The University of Southampton
University of Southampton Institutional Repository

Are equilibrium multichannel networks predictable? The case of the regulated Indus River, Pakistan

Are equilibrium multichannel networks predictable? The case of the regulated Indus River, Pakistan
Are equilibrium multichannel networks predictable? The case of the regulated Indus River, Pakistan
Arguably, the current planform behaviour of the Indus River is broadly predictable. Between Chashma and Taunsa, Pakistan, the Indus is a 264-km-long multiple-channel reach. Remote sensing imagery, encompassing major floods in 2007 and 2010, shows that the Indus has a minimum of two and a maximum of nine channels, with on average four active channels during the dry season and five during the annual monsoon. Thus, the network structure, if not detailed planform, remains stable even for the record 2010 flood (27,100 m3 s− 1; recurrence interval > 100 years). Bankline recession is negligible for discharges less than a peak annual discharge of 6000 m3 s− 1 (~ 80% of mean annual flood). The Maximum Flow Efficiency (MFE) principle demonstrates that the channel network is insensitive to the monsoon floods, which typically peak at 13,200 m3 s− 1. Rather, the network is in near-equilibrium with the mean annual flood (7530 m3 s− 1). The MFE principle indicates that stable networks have three to four channels, thus the observed stability in the number of active channels accords with the presence of a near-equilibrium reach-scale channel network. Insensitivity to the annual hydrological cycle demonstrates that the timescale for network adjustment is much longer than the timescale of the monsoon hydrograph, with the annual excess water being stored on floodplains rather than being conveyed in an enlarged channel network. The analysis explains the lack of significant channel adjustment following the largest flood in 40 years and the extensive Indus flooding experienced on an annual basis, with its substantial impacts on the populace and agricultural production.
0169-555X
Carling, Paul
8d252dd9-3c88-4803-81cc-c2ec4c6fa687
Trieu, Hai, Quang
4d1ee5ca-e853-4526-874a-0a4a5f5bb8f5
Hornby, Duncan
75cfaf57-72c1-4392-a78c-89b4b1033dca
Huang, He Qing
09aac111-fc3f-48a0-91ac-1bebca3d36fc
Darby, Stephen
4c3e1c76-d404-4ff3-86f8-84e42fbb7970
Sear, David
ccd892ab-a93d-4073-a11c-b8bca42ecfd3
Hutton, Craig
9102617b-caf7-4538-9414-c29e72f5fe2e
Hill, C.
f8e9fa28-fd5a-4ad1-9c1d-b1acd846c94e
Ali, Z
71da4e34-b07e-41c5-8bda-7f7005a7f5d8
Ahmed, A
63861b9a-b385-481a-9028-9b006ae9a4b8
Iqbal, I
de642ee8-486e-49fc-b8e0-d88ef8d8d81e
Hussain, Z
25ddc610-c2f6-41e0-9ed2-41002ecd4683
Carling, Paul
8d252dd9-3c88-4803-81cc-c2ec4c6fa687
Trieu, Hai, Quang
4d1ee5ca-e853-4526-874a-0a4a5f5bb8f5
Hornby, Duncan
75cfaf57-72c1-4392-a78c-89b4b1033dca
Huang, He Qing
09aac111-fc3f-48a0-91ac-1bebca3d36fc
Darby, Stephen
4c3e1c76-d404-4ff3-86f8-84e42fbb7970
Sear, David
ccd892ab-a93d-4073-a11c-b8bca42ecfd3
Hutton, Craig
9102617b-caf7-4538-9414-c29e72f5fe2e
Hill, C.
f8e9fa28-fd5a-4ad1-9c1d-b1acd846c94e
Ali, Z
71da4e34-b07e-41c5-8bda-7f7005a7f5d8
Ahmed, A
63861b9a-b385-481a-9028-9b006ae9a4b8
Iqbal, I
de642ee8-486e-49fc-b8e0-d88ef8d8d81e
Hussain, Z
25ddc610-c2f6-41e0-9ed2-41002ecd4683

Carling, Paul, Trieu, Hai, Quang, Hornby, Duncan, Huang, He Qing, Darby, Stephen, Sear, David, Hutton, Craig, Hill, C., Ali, Z, Ahmed, A, Iqbal, I and Hussain, Z (2018) Are equilibrium multichannel networks predictable? The case of the regulated Indus River, Pakistan. Geomorphology. (doi:10.1016/j.geomorph.2017.09.021).

