Understanding sediment sources in data poor environments: an example from Eastern Indonesia

Understanding sediment sources in data poor environments: an example from Eastern Indonesia

Fri, 13/06/2014 - 10:00 to 11:00


About the Presenter

Sarah Hobgen is in the final stages of her PhD, this project has been supervised by Dr Bronwyn Myers, Rohan Fisher, Prof. Robert Wasson (NUS) and Dr Guy Boggs. Sarah completed undergraduate studies in Environmental Science at Monash University and previously worked in bushfire management in Victoria and with Landcare in southern NSW. Sarah has been based in Sumba, Indonesia since 2008.


Venue

Charles Darwin University
Ellengowan Drive
Building Red 1.3.01
Casuarina NT 0810
Australia

Sedimentation of water storages is a major problem throughout the wet-dry tropics of Asia. High sediment loads are often attributed to topsoil erosion from agriculture in upland areas. Sediment budgets aim to quantify the relative contribution of a range of sediment sources and sinks, and can be a useful tool for catchment managers in planning erosion mitigation strategies.

This project developed a first-order sediment budget in a data-poor environment, the Kambaniru River catchment in Sumba, Eastern Indonesia. This method utilised free and open source GIS and remote sensing, key informant interviews, field measurements and radionuclide tracers.

In the first 18 years of operation, 87% of the storage capacity of the Kambaniru Weir pool filled with sediment. Sediment sources include topsoil erosion (31%), channel change (22%), gully erosion (8%) and landslides (1%). Using this first-order approach, approximately 37% of sediment remains unaccounted for. These results combined with interviews with local farmers indicate that gully erosion and channel change causing loss of fertile cropland and forcing conversion of rice paddies to maize fields have immediate negative impacts on livelihoods and increase sediment loads in the river. 

 

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