BANJIR BANDANG DI ALASMALANG BANYUWANGI DAN ALTERNATIF PENANGANANNYA (Flash flood at Alasmalang Banyuwangi and alternatives for its completion)

ABSTRACT Flash floods frequently occur in Indonesia. Flash flood can be caused by natural and human factors. This paper discusses the causes and mitigation of flash flood using a case study in Banyuwangi. On June 22th 2018, flash floods occurred in the residential areas of Garit, Karang Asem, and Bangunrejo Hamlets. Flash floods were triggered by heavy rainfall the day before, which reached 90 mm/day. The three hamlets are located in Alasmalang Village, Singojuruh Subdistrict, Banyuwangi District. The study began with a field survey, analysis of the damage, and the causes of a flash flood, and its alternative treatments. The suspected source of the material was the landslide material, approximately two million cubic meters from the Pendil Mountain. Some of the material were carried away by the river flooding caused flash floods in the three hamlets. The small width of the bridge was not able to be passed by trees and other flash flood material, so water overflowed the roads and houses. Based on the results of the study, it is recommended for disaster mitigation in the form of structural and non-structural actions. Structural measure in the form of bridge elevation and construction of sediment retaining weirs, while non-structural actions are in the form of an early warning system and dissemination of flash flood hazards.