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Table 4. Per County List of Photo Indexes Acquired from the Aerial Photography Field <br />Uffice (AYN'U) in the SYllSS Stud Area in the 1950s to Earl 1960s <br />County Namel Year of APFO imagery Number of photo indexes <br /> within SPDSS <br />Adams 1957 8 <br />Arapahoe 1957 4 <br />Boulder 1955 1 <br />Denver 1957 1 <br />Douglas 1955 1 <br />E1 Paso 1955 2 <br />Elbert 1957 5 <br />Jackson 1962 2 <br />Jefferson 1955 4 <br />Larimer 1957 3 <br />Lincoln 1956 2 <br />Logan 1957 8 <br />Morgan 1956 4 <br />Sedgwick 1961 2 <br />Washington 1953 6 <br />Weld 1957 16 <br /> Total Indexes 69 <br /> Total Cost $1,380 <br />No 1950's imagery was available through APFO for Park, Teller, and Clear Creek counties. <br />~ Cost of photo indexes = $20/index. <br />4. Total Cost <br />The cost of the 48 acquired Landsat images was $12,040. The cost for the 69 acquired aerial photography <br />indexes and 25 aerial photos was $1,380. The total cost for acquired imagery was $13,420. <br />5. Comments/Concerns <br />Although most of the purchased Landsat imagery is nearly cloud-free, some scenes have areas of <br />scattered clouds or haze as well as areas of dense cloud cover. As presented in the SPDSS Task 89.1 <br />memo, one of the advantages of the multi-temporal satellite imagery approach to mapping irrigated lands <br />is the possibility of replacing areas obscured by clouds on a particular date with imagery from another <br />date. However, there may be cases where cloud-covered areas may compromise the classification <br />method. <br />As stated in SPDSS Task 89.1 memo, the Landsat MSS resolution of 80 meters with four bands of data is <br />much coarser than Landsat TM with 30-meter resolution and seven bands of data. Therefore, 1970s <br />mapping using Landsat MSS data will be less detailed as compared to 1980s (Landsat TM data) or 2001 <br />irrigated lands mapping (Landsat ETM). <br />The search for historic aerial photographs was conducted to identify and assess imagery sources for 1950s <br />irrigated lands mapping. As described above, individual aerial photographs for most of the entire study <br />area were available. However, the purchase cost alone for approximately 1600 individual photographs <br />would have been about $8,000 and would have required a large amount of labor for scanning and <br />georeferencing, which would have costs considerably beyond the budget estimate for this task. As an <br />alternative, the 69 index maps were evaluated and determined to be usable and adequate to meet the <br />objectives of this task, and they were acquired at a cost of $1,380. Although the indexes required some <br />special image processing to correct for mosaicking errors, the result is acceptable and cost-effective. <br />Page 6 of 6 ~lzlverslde Technology, Inc. <br />l"Aalc: Resources Engrnee.•rag antl L'nnsufVing <br />