Groundwater Flow Analysis at Coastal Peatland Area of Bengkalis Island Using Paper Disk Velocimeter (PDV)

Abstract

Bengkalis Island is an island with about 89% of its land area consisting of peatlands. Because of the land use conversion from peat swamp forest to plantation and shrubs, the island has experienced massive degradation, such as abrasion, subsidence and land fires. The abrasion at western area of Bengkalis Island has occurred since the last 30 years with an abrasion rate up to 30 m/year. The previous studies showed that this is because of unbalanced hydrological conditions. The more advanced research related to groundwater flow impact on degraded peatland in Bengkalis Island is important in order to understand the mitigation alternative. To study the groundwater flow on the peat coast of Bengkalis Island, this study used Paper Disk Velocimeter (PDV) for measuring at 2 monitoring wells. The measurements were carried out at a depth of 2 m and 5.5 m and a depth of 2 m, 3 m and 4 m for Well-1 and Well-2 respectively. All measurements were carried out for 3 times on different month. This research found that the groundwater slope dropped significantly near the coastal line. This made the groundwater discharge to the coastal area become higher that may cause failure on the coastal cliff. The failure was identified as the initial phenomenon of the abrasion mechanism in the Bengkalis coast.