Improving Flood Resiliency in Indonesian Cities

Flood events in Indonesia are becoming more frequent due to a combination of climate change, deforestation, urbanisation and sprawl, land subsidence, watershed degradation and poor waste-disposal practices that affect drains and rivers. Low-density sprawl – the result of rapid urban development with only ad hoc planning – coupled with limited investments in flood and drainage infrastructure has resulted in metropolitan areas accounting for about half of all recorded disaster-related fatalities between 2003 and 2017. Climate change effects, such as projected sea level rise, changing precipitation patterns, and more intense storm events, are also expected to exacerbate flood risk in Indonesia’s cities with the number of population exposed to river flooding expected to increase by 74 percent. Projected sea level rise will expose cities even further to coastal flooding. The proportion of Indonesians living in coastal flood hazard zones could increase 73 percent by 2055, with 36 percent of the increase stemming from population growth and 26 percent from the effects of climate change.

To better inform the mapping of proposed interventions and stakeholder-community engagements, Ramboll conducted an array of technical studies and background and multi-hazard risk analyses. Flood hazard and risk assessments, mapping and modelling were also performed, together with the identification of investment options via Cost Benefit Analysis (CBA) and Multi Criteria Analysis (MCA). These activities were rounded out by technical workshops to support the development and verification of urban flood resilience diagnostics.

Working hand in hand with both client and affected communities, we were able to conceptualise integrated urban design solutions and long-term urban flood resilience assessments, and identify priority investment options for selected cities. Assignments such as these endeavour to build local preparedness and to affect action in the mitigation of future flood risk in a fast-developing Indonesia.