Estimation of river depths and bedload based on dimensions in plan view

Historical maps are a very valuable source of information on the morphology of rivers in an earlier, more natural state. However, these maps provide no or limited information on river depth, whereas knowledge of river depth distribution is required for the calculation of historical bedload. In times when rivers are impacted by multiple pressures on the sediment cycle, such knowledge would help to define a range of realistic bedload supplies required for successful river restoration.

This paper presents a tool that can be used to estimate the elevation distribution of the river bed and the resulting bedload based on active and bankfull channel widths obtained from maps. A power function represents the width-depth curve and is fitted to the mean active and bankfull widths and the respective discharge capacities. The applicability to historical maps of the Upper Drava River was confirmed by archive material on historical lowest flow depths.