Mapping and modelling of petrophysical and stratigraphic properties of peat soil with ground penetrating radar

Abstract

Peatland’s economic importance and environmental impact have made it attractive to scientific research. Great amount of works were done in studying its petrophysical behaviours. Most of the works are however done with reference to the peatland deposit of the temperate and cold belt region of the Northern Hemisphere. The complex behavior of petrophysical properties of peat soil especially in relation to changes in climatic conditions necessitates the need for extensive research toward understanding the behavior of these properties in relation to tropical climate. In this work, field survey data acquired with ground penetrating radar and laboratory analysis of core samples collected were used to model Ground Penetrating Radar (GPR) data with moisture content for the purpose of developing empirical relationship between the two parameters. A third-order polynomial relation was found to be the best fitting model (R2=0.9657, N=36, P <0.001) with a standard error of 0.0124. The model was used to map the spatial distribution of moisture content of the study area. A texture extraction technique was used to map the biogenic gas content of the deposit based on the effect of the gas on radar image texture and signal parameters. Three regions of high gas concentration were identified with a maximum content of 19.57% recorded at the northwest end of the study area. The regions are therefore considered as forest fire hotspot. Stratigraphic sequences of the peat deposit were also delineated based on signal reflection boundaries. Three major stratigraphic layers were identified and analyzed with core samples. The layers and their mean ash contents are experimentally found to be: Fibric (33.34%) at 0.3-1.2 m depth range, Hemic (3.74%) at 1.2 - 2.6 m depth range and kaolinite clay (20.27%) at 1.7-2.5 m depth range. The work provides bases for the survey of tropical peatland with GPR