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Creating Sediment Budgets in
data poor regionsThe case for combining radionuclide tracers
with Remote Sensing & GIS techniques
Sarah Hobgen
Research Institute for Environment and Livelihoods
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Why are sediment budgets important?
What is a sediment budget?
Creating a sediment budget
Radionuclide tracers
RS/GIS methods Summary
Overview of presentation
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Why are sediment budgets important?
Domestic water supply
Agricultural water supply
Hydroelectricity
generation
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What is a sediment budget?
Landslides GullyErosionRiver bank collapse/ Channel change
Rill & Sheet erosion
(Topsoil)
Storage in channel,
sediment bars
Sediment
discharged
Aims :
1. Determine relative importance ofdifferent erosion processes
2. Locate erosion sources
3. Quantify sediment volumes
4. Use simplified methods that require
minimal resources
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Creating a sediment budgetWhat are the
dominant erosionprocesses?
Radionuclide topsoiltracers
Manual imagery
analysis
Where in thecatchment is the
erosion occurring?
Topsoil Erosion RiskAssessment
Manual imagery
interpretation
Sedimentfingerprinting
How much sediment isreaching the weir or
river mouth?
RS & GIS
Field measurements
Generalisedequations
How are we going to use this information?
Determines the level of detail required
Resources available to complete the task
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Radionuclide Topsoil Tracers From nuclear weapons testing
Half life of 30 years
Useful for medium term erosion studies
Caesium - 137
Naturally occurring
Half life of 22 years
Medium term erosion studies
Lead - 210(excess)
From nuclear weapons testing
Long half life of 24,110 years
Medium term erosion studiesPlutonium - 239
Naturally occurring
Short half life of 53 days Short term or single flood event studies
Beryllium -7
Naturally occurring
Long half life of 1.5 million years
Estimating natural erosion ratesBeryllium 10
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Creating a sediment budgetWhat are the
dominant erosionprocesses?
Radionuclide tracers
Manual imageryinterpretation
Where in thecatchment is the
erosion occurring?
GIS Rapid TopsoilRisk Assessment
RS Manual imagery
interpretation
Sediment chemicalfingerprinting
How much sediment isreaching the weir or
river mouth?
RS & GIS
Field measurements
How are we going to use this information?
Determines the level of detail required
Resources available to complete the task
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RUSLE-based Rapid Topsoil Risk AssessmentFactor Methods Data Source Availability
R factor
Rainfall
Intensity
Monthly rainfall averages
interpreted to estimate
intensity using Fournier
equation
World Clim Global
climate model
Free to download
www.worldclim.org
LS factor
Slope length
Slope angle
LS module in many raster
GIS applications
ASTERv2 global DSM
SRTM DTM
Free to download
www.gdem.aster.er
sdac.or.jp
C factor
Land Cover
Supervised classification of
land cover classes
Landsat imagery,
30m resolution
Archive free to
download
glovis.usgs.gov
K factor
Soil erodibility
Determination of land units
from DEM
Field data collection at
representative locations
ASTER DEM -
Geology mapping
Field soil
classification
Field work or existing
soil mapping
required
P factor *
Land conserv.
practices
Manual identification on
high resolution imagery,
field mapping
Google Earth Free to use online
earth.google.com
http://www.worldclim.org/http://www.gdem.aster.ersdac.or.jp/http://www.gdem.aster.ersdac.or.jp/http://www.glovis.usgs.gov/http://www.glovis.usgs.gov/http://www.gdem.aster.ersdac.or.jp/http://www.gdem.aster.ersdac.or.jp/http://www.worldclim.org/8/2/2019 201228 Hobgen, Sarah Creating Sediment Budgets in Resource and Data Poor Environments
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RUSLE-based Rapid Topsoil Erosion Risk
Assessment
Kambaniru Catchment
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Connectivity of sediment sources to
the river
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Mapping gullies, landslides and
channel changeData Application Availability
Quickbird, SPOT
imagery
(High resolution)
Manual interpretation of
imagery to map gully,
landslide and channelmigration.
Accuracy assessments.
Google earth
Planet Action Initiative*
www.planet-action.org
Landsat Manual interpretation of
imagery to map gully,
landslide and channelmigration.
Archive free to
download
http://glovis.usgs.gov
http://www.planet-action.org/http://www.planet-action.org/http://www.planet-action.org/http://www.planet-action.org/8/2/2019 201228 Hobgen, Sarah Creating Sediment Budgets in Resource and Data Poor Environments
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Creating a sediment budgetWhat are the
dominant erosionprocesses?
Radionuclide tracers
RS & GIS
Where in the
catchment is theerosion occurring?
Rapid RiskAssessment
Manual imagery
interpretation Sediment
fingerprinting
How much sediment is
reaching the weir orriver mouth?
RS & GIS
Field measurements
Generalised
equations
How are we going to use this information?
Determines the level of detail required
Resources available to complete the task
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Quantifying sediment productionData Application Availability
Cartosat, LiDAR,Digital globe
DEM
Change detection for gully erosionand channel migration.
Quantifying sediment production
Purchase/order onlineLiDAR Cartosat websites
Aerial
photographs
(multiple imagedates)
Change detection
Sediment volumes can be estimated
using predictive equations
Dependent on location ,
project budget and security
requirements to accesshistorical imagery
Field
measurements
Estimating sediment volumes to
supplment aerial photo or imagery
analysis
Survey of weir and comparison with
blueprints
Require time and field
budget
Access to original plansand reports can be difficult
Generalised
equations
Estimate sediment yield using
results from RS and published results
Accuracy difficult to assess,
also does not capture
changes due to
management actions
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Sediment budget
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Sediment budgets are an important tool for landand water managers
Constant trade-off between accuracy andresources required
Radionuclide and spatial methods combined area powerful tool
Freely accessible data combined with opensource software provides an economical andefficient approach in data poor regions
Summary
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Acknowledgements
Research Award 2010
Postgraduate Research Award 2011-2013
Prime Ministers Australia Asia Award 2012
RESEARCH FUNDING:SUPERVISION:
Dr Bronwyn Myers
Research Institute for Environment and LivelihoodsCharles Darwin University
Prof Robert WassonDept. of Geography
National University of Singapore
Rohan FisherResearch Institute for Environment and Livelihoods
Charles Darwin University
Dr Guy BoggsAdjunct
Research Institute for Environment and Livelihoods
Charles Darwin University