Record type: Article

Abstract

Arguably, the current planform behaviour of the Indus River is broadly predictable. Between Chashma and Taunsa, Pakistan, the Indus is a 264-km-long multiple-channel reach. Remote sensing imagery, encompassing major floods in 2007 and 2010, shows that the Indus has a minimum of two and a maximum of nine channels, with on average four active channels during the dry season and five during the annual monsoon. Thus, the network structure, if not detailed planform, remains stable even for the record 2010 flood (27,100 m3 s− 1; recurrence interval > 100 years). Bankline recession is negligible for discharges less than a peak annual discharge of 6000 m3 s− 1 (~ 80% of mean annual flood). The Maximum Flow Efficiency (MFE) principle demonstrates that the channel network is insensitive to the monsoon floods, which typically peak at 13,200 m3 s− 1. Rather, the network is in near-equilibrium with the mean annual flood (7530 m3 s− 1). The MFE principle indicates that stable networks have three to four channels, thus the observed stability in the number of active channels accords with the presence of a near-equilibrium reach-scale channel network. Insensitivity to the annual hydrological cycle demonstrates that the timescale for network adjustment is much longer than the timescale of the monsoon hydrograph, with the annual excess water being stored on floodplains rather than being conveyed in an enlarged channel network. The analysis explains the lack of significant channel adjustment following the largest flood in 40 years and the extensive Indus flooding experienced on an annual basis, with its substantial impacts on the populace and agricultural production.

Text
1-s2.0-S0169555X17303999-main - Version of Record
Available under License Creative Commons Attribution.
Download (3MB)

More information

Accepted/In Press date: 19 September 2017
e-pub ahead of print date: 27 September 2017
Published date: 1 February 2018

Identifiers

Local EPrints ID: 414785
URI: http://eprints.soton.ac.uk/id/eprint/414785
ISSN: 0169-555X
PURE UUID: 27dca3ee-d537-4952-95ac-9681b8a72193
ORCID for Duncan Hornby: ORCID iD orcid.org/0000-0001-6295-1360
ORCID for Stephen Darby: ORCID iD orcid.org/0000-0001-8778-4394
ORCID for David Sear: ORCID iD orcid.org/0000-0003-0191-6179
ORCID for Craig Hutton: ORCID iD orcid.org/0000-0002-5896-756X

Catalogue record

Date deposited: 11 Oct 2017 16:31
Last modified: 18 Feb 2021 17:02

Export record

Altmetrics

Contributors

Author: Paul Carling
Author: Hai, Quang Trieu
Author: Duncan Hornby ORCID iD
Author: He Qing Huang
Author: Stephen Darby ORCID iD
Author: David Sear ORCID iD
Author: Craig Hutton ORCID iD
Author: C. Hill
Author: Z Ali
Author: A Ahmed
Author: I Iqbal
Author: Z Hussain

University divisions

Download statistics

Downloads from ePrints over the past year. Other digital versions may also be available to download e.g. from the publisher's website.

View more statistics

Atom RSS 1.0 RSS 2.0

Contact ePrints Soton: eprints@soton.ac.uk

ePrints Soton supports OAI 2.0 with a base URL of http://eprints.soton.ac.uk/cgi/oai2

This repository has been built using EPrints software, developed at the University of Southampton, but available to everyone to use.

We use cookies to ensure that we give you the best experience on our website. If you continue without changing your settings, we will assume that you are happy to receive cookies on the University of Southampton website.

×