A new method for verification of delineated channel networks

Abstract

Several methods are used to delineate channel networks. The most widely used are the contributing area method, area-slope method, and grid network ordering method. The number of delineated channels depends on the threshold adopted when using each method. However, the appropriate threshold value required to delineate channel networks, and their corresponding accuracies, are still uncertain. The consistency between the delineated channels and actual channels can be evaluated by carrying out extensive field surveys, but these require significant time and cost. Accurate knowledge of delineated channel networks is vital, and is achievable more efficiently and simply. A new method of calculating the accuracy of delineated channel networks is introduced in this study. Channel cross-section profiles throughout the channel network were examined and three new incision indices were derived: an incised channel index, a partially incised channel index, and a nonincised channel index. The indices were found useful for setting appropriate threshold values for actual channel networks. Three small catchments in Wellington, New South Wales (NSW), Australia, were investigated in this study. Key Points Verification of delineated channel network Incision indices for checking the accuracy of channel network Appropriate thresholds for delineating channels © 2014. American Geophysical Union. All Rights Reserved.