When a flood comes, what can we do?

When a heavy rainstorm struck Jakarta, last month, the Indonesian capital’s ability to function literally went down the drain. For more than a week after, 250,000 people out of its population of over 10 million were either directly or indirectly affected by the flooding
which followed.

Jakarta is not the only city in Southeast Asia to suffer from flooding ? just last year Thailand’s capital, Bangkok, suffered the same fate too. And from these consecutive events, many have been left counting the real economic damage to countries who suffer such disasters.

Recently, JST had an opportunity to speak with Dr. Manabu D. Yamanaka of the Japan Agency for Marine-Earth Science and Technology (JAMSTEC) about the flood in Jakarta and the circumstances around it.

JST: I recently read reports stating that the BPPT (Indonesia’s Agency for Assessment and Application of Technology) used cloud-seeding technologies to stop the expansion of flooding in Jakarta. How does this work? And does it work?

Dr. Yamanaka: There is a special unit within BPPT called UPTHB. They are the ones who are responsible for this project. The unit was born during the 1970s when so-called “artificial rainmaking (or cloud seeding)” became a sort of boom in the U.S., Europe, and Japan. Back then, they used dry ice to change atmospheric temperature, or silver iodide to accelerate the growth of raindrops from cloud droplets. What they were trying to do was make the rain fall over the ocean before the clouds passed over land, or even guided those clouds to drought areas.

However, their attempts most likely failed because there are too many factors involved in natural phenomena and it turned out that their experiments caused even more unpredictable conditions. For example, during the 1980s in the U.S., this method were used on a hurricane but it actually brought about reverse result ? the hurricane actually got bigger and caused more damage. Also, during the same period in the Soviet Union, the method was introduced for areas with drought, but, in reverse, almost all it did was lead to an acceleration of desertification in central Asia. In the end, the prevailing scientific opinion was that we are better off leaving these things to nature.

JST: But in the case of Jakarta’s flooding, it has been used?

Dr. Yamanaka: Yes, In Asian countries such as China, Thailand, and Indonesia it is still used. A very public example of this was when cloud-seeding was used in Beijing in the lead-up to the Olympics in 2008.

In Indonesia, the UPTHB exists for the purpose of helping semi-drought areas. The researchers who work in this field are experts who studied and achieved degrees for cloud physics and radar. So they know the limit of the methods, but they do what they do because they need to get budgets approved for related studies.

JST: First in Bangkok, then in Jakarta ? How hard is flooding to predict? And how can it be prevented?

Dr. Yamanaka: Under international collaborations with us, BPPT has developed the data mapping system called “SIJAMPANG” which projects rainfall in real time based on data from radars on the internet. This helps them predict and prepare for flooding. The Indonesian agency for disaster prevention, BNPB, uses the SIJAMPANG rainfall map on a large display. The biggest change is the government could control all real-time information by itself. So they could prevent the society from being confused by hoax. Of course, it does not reach any goal yet. We still need to improve drain systems in the city.

To prevent flood or drought, it is necessary to grasp both climatological and geographical data. Some of the indicators are very biased towards anthropogenic activities and geographical features. For example, it took a couple of months for the land to dry out in Thailand after their flood last year because the area was so flat. In Jakarta on the other hand, when they had similar floods in 2007, it took only a week to dry because of the steeper incline the city sits on. Since then, an improved irrigation system funded by the Japanese government was installed and this time it took only a day for Jakarta to dry out because of that.

Having said that, I’d like to emphasize that the latest flood in Jakarta was the first time its cause – the rainfall was monitored 100% by the radar system, so more prevention options were available. That is one of our research project’s goals.

About Dr. Yamanaka:

Dr. Yamanaka is the leader of a project under the JST/JICA joint research program called “SATREPS”. His project is “Climate Variability Study and Societal Application through the Indonesia-Japan Maritime Continent COE – Radar-Buoy Network Optimization for Rainfall Prediction”. This project’s goal is to promote the creation of a climate observation network on both land and sea, including improved radar observation techniques for monitoring clouds and rainfall. As a “Maritime Continent”, the Indonesian Archipelago plays a role as a dam on the warm water flowing between the Pacific Ocean and the Indian Ocean, resulting in the world’s largest cloud activity and rainfall. In effect, it is pumping the warm, humid air upward and pole-ward, like a heart for global atmospheric circulation. Dr. Yamanaka and his research team have the task of researching this complex system.

Sumber: Masahito YANO, Friends of SATREPS –  http://www.jst.go.jp/global/english/kadai/h2104_indonesia.html