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a V 2 a V2 y. +Z +~=y. +z +-LL+h 2 2 2g 1 1 2g e (1) I I I I I I I I I I I I I I I I I I I the rod where the water was too deep to wade. Channel substrate, feature, and habitat type were communicated by radio to the total station operator where it was recorded with the total station coordinates using a HP48GX, with TDS48 software. Water-surface elevation and velocity were recorded at random points within each reach for use in calibrating the two-dimensional model. Velocities were measured at 0.6 ft depth, to represent average column velocity, using a Marsh-McBimey current meter. A staff stage was installed at both sites and a stage-discharge relationship was determined by taking flow readings several times throughout the summer. Topographic data collected over the summer were input into the Arclnfo software package to create a Triangular Irregular Network (TIN) surface model of the channel. By mapping the topographic points on the TIN it was possible to determine where additional survey points were needed in order to accurately represent channel topography. Aerial photographs were taken of the sites at a scale of 1 inch equals 600 feet on September 15, at which time the flow was 287 cfs on the Maybell gauge. The aerial photos were qualitatively used to determine how representative the study reach compared to reaches up and down stream. Additionally, images of the site were rectified using ground control points and the Imagine software package. These images were then registered in the Surface-Water Modeling Software (SMS) and were used for reference in creating the finite element mesh. HYDRAULIC SIMULATION Hydraulic simulation and 2-D flow modeling was contracted with the Earth Resources Depart.ment of Colorado State University (CSU). Greg Stewart, a graduate student at CSU, collected, input the data for hydraulic modeling and performed the analysis. Many attempts were made to run the 2-D model during the first year of this contract but unfortunately, at the time of this writing, RMA2 analysis has only been partially completed and no two-dimensional modeling results are available. HEC-RAS is a I-D hydraulic flow model created by the Hydrologic Engineering Center of the U.S. Army Corps of Engineers (Brunner, 1998), and is based on solution of the one-dimensional energy equation (1). where: Yl'y2 = Zl,Z2 = Vl,V2 = al,a2 = depth of water at cross sections elevation at cross sections average velocities (total discharge/total flow area) velocity weighting coefficients = gravitational acceleration = energy head loss g he 6