Improved estimates of opium cultivation in Afghanistan using imagery-based stratification

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dc.contributor.authorSimms, Daniel M.
dc.contributor.authorWaine, Toby W.
dc.contributor.authorTaylor, John C.
dc.date.accessioned2017-05-25T14:38:01Z
dc.date.available2017-05-25T14:38:01Z
dc.date.issued2017-03-30
dc.description.abstractThe United Nations O ce on Drugs and Crime and the US Government make extensive use of remote sensing to quantify and monitor trends in Afghanistans illicit opium production. Cultivation gures from their independent annual surveys can vary because of systematic di erences in survey methodologies relating to spectral strati cation and the addition of a pixel bu er to the agricultural area. We investigated the e ect of strati cation and bu ering on area estimates of opium poppy using SPOT5 imagery covering the main opium cultivation area of Helmand province and sample data of poppy elds interpreted from very high resolution satellite imagery. The e ect of resolution was investigated by resampling the original 10 m pixels to 20, 30 and 60 m, representing the range of available imagery. The number of strata (1, 4, 8, 13, 23, 40) and sample fraction (0.2 to 2%) used in the estimate were also investigated. Strati cation reduced the con dence interval by improving the precision of estimates. Cultivation estimates of poppy using 40 spectral strata and a sample fraction of 1.1% had a similar precision to direct expansion estimates using a 2% sample fraction. Strati ed estimates were more robust to changes in sample size and distribution. The mapping of the agricultural area had a signi cant e ect on poppy cultivation estimates in Afghanistan, where the area of total agricultural production can vary signi cantly between years. The ndings of this research explain di erences in cultivation gures of the opium monitoring programmes in Afghanistan and recommendations can be applied to improve resource monitoring in other geographic areas.en_UK
dc.identifier.citationDaniel M. Simms, Toby W. Waine and John C. Taylor. Improved estimates of opium cultivation in Afghanistan using imagery-based stratification. International Journal of Remote Sensing, 2017, Volume 28, Issue 13, pp3785-3799en_UK
dc.identifier.issn0143-1161
dc.identifier.urihttp://dx.doi.org/10.1080/01431161.2017.
dc.identifier.urihttp://dspace.lib.cranfield.ac.uk/handle/1826/11935
dc.language.isoenen_UK
dc.publisherTaylor and Francisen_UK
dc.rightsAttribution-NonCommercial 4.0 International
dc.rights.urihttp://creativecommons.org/licenses/by-nc/4.0/
dc.subjectOpium poppyen_UK
dc.subjectstratifcationen_UK
dc.subjectagricultural masken_UK
dc.subjectcultivation estimatesen_UK
dc.subjectbu eringen_UK
dc.titleImproved estimates of opium cultivation in Afghanistan using imagery-based stratificationen_UK
dc.typeArticleen_UK

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