Impacts of rapid land use change on the meandering dynamics of the Kinabatangan River, Borneo

Horton, Alexander 2017. Impacts of rapid land use change on the meandering dynamics of the Kinabatangan River, Borneo. PhD Thesis, Cardiff University. Item availability restricted.

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Abstract

Agricultural expansion is driving tropical deforestation and the conversion of fertile floodplains along large meandering rivers. Yet despite a wealth of research showing the importance of riparian vegetation to the processes of riverbank retreat, little is known of the geomorphic response of large rivers to the rapid removal of natural riparian cover. The Kinabatangan River in Northern Borneo offers an important opportunity to study the morphological change induced by extensive land conversion, as palm oil plantations have replaced much of the floodplain forest in recent decades. Using LANDSAT imagery from 1989 – 2014 I examine the impact of widespread land use change on the meandering dynamics of the Kinabatangan River, and quantify the provision of an ecosystem service by riparian reserves to adjacent oil palm plantations. Rates of channel migration following deforestation increase by >23%, and the correlation between planform curvature and rates of riverbank retreat only became strongly positive and significant after the removal of natural riparian cover, suggesting an important role of forests in the evolution of meandering rivers, even when riverbank heights exceed the depth of root penetration. By means of a numerical model of channel migration that explicitly represents the role of a dense root network in controlling the residency time of slump blocks, I then demonstrate that riparian vegetation can affect rates and patterns of channel migration by altering the composition and fate of failed bank material armouring the bank toe. Furthermore, I estimate the value of the geomorphic ecosystem service that riparian reserves provide by protecting adjacent oil palm plantations from bank erosion over long-term economic horizons.

Item Type:	Thesis (PhD)
Date Type:	Completion
Status:	Unpublished
Schools:	Earth and Environmental Sciences
Subjects:	Q Science > QE Geology
Funders:	Natural Environmental Research Council (NERC)
Date of First Compliant Deposit:	6 October 2017
Last Modified:	05 May 2021 09:11
URI:	https://orca.cardiff.ac.uk/id/eprint/105195

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