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EOFI Service Trial 1: UN-IFAD – Crop Acreage PowerPoint Presentation
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EOFI Service Trial 1: UN-IFAD – Crop Acreage

EOFI Service Trial 1: UN-IFAD – Crop Acreage

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EOFI Service Trial 1: UN-IFAD – Crop Acreage

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  1. EOFI Service Trial 1: UN-IFAD – Crop Acreage • ESA request D2.3 (19 Oct) to clarify discrepancies between EOFI results and IFAD statistics • Explain discrepancy in the absolute area covered by irrigated crops (rice & irrigated crops classes) compared to IFAD figures • Specifically provide reasoning for the different level of observed irrigated crops area in 1996 • Response by GeoVille on 29 Oct • Today’s telco important to... • Improve mutual understanding in interpreting IFAD’s area statistics • Put benefits & limitations of satellite based monitoring in context

  2. EOFI Service Trial 1: UN-IFAD – Crop Acreage • Benefits of satellite-based monitoring • Synopticviewsover large areas • Time serieswith flexible time intervals • Uniform scaleandcontent • Guaranteedqualitylevels • Low costcomparedtoterrestrialmeasurements 1996 2000 2007 2010

  3. 1996 irrigated area • IFAD: 1,061 ha irrigated land in IFAD statistics • UNOPS mission report 2001: 3,200 ha of irrigated rice fields in 1996 • EOFI: 6,230 ha rice + 2,713 irrigated crops from EOFI) EOFI Service Trial 1: UN-IFAD – Crop Acreage • Can we compare the area figures? • What are possible reasons for the “delta”? • Methods of data collection (terrestrial sampling vs. blanket satellite coverage) • Reference area • Definition of features • Accuracy / error margins of land cover maps • Others? IFAD EOFI 1,061 ha  5,230 ha + 4.169 ha 8,943 ha  11,612 ha + 2.669 ha Sources: http://www.capfida.mg/site/spip.php?article143 http://www.phbm.mg/appuiauxinitiatives/article_irrigation_sylvie.htm • Joint verification of area figures required

  4. EOFI Service Trial 1: UN-IFAD – Crop Acreage • #1: Are the figures representative for the same area? • EOFI covers entire PHBM project area (8,300 km²) for 1996-2010 • IFAD coverage depends on project phase – is this correct? • Phase 1 (1996-2001): 3,200 km² (4 northern communes of Tsivory, Elonty, Mahaly and Marotsiraka) • Phase 2 (2001-2009): 8,300 km² (11 communes) EOFI • Reduction to 4 communes of PHBM-I leads to a decrease from 8,943 ha to 5,290 ha irrigated land Sources: http://www.capfida.mg/site/spip.php?article143 http://phbm.mg/sommaire/cartes.htm

  5. EOFI Service Trial 1: UN-IFAD – Crop Acreage • #2: How shall the IFAD area figures be interpreted? • Was IFAD’s 4,169 ha increase achieved by establishing new irrigated land or by rehabilitating existing irrigation schemes or both? • Where does the 1996 value (1,061 ha) originate? Is our assumption correct, that this value only represents actively managed irrigated land? • An UNOPS mission report of PHBM-I states 3,200 ha of irrigated rice fields for 1996 – how does this relate? See below IFAD weblink • Has the area of 5,230 ha irrigated land for 2007 been measured with terrestrial methods? • Terrestrial field measurements provide more accurate area figures, but are more expensive and time-consuming Sources: http://www.capfida.mg/library/docpublic/Mesure_de_resultats_et_d_impacts_du_PHBM.pdf http://www.ifad.org/french/operations/pf/mdg/i548mg/photos/montage_photo1_0401.pdf

  6. EOFI Service Trial 1: UN-IFAD – Crop Acreage • #3: What exactly is measured? • IFAD reports 32 irrigation schemes rehabilitated from 1996-2001 and further 39 from 2001-2008 (total: 71), leading to an area of 5,230 ha irrigated land: • Does this figure represent the irrigated land from 71 rehabilitation projects or the total irrigated land in the entire PHBM area? • Is it valid for the PHBM-I or PHBM-II area? Selected locationsofrehabilitationprojects(Perimétresirrigués) • PHBM evaluation report states that only larger irrigation schemes are adressed: • “PetitsPerimetresirrigues” (PPI) larger 100ha • “Microperimetresirrigues” larger 10 ha • Is this correct? • Satellite-based monitoring detects much smaller cropland patches with an object size of > 1ha – thus increasing the total mapped area Sources: http://www.capfida.mg/library/docpublic/Mesure_de_resultats_et_d_impacts_du_PHBM.pdf

  7. EOFI Service Trial 1: UN-IFAD – Crop Acreage • #4: What about rice fields under dry conditions and irrigated cropland in remote locations? • Main focus on the PHBM projects were irrigated rice and crops • Do the area statistics only cover managed irrigated land or also dry rice fields or abandoned irrigated land? • PHBM evaluation reports state the “inaccessibility of the project zone” and the “insufficient coverage of villages outside the main towns” • Are existing rice fields and other irrigated cropland in remote regions covered? Irrigatedcropland in remote location Dry / abandonedricefield Sources: http://www.ifad.org/evaluation/public_html/eksyst/doc/prj/region/pf/madagascar/mg_376.htm http://www.ifad.org/evaluation/public_html/eksyst/doc/agreement/pf/madagascar_376.htm

  8. EOFI Service Trial 1: UN-IFAD – Crop Acreage • #5: Information content of available data not optimal for detecting small-scale irrigation structures • Poor availability of multi-temporal / multi-polarisation radar data • Sometimes ambiguous differentiation of crop types due to imagery from different seasonal dates (dry vs. wet season) • Limited availability of ground-truthing data EO imageryusedformapping High-resimageryforvalidation  Technical infrastructure for irrigation (incl. dams, narrow water channels) not visible in 10-30m satellite imagery  Irrigated cropland contains actually irrigated cropland PLUS in many cases also potentially irrigated cropland predominantly along water courses

  9. EOFI Service Trial 1: UN-IFAD – Crop Acreage • #6: Resulting area statistics have a defined level of reliability with known error margins Error marginofareastatistics Margin 15-20% Margin 30-40% • Overall accuracy: 80-85% Validation analysis shows a slight tendency towards overestimation of rice and irrigated crops - high level of completeness - lower level of correctness

  10. EOFI Service Trial 1: UN-IFAD – Crop Acreage • Summary of evaluation – assumptions • Direct comparison of area figures is hardly possible • Assumptions need to be verified in collaboration with IFAD • Could the outline of the areas surveyed by IFAD be delivered? • Shall we eliminate all patches <10 ha and re-compare?