HydroWidth: A small‐scale approach to calculate river width and its variability

Abstract

AbstractDigital map processing techniques have enabled new computational methods to extract geographic features from scanned map sources. These are mainly historical maps and are rich in spatiotemporal information which can be derived by descriptive metrics. River channel width is such a typical ecological metric used to calculate properties such as water discharge rates and, generally, often applied in hydrological and ecological monitoring. Measures of river channel width in previous ecological work have successfully measured width based on in situ measurements or remote sensing efforts, but poorly captured the variability in river width due to simplifications of the river network or due to sparse availability of in situ measurements. As river width can greatly vary and change over space and time, capturing its variability with modern geospatial processing techniques is a key interest in interdisciplinary fields studying spatiotemporal changes of riverine properties. This article proposes HydroWidth, a small‐scale approach to measure river width continuously along a channel, capable of capturing the variability in width in simple as well as complex river structures without the use of river masks. The small‐scale approach is compared to two conventional vector‐based discrete river width measurement techniques to test the robustness of the methods in terms of measuring river width and its variability. Furthermore, this article evaluates the adaptability of HydroWidth by performing three experiments measuring river width variability at rivers of different structure, length, and complexity. The methods are applied on rivers of historical map sources, allowing a novel perspective of applying algorithms measuring river width on non‐airborne data sources. Lastly, the computational performance results of the conventional and HydroWidth methods at each experimental site are presented and discussed.