#2 - The importance of accurate spatial data

Environmental data by its very nature consists of two key elements. The first is the attribute that has been measured. This could be a groundwater level, an analytical chemical result from a soil sample or the species of a plant. The second key element is that of the location of the measurement. Either data is meaningless without it's corresponding element.

Key decisions in any project revolve around the attribute and its location. Project boundaries are amended to stay out of sensitive vegetation or wildlife areas, excavation of material is based on knowing where the contaminant is and is not. Downstream activities are amended based on calculated groundwater flow directions. All these project outcomes are dependent on accurate spatial data. Think about how much money could be wasted making a poor decision on an excavation boundary based on the location of analytical data that might be several meters out, or the cost to redesign the right of way of an access road because of a poorly mapped boundary.

As a client, one question I would always ask my consultant is "How do you determine the spatial location of the data?" Listen carefully to the answer as it will provide you valuable insight as to the level of professionalism and care that your consultant provides. Historically, accurate spatial data was difficult and expensive to collect. Survey companies were the only choice and were often out of reach for most environmental project budgets. The environmental industry adapted and solutions were implemented that were acceptable at the time. This included use of measuring wheels and tapes, survey levels and rods, and the old standby of "guesstimating" on a sketch.

With the introduction of personal GPS units in the early 2000's, spatial data collection improved somewhat, but with the inherent positional errors of the system reducing accuracy to that of several meters, once again, only surveyors with expensive base stations and access to survey benchmarks could effectively employ GPS.

Within the last few years though, there has been an evolution in the survey industry and GPS technology. The new term is GNSS (global navigational satellite systems) reflects the introduction of several new constellations of navigational data providers. The Russians have GLOSNASS, China's BeiDou and the European Union's Galileo. Modern GNSS receivers can used data from some or all of these providers thus increasing accuracy. Ground based correction systems such as the FAA WAAS (Wide Area Augmentation System) can further enhance accuracy. Lastly, the development and implementation of Continuous Operating Reference Stations (CORS) can provide real time kinetic corrections to GNSS receivers and record satellite observation data so surveys can be post-corrected if RTK is not available at the project site.

As the demand for accurate spatial data increases (self driving vehicles, trackers etc.), the cost of entry into highly accurate survey equipment continues to decrease. Environmental consultants and service providers should have no excuse these days for not providing highly accurate spatial data. GNSS manufacturers such as Juniper Systems and others provide sub-meter accurate receivers that are relatively inexpensive. These sensors when coupled with field data collection apps such as ESRI Survey123 or OnPoz Cloud / Collect provide powerful and accurate data collection. To achieve centimeter accuracy, Emlid provides a suite of GNSS receivers and accompanying processing software which is quite affordable to even the small consulting companies. These systems are relatively easy to use and the processing of the data straightforward and simple. And if you need help, like most things these days, just look for a solution on YouTube.

So if your consultant isn't using the right survey equipment to get at least sub-meter accurate spatial data, it might be time to find a company that is as interested in the spatial location of the data as they are of the attribute. As a client, the end result is a better project outcome.