Application of Hydraulic Geometry to High Gradient Rivers in Southern Ecuador

Abstract

The Ecuadorian river system is comprised of more than 2,000 rivers and streams formed primarily in the Andes Mountains and discharging into the Pacific and Atlantic Oceans. Steep channels with coarse bed material constitute the main components of mountainous drainage systems (Buckalew et al., 1998). These channels are the principal source of sediment to lower gradient channels downstream. Historically, lower gradient rivers have received more attention due, in part, to their proximity to large population centers. Prior studies often did not consider slope explicitly or assumed slope to be a flow dependent variable (Andrews, 1984; Palucis & Lamb, 2017; Parker et al., 2007; Pitlick & Cress, 2002). Inclusion of slope as a determining parameter in the evolution of a river has been strengthened with the study of high gradient channels (Comiti et al., 2007; David et al., 2010; Ferguson, 2012; Tominaga & Nezu, 1992). Slope is an important controlling variable for fluvial characteristics such as sediment transport, development of stream habitat, and bed roughness (Palucis & Lamb, 2017). Hydraulic geometry (HG) theory is applied here to characterize mountainous rivers in Ecuador and determine the relation between slope and channel characteristics. HG was first presented by Leopold and Maddock (1953) and has been incorporated in a wide range of studies including habitat assessment, basin characterization, and flow resistance analysis (

Modeling Bankfull Channel Geometry Based on Watershed and Precipitation Characteristics Using Dimensionless Parameters

“…The lack of a relationship between discharge and channel bed slope, as shown by Equation , has also been reported by Carrillo et al. (2021), who studied high gradient rivers. For $$\tilde{D}$$ and $$\tilde{W}$$, all predictor variables are found to be significant.…”

“…𝐴𝐴 Q𝑄 , all predictor variables considered are found to be significant except for S v . The lack of a relationship between discharge and channel bed slope, as shown by Equation16, has also been reported byCarrillo et al (2021), who studied high gradient rivers. For 𝐴𝐴 P𝑃 is not a significant parameter for S c ,…”

“…An important limitation of the models developed by the Ames et al (2009) and Bieger et al (2015Bieger et al ( , 2016 studies is the use of dimensional variables rendering the so obtained regression equations dimensionally inhomogeneous. Some other studies have revisited the discharge-based models by Leopold and Maddock (1953) to develop dimensionless empirical relations between BHG and discharge along with acceleration due to gravity and median grain size as repeating variables (e.g., Carrillo et al, 2021;Parker, 1979;Parker et al, 2007 for gravel bed streams). Repeating variables used during nondimensionalization are a group of dimensionally independent variables that include all of the dimensions observed in the other variables (Munson et al, 2013).…”

Surface Transient Storage Under Low‐Flow Conditions in Streams With Rough Bathymetry

“…Numerous preceding studies have developed relationships among mean flow velocity, discharge, channel slope, water surface width and other stream parameters (e.g., Carrillo et al., 2021; Ferguson et al., 2019). For channel with rough bed, like pool‐riffle channels, some field works indicated that the exponent describing the mean velocity with discharge is between 0.48 and 0.6 (Comiti et al., 2007), of which our numerical work was also within the range.…”

A bankfull geometry dataset for major exorheic rivers on the Qinghai-Tibet Plateau

“…Three products are provided: a bankfull river surface dataset, a bankfull river width dataset and a bankfull river surface area dataset. These datasets provide a fundamental basis for various studies on the QTP, the third pole of the world, including studies on geological geomorphology 13 , hydroinformatics 14 , biogeochemical cycles 15 , plateau ecology, etc.…”