Remotely sensed land-cover change and floodplain disturbance following upstream-migrating river avulsions in tropical rainforests
Remotely sensed land-cover change and floodplain disturbance following upstream-migrating river avulsions in tropical rainforests
The displacement of a river to a new position within its adjacent floodplain is called avulsion, and here we examine how a newly recognized style, called retrogradational avulsion, affects the surrounding floodplain in tropical rainforests using remote sensing. Retrogradational avulsions begin with a channel blockage that causes self-propagating upstream dechannelization and flooding. While this flooding results in vegetation die-off and floodplain sedimentation, few quantitative measurements of disturbance by retrogradational avulsions exist. Here, we first focus on land-cover change following a single retrogradational avulsion in Papua New Guinea from 2012 to 2021. During the avulsion, the river dechannelized 892 m upstream, and the parent channel width doubled. Using maximum likelihood image classification, we observed healthy vegetation fluctuated around 4.3 km
2, vegetation regrowth peaked in 2017 at 3.2 km
2, dead vegetation peaked in 2013 at 2.1 km
2, and visible extent of deposited sediment was greatest in 2015 at 0.44 km
2. We also examined 19 other retrogradational avulsions in Papua New Guinea and South America using NDVI. The area of floodplain disturbance (i.e., vegetation die-off and possible sedimentation) for each avulsion ranged from <1 to >13 km
2 and scaled with the dechannelization area. Comparing our plan-view disturbance results with FABDEM digital-elevation data and ICESat-2 surface elevation measurements, we hypothesize floodplain disturbance extent is a function of topographic relief. Our results also suggest that retrogradational avulsions, on average, perturb larger areas of forest compared to blowdowns, suggesting this might be an important disturbance regime that influences gap-filling regeneration in tropical rainforests.
NDVI, disturbance regime, floodplain disturbance, image classification, land-cover change, remote sensing, retrogradational avulsion, tropical rainforests
559-574
Henson, Riley T.
4256666c-3952-4897-89f3-80e6691b9416
Edmonds, Douglas A.
4a2b385c-299a-422d-85e9-ecae8de7d702
Lazarus, Eli D.
642a3cdb-0d25-48b1-8ab8-8d1d72daca6e
18 February 2024
Henson, Riley T.
4256666c-3952-4897-89f3-80e6691b9416
Edmonds, Douglas A.
4a2b385c-299a-422d-85e9-ecae8de7d702
Lazarus, Eli D.
642a3cdb-0d25-48b1-8ab8-8d1d72daca6e
Henson, Riley T., Edmonds, Douglas A. and Lazarus, Eli D.
(2024)
Remotely sensed land-cover change and floodplain disturbance following upstream-migrating river avulsions in tropical rainforests.
River Research and Applications, 40 (4), .
(doi:10.1002/rra.4256).
Abstract
The displacement of a river to a new position within its adjacent floodplain is called avulsion, and here we examine how a newly recognized style, called retrogradational avulsion, affects the surrounding floodplain in tropical rainforests using remote sensing. Retrogradational avulsions begin with a channel blockage that causes self-propagating upstream dechannelization and flooding. While this flooding results in vegetation die-off and floodplain sedimentation, few quantitative measurements of disturbance by retrogradational avulsions exist. Here, we first focus on land-cover change following a single retrogradational avulsion in Papua New Guinea from 2012 to 2021. During the avulsion, the river dechannelized 892 m upstream, and the parent channel width doubled. Using maximum likelihood image classification, we observed healthy vegetation fluctuated around 4.3 km
2, vegetation regrowth peaked in 2017 at 3.2 km
2, dead vegetation peaked in 2013 at 2.1 km
2, and visible extent of deposited sediment was greatest in 2015 at 0.44 km
2. We also examined 19 other retrogradational avulsions in Papua New Guinea and South America using NDVI. The area of floodplain disturbance (i.e., vegetation die-off and possible sedimentation) for each avulsion ranged from <1 to >13 km
2 and scaled with the dechannelization area. Comparing our plan-view disturbance results with FABDEM digital-elevation data and ICESat-2 surface elevation measurements, we hypothesize floodplain disturbance extent is a function of topographic relief. Our results also suggest that retrogradational avulsions, on average, perturb larger areas of forest compared to blowdowns, suggesting this might be an important disturbance regime that influences gap-filling regeneration in tropical rainforests.
Text
River Research Apps - 2024 - Henson - Remotely sensed land‐cover change and floodplain disturbance following
- Version of Record
More information
Accepted/In Press date: 28 January 2024
Published date: 18 February 2024
Keywords:
NDVI, disturbance regime, floodplain disturbance, image classification, land-cover change, remote sensing, retrogradational avulsion, tropical rainforests
Identifiers
Local EPrints ID: 490713
URI: http://eprints.soton.ac.uk/id/eprint/490713
ISSN: 1535-1459
PURE UUID: aa682106-d4e1-4276-9060-6fd66f1867dc
Catalogue record
Date deposited: 04 Jun 2024 16:37
Last modified: 06 Jun 2024 01:58
Export record
Altmetrics
Contributors
Author:
Riley T. Henson
Author:
Douglas A. Edmonds
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
