TXT-tool 2.062-1.2 A monitoring and early warning system for debris flows in rivers on volcanoes

Abstract

Volcanic eruptions may produce large amounts of pyroclastic material. Such material will then be transported down a volcano’s rivers due to slope instability or rainfall, and then settle in alluvial fan areas. Further migration of this deposited sediment along the river may occur through both natural mechanisms (hydraulic phenomena) as well as anthropogenic processes (human interference). This paper presents the application of monitoring and early warning systems to mitigate the impact of debris flows, using adaptive, low-cost, and collaborative-based technology. A long-running and sustainable system for monitoring and early warning of debris flows in the rivers of Mt. Merapi volcano in Indonesia will be used as case study for the implementation of this model. The 2010 Mt. Merapi eruption produced approximately 140 million m3 of pyroclastic deposits, of which more than 10 million m3 deposits have a potential to move downstream through Boyong/Code River towards Yogyakarta City and cause damage to the settlement areas. A real-time monitoring and warning system has been developed by considering community wishes in determining the types and placement of monitoring equipment, and maintaining it sustainably. The equipment consists of an automatic rainfall recorder, automatic water level recorder, debris sensor, and interval camera. The information flow for the proposed early warning system has been set up. The central station receives both the results of the real-time monitoring, and information through radio communication from key persons. Afterward, a warning alert is sent to key persons and the debris flow monitoring radio. This newly built system is expected to be integrated with the monitoring system of rivers, not only at Mt. Merapi but also on other volcanoes in Indonesia.