Towards image-based monitoring of soil erosion risk in southern Australia.

Towards image-based monitoring of soil erosion risk in southern Australia. Megan Lewis

Place and Purpose Symposium 2009 Towards image-based monitoring of soil erosion risk in South Australian agricultural lands Assoc. Prof. Megan Lewis Dr Ken Clarke Dr Bertram Ostendorf Landscape Futures Program The University of Adelaide

Place and Purpose Symposium 2009 Overview • Collaborative research program 2002-present – University of Adelaide & Soil Conservation Council, Dept Water, Land & Biodiversity Conservation • Approaches and key findings • Collaborative process • Ongoing research

Place and Purpose Symposium 2009 Context • Cropping regions of SA • Cereal cropping is integral to Australia’s economy – ¼ of Australia’s cereal crops produced in SA: 5,382 kT • Soil conservation essential for economically viability & sustainability • Legislative requirement for soil conservation – Soil Conservation & Land Care Act Act 1989 – Natural Resources Management Act 2004 • State Strategic Plan target – 20% increase in land protected from erosion by 2014 • DWLBC monitors soil cover to minimise erosion – Land Condition Monitoring Project (2000 – present)

Place and Purpose Symposium 2009 DWLBC Land condition monitoring project methodology • Windscreen surveys along road transects, 5,500 locations – 4 surveys / year • Oblique visual estimate of: – Cover – Detachment

Place and Purpose Symposium 2009 DWLBC Land condition monitoring project methodology • Regional and State-wide reports Full cover Bare • Costly • Limited to spatial and temporal samples, not spatially explicit

Place and Purpose Symposium 2009 What about remote sensing? • Collaborative research with University of Adelaide & Dept. Water Land & Biodiversity Conservation 2002- present • Aim: To bring benefits of remote sensing to SA Land Condition Monitoring Program – Spatially explicit, comprehensive & objective assessment of cover – Improved assessment of areas at risk/protected – Increased temporal frequency – Cost effective • Funding: Soil Conservation Council, DWLBC, University of Adelaide, ARC Linkage grant

Place and Purpose Symposium 2009 Collaborative approach Windscreen Image Survey data indices • Develop & test image indices • Calibrate & validate with extensive existing WSS data • Demonstrate relationships between field & image measures • Enhance not replace field survey • Develop organisational understanding & confidence in remote sensing approach Operational use of remote sensing for land condition monitoring in SA

Place and Purpose Symposium 2009 Remote sensing approaches • NOAA AVHRR • AUSSIEGrass products • MODIS – Single date images – Nadir BRDF adjusted reflectance 16 day composites • Existing Indices NDVI PD54 • New index: UA Vegetation Index based on Cellulose Index • Single dates • Annual 16-day sequence • 2001-present 16 day sequence

Place and Purpose Symposium 2009 Key technical findings 1. UA Vegetation Index best predictor of Cover Rating – NDVI doesn’t discriminate bare soil from dry stubble – PD54 difficult to calibrate over time, difficult for operational use

Place and Purpose Symposium 2009 University of Adelaide Vegetation Index • Strongest relationships with Cover Rating • UAVI = (Band 6 – Band 7) / (Band 6 + Band 7) 0.8 MODIS Bands 6 & 7 0.7 0.6 0.5 Soil Reflectance 0.4 0.3 Dead vegetation 0.2 Growing 0.1 vegetation Blue Green Red Near infra-red Short wave infra-red 0 400 500 600 700 800 900 1000 1100 1200 1300 1400 1500 1600 1700 1800 1900 2000 2100 2200 2300 2400 Wavelength (nm) Clarke, K. and Lewis, M. (2009) Report 3: Development of a satellite image-based land condition monitoring system for South Australian agricultural regions. Land condition monitoring reports. Adelaide, The University of Adelaide.

