[REPORT]

LAND SUBSIDENCE IN SEMARANG

Reported by: Amama Ira Amalia Priyono

Around the coast is an area prone to abrasion and land subsidence. The abrasion itself is caused by waves eroding the land banks which are directly adjacent to the sea. The waves hit the land directly, causing the coastline to be increasingly eroded and filled with sea water. Then for land level decline it can be caused by several factors of oil and gas extraction, the further impact of abrasion which causes sea water to fill the land, the absence of a strong binder / root to tie the soil surface, and soil hoarding activities to raise the soil surface.

In Semarang, this problem has been around for a long time and has not yet been resolved. When it rains, it is certain that the city of Semarang near the sea coast will be submerged. In addition, this land subsidence also causes the area to experience flooding even when there is no rain. This is because the land is already lower than sea level. Based on observations in the settlement area around the coast, the ditch on the side of the road has a water level higher than the ground level and residents have made a fence around the trench so that water does not enter the residents' settlement. Because water is an object that can seep into the ground and flow out of the canal, every year in the area there are submerged houses that turn into swamps so that the community cannot live anymore. To overcome this, local people used to backfill land above the swamp to raise the surface of the land above sea water. This is wrong.

When the previously low land surface has become a swamp, the lower soil structure will become tough and easy to move. When the mobile land is filled with other soil, it is true that the upper part will dry up and new houses can be built. However, the bottom is prone to movement soon so that the surrounding containment will be more prone to submerging. The added land will increase the soil load above the water surface. Water can seep back into the soil and cause further soil subsidence.

To overcome this, there are several steps you can take:

1. Doing greening around the beach to prevent abrasion

2. Carrying out reforestation in the containment area around the coast as an effort to tie up mobile land.

3. Do not landfilling is possible because it will increase the load from the soil surface.

4. Provide a breakwater on the edge of the sea.

5. Increase understanding and awareness of the dangers of sustainable land subsidence.

One of the public burial places on the coast of Semarang is also a victim of this land subsidence disaster. Many of the bodies that were lost were carried by the ocean currents or were bodies that reappeared to the ground. The coastal area of ​​the city of Semarang sinks 10 cm every year. If this is not resolved immediately, it will change the coastline every year to be closer to the mainland and reduce the land area of ​​Semarang City