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MEMO 89.2 <br />Multitemporal <br />analysis of <br />irrigated lands and <br />NDVI <br />thresholding <br />Preliminary Irrigated Lands <br />Classification (mask) <br />'.~i~" '~ ~ ~ Irrigated Lands = 1 <br />NDVI Imagery 0 Non Irrigated Lands = 0 <br />Figure 9. Irrigated Lands Multitemporal Analysis and Thresholding <br />The second process consisted of a series of steps to refine the preliminary irrigated lands classification <br />(Figure 10). In the first step, non-irrigated areas were eliminated from the multitemporal NDVI <br />composite by applying the irrigated lands mask produced in the thresholding procedure. In preparation <br />for the next step, the multitemporal NDVI composite of irrigated lands was color coded to enhance crop <br />patterns that were hard to differentiate (i.e., crop patterns with white or light gray tones were colored in <br />red tones). In the second step, spectral information of the multitemporal NDVI of irrigated lands was <br />overlaid with the 1-meter resolution digital orthophotograph (DOQQ). In the third step, parcel boundaries <br />were delineated from the combined NDVI-DOQQ imagery (for more details on parcel boundary <br />delineation please refer to SPDSS Memorandum 90.2). The delineation was updated iteratively with <br />information obtained during meetings with irrigation authorities (for more details on meetings with <br />irrigation authorities please refer to SPDSS Memorandum 91). In the fourth step, delineated irrigated <br />parcels were converted to raster format for evaluation in the irrigated lands accuracy assessment <br />procedures (described in Section 2.7 below) and irrigated crop type classification (described in Section <br />2.5.2). Results of the irrigated lands acreage by district are presented in SPDSS Memorandum 91. <br />Page 14 of 45 ~Rlversfde FecAnotogy, fnc. <br />4'JaYer Resources Errgi~ecr:np an~i CansuFlrnp <br />