Evaluation and validation of model results

1. Evaluation and validation of model results Christian Folberth Systems Analyses, Integrated Assessment and Modelling EAWAG, Swiss Federal Institute for Aquatic Sciences christian.folberth@eawag.ch

2. Yield weighting • Rain-fed yield in cell: 5 t ha-1 • Irrigated yield in cell: 7 t ha-1  Average = 6 t ha-1 ?!? • Rain-fed area in cell: 100 ha • Irrigated area in cell: 500 ha  Average = (5 x 100 + 7 x 500) / 600 = 6.67 t ha-1

3. Yield weighting • Multiply rainfed and irrigated yields with resp. rainfed or irrigated area • Add rainfed + irrigated production • Divide total production by total area and... • Compare grid-wise with observed yields or • Extract production and total area country-wise through „Zonal Statistics As Table“ then evaluate in Excel with e.g. FAO data

4. Yield weighting Harvested area Production Yield irrigated = x + rain fed x =

5. Yield weighting Harvested area Weighted yield Production total = :

6. Observed yields

7. Simulated vs. observed yields dark blue = too low | light blue = good | yellow – red = too high

8. Data evaluation tutorial • Create maps for single years (rf/ir) • Calculate the average for 1990-2000 (rf/ir) • Weight the yield • Compare with reported yields • Evaluate the results

9. Data evaluation tutorial • Step 1: • For rain-fed and irrigated results seperately… • Copy the annual output files from the RomaniaHIxRF/IR directory to the Autocalendar directory • Copy RenMax.cmd to the Autocalendar directory • Double-click RenMax.cmd • Use the map generator to create „Multi-years“ output maps for yield from 1990 to 2000

10. Data evaluation tutorial • Step 2: • For rain-fed and irrigated results separately… • Load the yield maps for 1990-2000 into ArcGIS • From the Spatial Analyst toolbar choose „Cell Statistics…“ • Move all 11 raster files to the select box • Choose as output file name „yd1990_2000“ in the same directory in which the input files are • Remove all raster layers from the data frame

11. Data evaluation tutorial • Step 3: • Load the harvested areas into ArcGIS • mirca_02_30ir • mirca_02_30rf • mirca_02_30t • Load the rain-fed and irrigated yields into ArcGIS • Rename them to yd1990_2000ir and yd1990_2000rf • Open the Raster calculator and type in ((yd1990_2000ir * mirca_02_30ir) + (yd1990_2000rf * mirca_02_30rf)) / mirca_02_30t • Save the raster layer as yd1990_2000 in folder RomaniaHIx

12. Data evaluation tutorial • Step 4: • Load the observed yield raster maize_30_f from DVD:\Additional\ObservedYields\SAGE_YIELDS_30_F into ArcGIS • To obtain the goodness of agreement in % type in the raster calculator yd1990_2000 / (maize_30_f * 10)

13. Data evaluation tutorial • Step 5: • Check out the histogram • Check out the spatial distribution • Compare rain-fed, irrigated, and weighted yields • Look at the results of your seat neighbours

14. Results HI = 0.3 blue = too low yellow = good red = too high HI = 0.6

15. Results HI = 0.6 HI = 0.3