Sensitivity of one-dimensional hydrologic model simulations: A model study of Lemes Canyon, New Mexico

A Professional Project Report submitted in partial fulfillment of the requirements for the degree of Master of Water Resources, Water Resources Program, University of New Mexico.Stream channel restoration can increase flow storage and energy dissipation of passing flood waves (Sholtes and Doyle, 2011). Reestablishment of floodplain hydraulic function and increasing floodplain connectivity are increasingly goals of restoration programs, yet the magnitude of possible change to a range of variables remains poorly quantified Bernhardt and Palmer, 2011; Sholtes and Doyle, 2011). This study utilizes HEC-RAS to route floods under steady state, subcritical conditions in field-based impaired reach scale models. The study integrates collected channel data from Lemes Canyon, an ungaged ephemeral channel located near Monticello, NM as well as USGS topographic data (7.5 minute; 1:24,000) to construct a model at the reach scale. Peak discharge values were estimated using the USGS Generalized Least Squares Regression for Ungaged Streams. This study performed sensitivity analyses of one-dimensional hydrologic model simulations to quantify the magnitude of change with respect to two response variables, average total velocity and hydraulic depth, respectively. In this study synthetic ineffective flow areas were used as a proxy for engineered log jams to test the hypothesis of equal population means against the alternative that not all population means are equal for the two response variables among ten geometric plans. A One Way Analysis of Variance (ANOVA) of means among populations was performed to test the hypothesis for both response variables. At the .05 level, no statistically significant results were found. The results SENSITIVITY OF ONE-DIMENSIONAL HYDROLOGIC MODEL SIMULATIONS 6 from this study indicate there are no statistically significant differences in mean values with respect to the two response variables among all ten populations considered. These results suggest there is no statistical evidence that ineffective flow areas as a proxy for log jams are effective at decreasing the average velocity or increasing the hydraulic depth at the reach scale. The statistical results identify the relative importance of hydrologic design elements used in channel reconfiguration projects among ephemeral and intermittent channels in arid and semi-arid climates