Fluvial morpho-dynamics and climate change during the Late Quaternary in the Kampar Kanan River, Sumatra, Indonesia
Year: 2026
Type: dissertation
Abstract: Fluvial deposits with a robust chrono-stratigraphy can be used to establish the history of river morpho-dynamics and their relationship with paleoclimate. Quaternary climate change has impacted temperature, precipitation and sea-level, as well as land cover, and so is likely also to have impacted river flows and sediment yield. At such timescales, tectonic influences may also be important. Yet Quaternary landscape evolution in tropical river environments, such as Indonesia, remains poorly known, especially over Middle to Late Pleistocene and Holocene timescales. In this context, the focus of this thesis is the Kampar Kanan River, a meandering tropical river in Sumatra Island, Indonesia, that has a gentle slope, sand-gravel beds and bends that migrated laterally due to bank erosion. The aim of the thesis is to quantify how late Quaternary climate change impacted river morpho-dynamics in the Kampar Kanan River, with particular attention to the role of tectonic forcing as an additional control on fluvial behaviour. This study uses both a chrono-stratigraphic framework and fluvial modelling. Satellite images show the recent geometry of the river and combining remote sensing with field observations allowed current river dynamics to be established and links to tectonic history to be made. Sedimentological analysis, utilizing X-ray diffraction and granulometry, was used to investigate facies changes and associated paleoenvironments. This was supported by luminescence dating to provide dates for certain facies and hence to link fluvial morpho-dynamics to known Quaternary climatic histories. To obtain the lateral distribution of channel migration and erosion needed to understand fluvial behaviour, simulation of fluvial dynamics was conducted using a numerical model (eRiDynas model) of water flow and sediment transport to develop a deeper understanding of the drivers of morpho-dynamics. Conceptual scenarios of how climate change impacted the relative balance between monsoon and sediment supply were applied to the model to quantify how it impacted fluvial morpho-dynamics. Results of sedimentological and luminescence dating analyses showed that sedimentation of the Kampar River occurred in the Upper Middle Pleistocene with the presence of massive gravelly channel deposits. This happened in a period of high global glacier cover, cold conditions and low sea levels at Marine Isotope Stage (MIS) 6 or earlier, possibly suggesting a significant increase in sediment supply and/or reduction in sediment transport capacity due to drier conditions. A hiatus in the sedimentary record suggested that sedimentation reduced substantially, and intensive erosion and tectonic activities (particularly uplifting) occurred during glacial to interglacial periods between MIS-4 and 3. In the Late Pleistocene, fining-upward sandy gravels were deposited at late MIS-3, and the river became more associated with low amplitude point bars reflected in lateral accretion deposits. Overbank formations were deposited, indicating the onset of large-scale floodplain inundation and more intensive bend growth, driven primarily by tectonic uplift and reduced fluvial discharge rather than increased humidity, a pattern that continued into the Holocene. This evidence suggested that fluvial morpho-dynamics were primarily climate-controlled, whilst tectonic forcing, particularly uplifting, acted as an additional significant control on sedimentation and terrace development. Numerical modelling further confirmed these findings: decreasing water discharge, representative of drier glacial conditions, and increasing flow discharge, representative of interglacial conditions, produced contrasting river behaviours in terms of sediment deposition, erosion rates, inundation area formation, and bar development, with tectonic uplift amplifying these differences particularly in the southern floodplain. Tectonic forcing therefore exerted a substantial influence on these dynamics, highlighting the importance of accounting for both climatic and tectonic controls in tropical fluvial systems.
Source: IRIS
Author: Yuskar, Yuniarti
Language: English
Subfield: Earth-Surface Processes
Field: Earth and Planetary Sciences
Domain: Physical Sciences
SDG: Climate action
Open Access status: green
Funder: Universitas Islam Riau
OpenAlex ID: W7221735020