Mapping of drought distribution using the deciles index in Rokan Watershed, Province of Riau, Indonesia

Abstract

Among natural hazards, droughts are known to cause extensive damage and affect a significant number of people. Droughts also have wide impacts across the economy, society, health, and education. This research is expected to be a reference to estimate the existence of droughts. After performing the calculation of drought indices, a drought distribution map was made using a Geographic Information System (GIS). The results showed that the worst drought occurred in 2013 to 2014. The average comparison between the discharge data and the level of decile data of both rain stations is 50%. It is evident that the discharge and decile-level data have good conformity. The result of the analysis, when associated with the incidence of El Nino, has a suitability of 32%, which could be due to other factors that affect rain conditions in the study location. Based on the results of the analysis of the annual trend of rainfall accumulation, the year when climate change initially occurred was in 2003. From 1990 to 2003 the drought distribution conditions tended to be “Dry” to “Very Dry”, whereas from 2003 to 2014 the drought-level distribution conditions were likely to be “Dry” to “Very Dry”.