Based on news sources from Warta Kota dated 5/2/2020 about “Severe Flooding, Tangerang City Government Proposes Normalization of the Cirarab River” that after checking the current speed there was a decrease in speed compared to the upstream area of 0.5 meters per second due to being blocked by a bridge in Kota Bumi so that normalization was needed.
And based on coordination with the Tangerang Regency BPBD that there were many factors in the flood, especially in the housing area of Gelam Jaya Village which was caused by the overflow of the Cirarab River, that the elevation or embankment for the housing location was not checked for its final elevation, it is likely that the housing land embankment is only parallel to the riverbed so that if a flood occurs, the water will take a long time to recede.
And from the statement of the pump guard and the water gate located in Situ Bulakan regarding the flood in the Cirarab River, there was sedimentation and narrowing in the area of the akong factory located in the District. Sepatan so that river normalization and repair of the embankment are needed, especially the banks of the Cirarab River located in Villa Tomang Baru.
In this regard, the Ciliwung Cisadane River Basin Center needs to conduct a Flood Alert Level Review activity on the Cirarab River, considering the high changes in land use and climate change so that accurate information can be obtained as a basis for taking rapid action in flood disaster preparedness.
CONCLUSION
- Water resource infrastructure in the field includes Water Guessing Posts, Drainage Gates, Embankments, Dams and Other Infrastructure.
- There were 3 water guessing posts found in the field. One of them is from the Tangerang Regency BPBD early warning system with an online system. The other two are only in the form of Water Guessing Post (PDA) peilschaals at the Ledug River Estuary and Situ Bulakan Estuary.
- There were 9 (nine) water pumps found in the field, including as water discharge from the lake, drainage and the Ledug river estuary.
Of the 9 pumps in areas that are often flooded, there are water gates as a barrier against the entry of backwater from the river into the lake or into housing drainage channels. Some of these pumps are; pumps located at the Situ Bulakan discharge, pumps at the Ledug River Estuary and pumps in several drainage discharges of the Villa Permata Tangerang housing complex, Gelam Jaya Village, Pasar Kemis District.
- There are 16 drainage gates on the Cirarab River embankment, but 6 drainage gates are not functioning/damaged/not functioning. The six damaged gates are located in the Villa Permata Tangerang housing complex, Gelam Jaya Village, Pasar Kemis District.
The position of the drainage gates is almost parallel to the river flow, so the drainage gates function when the river water is in normal conditions. When it rains, the drainage gates are closed and pumps are used to drain water from the drainage. - Most of the Pile cap embankments are on the left of the Cirarab River in Gelam Jaya Village, Pasar Kemis District in the Villa Permata Tangerang housing complex are still in good condition and there are inspection roads, but there are a few cracks that are visible at several points.
- The dam infrastructure found along the Cirarab River is the Sarakan Dam. The location of the Sarakan Dam is on the border of Gitung Village and Kosambi Village, Sukadiri District. The dam is still in good condition, but there are several water gates that are damaged. There are 7 doors in total, consisting of four doors with a width of 2.5 m and three doors with a width of 1.5 m. The doors that are damaged are the 3 doors with a width of 2.5 m, which are currently replaced with wooden block partitions. 7. The calculation of the planned flood discharge is carried out using 3 methods, namely the calculation of flood discharge using the HSS method, the calculation of flood discharge using the HEC-HMS software, and the calculation of flood discharge based on AWLR data.