Intercontinental predictions of river hydraulic geometry from catchment physical characteristics

Morel, Maxime; Booker, D. J.; Gob, Frédéric

doi:10.1016/j.jhydrol.2019.124292

Cited by 23 publications

(30 citation statements)

References 60 publications

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“…-River hydraulic geometry: stream width and depth were calculated using a hydraulic model assuming a rectangular river section being constant over 24 hours (Morel et al, 2020):…”

Section: T-net Thermal Modelmentioning

confidence: 99%

Regional, multi-decadal analysis reveals that stream temperature increases faster than air temperature

Seyedhashemi

Vidal

Diamond

et al. 2021

Preprint

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Abstract. Stream temperature appears to be increasing globally, but its rate remains poorly constrained due to a paucity of long-term data and difficulty in parsing effects of hydroclimate and landscape variability. Here, we address these issues using the physically-based thermal model T-NET (Temperature-NETwork) coupled with the EROS semi-distributed hydrological model to reconstruct past daily stream temperature and streamflow at the scale of the entire Loire River basin in France (105 km2 with 52278 reaches). Stream temperature increased for almost all reaches in all seasons (mean = +0.38 °C/decade) over the 1963–2019 period. Increases were greatest in spring and summer with a median increase of +0.38 °C (range = +0.11– +0.76 °C) and +0.44 °C (+0.08– +1.02 °C) per decade, respectively. Rates of stream temperature increases were greater than for air temperature across seasons for 50–86 % of reaches. Spring and summer increases were typically the greatest in the southern headwaters (up to +1 °C/decade) and in the largest rivers (Strahler order > 5). Importantly, air temperature and streamflow exerted joint influence on stream temperature trends, where the greatest stream temperature increases were accompanied by similar trends in air temperature (up to +0.71 °C/decade) and the greatest decreases in streamflow (up to −16 %/decade). Indeed, for the majority of reaches, positive stream temperature anomalies exhibited synchrony with positive anomalies in air temperature and negative anomalies in streamflow, highlighting the dual control exerted by these hydroclimatic drivers. Moreover, spring and summer stream temperature, air temperature, and streamflow time series exhibited common change-points occurring in the late 1980s, suggesting a temporal coherence between changes in the hydroclimatic drivers and a rapid stream temperature response. Critically, riparian vegetation shading mitigated stream temperature increases by up to 16 % in smaller streams (i.e., < 30 km from the source). Our results provide strong support for basin-wide increases in stream temperature due to joint effects of rising air temperature and reduced streamflow. We suggest that some of these climate change-induced effects can be mitigated through the restoration and maintenance of riparian forests, and call for continued high-resolution monitoring of stream temperature at large scales.

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“…-River hydraulic geometry: stream width and depth were calculated using a hydraulic model assuming a rectangular river section being constant over 24 hours (Morel et al, 2020):…”

Section: T-net Thermal Modelmentioning

confidence: 99%

Regional, multi-decadal analysis reveals that stream temperature increases faster than air temperature

Seyedhashemi

Vidal

Diamond

et al. 2021

Preprint

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“…Hydraulic translations were made using the hydraulic geometry of Morel et al (2020). In brief, these models improve the classical hydraulic geometry relationships of Leopold and Maddock (1953).…”

Section: Translations Of Discharge Data Into Hydraulic Characteristicmentioning

confidence: 99%

“…However, these models were less accurate when predicting how the rate of change in width and depth with discharge varied among reaches. In detail, the models explained only 35% (width) and 13% (depth) of the exponent of hydraulic geometry for width and depth ( Figure 3 in Morel et al 2020). Hydraulic habitat translations were made for two fish guilds using the statistical hydraulic habitat models of Lamouroux and Souchon (2002).…”

Section: Translations Of Discharge Data Into Hydraulic Characteristicmentioning

confidence: 99%

“…In particular, air temperature alone did not allow to evaluate the potential influence of water temperature variations induced by hydropeaking (known as thermopeaking, Zolezzi et al 2011). In addition, although they are relatively accurate for describing hydraulic differences between reaches, the general hydraulic translations of Morel et al (2020) cannot reflect the presence of shelter or particular substrate configurations. More importantly, hydraulic geometry models are uncertain for describing the rate of change in width and depth with discharge.…”

