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<br />001743 <br /> <br />20 <br /> <br />backwaters and near-shore habitats for fish, in addition to mapping archaeological structural sites <br />and natural springs within the Grand Canyon. Airborne TIR data can provide an instantaneous <br />map of surface water temperature for very large regions, which cannot be obtained by in-situ <br />measurement methods. Detection of archaeological structures requires the use of an airborne <br />TIR sensor that can detect temperature differences as small as 0.1 degrees C, and provide at a <br />spatial resolution of no more than 25 cm. Detection would be optimized by data collection after <br />sunset or just after sunrise. Safety issues after dark and shadows during early morning make such <br />data collections very difficult. Detection of natural springs is better approached using TIR data <br />collected after sunset. The TIR data collected during daylight hours detect only the largest <br />springs, whose existence is already known. Detection of natural springs after sunset can and has <br />been accomplished using rather low-resolution imagery (1-3 meters) because the spring waters <br />spread from their source and present a large area and the spring water is much colder than the <br />surrounding warm, dry ground. <br />Monitoring Sand-Bar Deposits - The GCMRC evaluated light detection and ranging <br />(LiDAR) and photogrammetric methods for remotely mapping sand bar deposits along the <br />Colorado River to determine if these two remote-sensing technologies for mapping topography <br />could approach the accuracies currently obtained using field survey methods and at a comparable <br />cost, while providing more aerial coverage. Thus far, our studies have determined that LiDAR <br />appears to be a suitable method for rapidly obtaining the topography of bare sediment surfaces <br />over very large regions whereas photogrammetry produces more accurate ground topography in <br />vegetated terrain than LiDAR. <br />Members of the DASA are further investigating LiDAR and photogrammetry in terms of <br />their ability to map volumes of terrestrial sediments, which does not require knowledge of <br />absolute elevations. In FY2002-03, the Center staff investigated remote-sensing technologies to <br />determine vegetation habitat structures (area, volumes, heights), to map and monitor older river <br />terraces, to map and monitor channel bottom deposits, and to monitor the river water's <br />suspended load and turbidity. In November 2004, LiDAR data was collected for FIST reaches 2 <br />through 7 (Paria River to Palisades) during the steady flow periods before and after the <br />experimental high-flow of 42,000 cfs to capture the pre- and post-flood conditions of those sites. <br />Additionally, the Center is currently planning another LiDAR mission to further monitor the <br />same reaches in May 2005. <br /> <br />GCMRC FY2006 Annual Work Plan (Draft February 15,2005) <br />