scholarly journals River Dynamics Control Transit Time Distributions and Biogeochemical Reactions in a Dam‐Regulated River Corridor

2020 ◽  
Vol 56 (9) ◽  
Author(s):  
Xuehang Song ◽  
Xingyuan Chen ◽  
John M. Zachara ◽  
Jesus D. Gomez‐Velez ◽  
Pin Shuai ◽  
...  
2021 ◽  
Vol 4 ◽  
Author(s):  
Huiying Ren ◽  
Xuehang Song ◽  
Yilin Fang ◽  
Z. Jason Hou ◽  
Timothy D. Scheibe

Hydrologic exchange between river channels and adjacent subsurface environments is a key process that influences water quality and ecosystem function in river corridors. High-resolution numerical models were often used to resolve the spatial and temporal variations of exchange flows, which are computationally expensive. In this study, we adopt Random Forest (RF) and Extreme Gradient Boosting (XGB) approaches for deriving reduced order models of hydrologic exchange flows and associated transit time distributions, with integrated field observations (e.g., bathymetry) and hydrodynamic simulation data (e.g., river velocity, depth). The setup allows an improved understanding of the influences of various physical, spatial, and temporal factors on the hydrologic exchange flows and transit times. The predictors also contain those derived using hybrid clustering, leveraging our previous work on river corridor system hydromorphic classification. The machine learning-based predictive models are developed and validated along the Columbia River Corridor, and the results show that the top parameters are the thickness of the top geological formation layer, the flow regime, river velocity, and river depth; the RF and XGB models can achieve 70% to 80% accuracy and therefore are effective alternatives to the computational demanding numerical models of exchange flows and transit time distributions. Each machine learning model with its favorable configuration and setup have been evaluated. The transferability of the models to other river reaches and larger scales, which mostly depends on data availability, is also discussed.


2021 ◽  
Vol 598 ◽  
pp. 126283
Author(s):  
Xuehang Song ◽  
Yilin Fang ◽  
Jie Bao ◽  
Huiying Ren ◽  
Zhuoran Duan ◽  
...  

2019 ◽  
Author(s):  
Xuehang Song ◽  
Xingyuan Chen ◽  
John Zachara ◽  
Jesus Gomez-Velez ◽  
Pin Shuai ◽  
...  

2014 ◽  
Vol 34 (1) ◽  
pp. 53-64
Author(s):  
Rafał Krawczyk

Abstract Spatial distribution and habitat preferences of 55 river corridor plant species were analyzed on a local scale in the valley of a medium-size regulated river. The analysis was based on the results of a detailed mapping on a 50 km-long section of the Lower San River valley (366 cartogram cells of 1 square km). Selected species were divided into two groups: (1) strictly and (2) loosely confined to river corridors. River corridor plants were found throughout the valley (river channel, active and historical floodplain, older terraces, slopes); however, their frequency was diverse in particular areas. The highest concentrations were observed on the floodplain. Their number decreased towards the border areas of the valley. Species which were less confined to rivers were found more frequently in the valley (one species occupied, on average, 12.9% of grid cells), than plants strictly confined to the river system (one species occupied, on average, 5.9% of grid cells); however, the ranges of species of the second group were more restricted to the Holocene part of the valley, especially to the floodplain. River corridor plants were, ecologically, a highly diversified group. In the San river valley, they were found in riparian forests, pioneer ephemeral communities on the banks of water bodies, dry grasslands, meadows and old river beds; a lot of them grew in ruderal habitats.


2020 ◽  
Vol 478 ◽  
pp. 118513 ◽  
Author(s):  
Andrew W. Tranmer ◽  
Rohan Benjankar ◽  
Daniele Tonina

2005 ◽  
Vol 25 (1_suppl) ◽  
pp. S676-S676
Author(s):  
Masanobu Ibaraki ◽  
Hiroshi Ito ◽  
Eku Shimosegawa ◽  
Hideto Toyoshima ◽  
Keiichi Ishigame ◽  
...  

1986 ◽  
Vol 47 (12) ◽  
pp. 2025-2039 ◽  
Author(s):  
A. Titov ◽  
Yu. Malyshev ◽  
Yu. Rastorguev

1968 ◽  
Vol 07 (02) ◽  
pp. 125-129
Author(s):  
J. Měštan ◽  
V. Aschenbrenner ◽  
A. Michaljanič

SummaryIn patients with acquired and congenital valvular heart disease correlations of the parameters of the radiocardiographic curve (filling time of the right heart, minimal pulmonary transit time, peak-to-peak pulmonary transit time, and the so-called filling time of the left heart) with the mean pulmonary artery pressure and the mean pulmonary “capillary” pressure were studied. Further, a regression equation was determined by means of which the mean pulmonary “capillary” pressure can be predicted.


Sign in / Sign up

Export Citation Format

Share Document