A time-series analysis of three types of erosion in the Caraulun catchment, Timor-Leste

A time-series analysis of three types of erosion in the Caraulun catchment, Timor-Leste

Fri, 16/11/2012 - 09:30


About the Presenter

Juno Rouwenhorst

Juno Rouwenhorst is a PhD student with RIEL, CDU, and is currently living in Brisbane, QLD.  She previously collaborated on Projects 1 and 6 of the Timor-Leste Coastal/marine Habitat Mapping for Tourism and Fisheries Development Project. 

Her research interests include (fluvial) geomorphology, landslides, river bank erosion, sediment budgets, erosion transport processes, applied RS and GIS, as well as the social/anthropogenic aspect to each of these topics.


Venue

Charles Darwin University
Ellengowan Drive
Building Red 6.1.10
Casuarina NT 0810
Australia

Throughout many of Timor-Leste’s mountainous regions, rivers are filling up with sediment and causing increases in the severity of flooding.  The first step towards management of this situation is to understand where the sediment comes from.  This presentation is based on Juno’s PhD research in the Caraulun catchment, which aims to evaluate the three types of erosion likely to be main sources of sediment in the Caraulun River.  Sheet erosion, landsliding, and river bank erosion are analysed with regard to their spatial distribution and temporal changes in estimated sediment volumes. 

The approach to this research was kept relatively basic and low-cost to facilitate the reproduction of these analyses for other catchments.  Remote sensing and geographic information systems (GIS) techniques were applied to map vegetation cover from Landsat 5TM imagery from 1986, 1996, and 2006.  This dataset, in combination with ancillary data, forms the foundation for further analyses, and is linked with fieldwork and Revised Universal Soil Loss Equation (RUSLE) modelling, slope threshold models, and change analysis techniques to determine net sediment loss associated with sheet erosion, landslides, and river bank erosion.

The resulting (source-based) sediment budget shows that the total estimated denudation (lowering) rate for the catchment is 2.9±0.5 mm/yr over a twenty year period.  Landslides are the biggest contributors of sediment at an estimated 48% of the total sediment volume.  River bank erosion and sheet erosion are estimated to contribute 34% and 17% respectively.  Details of these results, including spatial and temporal findings, will be discussed in the seminar.

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