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Title: Drainage reorganization induces deviations in the scaling between valley width and drainage area
Abstract. The width of valleys and channels affects the hydrology, ecology,and geomorphic functionality of drainage networks. In many studies, thewidth of valleys and/or channels (W) is estimated as a power-law function ofthe drainage area (A), W=kcAd. However, in fluvial systemsthat experience drainage reorganization, abrupt changes in drainage areadistribution can result in valley or channel widths that are disproportionalto their drainage areas. Such disproportionality may be more distinguishedin valleys than in channels due to a longer adjustment timescale forvalleys. Therefore, the valley width–area scaling in reorganized drainagesis expected to deviate from that of drainages that did not experiencereorganization. To explore the effect of reorganization on valley width–drainage areascaling, we studied 12 valley sections in the Negev desert, Israel,categorized into undisturbed, beheaded, and reversed valleys. We found thatthe values of the drainage area exponents, d, are lower in the beheadedvalleys relative to undisturbed valleys but remain positive. Reversedvalleys, in contrast, are characterized by negative d exponents, indicatingvalley narrowing with increasing drainage area. In the reversed category, wealso explored the independent effect of channel slope (S) through theequation W=kbAbSc, which yieldednegative and overall similar values for b and c. A detailed study in one reversed valley section shows that the valleynarrows downstream, whereas the channel widens, suggesting that, ashypothesized, the channel width adjusts faster to post-reorganizationdrainage area distribution. The adjusted narrow channel dictates the widthof formative flows in the reversed valley, which contrasts with the meaningfullywider formative flows of the beheaded valley across the divide. Thisdifference results in a step change in the unit stream power between thereversed and beheaded channels, potentially leading to a “width feedback”that promotes ongoing divide migration and reorganization. Our findings demonstrate that valley width–area scaling is a potential toolfor identifying landscapes influenced by drainage reorganization. Accountingfor reorganization-specific scaling can improve estimations of erosion ratedistributions in reorganized landscapes.  more » « less
Award ID(s):
1946253 2139894
NSF-PAR ID:
10387643
Author(s) / Creator(s):
; ; ; ;
Date Published:
Journal Name:
Earth Surface Dynamics
Volume:
10
Issue:
5
ISSN:
2196-632X
Page Range / eLocation ID:
875 to 894
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
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