MEMOIR 4 High Mountain Streams: Effects of Geology on Channel Characteristics and Bed Material By JOHN P. MILLER Interpretation of quantitative measurements made in the Sangre de Cristo Range, north-central New Mexico 1 9 5 8 STATE BUREAU OF MINES AND MINERAL RESOURCES NEW MEXICO INSTITUTE OF MINING AND TECHNOLOGY SOCORRO, NEW MEXICO NEW MEXICO INSTITUTE OF MINING & TECHNOLOGY E. J. Workman, President STATE BUREAU OF MINES AND MINERAL RESOURCES Alvin J. Thompson, Director THE REGENTS MEMBERS EX OFFICIO The Honorable Edwin L. Mechem ............. Governor of New Mexico Mrs. Georgia L. Lusk ................. Superintendent of Public Instruction APPOINTED MEMBERS Robert W. Botts ............................................................... Albuquerque Holm O. Bursum, Jr. ............................................................... Socorro Thomas M. Cramer ................................................................. Carlsbad John N. Mathews, Jr. .............................................................. Socorro Richard A. Matuszeski .................................................... Albuquerque Contents Page SYMBOLS .........................................................................................................................................................................vi INTRODUCTION ........................................................................................................................................................... 1 Background of the present study ................................................................................................................................... 1 Acknowledgments ............................................................................................................................................................ 2 PHYSICAL SETTING ...................................................................................................................................................... 3 Geographical description ................................................................................................................................................ 3 Topography and drainage ........................................................................................................................................... 3 Climate 3 Vegetation...................................................................................................................................................................... 6 Summary of geology ........................................................................................................................................................ 6 BASIC DATA ..................................................................................................................................................................... 8 CHARACTERISTICS OF DRAINAGE BASINS ...................................................................................................... 9 CHARACTERISTICS OF STREAM CHANNELS ...................................................................................................11 Bankfull width and depth..............................................................................................................................................11 The thalweg ..................................................................................................................................................................11 Changes at junctions ...................................................................................................................................................13 Relation to drainage area ............................................................................................................................................16 Estimation of bankfull discharge .................................................................................................................................16 Downstream changes in bankfull width, depth, and velocity ..................................................................................18 Angle of tributary junctions ..........................................................................................................................................21 Channel slope .................................................................................................................................................................21 BED MATERIAL .............................................................................................................................................................23 Problems in sampling ....................................................................................................................................................23 Downstream changes in size and lithologic composition ........................................................................................23 Changes at junctions ..................................................................................................................................................25 Changes along specific channel segments ..............................................................................................................25 Rio Santa Barbara ....................................................................................................................................................25 Rio Santa Cruz .........................................................................................................................................................27 Pecos River ...............................................................................................................................................................27 Changes at the mountain front ................................................................................................................................30 Dilution .......................................................................................................................................................................30 Particle wear ................................................................................................................................................................30 Sorting 32 Particle shape ..............................................................................................................................................................32 Relation of channel slope to particle size ...................................................................................................................34 Downstream changes in channel roughness ..............................................................................................................36 Problem of competence ................................................................................................................................................36 EFFECT OF GEOLOGY ON STREAM CHARACTERISTICS ..........................................................................40 Drainage basins ..............................................................................................................................................................40 Drainage density .............................................................................................................................................................40 Channel dimensions .......................................................................................................................................................40 Changes at the mountain front ....................................................................................................................................40 Channel slope .................................................................................................................................................................42 Bed material ....................................................................................................................................................................42 Pools and riffles ..............................................................................................................................................................46 Page EQUILIBRIUM IN HIGH MOUNTAIN STREAMS .............................................................................................. 49 CONCLUSIONS ............................................................................................................................................................... 52 REFERENCES ................................................................................................................................................................ 52 INDEX ................................................................................................................................................................................ 53 Illustrations Tables 1. Variation in bankfull width, mean depth, and cross-sectional area of stream channels along segments one- fourth mile or less in length, where no tributaries enter .......................................................................................... 13 2. Relative position of the thalweg, or deepest point in channel cross-section ........................................................ 13 3. Change in bankfull width, mean depth, and cross-sectional area at stream junctions ........................................ 15 4. Changes in