully-documented API: For internal stakeholders to monitor hardware and network performance: Diagnostics viewer For validation of hardware performance before installation occurs Raw “Distance to water”, battery voltage, cell strength, standard deviation, and other parameters Status page For monitoring of network performance across each node Merging of operational metadata with ongoing performance on a site-by-site basis that is updated hourly Permissioned user access to display exclusively the stations that each partner cares most about - while protecting sensitive operational data Up-to-date operational plans for each station
  • How do you manipulate raw sensor data?
    Hohonu strives for "no black boxes." Data at each step of the pipeline can be accessed via our dashboard and API's, and our methodologies for data manipulation are well-documented and in accordance to NOAA standards (where applicable). Raw data D2W Standard deviation Other parameters such as battery voltage, cell strength and signal Processed QA/QC data “Cleaned” data following QARTOD methodologies, implemented over four years of collaboration with SECOORA, Axiom Data Science, and NOAA CO-OPS: Revised Hohonu QARTOD documentation Reference systems / datum’s D2W data converted to: NAVD88 (if a survey was conducted) MLLW / MHHW Requires 35 days of installation data Near-Term Water Level Predictions 4-day water level forecasts, updated every 6 hours Adaptive analytics allow for increasing frequency of forecast updates during approaching storms or flood events Additional features Custom high water thresholds Each site can have high water thresholds assigned, with a text description of what each threshold means (e.g. top of bulkhead) Text Alerting Users can sign up for text alerts when water levels reach the custom high water threshold
  • What options exist for outright buying vs subscription?
    Hohonu offers environmental data as a service and does not sell hardware outright, but we are flexible in how invoices can be generated for multi-year projects that may have difficulty budgeting or accounting for annual subscription services.
  • How is installation and maintenance done?
    Field installation and maintenance typically takes place in 2 ways: Customer installs and maintains the sensor themselves A contractor is hired to perform installation and maintenance What the process looks like Ship device to customer Remotely assist with entire installation process Verify device performance before installation Review site selection options based on defined criteria Closely monitor performance directly after installation On a daily basis, review network performance and flag problematic stations with station owners Actively outreach to station owner, recommending initial troubleshooting and debugging methods based on received data Continue to troubleshoot and debug until the station is working again If needed, ship a replacement device At no extra charge What is needed or included? Monitoring device is included Mounting materials are not included but we do provide standard recommendations on our onboarding manual: RTK GPS and related toolkits are not included, can be arranged by Hohonu Who is expected to do this? The identified Local Point of Contact is expected to: Install the device Physically receive the device and place it outside in the sun to charge Verify performance before it is installed Choose a site that satisfies selection criteria outlined on our manual: Install the device using our recommended procedures If surveying: To use approved equipment or approved vendors to perform the GPS survey, according to IOOS-approved methodology Register the device with Hohonu so that the data can be publicly displayed Be available for ongoing maintenance events Have access to the installation site in case troubleshooting or replacements are needed At what point does the company not provide support any more? Hohonu does not provide further support if: The customer is unresponsive for a non-functioning sensor for a period of 60 days There are no sites in the local area that provide data that meet Hohonu’s data standards In this case, the customer can be refunded
  • How are vertical control standards verified and maintained?
    We collaborate directly with NOAA scientists on best practices for surveying. Link to our surveying best practices documentation is here: The documentation includes multiple standard operating procedures that were developed through a collaborative, multi-institutional hyperlocal water level project led by SECOORA.
  • What is real-world performance like?
    Hohonu has deployed in over 130 locations in 15 states, from Alaska to Florida, and from Hawaii to Maine, in coastal marine, as well as inland lakes, streams, rivers, and reservoirs. Data uptime and quality will vary by site. On a typical day, our newest-generation ultrasonic sensors capture data 98% of the time with 99% passing of QARTOD tests.
  • What are the costs for your instrumentation and services?
    $3000/year per sensor base price (for lowest-cost ultrasonic sensor based model).
  • I'm applying for a grant and want to list Hohonu as a line item. Can you provide a paragraph about Hohonu I can include?
