Heavy rains and extreme weather in recent days have caused massive flooding in a number of areas. Why does Indonesia often flood?

Heavy rains and extreme weather in recent days have caused massive flooding in a number of areas. Last Saturday (6/2/2021), a large flood occurred in Semarang, paralyzing transportation routes in Pantura. Then on Sunday (14/2/2021), it was Nganjuk's turn to be hit by a large flood accompanied by landslides, 23 people were reported missing. Why does Indonesia often flood?

According to BNPB, flooding is one of the three most frequent disasters in Indonesia besides landslides and tornadoes. Almost every day, floods make headlines in online and print media. At the beginning of 2021 alone, the media was shocked by the news of a 2 meter high flood in South Kalimantan which had inundated 7 sub-districts.

Also read: Series of natural disasters in 2021, a sign of the end?

Based on analysis Aqueduct Global Flood Analyzer, Indonesia is among the largest flood-affected population in the world, and is ranked sixth in the world. Every year, 640,000 people in Indonesia are affected by floods. BNPB stated that there were five provinces most prone to flooding, namely West Java, Central Java, East Java, Riua, and North Sumatra.

Floods in Nganjuk (news.detik.com).

Why Does Indonesia Often Flood?

Quoting wri-indonesia.org, there are at least three main factors that are the reasons why floods often hit Indonesia. Much of this is due to human behavior that destroys nature. The three factors are reduced tree cover, extreme weather, and watershed topography (DAS). Without follow-up, this could be the end of the world.

Without trees, the hydrological balance of the watershed will be disturbed. Protected forests can minimize flooding. This is due to the presence of organic matter that makes the soil loose, coupled with the influence of the roots of the pohoh so that water is more easily absorbed into the soil. However, if the tree cover area decreases, it will be difficult for the water to be absorbed and become a flow.

Also read: The History of Jakarta Flood, Occurred Since the Dutch East Indies

Indonesia has two seasons, the rainy season and the dry season. The influence of an unstable climate due to global warming often creates weather anomalies in Indonesia. Rainfall can sometimes be very high during the rainy season (generally it exceeds 100 mm per day). And this has contributed to triggering a flood disaster in most parts of Indonesia.

Finally, the topographical conditions of an area. The steeper the slope, the faster the flow velocity and increase the destructive force when a flash flood occurs. Typically, a sloping slope topography has a natural weir that can hold water to a certain volume. When the natural weir cannot hold it, flood occurs.

Floods in Semarang (Between Photos / Aji Styawan).

Big Flood in Semarang

Almost every heavy rain, Semarang area will surely flood as if there is no solution to overcome it. Semarang conditions are different, the flooding that occurs is a consequence of subsidence or what is commonly called land subsidence. Quoted by Kompas.com, UGM hydrologist, Pramono Hadi, said that Semarang had an emergency flood as a result land subsidence.

Also read: 5 Cities in Indonesia Sinking Due to Global Warming

Four days a week, Semarang is bound to be hit by floods. Conditions can get worse if extreme weather happens for days like yesterday. There is nothing to be done but to revise the spatial layout. According to Pramono, a polder and embankment system that is integrated with an automatic valve or door can be a solution even though it is very expensive, such as PIK 1 and PIK 2 in Jakarta.

Source – 2021-02-16 04:10:42


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