New Publication: Hydrodynamic modelling for flood reduction and climate resilient infrastructure development pathways in Jakarta

Jakarta  is  increasingly  threatened  by  flooding  from  a  combination  of  land  subsidence, rising sea levels (particularly with relation to the spring tide cycle) and higher river levels resulting from increasing  rainfall  intensity  and  land  use  changes  within  the catchment areas. To respond to such challenges in a  manner that is both sustainable and encourages local capacity building,  the  CTCN is  providing  technical  assistance  to  Jakarta,  to  better  assess  flood  risks  and hazards, and to design climate-resilient pathways to reduce the magnitude and scale of the impacts from this flooding. 

The aim of this technical assistance includes the development of:
•    a hydrodynamic  flood  model  that  can  be  used  to  evaluate  a number  of  hard  and  soft  engineering  interventions  to  reduce  the  risk  of  flooding; 
•    a socio-cultural survey to examine inhabitants’ perceptions of flooding, levels of acceptable risks and preferred adaptation options;
•    a series of technology transfer workshops to increase local capacity in high resolution hydrodynamic modelling and use of the model;
•    resultant  policy  and  planning  recommendations  to  reduce  flood  hazards,  risk  and vulnerability; and
•    a roadmap  to  sustain  and  expand  the  project  using  additional  funding streams.

The UNEP-DHI Partnership – Centre on Water and Environment and Jakarta Research Council presents the publication, which describes hydrodynamic modelling for flood reduction and climate resilient infrastructure development pathways in Jakarta. The report's analysis draws the following important conclusions: 

•  The  current  flood  model  setup  generates  reasonable  flood  maps  consistent  with increasing rainfall, tide and subsidence;
•  Current flood maps are validated with other models and surveys on 2007 (~50-year return period) and 2013 (~25-year return period) flood events;
•  Jakarta flooding is  caused  more  by  increased  rainfall  rather  than  tide  and projected sea level rise;
•  Land subsidence significantly worsens the flooding, similar to the findings of previous studies;
•  Further analysis of tidal influence shows that coastal flooding from tides is observed only in future land subsidence scenarios (2025 projected ground levels);
•  If a worst-case climate change scenario is taken into account, i.e. increased rainfall, the study area is almost fully inundated compared to 2007 flood event;
•  The  hydrodynamic  model  also  provides  the  “weak  points”  where  flood  starts  to overflow. This will help to mitigate the flood with different options.