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Ultrasonic vs. Radar: What You Need to Know
- Kevin Mukai
- 4 days ago
- 5 min read
How to choose between Hohonu's 2 water monitoring sensor technologies, balancing budget and reliability
Hohonu offers both ultrasonic and radar technologies, with both having strong merits in including for the design of a water level monitoring sensor network.
Both sensor types use non-contact technology to measure water level from above the surface, transmit data in real time, and require no charging or maintenance. But depending on your environment, one may deliver more consistent results when conditions get tough.
At a Glance: Ultrasonic vs. Radar
The difference lies in how they measure and how they perform under different environmental conditions.
Feature | Ultrasonic Sensor | Radar Sensor |
Annual Cost | $3,000 / yearIncludes hardware and software (excluding labor) | $6,000 / yearIncludes hardware and software (excluding labor) |
How It Works | Measures distance using sound waves | Measures distance using radio waves |
Ideal Use Cases | Stable, predictable environments — e.g., inland stormwater basins, retention ponds, and sheltered tidal creeks | Challenging environments — e.g., coastal zones, bridges, flood-prone areas, or anywhere exposed to high wind, rain, or salt spray |
Weather Performance | Very accurate in calm conditions, but readings can become noisy in wind or rain | Performs reliably in all weather — unaffected by wind, rain, fog, or spray |
Reliability During Storms | May experience “noisy” data | Maintains continuous, accurate readings through storms and extreme events |
Maintenance | Maintenance-free; shares mounting materials and power setup with radar | Maintenance-free; shares mounting materials and power setup with ultrasonic |
Detection Range | 0.5 – 10 m | 0.5 – 20 m |
Sampling & Transmission | Averaged sampling every 30 seconds, transmitted every 4-12 minutes | Averaged sampling every 3 minutes, transmitted every 4-12 minutes |
Best For | Building cost-efficient, high-density networks where conditions are moderate | Ensuring uninterrupted, storm-proof data at high-priority or critical sites |
How They Work
Hohonu outfits trusted, industry-standard ultrasonic and radar sensors with its own proprietary, integrated hardware and firmware designs, so that both sensor types are:
Physically installed in the same way i.e. don't require different mounting materials
Digitally integrated into the cloud in the same way i.e. don't require any additional technical or engineering resources
Ultrasonic sensors are "temperature-compensated," meaning that they are highly accurate in most conditions but readings can be negatively impacted by noise in its line of sight such as water (e.g. heavy winds causing sideways rain, or wave action)
Radar sensors use electromagnetic radio waves, and are materially less impacted in noisy weather environments.
Ultrasonic Spec Sheet
Radar Spec Sheet
Which One Is Right for Your Site?
If you most care about high-quality data during intense conditions, radars can often be a worthwhile investment in order to maximize success during a weather event: particularly environments either on the coast and/or susceptible to high winds
If you’re uncertain about which sensor to choose, and/or your current budget doesn't allow for it, many customers start with ultrasonic for broader coverage and add radar sensors at high-priority or storm-exposed locations.
If you care most about... | Then choose... | Why |
Consistent data during storms, hurricanes, or high wind events | Radar | Performs reliably in turbulent, fast-changing conditions and maintains accuracy when ultrasonic signals can be disrupted. |
Day-to-day monitoring of tides in open ocean environments | Radar | Same as above |
Day-to-day monitoring in calm, predictable environments | Ultrasonic | Highly accurate and cost-effective for stable environments where extreme weather isn’t the primary concern. Offers excellent performance for ponds, culverts, and sheltered channels where environmental interference is minimal. |
Expanding coverage across a large number of sites on a limited budget | Ultrasonic | Ideal for building a high-density network of reliable sensors with predictable conditions and minimal maintenance. |
Balancing budget and performance | Start with Ultrasonic, upgrade to Radar as needs grow | Many communities deploy ultrasonics first, then upgrade select sites to radar once they see how conditions perform. Hohonu makes that transition seamless. |
A Practical Note on Budget and Reliability
We understand that not every community has the same resources.
If your goal is to establish a reliable monitoring baseline, starting with ultrasonic sensors is a perfectly sound choice. You’ll still gain accurate, day-to-day water level data across your network.
But if you’re relying on sensors to make critical decisions — for road closures, flood alerts, or emergency management — then radar becomes a worthwhile investment. It’s designed to deliver continuous, storm-proof data when it matters most.
Because Hohonu supports both models on the same platform, you can start with ultrasonics and upgrade any site to radar later — no retraining, mounting changes, or software changes required.
Performance in the Real World
Ultrasonic sensors are for stable days. Radar sensors are for storm days.
Ultrasonic data example - stable day-to-day but challenges during storms
When monitoring in stable, protected environments, ultrasonics perform very well. Below is an example of a Hohonu sensor measuring tides up an estuary in South Carolina.
An ultrasonic's performance could degrade in chaotic environments such as during a storm. Below is an example of how data in Surf City, NC looked stable before and after Hurricane Idalia. If you had needed to depend on this site in real-time and/or wanted to understand the high water mark during a post-storm analysis, the ultrasonic sensor did not perform as you may have hoped.
Radar example - reliable data even during a tornado
Radar sensors have a higher probability of withstanding challenging conditions, such as hurricanes and storms, as compared to ultrasonic sensors. Below is video footage of a Florida DOT webcam capturing a tornado hitting Matlacha Bridge during Hurricane Milton in October 2024.
During tornado conditions that exceeded 100mph, Hohonu's radar sensor continued to capture data in real-time that included the high water mark at the peak of the storm.
Elsewhere in Lee County, a radar sensor at New Pass Bridge seamlessly captured the high water mark from both Hurricane Helene and Milton over a 2-week period.
Price vs. Value
At first glance, radar’s higher price point—typically around $6,000 per year compared to $3,000 for ultrasonic—might seem like a significant difference. But it is important to consider the total value of the data:
Radar sensors will have:
Fewer gaps during critical storms mean complete datasets for modeling and decision-making.
Fewer maintenance visits that save labor and travel costs.
More reliable data that increases confidence for public reporting, funding justification, and risk planning.
Losing data during a storm can cost far more than the price difference between sensors. Many customers treat radar as an insurance policy for their data continuity.
Mixing and Matching: Flexibility Under One Roof
One of the advantages of choosing Hohonu is that you don’t have to choose ultrasonic or radar forever. You can deploy both.
“It just made sense to keep everything under one system. When we expand or upgrade, we know all our sensors will talk to each other.”
With Hohonu, upgrading an ultrasonic site to radar is straightforward. The same mounting hardware and telemetry apply, so you can adapt as your needs evolve—without new procurement cycles or dashboard changes.
Choosing between ultrasonic and radar doesn’t have to be a permanent decision. What’s important is designing a network that’s resilient and scalable:
Start with ultrasonics for coverage and affordability.
Add radars for high-priority or high-exposure sites.
Keep all your data unified through Hohonu’s dashboard, alerts, and APIs.
As your monitoring goals expand, your network can grow without fragmentation or retraining. That flexibility is why more communities are standardizing on Hohonu for their long-term flood-monitoring strategy.
Talk with our team about your site conditions, and we’ll help you design a sensor network that fits your environment, budget, and resilience goals.