Monitoring and empirical modelling for organic soil subsidence estimation in Sumatra

Abstract

A large area of peat swamp forests has disappeared due to either legally or illegally logging, drainage, agricultural conversion, fire, deforestation or large-scale developments for residential centers and industries. In Indonesia, less than 3% of the remaining forest is protected; the rest is available for logging and conversion to other land uses. Over 93% of the remaining swamp forests in Sumatera had been profoundly degraded. Change the land use to agriculture dramatically changes the characteristics of the peat substrate. Once drained, peat is highly flammable, and the fires can burn for month challenging to extinguish. The peat forest change to agriculture practices and other land use supposed to create short or long-term consequences. One of the consequences is surface degradation due to the oxidation process. A set of field measurements has been conducted using Hobo loggers. The measurement aimed at collecting data about the groundwater level and the soil temperature. The data was gathered within one and half year. The measurements were carried out on two conditions: during dry and wet periods. The difference of the model to other approaches into the measurement of land subsidence rate, this model adapts to the characteristics of the soil, the different temperature and the groundwater level over time as three additional factors that strongly affect to the rate of subsidence. The rate of subsidence in Sumatera varies from 2 to 13 cm per year due to the oxidation processes.