Andi Eka Sakya: We Must be Alert to the Causes of Flood Points  

TEMPO.CO, Jakarta - The rainy season has arrived but yet to reach its peak. Nonetheless, a number of areas have already been inundated. The worst area affected by the bad weather is Manado in North Sulawesi. On January 15, 2014, heavy rainfall that reached 185 cubic meters per second had caused havoc on the Sawangan and Tondano rivers, which were supposed to catch rainwater. Instead of ctahcing rain water, the rivers killed 13 people.

Chief of the Meteorology, Climatology and Geophysics Agency (BMKG) Andi Eka Sakya, said that the flood that occurred in Manado was a result of the weather anomaly, which caused by either a depression or a tropical storm pressure in Mindanao, southern Philippines.

"Usually, low pressure in the Philippines should be affecting us. This is rare," Andi explained. He remembered the rainfall in Manado last year was 10 cubic meters per second. 

Andi predicted that rainfall will remain high until February 2014. Almost 50 percent of Indonesia will be cloudy, while offshore areas of Sumatra, Kalimantan, Java and even Southern Sulawesi and Ambon will see 3 to 4 meters of high tide. Fortunately, a tropical storm is not predicted to enter Indonesia, because such storms tend to move away from tropical latitudes, where Indonesia is located.

Last week, Andi sat down with Tempo reporters Nugroho Dewanto and Heru Triyono for an interview in his office in Central Jakarta.

At the start of the rainy season there is usually no low pressure in the northern area. Yet, this is now happening? What does this mean? 

This is a weather anomaly, slightly different from the usual. The depression or low pressure is a result of the tropical storm in Mindanao and southern Philippines. Normally, when this happens, we don't get affected or rarely.

Yet, because of this weather anomaly Manado has been heavily flooded. 

Yes. The depression has created cloud formations containing huge rainfall over Manado, at the rate of 185 cubic meters per second. Yet the previous year, during the same period, the rain only fell at 10 cubic meters per second.

Could this be a residual impact of tropical storm Haiyan in the Philippines? 

No. This is a depression, which sucks air from its surroundings to become cloud formations. It can be quite worrying viewed from a satellite. The cloud is very thick. This is different from when it happened in 2001: heavy rainfall but not as bad as this.

Do such weather anomalies occur in yearly cycles?

It's unpredictable. What is certain, this is also linked to the warming of the sea north of Papua, which triggered the depression.

The cloud depression points besides those in the north such as over Manado where else is it happening?

Nowhere else. There are some in the southern areas, but very far away. So it would not affect Indonesia.

What about Jakarta? Is the sky over Jakarta affected by the depression?

Clouds over Jakarta are also thick. According to our observation, on January 8 rainfall in Jakarta was 574 cubic meters per second. Then on January 10 and 11, the rainfall was about 571 cubic meters per second and 674 cubic meters per second, respectively. This is high.

What about compared to last year's rainfall?

Last year rainfall was even higher. On January 17, 2013, it reached 1,300 cubic meters per second. That means five times the water from the Brantas River flowing into Jakarta.

If rainfall this year is lower and reparations have been done on river banks and weirs, why is Jakarta still flooding? 

When water descends on earth, it goes through three processes: it evaporates, it gets absorbed and it flows. Evaporation rarely happens in Indonesia, except in very hot weather. So, there are only two possibilities: it is absorbed and it flows. Absorption depends on open spaces. Flowing depends on rivers and how water drains are managed.

Can the Jakarta land surface absorb high rainfall? 

What I know, Jakarta can only absorb 20 percent of water. This means if 1 liter of water falls on 1 square meter of land, only 0.2 liters of it will be absorbed. The rest will flow. Where? Well, through drains, ditches and rivers.

The complete version of this interview can be read in this week's edition of Tempo English magazine.