Flooding in Central Java: Time is Running Out, Coastal Cities are Sinking


The Occurence

Nine regencies/cities in Central Java were affected by the disaster due to heavy rains that fell on Sunday (6/11/2022) afternoon and evening. The disaster, which consisted of floods, landslides, and strong winds, did not result in injuries or lives, but caused damage to buildings and infrastructure.

Based on the records of the Central Java Regional Disaster Management Agency, the nine disaster-affected areas include Cilacap, Kebumen, Pekalongan, Kendal, Grobogan, Batang, Jepara, Demak, and the City of Semarang.

In Cilacap Regency, the disaster that occurred due to heavy rains on Sunday was flooding in five villages in Kroya District. The people affected by the flood were 2,718 people. Of that number, 37 people took refuge in the homes of relatives or relatives.

Meanwhile, in Kebumen Regency, there were three natural disasters that occurred due to heavy rains that fell on Sunday evening, namely floods, landslides, and strong winds.

In that area, floods inundated five sub-districts, landslides occurred in three sub-districts, and strong winds occurred in one sub-district. As a result of the landslide, 36 houses were damaged. A number of village roads, coastal tourism objects, and fish auction sites were also covered by landslides.

In Pekalongan Regency, strong winds hit the Kajen District. A number of buildings in the administrative center of Pekalongan Regency were lightly to moderately damaged by falling trees. Damage to buildings was reported at the offices of the Pekalongan Regional Secretariat, Pekalongan Resort Police, Pekalongan Health Service, Pekalongan Tourism Office, Pekalongan Bappeda, Pekalongan DPRD Secretariat, and the trade office.

Strong winds also hit three other districts in Central Java, namely Batang, Jepara, and Demak. In Batang, strong winds damaged 17 houses and slightly damaged one house. Meanwhile, in Jepara and Demak as many as 37 houses and one mosque were damaged by strong winds.

In the city of Semarang, the disasters that occurred included floods and landslides. Floods occurred in Mangkang Wetan Village in Tugu District and Wonosari Village and Tambakaji Village in Ngaliyan District. Meanwhile, a landslide occurred in Bambankerep Village, Ngaliyan.

The Causes

Flooding in Mangkakang Wetan Village was caused by an open embankment measuring 12 meters. The open embankment is an unfinished embankment construction project. The flood level in Mangkang Wetan is 20-50 cm. In Ngaliyan District, flooding is caused by runoff of water in the river due to heavy rains. As a result, 70 families in Tambakaji Village and 200 families in Wonosari Village were affected.

"The landslide that occurred in Bambankerep was caused by a fault in the Mount Kelir hill. This condition causes the material on the hill to slide and disrupt traffic. In the future, there is still the potential for more ground cracks on this hill. For that, we will continue to monitor it so that the impact can be minimized," said the Ngaliyan sub-district head, Moeljanto.

According to residents, runoff water from the river overflowed into the housing very quickly and quickly. This condition made a number of motorcycles and six cars of residents washed away in the river. Three houses of residents were also damaged by the disaster.

The Daily Executive of the Mayor of Semarang, Iswar Aminuddin, said that the flooding that hit the Ngaliyan and Tugu sub-districts occurred due to the damage to the dam due to the heavy flow of water from the upstream area. Damaged canals will be repaired immediately and land use in the upstream area will be evaluated.

Meanwhile, the Semarang City Government will immediately distribute assistance to residents affected by the disaster. The assistance provided is in the form of food assistance and energy assistance to clean the affected community's environment.

The Methods of Controlling Flood

The study of causes and effects of floods, management and protection of flood are carried out by experts of meteorology, hydrology, geomorphology and engineering. Several methods are adopted to control the floods and minimize the impacts of flooding. They are mainly attempted

1. To Modify the flood by construction of reservoirs, river channels, natural detention basins, inter-basin water transfer, construction of levees and flood walls, diversion canals, bank stabilization, best agronomic practices, afforestation and catchment zone management

2. Flood control measures are done to modify the susceptibility of flood damage through flood plain management, structural changes, flood proofing, disaster preparedness, flood forecasting and flood warning

3. The methods are also adopted to reduce the loss though emergency evacuation, flood fighting, public health, disaster relief, flood insurance and tax remission.

It is possible to lessen the impact of a disaster. It is necessary to understand the nature of hazard in order to reduce the harmfull effects. In flood controls, the main aspect lies in the identification of risk areas or flood-prone areas. 

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