Uji Plagiasi_Water Table Variability and Flow Response of Tropical Peatland_A Case Study

Abstract

Peatland is a type of soil that characterized by high water content. The use of peatlands, especially for agriculture and plantations is carried out by channel to control the water table level such that the water content in the root zone is in accordance by the variety of plant. Water table on drained peatlands will have a decline in groundwater level to a certain depth. Excessive continuous water table decreasing through below the surface of the land which occurs continuously can create irreversible dryness that causes land subsidence and increase the risk of fire . The study aims to observe characteristics of water table level in the rainy season due to the construction of canal networks on peatlands. The study was conducted in Pulau Padang Riau Province of Indonesia which is a drained peatland that has been developed for industrial crop cultivation. The land is managed by two different groups; those maintained by the local community and those by private companies. The analysis was carried out by using a balance of water budget on peatland specifically by calculating the dynamic interaction of the hydrological parameters of land and channels flow. The results showed that the condition of water table elevation had changed during the period of data collection. The rainfall transformed quickly into overland flow and direct runoff. The decrease in the water table on local community management areas is higher than that occurring in companies land with a variety in the value of the up and down is greater. This phenomenon occurs because there are no canal blocks on the peatland, which is managed by the local community so that the rise and fall of the water surface occur naturally. In addition, since it is located in the downstream area, the state of the flow will be influenced by the flow in the upstream. When the upstream flow is retained, hence no current flows to the downstream, and as a result, the water table level continues to decrease.