201212 lowry, john using lidar data to derive geomorphic parameters for landform design

8/2/2019 201212 Lowry, John Using LIDAR Data to Derive Geomorphic Parameters for Landform Design

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Supervising Scientist - working to protect the environment from the impacts of uranium mining

www.environment.gov.au/ssd

Using LiDAR data to derive geomorphic

parameters for landform design

John Lowry

Environmental Research Institute of the Supervising Scientist


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2Supervising Scientist Division

Presentation outline

SSD background and role

Landform design process

Creation and collection of input data

Geomorphometry

Application of LiDAR Derivation of geomorphic parameters

Results to date

Concluding thoughts


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SSD background

Protects the Alligator RiversRegion from the effects of

uranium mining

Conducts environmental

research and monitoring,environmental supervision,

audit and inspection.

Encourages best practice in

wetland conservation andmanagement.


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Production at Ranger scheduled to continue until 2020

Need to rehabilitate landform at cessation of mining Landform design parameters developed ~2000

Relatively coarse (20m) DEM used to derive parameters

Higher resolution data opportunity to revisit parameters

Ensure landform design meets closure criteria

Environmental requirements for closure state that

The company must rehabilitate the Ranger Project Area toestablish an environment similar to the adjacent areas ofKakadu National Park such that, in the opinion of the

Minister with the advice of the Supervising Scientist, therehabilitated area could be incorporated into the KakaduNational Park.


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Landform design

(ERA)

Gullies, incision,Contaminant exposure

sediment loss

Criteria:

Cap thickness

Slope/Gradient change

Vegetation/ecosystemRadiation

Hydrology

No / acceptable

impact

Predictive modelling

ErosionHydrology

LEM

(SSD)

Unacceptable impact

Landform design and modelling process

Catchment impactLandform stability

Stream sediment load,water quality

radiation

Next approvalphase

Erosion assessment


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Landform design Design parameters

derived from

geomorphometricanalysis of analoguelandforms Geomorphic properties

controlling watermovement, erosion

and sedimentation Underpin ecological

function, soildevelopment andecological patterns

Environmental values

of adjacent areas ofKakadu National parkrepresented in theGeorgetownanalogue area.


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Table 1Landform design parameters

Parameter Definition Environmental significance

Slope Gradient Affects overland and subsurface flow velocity andrunoff rate, geomorphology

Profile Curvature Slope profile curvature Affects flow acceleration, erosion/deposition rate,geomorphology

Plan Curvature Contour curvature Affects converging / diverging flow, soil watercontent, soil characteristics.

Slope Length (flow path length) Maximum distance of water flow toa point in the catchment

Affects erosion rates and sediment yield.

Elevation Height relative to sea level Affects climate, vegetation composition,distribution and abundance

LS_Factor (erosion index) Represents effect of slope length onerosion; ratio of soil loss from agiven hillslope length and gradientto soil loss from a standard unitplot.

Predicts areas of net erosion and net depositionareas

Erosion Deposition Index (streampower index)

Measure of erosive power thatpredicts net erosion in convex areasand net deposition in concave areas

Affects erosion / sedimentation rate, nutrientsupply, soil depth and texture,

Aspect The direction or orientation(compass bearing) in which a slopefaces

Position of a site in relation to climatic elements(winds, sunlight) received. Affects vegetationcomposition and distribution

Relief Absolute difference in elevationwithin a [300m] radius of a definedpoint

Range in elevation within a defined radius of apoint

TWI (topographic wetness indices) Describes the distribution and extentof zones of saturation for runoffgeneration

Identifies areas/ zones of water concentration inthe landscape. Will affect vegetation compositionand distribution through plant available water,



Poor landformdesign may causea range ofenvironmentalproblems

Erosion

Landform instability

Transportation ofcontaminatedmaterials

Changes to thecomposition andstructure ofvegetationcommunities



Why DEMs

Geomorphometry = quantative analysis of a land surface

Multiple geomorphometric parameters may be generatedfrom a single DEM:

slope,

curvature,

topographic wetness index

aspect

slope length

plan / profile curvature

etc



Available elevation data for Ranger...

1& 3 SRTM DEMs

ALOS PRISM 5-metre DEM

5 & 10-metre DEM derived from Aerial Photography

Topographic contours 0.5 3 metre contours Terrestrial laser scan data - 20 cm resolution

LiDAR - 1 metre resolution

Miscellaneous ad-hoc

20m floodplain



LiDAR data acquired for Ranger project area 1 October2010.

Data captured with horizontal resolution of 0.25m and verticalresolution of 0.15m

0.5 metres contours supplied

1m-resolution grid surface generated for the Georgetownanalogue surface



ArcGIS spatial analyst, Whitebox, SAGA andLandserf software used for geomorphometricanalysis

Good correspondence between different models used

LiDAR DEM common input

Comparison Profile curvature



Results

Previous results derived from 20m DEM



Pluses and minuses for LiDAR vs earlier DEMdata

LIDAR 20m DEM

Cost

Useable format

Metadata

Resolution

Areal extent

Bare earth and surfacecomponents

Point classification

Known accuracy

Appropriate resolutionfor erosion modellingand assessment



Concluding thoughts...

Geomorphometric parameters have been derived fromthe LiDAR DEM of the analogue with increasedconfidence and accuracy.

Enables a more accurate assessment of stability oflandform designs.



Questions?

Thank you : P Puig (ERA), C Humphrey, G Fox, M Saynor (SSD)

201212 lowry, john using lidar data to derive geomorphic parameters for landform design

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