Flood risk of today and tomorrow

Spatial analysis of flood vulnerability in Pontianak City

Abstract

A flood is like a silent killer. Although small floods may appear harmless, they can be deadly when they become massive. For example, the annual damages from flooding in Pontianak, Indonesia reached 30 million dollar in 2015 and could increase to 83.6 million dollar by 2055. To counter these events, we need to assess the vulnerability of a city by making a flood risk map and comparing the current vulnerability state in 2020 and the future vulnerability state in 2050. The present study involved quantitative research using variables and measurements to indicate the vulnerability state of each district of Pontianak. The variables consisted of evacuation route efficiency and sheltering capacity, with these variables representing how easily people can be evacuated and the sufficiency of shelter, respectively. The efficiency of evacuation routes was measured by integration measures from space syntax methods, while sheltering capacity was determined by the data and simple equations. A quadrant diagram was used to record the results of both measurements and present the vulnerability. This research projected the population in 2050 and repeated the measurements to predict future changes. By comparing the flood vulnerability of Pontianak City in 2020 and 2050, this research found that Pontianak City will become more resilient against flooding. The reason for this finding is the implementation of a ring road to Pontianak City. The ring road will significantly improve the evacuation route of the city. Howeover, the capacity rate decreased, which should be addressed as a serious risk.