Low-cost micro electro-mechanical system (MEMS) acoustic sensors for detecting bedload transport in mountain rivers

Measurements of bedload transport play an important role in river monitoring and management, particularly in mountain rivers where predictions of bedload dynamics are subject to large uncertainties under supply-limited sediment regimes. Bedload instrumental monitoring remains limited, also for the high costs of the equipment. Here we report on flume and field tests carried out to assess the potential use of low-cost (~€ 200) MEMS-based microphones mounted under steel plates to detect bedload transport. The results show that the MEMS-based acoustic system can be used efficiently to detect the timing and occurrence of bedload events, although quantitative impact mass estimation is not currently achievable with such low-cost instrumentation.