Investigating water distribution in the Luitel Lake peat bog using MRS, ERT and GPR

Abstract

ABSTRACTIn this paper we present the results of a geophysical study of water distribution in the peat bog at Luitel Lake. The goal of the study was to determine water distribution within the bog, which is part of a protected nature preserve. The small peat bog (17 ha) provides a good test site for developing and testing surface geophysical methods. For this study we used magnetic resonance sounding (MRS), electrical resistivity tomography (ERT) and ground‐penetrating radar (GPR). Because the water distribution in the bog is a 2D target for MRS, we had to develop a measuring procedure and 2D inversion routine for MRS. The fieldwork consisted in establishing seventeen MRS stations and conducting three ERT profiles and one GPR line. The MRS, ERT and GPR results on the reservoir geometry correlated well with each other. Pine and birch trees cover most of the bog surface but they have not yet populated the centre of the bog, the location where the maximum water content was observed. This result agrees well with vegetation distribution in the study area: at the centre of the bog, vegetation is typical of a swampy environment but outside the centre the vegetation is typical of a forest. According to MRS, the water content of the peat formation at the centre of the bog is 60–70%, whereas GPR estimated the water content to be between 64–70%. Outside the centre, MRS showed the water content of the peat to be about 30%.