Merapi’s Lahar Benefit at Putih River, Magelang

Abstract

A. IntroductionLahar classified as secondary hazard which the primer hazard is eruption from Merapi Volcano which can be in the form of scattering, lava flows, and pyroclastic glides. The Merapi Volcano eruption in 2010 was a higher eruption rate than the previous eruption in 2006, 5 times greater with the amount of material that came out in 2010 as much as ± 150 m 3 , whereas in 2006 only issued as much as ± 60 m 3 material (Kumalawati R. R., 2013).Lahar is variant type of mudflow or debris flow that composed of pyroclastic material. Lahar in Putih River causes by material that Merapi Volcano which had accumulated in the upstream due to rainfalls having an average intensity of about 40 mm in 2 hours that start occurs at November 4, 2010 (Lavigne, 2000). There other river that effected by Lahar beside Putih river, there are Pabelan, Blongkeng, Lamat, Putih, Batang, Bebeng, and Krasak Rivers. Lahar hazard will be more dangerous when it concerns flat areas and densely populated areas.Putih River is part of the Progo Watershed. Putih River is one of the western rivers that was badly affected by the lahar disaster caused by the eruption of the Merapi Volcano in 2010.