Mapping biogenic gas concentration of Pontian Peatland, Southwest Malaysia with ground penetrating radar

Abstract

In this work, we surveyed the internal structure of peat deposit with ground penetrating radar with the aim of mapping the spatial distribution of biogenic gas produced and accumulated as a bye product of anaerobic decomposition of the deposit. The objective of the work is to identify the spatial distribution of hotspots prone to forest fire due to high concentration of the flammable gas. Four profiles of 20 m each at equidistant separation of 4 m were scanned and the radargrams obtained were processed with reflexw ground penetrating radar (GPR) processing tool. Regions of higher accumulation of biogenic gas were spatially identified based on the effect of the gas concentration on the velocity and amplitude of radar signals. Fractional volumes of the gas were numerically estimated based on complex refractive index model (CRIM). A maximum gas content of 0.1284 was obtained with a mean and variance of 0.05268 and 0.0136, respectively. Cross sectional plots of the spatial distribution of the gas were used to identify regions of anomalously higher gas content and interpreted as hotspot that are prone to forest fire. The area was generally observed to have relatively low level of biogenic gas concentration.