ESTIMATING AREAS OF LAND UNDER SMALL-SCALE IRRIGATION USING SATELLITEIMAGERY AND GROUND DATA FOR A STUDY AREA IN NE NIGERIA

SPOT XS imagery and ground data in the form of an area frame sample we re collected simultaneously. The aim of the survey was to test a metho dology for the provision of area estimates of land under small-scale i rrigation in a complex floodplain terrain in north-east Nigeria. The f easibility of carrying out the ground survey was demonstrated. The cla ssification of the satellite imagery produced low mapping accuracies a nd the area estimated from pixel counts was highly dependent on the cl assification procedure. The combination of the image and field data to allow the use of the regression estimator provided much more consiste nt measurements of area. While the confidence intervals on these resul ts are relatively wide there is no regular alternative source of infor mation for planners in the region. Fieldwork would have to be increase d by a factor of three to gain comparable results.