    Absolutely! You can copy and paste the below text. Hohonu provides actionable data and insights to protect communities from future flooding. Hohonu has helped resilient communities across 15 states and 130 locations capture 2 million hours of water level data. You can see all of their active stations on their dashboard as well as their TideCast iOS app . What Makes Hohonu Different With Hohonu, communities don't need to be technical experts to capture, access, understand, and share real-time water level data. They make large-scale deployments possible by making it easy for sensors to be deployed, maintaining scientific rigor for the data to be trusted, and offering different ways for the data to be accessed. Federal Multiple offices within and adjacent to NOAA, including IOOS, Sea Grant, NERRS. We are working with the Southeast office of IOOS to deploy 50+ sensors in communities from Florida to North Carolina. More below. Funding from Senator Schatz's office as part of a grassroots effort to restore Hawaiian fishponds across the state Army Corps for dredging-related monitoring Municipal Municipalities from states that include Florida, South Carolina, Massachusetts, Maine, Washington, California, and more Emergency management, resilience offices, town planners, town administrators Environmental Consulting Firms Woods Hole Group, Moffatt & Nichol, Integral Consulting Nonprofits American Shore and Beach Preservation Association Gulf of Maine Research Institute
  • How do I access TideCast?
    TideCast for Web: TideCast for iOS:
  • How do I navigate the map and view different stations?
    Each pin on the map represents a "location" of predictive and/or real-time water level data. Clicking on a pin will bring up that location's corresponding data.
  • What do the different icons and colors on the map represent?
    Blue pins represent data provided by NOAA. Purple pins represent data provided by Hohonu. The legend at the top right of the map allows you to toggle the location types on/off.
  • Can I search for a station?
    Use the search bar at the top right at the map to search for a location. Clicking on the pin from the search dropdown will bring you to that location.
  • Can I set a station as "home" by default?
    By default, TideCast opens to the location nearest to you. If you'd like for TideCast to default to a different location, click on the button that looks like a house at the top right of the graph in order to set the "home" location. Once set, TideCast will open this location automatically when visiting. Note: You must be logged in to use this feature.
  • Why do some regions seem color-coded?
    Some locations on the map have a "regional view" implemented. The purpose of these regional views is to easily compare nearby locations. If you would like a new region to be set up, please contact us at
  • Can I toggle to Satellite view?
    Use the toggles on the top right of the map to toggle between Street and Satellite view.
  • Can I access different datum's and time periods?
    Use the dropdowns and buttons below the graph to adjust the datum you're viewing as well as the time period. Stations must be installed for at least 35 days in order to view MLLW data Stations must be surveyed in order to view NAVD88 data
  • What do the different lines on the graph represent?
    The lines on the graph follow consistent color schemes with the pins on the map. Blue corresponds to NOAA and Purple corresponds to Hohonu. You can toggle the data types on/off by clicking on the label directly below the graph.
  • How do I download data?
    Contact us at for API and CSV download access
  • How do I set up text alerts?
    Click on the bell button at the top right of the graph Enter your phone number Click on the threshold you'd like to sign up for - you will be texted whenever observed data exceeds the thresholds Agree to the terms Note: You must be logged in to use this feature and the location you're signing up for must have thresholds set up. Contact us at if you are having trouble
  • Can I set up a flood threshold myself?
    Please contact us at if you'd like this feature!
  • How often is data updated?
    Data is updated instantaneously as soon as it receives data from a sensor. Each sensor updates around every 12 minutes.
  • Do you also display flooding and inundation data?
    Flooding and inundation data is displayed for sensors that are installed over land rather than over water. For these sites you will notice that data is displayed in "Flood Depth." Below is an example for an inundation site in Boston.
  • What data sources are you using?
    We primarily show data from NOAA and Hohonu. More coming soon!
  • How do you generate predictions?
    Hohonu's proprietary machine-learning algorithms are used in order to generate predictions at most tidal locations. NOAA's tidal predictions are also included for most tidal locations.
  • Who can I contact for more information or support?
    Please contact us at
  • Can I report bad data to someone?
    Please contact us at
  • Can I see other parameters like moon phase, wind, rain, etc?
    TideCast for iOS includes other parameters such as moon phase, wind, rain, temperature, and more
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