Intercomparison of high-accuracy water level gauges in the scale of small experimental catchment

At present,high-accuracy water level data are urgently required for small experimental catchments. However,conventional water level gauges (WLGs) with an accuracy of one centimeter do not meet the need of high-accuracy water levels. To determine an applicable high-accuracy WLG for small experimental catchments,we primarily selected five types of relatively high-accuracy WLGs,and systematically compared these gauges under the following four conditions:a stationary water level,step-by-step increasing and decreasing water levels,a simulated food peak,and a natural rainfall-runoff process in situ. The results demonstrated that:① Based on the comprehensive absolute error,the accuracies of probing-needle,pressure-type model 2(i.e. capacitance-type),and magnetostriction WLGs were within 0.4 mm;② The accuracy of the float-type WLG was around 0.5 mm;③ The accuracy of the pressure-type model 1(i.e. resistance-type) WLG was higher than 1 mm;and ④ the magnetostriction WLG can accurately determine water level processes under the condition of low water head;therefore,this gauge is suitable for the measurement of high-accuracy water levels in small experimental catchments. These findings provide a significant reference for high-accuracy monitoring runoff,rainfall,evaporation,and infiltration processes.