Real-time debris flow monitoring and automated warning system

At present, debris flow warning uses precipitation threshold and issues regional warning throughout the world. Precipitation threshold warning is less accurate and in most of the time large portion of unaffected population are evacuated. More precise warning should use direct monitoring. There are many debris flow monitoring stations but no real time warning system in use. The main reason is that the identification and confirmation of debris flow occurrence requires human interaction and it is too slow. A debris flow monitoring and warning system has been installed in the midstream section of Yusui Stream, Taiwan. The monitoring station operates fully automatically, providing early warnings without the need for manual intervention. The system comprises two webcam cameras, two Micro-Electro-Mechanical Systems (MEMS), and a rain gauge. The arrival of debris flows is detected and confirmed through both webcam images and MEMS signals. Once debris flow is detected, the system automatically issues a warning to the affected areas via voice messages, line messages, broadcasts, and web-based alerts. The webcam cameras are also used to estimate debris flow velocity and flow height, while the MEMS sensors are utilized to determine the phase speed and flow rate. On July 24th, 2014, Typhoon Gaemi triggered several debris flows, and the system successfully issued several warnings automatically. The entire video record, along with depth variation data, was recorded automatically.