Subsidence of peat soils the tidal swamplands of Barambai, South Kalimantan

Large-scale reclamation of tropical peats in tidal swamplands areas for agriculture through the installation of irrigation-drainage system has been carried by the Department of Public Works since 1970. One of the effects of such a scheme is subsidence, or the decrease in the level of the peat layer. In general subsidence can be both advantageous and disadvantageous. It has favorable effects in deep peats because it renders the soil more suitable for agriculture as long as good water management is maintaned. In contrast subsidence has a detrimental effect in soil having a thin a shallow peat layer. Even in their natural state such soils can already be use for agricultural purposes, therefore subsidence will only lead to their degradation. It is in the latter soils where subsidence must be controlled to preserve the soil organic matter. On these consideration studies on the rate of subsidence and its impacts on the characteristic and quality of peat soils are important. Their implication in land use planning and development specially at the initial phase one equally of great significant. In this paper the rate of subsidence and the processes controlling it are discussed and the case studied area is South and Central Kalimantan