Assessment of the hydrological condition of raised peat bog systems

Assessment of the hydrological condition of raised peat bog systems using differential GPS to acquire high quality topographic data.

Dennis Sinnott is employed as a research member of staff at the University of Central Lancashire's Department of Environmental Management. He is part of a small team working on the conservation of wetlands. An important element of this work involves developing the use of GPS to help evaluate past damage to the self-sustaining hydrology of raised peat bogs.

Raised peat bog systems are considered a rare and valued habitat globally, having often been compromised by threats such as peat extraction for fuel or horticultural use and drainage for agriculture.

The work involves carrying out a topographical and hydrological survey of a site. Such topographic surveys using conventional techniques were difficult and time-consuming given the large and remote areas sometimes involved, the nature of the vegetation cover and the difficulty in establishing fixed stations in peaty terrain. To react to this an innovative approach that uses a differential GPS to create survey-quality data has been adopted.

The data was subject to post-processed differential correction (DGPS) for further accuracy. Positions were computed using carrier phase data at the local receiver and from the reference stations. The purpose of this DGPS survey was to evaluate the relationships between the patterns of topography, artificial drainage and the water table.

The data were used to compute representations of the profiles of the water table, at the time of the survey, and topography across the raised bogs and peripheral zones. Field notes of any key features, made at individual survey points, were subsequently plotted onto the profiles using their National Grid references.

Results enable valuable understanding of hydrological functions, which provides for highly informed evaluation of the quality of a site. These data also allow identification and assessment of past damage, and threat of damage, to the raised water table. This provides for highly informed recommendations to be made for the hydrological restoration and conservation of these wetland habitats.