ABSTRACT

Observation of flooding events over years and years have shown that all kinds of ultrasonic flow measuring devices − Transit time and Doppler systems alike − fail, when data is most needed: in case of peak flooding! This happens because with higher velocity the sediment content is rising dramatically thus leading to catastrophic acoustic attenuation. Events in Europe, even more so in situ measurements in sediment loaded rivers near the Himalayan mountains have shown that the acoustic attenuation rises with sediment load, but never blocks completely. That means it should be possible to obtain reliable data, if the signal to noise ratio can be significantly improved. This can be done by new hardware and software designs. Freely Programmable Silicon chips allow compact and cost effective solutions. We report about improvements in the 30 to 50 dB order by applying mathematical data processing routines like pulse compression, cross-correlation and clever signal analysis.