Mapping drought risk in Indonesia related to El-Niño hazard

This work is aimed to identify areas in the country that are at high propensity to the impact of global climate phenomenon i.e. El-Nino. An affected area is recognized when rainfall decreases up to below normal condition which frequently leads drought event. For this purpose, two packages of gridded rainfall data at monthly basis with 0.5 spatial resolutions for 1950 2010 period were used, e.g. GPCC Full Data Reanalysis V.6 (product of Global Precipitation Climatology Centre) and CRU TS3.22 (product of Climatic Research Unit). El-Nino years were labelled based on Oceanic Nino Index, ONI. We applied frequency analysis to quantify the chance of El-Nino impact. GPCC data was found more accurate in representing rainfall observation than CRU data based on correlation test against station data. The results indicate the strong spatial and temporal dependencies of El-Nino impact. During peak of rainy and first transitional season (DJF and MAM), the probability to be affected by El-Nino is mostly less than 20% over whole country In contrast, July-October are months where areas with high and very high risk were observed over many regions such as Southern part of Sumatera, Java, Kalimantan, Sulawesi, Maluku and Papua. Further investigation at province level found that the timing of El-Nino impact starts in June. These results are potential to improve national capacity in risk management related to weather-climate hazards.