By Craig B. Boroughs, and Edith A. Zagona, Proceeding of the Second Federal Interagency Hydrologic Modeling Conference, Las Vegas, Nevada, July 2002.

Abstract: One of the major efforts for development of a daily timestep water operations model for the Pecos River in New Mexico was to implement a routing methodology that would appropriately represent flood wave travel times (translation) and reduction in peak discharge (attenuation) of flood waves. The model is to be used to evaluate the impacts of modified dam operations on flow conditions in critical habitat for a federally “threatened” fish species. It is important for travel times of flood waves to be represented appropriately. Due to the morphology of the Pecos River and shape of typical inflow hydrographs, flood waves during the summer monsoon season significantly attenuate as these waves propagate down the Pecos River. The Muskingum-Cunge method was selected as a routing method to add to the water operations model, but it was coded in a different manner than it is conventionally coded in other models. The water operations model was developed with the RiverWare software application that is a general river basin modeling tool that runs in an object-oriented modeling environment. While this modeling environment provides flexibility for developing models, it provides a restriction to simulate the entire river system one model timestep at a time. Due to this simulation style, the routing method for each river reach must also run one model timestep at a time. The resulting routing method in RiverWare requires the user to input an incremental routing timestep that will be used to route flood waves within each model timestep. The model then uses other input parameters to determine the best incremental routing spatial step to minimize numerical dispersion. In addition, the water operations model simulates with daily average flows, so assumptions were made to implement the Muskingum-Cunge method that routes instantaneous flows.