Articles | Volume 16, issue 3
Research article
17 Mar 2016
Research article |  | 17 Mar 2016

River flood risk in Jakarta under scenarios of future change

Yus Budiyono, Jeroen C. J. H. Aerts, Daniel Tollenaar, and Philip J. Ward

Abstract. Given the increasing impacts of flooding in Jakarta, methods for assessing current and future flood risk are required. In this paper, we use the Damagescanner-Jakarta risk model to project changes in future river flood risk under scenarios of climate change, land subsidence, and land use change. Damagescanner-Jakarta is a simple flood risk model that estimates flood risk in terms of annual expected damage, based on input maps of flood hazard, exposure, and vulnerability. We estimate baseline flood risk at USD 186 million p.a. Combining all future scenarios, we simulate a median increase in risk of +180 % by 2030. The single driver with the largest contribution to that increase is land subsidence (+126 %). We simulated the impacts of climate change by combining two scenarios of sea level rise with simulations of changes in 1-day extreme precipitation totals from five global climate models (GCMs) forced by the four Representative Concentration Pathways (RCPs). The results are highly uncertain; the median change in risk due to climate change alone by 2030 is a decrease by −46 %, but we simulate an increase in risk under 12 of the 40 GCM–RCP–sea level rise combinations. Hence, we developed probabilistic risk scenarios to account for this uncertainty. If land use change by 2030 takes places according to the official Jakarta Spatial Plan 2030, risk could be reduced by 12 %. However, if land use change in the future continues at the same rate as the last 30 years, large increases in flood risk will take place. Finally, we discuss the relevance of the results for flood risk management in Jakarta.

Short summary
The paper describes a model framework for assessing flood risk in Jakarta under current and future scenarios (2030 and 2050) including climate change, sea level rise, land use change, and land subsidence. The results shows individual impact of future changes and serve as a basis to evaluate adaptation strategies in cities. They also show while the impacts of climate change alone on flood risk in Jakarta are highly uncertain, the combined impacts of all drivers reveal a strong increase in risk.
Final-revised paper