Table Of Content

Historic, Archive Document Do not assume content reflects current scientific knowledge, policies, or practices. aTC529 R47 USDA Department of United States Agricultural Geography Department of Research Nottingham University Agriculture Service United Kingdom > , ' \ Channel & Watershed Processes Research Unit 0 National Sedimentation Laboratory ^ Oxford, Mississippi 38655 An Experimental Study of Alluvial Channel Response to Large Woody Debris By N.P. Wallerstein, C.V. Alonso, S.J. Bennett & C.R. Thorne Research Report No. 10 January 1999 ¥ \ .. <il jO r\ A Department of I United States Agricultural Geography Department of Research Nottingham University Agrieulture Service United Kingdom Channel & Watershed Processes Research Unit National Sedimentation Laboratory Oxford, Mississippi 38655 An Experimental Study of Alluvial Channel Response to Large Woody Debris & By N.P. Wallerstein, C.V. Alonso, S.J. Bennett C.R. Thorne Research Report No. 10 January 1999 . < ( ' . .1,) . : , ; \- •vc.•rxt, /.. • yl'V'V.' f ilt•!%,^’X It ' ' ''’'fi!/ Jif % .'Mr '<>' • 'V’,'vj.< : • '’^i'. .-A;. K • V- r^> *s• 4 .. 0- ^„< '•«', ' 'P'" • '/" h' '•^1 wr V.. ,. % • , V-'.. X! jJ^Py 1 ' "' , ' % '* -3•''» ' ..) • • . '**> ' A' . "r ^ .."f';'x . W, -' •.. ": • ' >VLi:ii- ! '<l‘lu/’' 4' -t" / ''Pi') ^4' vIL.. ' ,3' *' PP. "Tr . :»,C;’,/ ^ , x/.I»?Vs,"'st^Wrv! :>v, ';iPv 'H' '''V.;lI"x'.,.,I''''\y ’k’ ' Vi'V.yr '• J'. n. r) h I , • r » 4 i,\‘ Table ofContents Acknowiedgements iv List ofFigures V List ofTables vii List ofPlates vii Chapter Introduction 1 ; LWD Chapter 2: Literature concerning the hydraulic impact of LWD 2.1 Effect of on stage/discharge relationships, the hydrograph and flood frequency LWD 2.2 Modeling the impact of on flow afflux 3 EWD 2.3 Effect of on channel roughness 6 2.4 Elume techniques 9 Chapter 3: Similarity in model scaling 10 3.1 Basic principles 10 3.2 Secondary scale ratios 12 3.3 Influence ofviscous forces 13 3.4 Scaling channel boundary resistance in fixed bed models 15 3.5 Scale distortion 17 3.6 Moveable bed models 18 Chapter 4: Abiaca Creek scaling method 21 Chapter 5: Flume design and construction 33 Chapter 6: Description offlume results 40 6.1 Introduction 40 6.2 Expansion offlume results to prototype dimensions 40 6.3 Limitations ofthe flume model 41 Chapter 7: Discussion ofResults 44 7.1 Drag coefficient calculations for simulated debris elements 44 7.2 Selection ofdrag coefficient values 48 EWD 7.3 Estimation offriction factor due to 49 LWD 7.4 Drag force on elements in the model 51 I) c » <1 1 ll. Ill LWD 7.5 Drag force on elements in the prototype 52 LWD 7.6 Incident flow veloeity on elements in the model 55 LWD 7.7 Incident flow velocity on elements in the prototype 56 7.8 Conclusions from the hydraulie data 57 7.9 Geomorphic results: Flume 58 7.10 Geomorphic Results: Prototype 66 Chapter 8: Conclusions 72 Appendix 74 References 75 '1 I ). 1;• •’ •. ' , ; If ’ I , !('. ;i V '.J • • * ' ! » » I ‘I' , ’ - ' ^ '* A, I • “ JI'-i/M' •