Dam Break Analysis of Jatibarang Dam in Central Java Indonesia

UK, SAMSEIHA , Dr.Ir.Istiarto, M.Eng

2016 | Tesis | S2 TEKNIK PENGELOLAAN BENCANA ALAM

Flooding is one of the most damaging and frequent disasters, having huge impacts on people worldwide. According to numerous economic losses, flooding accounts for one-third of all naturally disastrous catastrophes throughout the world. Annually, three phenomena generate flood in Semarang: high tide, land subsidence caused by over exploitation of groundwater and the load of constructions and high rainfall intensity from upstream catchment and in the city through the drainages. Jatibarang Dam is located in the upper part of Semarang city, where the construction was completely constructed in July 2013. Jatibrang Dam has main purposes (1) to maintain urban flood control system and (2) to store a potential source of water for human consumption. The reservoir is able to store 20.4 million cubic meters of hydraulic capacity. Flash flood will occur with massive capacity million cubic meters as the consequence of dam breach. This thesis aims to study (1) dam break analysis event on Jatibarang Dam; (2) flood routing and (3) floodplain due to structure failure. Two software programs are implemented: (1) HEC-RAS to predict flood routing frequency and hydraulic simulation (2) ArcGIS equipped with HEC-GeoRAS tool to facilitate this study. Primary data as the cross section of the river are generated from contour map conducted by the consultant and DEM taken from SRTM. Secondary data collection can be obtained from through conducting numerous literature reviews and these data can accelerate study progress. Dam break flood simulation was employed by using QPMF discharge at Jatibarang catchment area and for two lateral inflows designed for Q100 at downstream reach. The result of QPMF breach shows at SWS118m the maximum discharge is 6775m3/s with the volume of 48.6 million cubic meter and the maximum velocity flowed to the downstream is 30.93m/s while at SWS120m the maximum discharge is 6481m3/s with the volume of 48.8million cubic meter and 31.25m/s of maximum velocity flowed to the downstream.

Flooding is one of the most damaging and frequent disasters, having huge impacts on people worldwide. According to numerous economic losses, flooding accounts for one-third of all naturally disastrous catastrophes throughout the world. Annually, three phenomena generate flood in Semarang: high tide, land subsidence caused by over exploitation of groundwater and the load of constructions and high rainfall intensity from upstream catchment and in the city through the drainages. Jatibarang Dam is located in the upper part of Semarang city, where the construction was completely constructed in July 2013. Jatibrang Dam has main purposes (1) to maintain urban flood control system and (2) to store a potential source of water for human consumption. The reservoir is able to store 20.4 million cubic meters of hydraulic capacity. Flash flood will occur with massive capacity million cubic meters as the consequence of dam breach. This thesis aims to study (1) dam break analysis event on Jatibarang Dam; (2) flood routing and (3) floodplain due to structure failure. Two software programs are implemented: (1) HEC-RAS to predict flood routing frequency and hydraulic simulation (2) ArcGIS equipped with HEC-GeoRAS tool to facilitate this study. Primary data as the cross section of the river are generated from contour map conducted by the consultant and DEM taken from SRTM. Secondary data collection can be obtained from through conducting numerous literature reviews and these data can accelerate study progress. Dam break flood simulation was employed by using QPMF discharge at Jatibarang catchment area and for two lateral inflows designed for Q100 at downstream reach. The result of QPMF breach shows at SWS118m the maximum discharge is 6775m3/s with the volume of 48.6 million cubic meter and the maximum velocity flowed to the downstream is 30.93m/s while at SWS120m the maximum discharge is 6481m3/s with the volume of 48.8million cubic meter and 31.25m/s of maximum velocity flowed to the downstream.

Kata Kunci : Dam break, Floodplain, HEC-RAS, ArcGIS, HEC-GeoRAS