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MEMO -TASK 89.1 <br />5.3 Irrigated parcels map <br />The classification of agricultural crops will begin with an irrigated parcels map manually interpreted and <br />drawn using the NDVI composite described in the previous section. A mask will be produced to eliminate <br />areas not classified as potentially irrigated. This will eliminate errors associated with spectral similarities <br />between crops and other land cover types (e.g., riparian vegetation). <br />5.4 Reference data acquisition <br />Ground truth data will be collected from primary and secondary sources. The primary source will be field <br />observations conducted by RTi personnel of permanent cover types like rangeland, wetlands, deciduous <br />trees, urban areas, etc., and semi-permanent cover types like irrigated meadows and hay fields, dry land <br />agriculture, etc. Secondary sources correspond to reference data obtained from other sources like the <br />Farm Service Agency (FSA) Colorado State University, etc. The main source of ground truth data will be <br />the FSA's annual delineation of crop types provided by producers on high-resolution aerial photographs, <br />which cover approximately 50 percent of farmlands in the study area. <br />Approximately fifty percent of the "ground truth" reference data described above will be used to develop <br />spectral signatures of the agricultural and other cover types to be classified. The other fifty percent will be <br />set aside for the accuracy assessment. <br />The information will be selected following standard statistical sampling procedures as much as practical. <br />As recommended in the literature (Jensen 1996, Congalton and Green 1999), these data will include at a <br />minimum 50 field polygons for each major crop type. <br />Page 10 of 13 ~,~tversFde TecAnafagy, lnc. <br />4'J:.fr: !?es'ourccs Frrr~mec.•r.?g ~~nd L'nr+suilrnq <br />Figure 5: Resolution merge of NDVI classification and DOQQ <br />