An Analysis of Extreme Rainfall Trends from 1960 to 2015 in Urban Areas of Surabaya

Abstract

Extreme rainfall event considered as the primary cause of many hydrometeorological disasters around the world. Extreme rainfall event propagated more prolonged disaster when occurring in urbanised areas. This research presents an analysis of trend and rainfall variability in the most urbanised areas of East Java. The study is conducted at Surabaya City and its sub-urban areas (Mojokerto, Sidoarjo). Daily rainfall data from 1960 to 2015 obtained from existing measurement sites are used as input for this study. Firstly, a frequency distribution of extreme rainfalls (1-day maximum) is presented. Then, analysis of trend detection conducted using Mann-Kendall, Rank-Sum and Median Crossing test. Finally, spatial variability of extreme rainfall was presented by interpolating point measurement to produce thematics maps. The interpolation was conducted using IDW methods. The results show the trend and variability (temporal and spatial) of extreme rainfalls on the regions of Surabaya.