Retarding basin modeling for lahan hazard management : Case study in Bladak Catcthment, East Java

Alzaena Ulya Rusdimi,

2015 | Tesis |

Bladak catchment is situated in the west side of Kelud volcanic slope. Bladak river has high potential to be overflown by lahars as most of the material deposits from the provious eruption in February, 2014 are still detained in its upstream. Retarding basin is one of structural mitigation measures that can be applied to reduce lahars and flash flood risk in a small catchment. The objectives of the research are: (1) to simulate rainfall-runoff generation in Bladak catchment using hydrological model, and (2) to investigate the preferable location for building retarding basin and its effectiveness to reduce lahars impacts, and (3) to suggest the possible adjustment on the land use and retarding basin locations with spatial planning principles. The rainfall-runoff simulation and retarding basin modeling are conducted by using hydrological model LISEM and PCRaster with spatial analysis using ArcGIS 10.1. Evaluation on the existing land use in Bladak catchment and the predermined spatial plan of Blitar Regency is conducted by comparative-descriptive approach. The rainfall-runoff simulation shows relevant result to the possibility of predicted site where excessive runoff might occur, which is highly influenced by the presence of its physical parameters. The implementation of retarding basin along the drainage system has been assessed to reduce the peak discharge in a small distinction. This result can be due to the size and number of the retarding basin applied in the catchment. The evaluation on land use in Bladak catchment shows some deviations on the presence land use with the predetermined spatial plan, which reflects the necessity to review land use planning to be more comprehensive.

Kata Kunci :