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• <br />C. Specific Task Descriptions <br />Task 89. Conduct Full Refresh of SPDSS Irrigated Lands <br />Update of SPDSS irrigated acreage mapping. Classify crop types, create new irrigated parcel layer, <br />attribute parcels with water source, and create new water features layer. <br />Objective: The objective of the refresh is to utilize 2005 Landsat data to conduct a comprehensive refresh <br />of the South Platte irrigated lands mapping. <br />Background: Landsat 5 is beyond its design life and has been experiencing significant operating <br />difficulties in 2005-6 (Landsat 7 has been delivering degraded data since 2003). The high potential for <br />failure of Landsat 5 in the near future makes utilization of 2005 Landsat 5 data an attractive option to <br />ensure a timely refresh is achieved for the South Platte. Considerable savings will also be achieved by <br />conducting this refresh in parallel with the Statewide Landsat Image Processing task (90). <br />Approach: <br />89.11 Collect and process reference data. Reference data will be collected from Northern Colorado <br />Water Conservation District and other sources, and processed to create a GIS (shapefile) database for <br />referencing and validating irrigated land and crop-type updates. Approximately fifty percent of the <br />ground truth reference data will be used to develop spectral signatures of the agricultural and other cover <br />types to be classified. The other fifty percent will be set aside for accuracy assessment. <br />89.12 Update irrigated vs. non-irrigated lands. The refresh classification will begin with irrigated <br />parcel maps interpreted and drawn using Landsat-derived 2005 NDVI composites, developed using <br />methods described in Phase 3 Memo 89.2. A mask will be produced to eliminate areas not classified as <br />potentially irrigated, eliminating errors associated with spectral similarities between crops and other land <br />cover types (e.g., riparian vegetation). These NDVI data, together with base maps derived from DOQQ's <br />in previous phases, will be used to identify and flag changes in irrigated lands. <br />89.13 Update irrigated parcel boundaries. Flagged changes in irrigated lands will attract further <br />attention, analysis, and interpretation. The 2005 NDVI composites will be used to highlight parcels that <br />need to be changed, due to changes in crop type or parcel shape. Existing 2001 parcel boundaries will be <br />edited with `heads-up' digitizing, to create the updated 2005 irrigated parcel boundaries. <br />89.14 Identify crop types in each polygon. Crop classification algorithms applied in the refresh process <br />will be hierarchical, combining multi-temporal NDVI, multi-spectral information from the individual <br />Landsat TM images, GIS data, and ancillary data in a maximum likelihood algorithm and rule-based <br />classification method as described in Phase 2 Memo 89.2. <br />89.15 Attribute ditch service areas and water sources. 2005 irrigated parcels will be attributed with <br />current diversion structure service areas and irrigation wells. 2001 service area boundaries will be used as <br />a starting point. Current active diversion records will be used to add, remove, or modify the service areas <br />and create 2005 irrigation service area boundaries. The proper diversion structure ID from the service <br />Table 1. Phase 4 Spatial System Integration Task List <br />