Satellite based ground motion surveys
for environmental safety and security
Satellite based ground motion surveys
for environmental safety and security
Land Motion Surveys for Environmental Safety and Security
Baseline Field Survey
What is the Baseline Field Survey?
Before the restoration activities have begun, a baseline field survey is needed to confirm the eligibility of the site, the pre-restoration water table depth (WTD) and the condition of the peat. The data gathered will also be used to calibrate the satellite observations.
The activities of this survey are primarily based upon gathering enough samples to confirm what is already known about the site, rather than to act to definitively survey the site from scratch.
Activities for the Baseline Field Survey
Locate Survey Points
Survey point locations are position where the activities, such as measuring past depth etc., will be applied across the site. In order to maintain some statistical independence, these should be at random locations across the site but, clearly, not at any position where samples are unlikely to be made, where access is not permitted or where there is some hazard or risk to the surveyor.
The number of points to use should be statistically significant and depends on the accuracy of the maps of the condition and peat depth available. A useful guide to how many points (samples) to use is given in Rosenfield et al., 1982, which is reproduced below.
*Rosenfeld et al., 1982, Sampling for Thematic Map Accuracy Testing, PE & RS,48(1), pp.131-137
Measuring Peat Depth
Peat depth needs to be measured at the survey points, but only to confirm that the location is in an area of deep peat (usually greater than 40cm deep). Thus, precise measurement is not required.
Measurement can best be performed using Peat Probes which are very effective and easy to use.
If a full peat depth survey has already been undertaken of the site following recognised procedures, such as those proposed by Peatland Action, then this step is unlikely to be necessary.
Measuring Annual Water Table Depth
Water table depth (WTD) requires measurement at the survey points to confirm eligibility and to calibrate the satellite measurements. It can be measured several ways, using dip wells, rust rods or peat cameras, for example.
Importantly, WTD needs to be measured several times a year as the main parameter that we need to calculate is the annual WTD, which is the average of all observations over the course of the year. A permanent installation, such as a peat camera, will be making measurements very frequently but the digital measurements still have to be collected in the field, albeit infrequently. For more manual methods, such as using dip wells and rust rods, the locations will need to be re-visited at least four times per year and the measurements made in the field.
Identifying Ineligible Peat Categories
Ineligible areas of peat include modified peat, fens and flushes and areas of peat that are consolidated or shrinking. For the baseline survey, we assume that the general location of such categories are known and that we are providing further information to ensure that the net project area is free of such classes. Therefore, we expect that the survey will look for signs in the field of, for example, bare peat, grazing, fires, scrub etc. We would expect that signs would be supported by photographs and reports.
A good example of this sort of assessment is provided by Peatland Action.
Identifying Peat Condition
Peat condition at the survey points can be ascertained using a number of approaches and methodologies, most of which rely on good observations of general landscape features.
The features to be reported on include:
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Hydrology (e.g. the water levels in ditches)
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Peat structure, such as wetness under foot, the bounciness of the peat and the 'humification' (how much is is rotting)
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The condition of management structures such as dams, bunds and boardwalks
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Inspection of natural site features such as pools and plant communities
Surveys like this will be repeated frequently as a part of the monitoring survey, so the use of digital technology such as smartphones to collect time- and geo-tagged pictures and panoramic views from the same locations each time will be necessary.
There are a number of academic and institutional groups that have written some good guides on the collection of field data over peatlands. For example: Eyes on the Bog, Defra Report.
The Peatland Protocol Field App
The Peatland Protocol team are developing a field app for the collection of data using a smartphone or tablet mobile device. The app will be easy to use and facilitate the collection of data and the GPS location of waypoints. Furthermore, it will allow the automatic download of data into the Peatland Protocol data environment.