scholarly journals Solving the mystery of vanishing rivers in China

2019 ◽  
Vol 6 (6) ◽  
pp. 1239-1246 ◽  
Author(s):  
Yichu Wang ◽  
Jinren Ni ◽  
Yao Yue ◽  
Jiaye Li ◽  
Alistair G L Borthwick ◽  
...  
Keyword(s):  
Mixed Mode ◽  
River Networks ◽  
Stream Order ◽  
Previous Estimate ◽  
River Systems ◽  
Natural Streams ◽  
Rivers And Lakes ◽  
Order Scheme ◽  
National Water

Abstract A major controversy was sparked worldwide by a recent national water census claiming that the number of Chinese rivers with watersheds ≥100 km2 was less than half the previous estimate of 50 000 rivers, which also stimulates debates on the potential causes and consequences. Here, we estimated the number of rivers in terms of stream-segmentation characteristics described by Horton, Strahler and Shreve stream-order rules, as well as their mixed mode for named rivers recorded in the Encyclopedia of Rivers and Lakes in China. As a result, the number of ‘vanishing rivers’ has been found to be highly relevant to statistical specifications in addition to the erroneous inclusion of pseudo-rivers primarily generated in arid or frost-thaw areas. The modified Horton stream-order scheme reasonably depicts the configuration of complete natural streams from headwater to destination, while the Strahler largely projects the fragmentation of the named river networks associated with human aggregation to the hierarchical river systems.

scholarly journals Automated Detection of Instability-Inducing Channel Geometry Transitions in Saint-Venant Simulation of Large-Scale River Networks

Water ◽  
2021 ◽  
Vol 13 (16) ◽  
pp. 2236
Author(s):  
Cheng-Wei Yu ◽  
Ben R. Hodges ◽  
Frank Liu
Keyword(s):  
Large Scale ◽  
Open Channel ◽  
Search Algorithm ◽  
Shallow Water Equation ◽  
Stable Solution ◽  
River Networks ◽  
River Systems ◽  
Channel Network ◽  
Channel Geometry ◽  
Venant Equation

A new sweep-search algorithm (SSA) is developed and tested to identify the channel geometry transitions responsible for numerical convergence failure in a Saint-Venant equation (SVE) simulation of a large-scale open-channel network. Numerical instabilities are known to occur at “sharp” transitions in discrete geometry, but the identification of problem locations has been a matter of modeler’s art and a roadblock to implementing large-scale SVE simulations. The new method implements techniques from graph theory applied to a steady-state 1D shallow-water equation solver to recursively examine the numerical stability of each flowpath through the channel network. The SSA is validated with a short river reach and tested by the simulation of ten complete river systems of the Texas–Gulf Coast region by using the extreme hydrological conditions recorded during hurricane Harvey. The SSA successfully identified the problematic channel sections in all tested river systems. Subsequent modification of the problem sections allowed stable solution by an unsteady SVE numerical solver. The new SSA approach permits automated and consistent identification of problem channel geometry in large open-channel network data sets, which is necessary to effectively apply the fully dynamic Saint-Venant equations to large-scale river networks or for city-wide stormwater networks.

Investigating the Response of Tectonic Loading in the Himalayas on the Peripheral Forebulge through Drainage Network Analysis

2021 ◽  
Author(s):  
Parv Kasana ◽  
Vimal Singh ◽  
Rahul Devrani
Keyword(s):  
Dynamic Equilibrium ◽  
Ganga River ◽  
Indian Plate ◽  
River Networks ◽  
Drainage Network ◽  
River Systems ◽  
Himalayan Orogeny ◽  
Narmada River ◽  
Indian Lithosphere ◽  
Tectonic Loading