Place and Purpose Symposium 2009 Key technical findings 1. UA Vegetation Index best predictor of Cover Rating – NDVI doesn’t discriminate bare soil from dry stubble – PD54 difficult to calibrate over time, difficult for operational use 2. Relationships between image indices & Cover Rating from field survey – Adequate correlations across whole Cropping District – Stronger correlations when stratified by region – Relationship to Cover Rating changes with season – Strong relationships UAVI vs Cover rating when soil exposure high

Place and Purpose Symposium 2009 Relationship between Vegetation Index and Cover Rating changes through seasons Bare soil 8 7 6 Cover Rating 5 2003 March 09 4 3 2 Full cover 1 0 0.2 0.4 UAVI Clarke, K., Lewis, M. and Ostendorf, B. (2004, rev. 2009) Report 2: Assessing the potential of MODIS imagery for monitoring land condition in the crop lands and non pastoral lease rangelands of South Australia. Land condition monitoring reports. Adelaide, The University of Adelaide.

Place and Purpose Symposium 2009 Relationship between Vegetation Index and Cover Rating changes through seasons Bare soil 8 7 6 Cover Rating 5 2003 March 09 2003 June 11 4 3 2 Full cover 1 0 0.2 0.4 UAVI Clarke, K., Lewis, M. and Ostendorf, B. (2004, rev. 2009) Report 2: Assessing the potential of MODIS imagery for monitoring land condition in the crop lands and non pastoral lease rangelands of South Australia. Land condition monitoring reports. Adelaide, The University of Adelaide.

Place and Purpose Symposium 2009 Relationship between Vegetation Index and Cover Rating changes through seasons Bare soil 8 7 6 R2 = 0.65 Cover Rating 2003 March 09 5 2003 June 11 4 2003 October 12 3 2 Full cover 1 0 0.2 0.4 0.6 UAVI Clarke, K., Lewis, M. and Ostendorf, B. (2004, rev. 2009) Report 2: Assessing the potential of MODIS imagery for monitoring land condition in the crop lands and non pastoral lease rangelands of South Australia. Land condition monitoring reports. Adelaide, The University of Adelaide.

Place and Purpose Symposium 2009 Relationship between Vegetation Index and Cover Rating changes through seasons Spearman Rank Correlation Coefficients Region/ March May July October All index 2006 2006 2006 2006 2006 NDVI Eyre Peninsula -0.038 -0.286 *** -0.353 *** -0.425 *** -0.108 Murraylands +0.031 -0.281 *** -0.371 *** -0.241 *** -0.124 * Northern and Yorke -0.032 -0.251 *** -0.296 *** -0.374 *** +0.052 South East +0.076 -0.031 -0.065 +0.007 -0.196 ** All regions combined -0.122*** -0.305 *** -0.382 *** -0.234 *** -0.022 UAVI Eyre Peninsula -0.223 ** -0.304 *** -0.305 *** -0.407 *** -0.187 ** Murraylands -0.098 -0.275 *** -0.381 *** -0.143 *** -0.241 *** Northern and Yorke -0.358 *** -0.365 *** -0.277 *** -0.372 *** -0.278 *** South East +0.023 -0.054 -0.094 +0.052 -0.037 All regions combined -0.201 *** -0.339 *** -0.398 *** -0.258 *** -0.211 *** p * 0.05 ** 0.01 *** 0.001 Clarke, K. and Lewis, M. (2009) Report 3: Development of a satellite image-based land condition monitoring system for South Australian agricultural regions. Land condition monitoring reports. Adelaide, The University of Adelaide.

Place and Purpose Symposium 2009 Key technical findings 1. UA Vegetation Index best predictor of Cover Rating – NDVI doesn’t discriminate bare soil from dry stubble – PD54 difficult to calibrate over time, difficult for operational use 2. Relationships between image indices & Cover Rating from field survey – Adequate correlations across whole Cropping District – Stronger correlations when stratified by region – Relationship to Cover Rating changes with season – Strong relationships UAVI vs Cover rating when soil exposure high 3. Large proportion of variation in cover/soil exposure is explained by climate (intra- & inter-annual variation) – Seasonal index profiles track land cover changes through year – Possible to identify land management influences as deviation from regional mean

Place and Purpose Symposium 2009 Annual profiles of image indices

Place and Purpose Symposium 2009 Annual profiles of image indices • Summer (no growth, NPV decay)

Place and Purpose Symposium 2009 Annual profiles of image indices • Summer (no growth, NPV decay) • Germination (weed & non-cereal crops)

Place and Purpose Symposium 2009 Annual profiles of image indices • Summer (no growth, NPV decay) • Germination (weed & non-cereal crops) • Ploughing, spraying off, direct seeding

