Spatial Distributions Of At-Many-Stations Hydraulic Geometry For Mountain Rivers Originated From The Qinghai-Tibet Plateau

At-many-stations hydraulic geometry (AMHG) has provided a novel way to understand river network development, simulate water flow, and retrieve river discharge in data-scared regions. Based on in-situ measurements of six major rivers originating from the Qinghai-Tibet Plateau (QTP), this study verifies the existence of AMHG relations along the rivers and explores AMHG relations for cross sections that are not located in the same river reach. The mainstreams and tributaries of the studied rivers in the southern and the eastern portions of the QTP have satisfactory AMHG relation strengths with R-2 > 0.9 for over 60% of the relations. For cross sections located in the same stream order or within a certain range of contributing area (CA), approximately 60% (9/15) and 53% (8/15) of the AMHG relations have an R-2 > 0.6. AMHG strength increases with increasing stream order and CA; this finding reflects the increasing coherence and maturity of the river networks associated with the geomorphic shaping power of increased discharge. Width-AMHG intercepts are larger than those of depth-AMHG and velocity-AMHG for all stream orders and CAs. Most of the congruent hydraulics generated from cross sections located in middle-scale rivers (orders 7-8) are within the observed range. Congruent hydraulics generally increase with an increase in in-situ measured hydraulics when the stream order or the CA increases. The AMHG relations existing among cross sections that are not located in the same reach, which is named as cross channel AMHG, indicate linear variability of cross-sectional geometric and hydraulic similarities in the same stream order or within a certain CA range. The results break the watershed divide boundary control on AMHG and have the potential to provide background knowledge for discharge estimation in mountain rivers located in the QTP.