Soil Physics and the Wise Use of Tropical Peatlands.

Tropical peatlands are increasingly under pressure from agriculture, urbanisation and industry. These human interventions all require drainage of peatlands which are naturally waterlogged. Drainage of peatlands starts the process of soil subsidence. Part of the total subsidence is caused by oxidation resulting in CO₂ emissions to the atmosphere. The hydrology of the Air Hitam Laut watershed in Jambi Province, Sumatra, Indonesia, is modelled with an existing model that combines groundwater and surface water flow. Considerable attention has been given to the collection of input data required by the model including soil physical characteristics, elevation of the watershed, groundwater levels and rainfall data. Model outcome is calibrated and validated using measured groundwater levels at representative sites in the watershed, measured discharge in the Air Hitam Laut river and flooding patterns as deducted from radar images. The eco-hydrological model is used to evaluate the consequences of realistic future scenarios. The study demonstrates a significant relationship between land-use (clearance of forest, agriculture and accompanying drainage) in the upper-catchment of the Air Hitam Laut watershed and the peatland forest ecology downstream, including enhanced drought and increased vulnerability to fires. Soil physical characteristics of peat proofed to be a key factor in describing the functioning of a peatland ecosystem.