When we consider the practical application of survey products in the field, we often forget the size and scope of programs like NOAA’s National Geodetic Survey, which has been working to support a variety of activities involving mapping, charting, risk assessment, and transportation needs all over the United States.
One area of concentration that isn’t commonly considered is the NGS’s role in supporting the resilience of coastal communities throughout the country. In response to changes brought on by shifts in climate, measuring and tracking the ecological integrity of our coastlines has become a growing concern over the past few years.
Organizations like the NGS’s Ecosystem and Climate Operations Program use geodetic surveying technologies and equipment to accomplish the important goals before them.
Surface Elevation Tables Give Researchers Vital Tidal Measurements
One of the biggest hurdles to surveyors and researchers tasked with making these measurements is ensuring their instruments are capable of providing accurate water level markings in areas that are particularly unstable such as marshlands and swamps.
To solve this problem, researchers have been using Surface Elevation Tables (SETs), which combine several surveying elements to create both a stable base for secure placement and a highly accurate measurement system capable of recording tidal data to the nearest millimeter.
SETs are held firmly in place by a monument driven deep into the surface. While some researchers track and record ongoing rates of change by referencing their measurements to the monument itself, new technology and a recently expanded system of benchmarks has given others the ability to reference their measurements to common vertical geodetic datums or local datums using tidal benchmarks.
Sectional Rod Monuments Provide Secure Support System Under Unstable Conditions
The accuracy of these SET devices relies entirely on the ability to remain completely stable in difficult terrain. To achieve this, scientists use sectional rod monuments as a benchmark that can be driven deep into the sediment to ensure the SET will be able to provide consistent tidal measurements over a long period of time.
The design of these rod monuments allows for teams to customize the total length of the rods depending on the point of refusal. Simply add sections to the rod until it cannot be driven any deeper––an assurance that the SET will be as stable as possible.
Once in place, the monument can be fitted with the SET’s instrumentation unit, which attaches to the top of the monument in such a way that the orientation and position of the device remains consistent, ensuring any changes in tidal level can be attributed to changes in the marsh rather than shifting positions of the device.
Berntsen’s sectional rod monuments are designed to provide a stable benchmark solution for exactly these kinds of highly precise measurement projects. Consisting of a simple series of rods available in one-foot to five-foot lengths, each rod section is connected with a floating thread for precise alignment.
Available in both 6000 series aluminum as well as 304 series stainless steel, Berntsen’s sectional rod monuments are constructed to withstand virtually any natural condition and can be used in conjunction with a variety of SET instrumentation commonly used by researchers and surveyors alike.
As sea levels continue to rise in many areas of the country, measuring the vulnerability of marsh systems near coastal towns and cities directly impacts the safety of coastal residents by assessing the threats posed by storm surges and other natural dangers. With this in mind, it’s important for researchers, scientists, and surveyors to take advantage of the highest quality surveying equipment available.
If you want to learn more about our selection of Sectional Rod Monuments or have questions about finding the best solution for your survey project, visit Berntsen’s Survey Monument product pages or request a catalog today.
Photo credit: NOAA's National Ocean Service