Sediment transport pre-measurement as revealed by the hydrophone monitoring technique at a volcanic river

Abstract

Recognizing the real-time sediment transport phenomena of rivers in the Mt. Merapi area has become an important issue, particularly in the efforts to mitigate risks of lahar flow disasters. The development of a lahar-related monitoring system in the Mt. Merapi area has currently become more challenging since contact and direct lahar flow measurement is very risky. Former techniques for lahar flow occurrences such as cable sensor and video shooting are considered good enough in terms of identifying the occurrence, but not the intensity. Furthermore, after the cable is cut, re-installation often meets its practical limit. The hydrophone measurement technique seems to be an acceptable technique subject to sufficient field calibration. This paper reports the performance of a hydrophone equipment, which can be used for monitoring bedload transport with diameters greater than 4 mm.