Spatio-temporal rainfall variability of equatorial small island: case study Bintan Island, Indonesia

Abstract

The water resources of Bintan Island depend much on rainfall since the impervious granitic basement that bears a low water storage capacity dominates the geology of Bintan Island. Water demand in Bintan is increasing due to both population and economic growth. This paper aims to determine the spatial and temporal rainfall variability over Bintan Island using the daily corrected-CHIRPS (Climate Hazards Group InfraRed Precipitation with Station data) version two (v2.0) dataset to a ground-based observation dataset (Kijang station) using quantile-base bias correction for period 1 January 1981–31 August 2018. For the analysis process, we used monthly corrected-CHIRPS, NINO 3.4 anomaly index, the DMI (dipole mode index), zonal and meridional wind, and specific humidity from January 1981 to December 2017. Semi-annual, annual, and interannual variations influence monthly rainfall amounts over the island. Two peaks representing equatorial and monsoonal patterns characterize the temporal variability of rainfall. Spatially, the southern part of the island receives more rainfall than the northern part especially in MAM and SON related to the more convergence of moisture. The effects of interannual variation, ENSO (El Niño-Southern Oscillation) and IOD (Indian Ocean dipole), vary with season. ENSO contributes more to rainfall variability than IOD during the period of study.