Potgieter, A. B. and Apan, A. and Hammer, G. and Dunn, P. (2010) Early-season crop area estimates for winter crops in NE Australia using MODIS satellite imagery. ISPRS Journal of Photogrammetry and Remote Sensing, 65 (4). pp. 380-387. ISSN 0924-2716
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Official URL: http://www.elsevier.com/locate/isprsjprs
Identification Number or DOI: doi: 10.1016/j.isprsjprs.2010.04.004
To date, industry and crop forecasters have had a good idea of the potential crop yield for a specific season, but early-season information on crop area for a shire or region has been mostly unavailable. The question of how early and with what accuracy? area estimates can be determined using multi-temporal Moderate Resolution Imaging Spectroradiometer (MODIS) enhanced vegetation index (EVI) imagery was investigated in this paper. The study was conducted for two shires in Queensland, Australia for the 2003 and 2004 seasons, and focused on deriving total winter crop area estimates (including wheat, barley and chickpea). A simple metric (1E), which measures the green-up rate of the crop canopy, was derived. Using the unsupervised k-means classification algorithm, the accumulated difference of two consecutive images(one month apart) for three EVI threshold cut-offs (1Ei, where i D 250, 500 and 750) at monthly intervals from April to October was calculated. July showed the highest pixel accuracy with percent correctly classified for all thresholds of 94% and 98% for 2003 and 2004, respectively. The differences in accuracy between the three cut-offs were minimal and the T500 threshold was selected as the preferred cut-off to avoid measuring too small or too large fluctuations in the differential EVI values. When compared to the aggregated shire data (surveyed) on crop area across shires and seasons, average percent differences for the 1ET500 for July and August ranged from 19% to 9%. To capture most of the variability in green-up within a region, the average 1ET500 of July and August was used for the early-season prediction of total winter crop area estimates. This resulted in high accuracy (R2 D 0:96; RMSE D 3157 ha) for predicting the total winter crop from 2000 to 2004 across both shires. This result indicated that this simple multitemporal remote sensing approach could be used with confidence in early-season crop area prediction at least one to two months ahead of anthesis.
|Item Type:||Article (Commonwealth Reporting Category C)|
|Additional Information:||Author version not held.|
|Uncontrolled Keywords:||early-season; crop area estimates; simple metric; multi-temporal; shire-scale|
|Fields of Research (FOR2008):||07 Agricultural and Veterinary Sciences > 0701 Agriculture, Land and Farm Management > 070104 Agricultural Spatial Analysis and Modelling|
09 Engineering > 0909 Geomatic Engineering > 090905 Photogrammetry and Remote Sensing
07 Agricultural and Veterinary Sciences > 0703 Crop and Pasture Production > 070301 Agro-ecosystem Functionand Prediction
|Socio-Economic Objective (SEO2008):||B Ecomonic Development > 82 Plant Production and Plant Primary Products > 8205 Winter Grains and Oilseeds > 820507 Wheat|
|Deposited On:||14 Mar 2011 12:17|
|Last Modified:||07 Feb 2012 09:53|
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