<p>Drainage divide migration is a conspicuous natural process through which a landscape evolves. In response to a forced climatic and tectonic disturbance, susceptible river networks transfer the transient signals to the entire river basin, which results in an incision or aggradation. The Himalayan orogeny and subduction of the Indian plate have resulted in an upward flexure in the Indian lithosphere known as a peripheral forebulge. A forebulge can flexurally uplift and migrate following the variation in tectonic load. The emergence of the central Indian plateau is a consequence of the upwarping of the Indian lithosphere (Bilham et al. 2003).  In this work, we are trying to assess the drainage network dynamics between the Narmada and Ganga river systems, which drain the uplifted central Indian plateau. We have calculated the Chi(χ) metrics, steepness index (Ksn), knickpoints for the channels in the study area. We have generated Topographic swath profiles to analyze the topographic variations on the plateau. It has been observed from the results that the rivers in the study area lack dynamic equilibrium, and river capturing is an evident response to the perturbations. Our analysis shows that the Narmada River tributaries are gaining drainage area and aggressing Northwards by capturing adjacent Ganga river tributaries. The field observations show a variation in the surface slope and presence of knickpoints (waterfalls) along the "aggressor" drainages. We propose a model to show a correlation between the tectonic loading of Himalayas, movement of forebulge, and its feedback to the river systems present on the forebulge.</p>

scholarly journals AN AUTOMATED BOTTOM UP HYDROLOGIC CODING SYSTEM FOR DENDRITIC RIVER SYSTEM

2019 ◽  
Vol XLII-4/W16 ◽  
pp. 169-175 ◽  
Author(s):  
Z. X. Dai ◽  
C. M. Li ◽  
P. D. Wu ◽  
Y. Yin
Keyword(s):  
Source Coding ◽  
River System ◽  
Coding System ◽  
Topographic Map ◽  
Stream Order ◽  
River Systems ◽  
Bottom Up ◽  
Coding Systems ◽  
Definition Of ◽  
Map Data

Abstract. The hydrologic coding of a dendritic river system can be used to indicate the stream order and spatial-structure features of a river system. However, most conventional hydrologic coding systems use a top down (i.e., from the source to the estuary) approach, which does not accurately reflect the hierarchies of a dendritic river system. Based on Gravelius’ definition of stream order, we have proposed an automated bottom up (i.e., traced from the estuary to the source) coding system for dendritic river systems. Firstly, directed topology trees are constructed to organize the data of a river network, followed by the calculation of stroke connections to construct river entities and identify the main stem. Secondly, the river system is then progressively coded from the estuary up to the source according to the definition of stream order in our system. Finally, actual topographic map data of a river system in some regions of Hubei Province are used to comparatively validate our hydrologic coding system against Horton’s coding system. The experimental results demonstrate that our coding system is very effective in highlighting hierarchies formed by catchment relationships. Our method is also found to be suitable for the selection of streams in topologically shallow dendritic river systems with uniformly distributed tributaries.

scholarly journals Urban Sewers Evolve Similarly to River Networks

Eos ◽  
2017 ◽  
Author(s):  
Sarah Stanley
Keyword(s):  
River Networks ◽  
River Systems ◽  
Drainage Networks

Like river systems, engineered drainage networks become increasingly fractal as they grow.

“To Corrupt a Man in the Midst of a Verse”: Ben Jonson and the Prose of the World

2017 ◽  
Vol 24 (1) ◽  
pp. 46-72
Author(s):  
Jacob Tootalian
Keyword(s):  
Mixed Mode ◽  
Ben Jonson ◽  
Digital Analysis ◽  
Interactive Engagement ◽  
Sentence Level ◽  
Linguistic Patterns ◽  
The World ◽  
Selection Of ◽  
Bartholomew Fair

Ben Jonson's early plays show a marked interest in prose as a counterpoint to the blank verse norm of the Renaissance stage. This essay presents a digital analysis of Jonson's early mixed-mode plays and his two later full-prose comedies. It examines this selection of the Jonsonian corpus using DocuScope, a piece of software that catalogs sentence-level features of texts according to a series of rhetorical categories, highlighting the distinctive linguistic patterns associated with Jonson's verse and prose. Verse tends to employ abstract, morally and emotionally charged language, while prose is more often characterized by expressions that are socially explicit, interrogative, and interactive. In the satirical economy of these plays, Jonson's characters usually adopt verse when they articulate censorious judgements, descending into prose when they wade into the intractable banter of the vicious world. Surprisingly, the prosaic signature that Jonson fashioned in his earlier drama persisted in the two later full-prose comedies. The essay presents readings of Every Man Out of his Humour and Bartholomew Fair, illustrating how the tension between verse and prose that motivated the satirical dynamics of the mixed-mode plays was released in the full-prose comedies. Jonson's final experiments with theatrical prose dramatize the exhaustion of the satirical impulse by submerging his characters almost entirely in the prosaic world of interactive engagement.

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