20 January 2020
At New Year’s Day 2020, Jakarta has been hit by significant flooding due excessive precipitation amounts. The meteorological organization BMKG recorded precipitation volumes with return periods varying from T=150 to more than 1000 years. For the Jakarta area a flood forecasting system (called J-FEWS) is operated by the hydrological department of Pusair, the hydraulic research and development institute under the ministry of Public Works. The J-FEWS application collects all the available telemetry data (both fluvial and meteo), next to a radar product, various satellite images and meteorological forecasts from ECMWF and GFS.
Unfortunately, the operational forecasting system J-FEWS did not function well. All in all, a real-life situation in which the Indonesian government started to realize the value of early warning, and that more attention to the institutional framework and preparation should be given. This led to renewed attention regarding the use of the system, both as application, but also in terms of dissemination: what to do with a forecast?
Given that for January 10th, again severe rainfall and high tides were expected, Pusair requested Deltares to provide with on-site support on operation and use of the flood forecasting system in this kind of extreme and real-life situations. After formal approval by the Dutch embassy in Indonesia, I catched the first flight and went to Bandung, Indonesia, where Pusair is seated. Luckily, the 2nd flood did not come (yes, a false alarm). I therefore spent my time to evaluate the first flood and the performance of J-FEWS. The flood of January 1st was not forecasted (so a missed alarm) for various reasons. Firstly, J-FEWS was not running properly due to a hard disk error. Secondly, the forecasted rainfall volumes were only half of the actual values. Finally, I could also give recommendations on improving the organization of operational hydrological forecasting.
I did not see any drop of rain during my visit, but got some pictures and an interesting link on twitter from Koos Wieriks (Ministry of Public Works).
All in all, a real-life situation in which the Indonesian government started to realize the value of early warning, and that more attention to the institutional framework and preparation should be given.
Klaas-Jan van Heeringen
Specialist operational water management