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SPDSS Memorandum -Final <br />To: Ray Alvarado, Ray Bennett <br />From: Riverside Technology, inc., Chris Woodward and Tim Martin <br />Subject: SPDSS, Spatial System Integration Component, Subtask 93.1 - Historic Aerial <br />Photography and Satellite Imagery Search <br />Date: 11 July 2006 <br />1. Introduction <br />This memorandum summarizes Task 93 -Mapping of Historic Land Use, Subtask 93.1 Historic Aerial <br />Photography and Satellite Imagery Search. These activities are described in RTi's Scope of Work for <br />SPDSS Phase 3 Spatial System Integration Component. As described in the Scope of Work (page 6) the <br />objective of Task 93 is the following: <br />Historic land use for the 1980s, 1970s, and 1950s including irrigated areas, water supply, and <br />major crop types will be mapped using satellite imagery, historic maps, aerial photography, <br />and applicable GIS data and agricultural statistics. <br />Also described in the Scope of Work (page 7) is the approach for this Subtask that includes: <br />Conduct an extensive search for historic satellite imagery, aerial photographs, historic land use <br />maps, and reference data for use in this task. Assess the availability of multispectral Landsat TM <br />and MSS satellite imagery. Prepare a list of recommended satellite, maps, and aerial <br />photography for acquisition, to be purchased under Subtasks 93.2, 93.3, and 93.4. <br />2. Landsat Satellite Imagery Purchase <br />This section summarizes satellite imagery acquired for mapping historic irrigation in the SPDSS in the <br />1980s and 1970s. The procedure used to search and assess the availability of Landsat satellite imagery <br />began with Landsat frame selection by intersecting the SPDSS boundary with Landsat TM and MSS path <br />and rows. After frame selection, the USGS Earth Resources Observation Systems (EROS) data center <br />archive was extensively searched via online tools (Earth Explorer & Global Visualization Viewer) for <br />suitable imagery for the years 1975 to 1979 and 1987 to 1992. These date ranges were selected as <br />recommended in the SPDSS Scope of Work (page 7) under Subtasks 93.2 and 93.3, Mapping of Historic <br />Land Use for the 1980s and 1970s. <br />The representative year for 1970s and 1980s irrigated lands mapping was selected to achieve the greatest <br />number of scenes per frame, the least amount of cloud cover, and the optimum spacing of imagery during <br />the growing season. The years 1987 and 1976 best met these criteria. When searching for 1980s <br />imagery, Landsat MSS data were not considered because Landsat TM data are much better for the <br />requirements of the SPDSS. Table 1 compares spatial resolution, number of bands, and radiometric <br />resolution among the three main Landsat platforms and 1950s aerial imagery. As shown in this table, <br />Landsat TM has many advantages over Landsat MSS data. Landsat TM has 8-bit radiometric resolution, <br />30-meter spatial resolution, and seven bands of data, whereas MSS data has four bands of data, 4-bit <br />radiometric data, and 80-meter resolution (Table 1). <br />Page 1 of 6 ~Riversfde Technalagy, Tnc. <br />4^rsfe: l1e.nurx'es ErgrnecrvnG enn Consvrf~ng <br />