Application of electrical resistivity test to estimate carbon storage of tropical peat deposit (Case study of Bengkalis island)

Department of Civil Engineering, Universitas Riau, Pekanbaru, Indonesia

^* Corresponding author: m.yusa@eng.unri.ac.id

Abstract

Indonesia has approximately 21 million hectares (ha) of tropical peat land, equivalent to 80% of peat deposit in Southeast Asia. It was estimated that Indonesia has 1.5 Giga tonne of carbon stock. However the estimation is still rough because there was no calculation of volume yet. This study explain the use the geophysical method of electrical resistivity test (ERT) combined with real time kinematic (RTK) and laboratory test to estimate the volume of peat deposit. Direct boring was also done to verify the ERT results. The location of study is in Bengkalis Island, Riau-Indonesia. Twelve (12) locations of ERT has been conducted covering area of 127164.667 ha. Visual observation from boring sample reveal that the peat in generally are fibric to hemic or H2-H6 according to Von Post classification. The peat layer has resistivity value range between 20-150 ohm meter. In general the peat can be classified as very deep peat with average thickness of 6.4 m. The ERT revealed that average lateral variability of peat thickness electrode line is less than 0.6 m. The estimated peat volume is 6803206275.152 m³. The average ash content is 6.5% which equivalent to 53.9% of carbon content. The average bulk density is 0.09 tonne/m³. It was estimated the carbon sink of the location is 330023536.41 tonnes which equivalent to 2595.3 tonne/ha.