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| <H2><a class="intext" HREF="/dokuwiki/doku.php?id=capri:concept:spatialdownscaling">Agricultural land use and environmental indicators at 1x1 km grid resolution</A><BR> - Yields and Irrigation share</H2> |
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| <hr style="color: 'blue'; height: '2'; text-align: 'left';"> |
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| Main Contributors: Wolfgang Britz and Gunter Wriedt<BR> |
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| GIS processing of MARS yields: Renate Koble and Giulio Marchi |
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| <hr style="color: 'blue'; height: '2'; text-align: 'left';"> |
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| <P>The <B>crop yields</B> are estimated based on estimates of water limited and non-water limited yields, courtesy of the JRC's |
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| <a class="intext" HREF="http://www.marsop.info/scripts/mars.exe?page=bg">MARS</a> project, and per grid cell reported as the |
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| average of the water limited yield times unity minus the estimated irrigation share for that crop in the pixel cluster plus the non-water |
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| limited yields times the estimated irrigation share. A statistical estimator ensures that the average yields as reported in regional agricultural statistics from Eurostat are recovered.</P> |
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| <div style="float:right;padding:20px;padding-right:0px"> |
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| <a href="images\IRR.jpg"><img style="text-decoration: none;border: none;color: white;" src="images\IRR.jpg" width="400px"/></a> |
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| </div> |
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| <P>The <B>irrigation shares</B> and yields per crop and 1x1 km cell cluster are statistically estimated |
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| based on a Highest Posterior Density estimator, which ensures the following conditions:</P> |
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| <UL> |
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| <LI><P>The total irrigated area at NUTSIII/NUTSII region reported in the 1999 Farm Structure Survey is recovered</P></LI> |
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| <LI><P>The area weighted average yield per 1x1 km grid cell and crop is identical to the yield found in regional statistics</P></LI> |
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| <LI><P>Average yield per 1x1 km grid cell and crop are a weighted average of the non-irrigated and irrigated potential yields from MARS, multiplied with an identical scaling factor</P></LI> |
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| </UL> |
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| <P>Given the fact that there are more variables to estimate (irrigation shares per crop and <A HREF="/dokuwiki/doku.php?id=capri:concept:HSMU">HSMU</A>, scaling factors for yields per region), the statistical estimator picks the most probable |
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| combination based on minimizing deviations from given information:</P> |
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| <UL> |
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| <LI><P>The reported or average irrigation shares at NUTS II level for selected crops. Where no shares had been reported, those had been estimated based on regression models based |
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| the reported average irrigation shares, and using climate data as explanatory variables.</P></LI> |
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| <LI><P>The average irrigation shares per HSMU, defined from the global irrigation map of FAO</P></LI> |
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| <LI><P>A preferred scaling factor of unity for the crop yields</P></LI> |
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| </UL> |
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| <hr style="color: 'blue'; height: '2'; text-align: 'left';"> |
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| <H3>More information</H3> |
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| <P class="pubparagraph"><span class="pubAuthor">Britz W. and Wriedt G.</span>:<BR> |
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| <I><a HREF="..\docs\yields.pdf" class="intext">Pan-European Estimation of crop specific yields and irrigation shares at 1x1 km grid, JRC, 2007 (pdf, foils)</a></I></p> |
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| <BR> |
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| <font size=1>Last Updated:Tuesday, October 28, 2008 |
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