Place and Purpose Symposium 2009 Annual profiles of image indices • Summer (no growth, NPV decay) • Germination (weed & non-cereal crops) • Ploughing, spraying off, direct seeding • Cereal crop germination and tillering & growth to full canopy

Place and Purpose Symposium 2009 Annual profiles of image indices • Summer (no growth, NPV decay) • Germination (weed & non-cereal crops) • Ploughing, spraying off, direct seeding • Cereal crop germination and tillering & growth to full canopy • Crop ripening (senescence) and harvest

Place and Purpose Symposium 2009 Annual profiles of image indices • Summer (no growth, NPV decay) • Germination (weed & non-cereal crops) • Ploughing, spraying off, direct seeding • Cereal crop germination and tillering & growth to full canopy • Crop ripening (senescence) and harvest • Summer (NPV decay)

Place and Purpose Symposium 2009 Importance of climatic influence Relationship between AUSSIEGrass model & Cover rating Rainfall Seasonal + Total Pasture Growth Cover Rating +Total Standing Dry Matter March May June October Grech, A., Ostendorf, B. and Lewis, M. (2003) Report 1: Land condition monitoring: integrating ground surveys, Aussie GRASS and satellite remote sensing. Land condition monitoring reports. Adelaide, The University of Adelaide.

Place and Purpose Symposium 2009 Importance of climatic influence Cover Rating 2001 predicted from AussieGRASS model developed with 2000, 2002, 2003 data Grech, A., Ostendorf, B. and Lewis, M. (2003) Report 1: Land condition monitoring: integrating ground surveys, Aussie GRASS and satellite remote sensing. Land condition monitoring reports. Adelaide, The University of Adelaide.

Place and Purpose Symposium 2009 Average annual UAVI (2006) Clarke, K. and Lewis, M. (2009) Report 3: Development of a satellite image-based land condition monitoring system for South Australian agricultural regions. Land condition monitoring reports. Adelaide, The University of Adelaide.

Place and Purpose Symposium 2009 Cumulative difference from regional mean UAVI: Murraylands

Place and Purpose Symposium 2009 Cumulative difference from regional mea UAVI : Northern and Yorke • Demonstrates local management influence – Snowtown example

Place and Purpose Symposium 2009 Land management influences on cover detected by UAVI

Place and Purpose Symposium 2009 Methodological findings Windsceen Image Survey data indices • Oblique view • Vertical view • Ranked classes of Cover Rating – not • Integrated response of projected soil a direct measure of projected cover & vegetation cover • Surveyor variability • Objective, calibrated repeatable Advantages • Extensive field survey data available • Familiarity of field method Disadvantages • Field & image indices measure soil/cover in different ways • Error, variability in field data not known • Need independent cover data for calibration & validation • Calibration relationship Cover Rating/Image Index not possible

Place and Purpose Symposium 2009 Institutional change process • Considerable shift in organizational understanding & acceptance of remote sensing approach – Collaboration in projects – Sharing of data, findings – Increased investment in research • Personnel change a significant factor – new staff with remote sensing backgrounds

Place and Purpose Symposium 2009 The future • Current ARC Linkage project – Extend MODIS temporal analysis 2001-present – Relative Spectral Mixture Analysis: time traces of soil, photosynthetic, non-photosynthetic vegetation – Identify management influences on soil exposure through comparison of actual vs. climatically-predicted cover • Relationships with Australian Collaborative Land use and Management Program (ACLUMP): development of field and remote sensing methods for monitoring fractional landcover • Development of reporting products, information delivery with DWLBC

Place and Purpose Symposium 2009 Acknowledgements Researchers • Ken Clarke • Bertram Ostendorf • Alana Grech Collaborators – DWLBC • Anna Dutkiewicz • Giles Forward • Glenn Gale • Andy McCord • Richard Payne Funding • Soil Conservation Council • Dept. Water Land & Biodiversity Conservation • Australian Research Council

The Environment Institute

Towards image-based monitoring of soil erosion risk in southern Australia.

by University of Adelaide on Oct 02, 2009

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Towards image-based monitoring of soil erosion risk in southern Australia. — Webinar Transcript