H014-01
Planform mobility and indicators of enhanced sediment supply from rivers in the Philippines
Monday, 7 December 2020: 05:30
Virtual
Richard Boothroyd1, Richard Williams2, Brian Barrett2, Martin D Hurst2, Trevor Hoey3, Pamela Tolentino4, John Edward Perez4, Esmael Guardian4 and Carlos Primo David4, (1)University of Glasgow, School of Geographical and Earth Sciences, Glasgow, G12, United Kingdom, (2)University of Glasgow, School of Geographical and Earth Sciences, Glasgow, United Kingdom, (3)Brunel University London, Department of Civil and Environmental Engineering, London, United Kingdom, (4)National Institute of Geological Sciences, University of the Philippines, Quezon City, Philippines
Abstract:
By integrating remotely sensing data from multiple sources (e.g. optical satellite imagery with high resolution digital elevation models, DEMs) we can build a more complete understanding of river morphology trajectories and behaviours. Google Earth Engine (GEE) is transformative in enabling the quantification of planimetric form using multi-temporal, multi-spectral satellite imagery, facilitating inter-catchment comparisons at unprecedented spatiotemporal scales. Using high-resolution DEMs, relief and flow pathway analyses reveal geomorphological characteristics of catchments, indicating tectonic, geologic and climatic signals across landscapes. These characteristics will in turn dictate the processes through and rates at which sediment is eroded, influencing channel morphology and patterns of sediment storage and release. However, the potential for data integration between (i) multi-temporal satellite imagery and (ii) topographic analyses has yet to be fully realised as a resource base to underpin analyses of river character, behaviour and evolution to map geomorphological process zone distributions, accommodation space and responses to disturbance events.
Focusing on the 20 largest catchments in the Philippines, we analyse planform mobility and topographic indicators of enhanced sediment supply at the catchment-scale. We leverage freely available satellite imagery (Landsat and Sentinel collections) in GEE to extract and map changes in the active river channel (including the wetted channel and unvegetated, alluvial deposits) and derive topographic indicators from a nationwide DEM generated through airborne IfSAR technology. The findings exemplify the dynamism of tropical river systems and offer new insights into their morphological behaviour, from source to sink. By understanding the conditions that promote planform mobility, we improve our ability to predict and build resilience to both flood risk and wider geomorphic hazards related to active channel change, across these dynamic landscapes.
