Relation of groundwater level and rainfalls in the peat swamp forest, burned peatland and mixed plantation areas of Kampar Peninsula, Riau Province

Abstract

Peatland forest in the Kampar peninsula have converted into various land uses, mainly converted to palm oil plantation. The massive conversion has decreased biodiversity, changed the hydrological cycle, and increased the peatland fire that dramatically decreased the quality of the peatland ecosystem. It is essential to understand the peatland characteristics and its hydrological cycle to develop sustainable peatland management. This study aimed to determine the characteristics of peat soil and the response of groundwater level to rainfall on burned peatland, mixed plantation and primary peat swamp forests in Siak district. The study was conducted from July to December 2018 by using a hydrometeorological station equipped with rainfall and groundwater level sensors. Disturbed and undisturbed soil samples were analyzed to identify the soil characteristics. The response of groundwater level to rainfall was analyzed using simple regression. The results showed that the burned peatland and mixed plantation have increased bulk density, decreased soil porosity, and caused a decrease of water infiltration. Simple regression analysis between the rainfall and the increase of GWL on the primary peat swamp forest resulted in 0.941(P)0.5106 and an R² value 0.6189, meanwhile on the burned peatland resulted in 1.2127(P)0.7818 and an R² value 0.8616, and on the mixed resulted 0.7455 in (P)0.7831 and an R2 = 0.7557.