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00841 and historic sites. and traditional tribal resources. such as elhnobolanical. faunal and physical (springs. sediment deposits, and mineral deposils) resources. Four specific program objeclives are: (I) to conserve downstream resources; (2) to design mitigation procedures where necessary; (3) to maintain physical access to cuUural resources; and (4) to provide quality recreational resources that do not adversely affect naturaJ/cultural resources. There are other socio-economic objectives associated with hydropower supply and water resources. but Ihese are outside the realm of remole sensing. Many of the traditional tribal resources (such as ethnobotanical stands) are very small (< I m) and dimcult to discriminate from similar. surrounding materials using airborne approaches. Some other resources (such as mineral occurrences within wall adits) are obstructed from aerial view. Resource monitoring that might benefit from a remote,sensing approach include: (I) detecting of natural springs; (2) monitoring beach and camp-site changes through time associated with different flow regimes; (3) detecting and monitoring of archaeological structures (including those that are partly buried); and (4) evaluating the effectiveness of vegetation and earth check dams in mitigating erosion and degradation of historic and prehistoric resources, 2./ Natural spri1lgs The most identifiable characteristic of spring water in remote-sensing data is their colder temperature relative to the surrounding geologic materials or vegetation. This characteristic is best detected using thermal-infrared (TIR) image data. Thus, our investigation of natural springs centered on the ability ofTlR imagery 10 detect the occurrence of small, less obvious springs. Thermal imagery used in this evaluation was collected at a spatial resolution of I meter in mid, afternoon, A mullispectral instrument was used to collecl 12 differenl wavelength bands. two of which were TIR bands, These data were collected for our evalualions ofa number ofGCMRC parameters, which included (I) mapping terrestrial vegetal ion. (2) mapping warm-water eddies and backwaters. (3) detection and monitoring of partly buried or degraded archaeological structures, and (4) detection of natural springs. The mid,afternoon collection lime for these dala was dictated by the period of maximum solar heating for quiescenl water in order to detect wann backwaters and by full illumination of vegetation in order to map vegetation, but Ihis was n01lhe optimal time for data acquisition for detecting natural springs. Alternatively, the springs might have been detected under illuminated condilions necessary for vegetation monitoring by looking for curvilinear vegetation alignmenls along Ihe talus slopes, but this was not attempted. Our analysis of the TIR data showed that the thcnnal contrast between Ihe spring water and surrounding ground was too small during our daylight acquisition time to distinguish small . ~ springs from the surrounding geology on the walls of the canyon (Davis, 2002b). Only the larger springs (such as Vaseys Paradise) were detected. Previous TIR investigations using data collected just after sunset or just after sunrise seemed to be more successful at detecting wann springs along the Little Colorado River (Holroyd. I 995a. b) because Ihennal conductivity and emissivity differences between surface materials are most pronounced during these two time periods. However. these "delections" could not be confirmed by ground studies due to poor aircraft positional information. If springs are to be mapped within Ihe canyon. it would require a separate. georeferenced T1R survey during post-sunrise hours; a post,sunset flight within the canyon would be unsafe. 2.2 Archaeological structures One of Ihe priorities of the cul1ural reSource program is monitoring historic and pre- hisloric structures and check dams at certain structures to determine (I) the degradation of these 7