Hydraulic Causes for Basin Hydrograph Skewness. Issue 12 (19th December 2017)

• Record Type: Journal Article
• Authors: Collischonn, Walter; Fleischmann, Ayan; Paiva, Rodrigo C. D.; Mejia, Alfonso
• Is Part Of: Water resources research. Volume 53:Issue 12(2017)
• Page Start: 10603
• Page End: 10618
• Publication Date: 2017-12-19
• Subjects: celerity‐discharge relationship -- flood waves -- hydrograph skewness -- basin response; Hydrology -- Periodicals; 333.91
• DOI: 10.1002/2017WR021543
• Languages: English
• ISSNs: 0043-1397

Abstract

Abstract: It has been suggested that hydrograph skewness depends on the relative dominance between hillslope and channel network transport processes, where the former ones make the hydrograph positively skewed while the latter tends to make it negatively skewed. More recently, however, the role of river hydraulics in shaping the hydrograph has been highlighted. We present a set of numerical modeling experiments using a hydrodynamic model of river networks in which we investigate how channel hydraulics influence the shape of the hydrograph, particularly its skewness. We further investigate the influence of base flow, rainfall intensity, cross section geometry, and basin scale on unit hydrograph response. We show that river hydraulics has a decisive role because positively skewed hydrographs may occur even when water inputs to the river network are negatively skewed, and in catchments whose width function is also negatively skewed. We show additional results related to the effect of the degree of nonlinearity in the relationship between celerity and discharge, the effects of base flow and rainfall intensity. These further confirm that hydraulic factors may be decisive in determining hydrograph shape. Key Points: Celerity‐discharge relationship at a cross section is an important driver of basin hydrograph skewness Positive skewed form of hydrographs may be less related to hillslope processes and geomorphology as previously supposed and more to river hydraulics Base flow discharge conditions prior to a rainfall event affect the hydrograph skewness associated with that event