Hydraulic Modeling Analysis of the Middle Rio Grande River from Cochiti Dam to Galisteo Creek, New Mexico
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THESIS HYDRAULIC MODELING ANALYSIS OF THE MIDDLE RIO GRANDE RIVER FROM COCHITI DAM TO GALISTEO CREEK, NEW MEXICO Submitted by Susan J. Novak Department of Civil Engineering In partial fulfillment of the requirements For the degree of Master of Science Colorado State University Fort Collins, Colorado Spring 2006 COLORADO STATE UNIVERSITY October 24, 2005 WE HEREBY RECOMMEND THAT THE THESIS PREPARED UNDER OUR SUPERVISION BY SUSAN JOY NOVAK ENTITLED HYDRAULIC MODELING ANALYSIS OF THE MIDDLE RIO GRANDE RIVER FROM COCHITI DAM TO GALISTEO CREEK, NEW MEXICO BE ACCEPTED AS FULFILLING IN PART REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE. Committee on Graduate Work ______________________________________________ ______________________________________________ ______________________________________________ Adviser ______________________________________________ Department Head ii AB ST R A CT O F TH E SI S HYDRAULIC MODELING ANALYSIS OF THE MIDDLE RIO GRANDE FROM COCHITI DAM TO GALISTEO CREEK, NEW MEXICO Sedimentation problems with the Middle Rio Grande have made it a subject of study for several decades for many government agencies involved in its management and maintenance. Since severe bed aggradation in the river began in the late 1800’s, causing severe flooding and destroying farmland, several programs have been developed to restore the river while maintaining water quantity and quality for use downstream. Channelization works, levees, and dams were built in the early 1900’s to reduce flooding, to control sediment concentrations in the river and to promote degradation of the bed. Cochiti Dam, which began operation in 1973, was constructed primarily for flood control and sediment detention. The implementation of these channel structures also had negative effects, including the deterioration of the critical habitats of some endangered species. The reach under analysis stretches 8.2 miles from Cochiti Dam to Galisteo Creek. This study quantifies spatial and temporal trends in channel geometry, discharge, and sediment in the reach, and estimates future potential conditions of the Cochiti Dam reach. This will help various management agencies identify areas of the Middle Rio Grande that are more conducive to restoration efforts for these endangered species. This study focuses on post-dam trends in the Cochiti Dam reach. The existing Middle Rio Grande database was updated and completed for facilitation of this analysis. The highly controlled dam reduced peak annual flow rates to less than 10,000 cfs. Decreasing trends in width, width/depth ratio, and cross-sectional area were noted. Thalweg degradation averaged 2 feet over the entire reach. Median bed sediment sizes increased from an average of 0.1 mm in 1962 to an average of 24 mm in 1998. This was due to the 98% decrease in suspended sediment iii after the dam construction. The clearwater discharge from the dam scoured the bed and has narrowed the channel slightly. The bed degradation and bed material coarsening seen in this reach is consistent with previous studies on the Middle Rio Grande River. The planform has changed from a braided to single thread meandering channel from 1918 to 2004. The sediment transport capacity of the river is very high at the outlet of Cochiti Dam due to the release of clear, sediment starved water. The capacity has decreased since 1972, however, because the bed has coarsened. The upstream bed has armored and the sediment-starved water may soon begin eroding the banks and increasing lateral motion. Susan J. Novak Department of Civil Engineering Colorado State University Fort Collins, CO 80523 Spring 2006 iv A CK NO W LE D GEM E N TS I would like to thank the USBR in Denver and Albuquerque for the opportunity to work on this project. I would like to especially thank Chris Holmquist-Johnson, Jan Oliver, and Suzanne DeVergie for sending me so much data and then taking the time to explain it to me. Thanks to Drew Baird and my advisor Dr. Pierre Julien for overseeing the project and keeping me on track. I am grateful to Mark Velleux for helping me with my project and with schoolwork and to the rest of the group, Forrest, Seema, Chad, James, Un, and Max. Thanks to my friends Erin, Tessa, Esther, and Paul for their support and to my parents for taking care of my dog when I had working marathons. Thanks to my dog Millie for never complaining and sleeping quietly in my office when I had to work late at night. Finally, thanks to my committee members, Dr. Bill Fairbank of the Physics Department and Dr. Jose Salas of the Civil Engineering Department. v T AB LE O F CO NT EN T S ABSTRACT OF THESIS........................................................................................................... III ACKNOWLEDGEMENTS ......................................................................................................... V TABLE OF CONTENTS ............................................................................................................VI LIST OF FIGURES..................................................................................................................VIII LIST OF TABLES........................................................................................................................ X CHAPTER 1: INTRODUCTION................................................................................................. 1 CHAPTER 2: LITERATURE REVIEW..................................................................................... 4 2.1 REACH DESCRIPTION...........................................................................................................4 2.2 MIDDLE RIO GRANDE HISTORY ...........................................................................................6 2.3 HYDROLOGY, GEOLOGY, AND CLIMATE OF THE MIDDLE RIO GRANDE..............................9 2.4 PREVIOUS STUDIES OF THE MIDDLE RIO GRANDE.............................................................11 CHAPTER 3: GEOMORPHIC CHARACTERIZATION...................................................... 17 3.1 SITE DESCRIPTION AND BACKGROUND ...............................................................................17 3.1.1 Subreach Definition......................................................................................................22 3.1.2 Available Data .............................................................................................................22 3.1.3 Channel Forming Discharge........................................................................................24 3.2 METHODS ............................................................................................................................26 3.2.1 Channel Classification ................................................................................................26 3.2.2 Sinuosity .......................................................................................................................32 3.2.3 Valley Slope..................................................................................................................33 3.2.4 Longitudinal Profile.....................................................................................................33 Thalweg Elevation ............................................................................................................33 Mean Bed Elevation..........................................................................................................33 Friction and Water Slopes.................................................................................................34 3.2.5 Channel Geometry.......................................................................................................34 Hydraulic Geometry .........................................................................................................34 Overbank Flow/Channel Capacity....................................................................................35 3.2.6 Sediment ......................................................................................................................35 Bed Material .....................................................................................................................35 3.3 RESULTS..............................................................................................................................36 3.3.1 Channel Classification ................................................................................................36 3.3.2 Sinuosity ......................................................................................................................41 3.3.3 Longitudinal Profile ....................................................................................................41 Thalweg Elevation ............................................................................................................41 Mean Bed Elevation..........................................................................................................44 Friction Slope....................................................................................................................48 Water Surface Slope .........................................................................................................49 3.3.4 Channel Geometry........................................................................................................50 Hydraulic Geometry .........................................................................................................50 Overbank Flow/Channel Capacity....................................................................................56