Validation - Agricultural Service Products by Professor R Validation - Agricultural Service Products by Professor R. Tsheko, Agriculture Service Capacity Building Partner - BUAN 14-17 March 2016, Windhoek, NAMIBIA

SURVEY METHODOLOGY GPS The validation route was mapped using a handheld Global Positioning unit, Garmin etrex Legend with a horizontal positioning accuracy of about 6m. The unit was set to track the route every 30 seconds for the entire validation period. Camera Photographs along the validation route were taken with a Nikon D60 camera fitted with 70-300mm Nikon zoom lens. The clock on the camera was synchronized to the one on the GPS unit so that the exact location of the photo may be related to the coordinates on the GPS unit using time imprints. SURVEY METHODOLOGY

SURVEY METHODOLOGY After the photographs were taken, they were downloaded into a computer. The track information from the GPS unit was downloaded using the DNR Garmin software by the Minnesota Department of Natural Resources, USA. PhotoPoint version 2 software was used to geo-reference the photographs by using the time stamps on both the track information and the images

RESULTS Rainfall estimates Probability of rainfall detection (POD) is 98%, probability of false rainfall detection (POFD) is 30%, correlation (r) (Actual rainfall versus FEWSnet RFEs averages 88% for all stations, root mean square error (RMSE) averages 74% for all stations

RESULTS Crop Mask Crop Mask estimation has an overall accuracy of 58%. On the other hand, the kappa coefficient is 0.0973, indicating only a slight agreement. Field sizes are small and it is difficult to isolate them from satellite imagery with a spatial resolution of 1km, especially when the surrounding areas are well vegetated.

WRSI The results of the WRI validation show that there is low agreement between the FEWSnet values and the Photo Estimated values. This result is largely influence by the small size of the ploughing fields relative to the pixel resolution of 1km. The validation method should be applied to field sizes that are large. Additionally, the crop fields had a lot of weeds which influenced the estimated value of the WRSI since the crop was not a pure stand of maize.

THANK YOU This presentation has been prepared with the financial assistance of the European Union. The contents are the sole responsibility of MESA SADC THEMA and can under no circumstance be regarded as reflecting the position of the European Union