Various applications of bedload‐surrogate observations, e.g., Japanese pipe hydrophones, have been proposed, including their use to verify calculations of riverbed deformation and active sediment transport after catastrophic sediment production events or during high probability flood events. Notably, bedload‐surrogate data are expected to be used soon to verify sabo (erosion control) master plan. For this purpose, cross‐sectional averages of bedload flux must be obtained; however, no established technology for the conversion of information obtained from a small part of a cross section to the whole cross section is available. In this study, we attempted to estimate the cross‐sectional averaged bedload flux based on the transverse distribution of shear stress obtained through the two‐dimensional open‐channel flow simulation. We demonstrate that the results of such analysis can be used to obtain cross‐sectional averages of bedload flux.