Section: Perspectivesmentioning

confidence: 99%

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Consistent but secondary influence of hydropeaking on stream fish assemblages in space and time

Judes

Gouraud

Capra

et al. 2020

Journal of Ecohydraulics

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Hydropeaking corresponds to rapid artificial discharge variations, designed to address subdaily peaks in electricity demand. It generates rapid changes in physical habitat (e.g., flow velocity and water depth) with potential impacts on stream assemblages. For assessing the generality of hydropeaking effects on fish assemblages, we present an original combination of spatial (among 45 reaches, including six groups of nearby reaches) and temporal (over 3-17 years) analyses of these effects. Our analyses involved descriptions of natural and artificial hydraulic variations in reaches, obtained after translating hourly discharge data into hydraulics. We found that the influence of hydropeaking was secondary compared to well-known spatial variations in fish assemblage structure along longitudinal gradients, and negative influences of floods on annual densities. However, the spatial and temporal analyses consistently suggested that hydropeaking may disfavour fish species typical of medium-sized streams relative to species of headwater streams (Salmo trutta, Phoxinus phoxinus, Cottus gobio). The magnitude of hydropeaking effects observed here, as well as an apparent weaker effect of ramping rates than the frequency of hydropeaks, may be due to lower ramping rates in our data set than in other studies.

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“…Despite these difficulties to relate AHG to geomorphic features, a recent empirical analysis of data from 492 reaches in France suggested that AHG exponents could be partly predicted from hydraulic characteristics measured at a single discharge: the Froude number of the reach and the ratio of wetted width to bankfull width (Morel et al, 2019). In the same vein, environmental descriptors available in GIS databases (e.g., reach slope and catchment area) partly (although weakly) explained AHG exponents in both France and New Zealand data sets (Morel et al, 2020). These results suggest potential intercontinental similarities in reach-scale AHG patterns.…”

Section: Introductionmentioning

confidence: 99%

Consistent Theoretical and Empirical Predictions of at‐a‐Station Hydraulic Geometry Exponents in Stream Reaches

Morel

Booker

Gob

et al. 2020

Water Resources Research

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Reach-scale at-a-station hydraulic geometry (AHG) relationships are power laws that describe variations of reach-averaged water depth, wetted width, and current velocity in stream reaches when discharge varies. Modeling AHG exponents is important, because the variations of hydraulics with discharge in stream networks influence physical habitats of aquatic species, biodiversity, water temperature, nutrient fluxes, and sediment transport. Theoretical approaches indicated that AHG exponents should depend on topographic descriptors of cross sections and roughness elements. Empirical approaches suggested that AHG exponents partly depend on hydraulic characteristics measured at a single discharge. We used a unique data set of AHG observed in 812 stream reaches (obtained from measurements at several discharge rates or from hydrodynamic models) to (1) test the consistency of theoretical and empirical predictions of AHG exponents and (2) test the generality of AHG predictions across rivers of different countries with variable landscape settings. We found that observed AHG depended on topographic predictors (describing cross-section shape and substrate size) as expected from theory. However, AHG exponents were better predicted by empirical hydraulic characteristics of reaches: the ratio of wetted width to bankfull width and the reach Froude number. The effects of hydraulic variables were consistent with those of topographic predictors. In addition, relations between AHG and hydraulic predictors were significant and with similar direction in different data sets. Despite limited explanatory power, our results help identifying general drivers of AHG exponents. Their application still requires measurements at a single discharge rate but open perspectives of generalized AHG prediction by remote sensing.

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Intercontinental predictions of river hydraulic geometry from catchment physical characteristics

Cited by 23 publications

References 60 publications

Regional, multi-decadal analysis reveals that stream temperature increases faster than air temperature

Regional, multi-decadal analysis reveals that stream temperature increases faster than air temperature

Consistent but secondary influence of hydropeaking on stream fish assemblages in space and time

Consistent Theoretical and Empirical Predictions of at‐a‐Station Hydraulic Geometry Exponents in Stream Reaches

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