Application of a portable measuring system with acoustic Doppler current profiler to discharge observations in steep rivers

Obtaining discharge measurements during high flows is very difficult in steep rivers (slopes greater than about 0.1%) because of the highly unstable free surfaces and bed elevations. In this study, a portable flow measuring system with an acoustic velocimeter was developed. The proposed system has been proved to be better than existing systems for streamflow measurements in steep rivers. Field data collected by conventional velocimeters were analyzed, and compared with the flow measurements using the portable system with an ADP (acoustic Doppler profiler) or ADCP (acoustic Doppler current profiler). The effects of channel patterns on the applicability of the highly efficient discharge estimation method, as proposed by C.L. Chiu [An efficient method of discharge measurement in rivers and streams. In: Lecture of the workshop for development and application of discharge measurement in Taiwan. Taichung (Taiwan): National Chung-Hsing University, 1996. p. 55 [in Chinese]], were also discussed. In general, the method was applicable to higher flows where the measuring verticals were reasonably stable.