7629 - Laserfiche WebLink

Home Browse Search

2 Approximate River Mile* Si te Name Site 1 2 3 186 - 189.7 134.8 - 137.8 , 117.8 - 121 Spl it Mountai n Ouray Willow Creek *Note: River miles were transferred to the data base from Evans and Belknap's Green River Wilderness, Desolation River Guide. River miles along this portion of the Green River begin with o mile at the city of Green River, Utah. We chose four flow scenarios to be examined in this study: 1,500, 3,000, 3,500, 4,000 ft3/s. Due to dam operations, logistics, adverse weather conditions and unmeasured tributary flows, the actual flows examined were approximately 1,889, 3,119, and 4,359 ft3/s. When dam releases were attained and stabilized, aerial photography was acquired on each study site. Field trips were taken to ground truth the photography and become familiar with defining backwater habitats and to place paneled markers at each site to accurately compile photograph scale. In addition, ground truthing enabled photointerpreters to locate small backwaters. Upon receipt of aerial photography, photographs were fitted with mylar overlays and interpreted for the following cover types: 1: Open Water 2: Backwaters 3: Isolated Pools 4: Sandbars 5: Vegetated Sandbars 6: Vegetated Islands Normally these data would be transferred to U.S. Geological Survey stand- ard map quadrangles. Because the aerial photography is at a relatively large scale (1:4,000), it is very difficult to accurately transfer the interpreted data to map bases at 1:24,000 scale. Furthermore, it is not practical to make the transfer to USGS quads as the integrity of the data would be lost. Planning the aerial photography missions for large scale imagery, allows backwaters to be mapped as small as 20 square meters; therefore, to maintain this mapping accuracy, pseudomap bases at the same scale of the photography were created. River mile markers and roads were also added to the overlays. The map products were then digitized into a GIS using the G.E.S. (Geographic Entry System) software. Digitization was done in vector format using a Calcomp 9000 digitizing tablet linked to a Tektronix 4014-1 display screen. Software and peripherals are run by the HP 3000 computer.