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17 <br />Study approach <br />A paired-site comparison of channel dynamics, hydraulics, temperature, and physical <br />habitat characteristics between the Green and Yampa River study sites was conducted. <br />The study approach entailed repeated hydrographic surveys at both locations to quantify <br />changes in channel morphology that occurred over the course of one snowmelt runoff <br />hydrograph during 1999-2000. Transects were surveyed before, during, and after the <br />snowmelt runoff to monitor changes in cross-sectional profiles resulting from scour and <br />fill. Topographic and bathymetric data, which served as input to a 2-dimensional <br />hydrodynamic simulation model, were collected. The 2-D hydraulic model was used in <br />conjunction with the Arc/Info Geographic Information System (GIS - ArcInfo V8.0.1, <br />ESRI 2000) to evaluate habitat for the razorback sucker during the spawning season for <br />water years 1984 and 2000. In addition to the hydrographic surveys, continuous <br />temperature recorders were installed at both sites in order to compare the thermal regimes <br />of the two rivers during the 2000 water year. Biological data on habitat use by razorback <br />sucker were obtained from existing literature and a radio telemetry study of fish habitat <br />use and movement. <br />Physical data collection <br />Hydrology <br />The pertinent hydrologic records for our study sites included data from the USGS <br />gages on the Green River at Jensen (# 9261000) and the Yampa River at Deer Lodge <br />Park (#9260050). The Jensen gage had the longer period of record, extending from water <br />year 1947 to present, whereas the Yampa gage at Deer Lodge Park existed only from