United States Department of the Interior DOUGLAS McKAY, Secretary Bureau of Reclamation W. A. DEXHEIMER, Commissioner . L. N. McCLELLAN, Assistant Commissioner and Chief Engineer Engineering Monograph No. 16 SPILL WAY TESTS CONFIRl\f MODEL-PROTOTYPE CONFORMANCE By A. J. Peterka Engineer, Hydraulic Laboratory Branch Engineering Laboratories Division . Technical Information Branch Denver Federal Center Denver, Colorado . ENGINEERING MONOGRAPHS are published in limited editions for the technical staff of the Bureau of Reclamation and interested technical circles in government and private agencies. Their purpose is to record developments, inno- vations, and progress in the engineering and scientific techniques and practices that are em- ployed in the planning, design, construction, and operation of Reclamation structures and equip- ment. Copies may be obtained from the Bureau of Reclamation, Denver Federal Center, Denver, Colorado, and Washington, D. C. CONTENTS Page INTRODUCTION.. .. .. .. .. .. .. .. .. 1 HEART BUTTE DAMSTUDIES. .. .. 1 Description of Project. .. .. .. .. 1 Model Tests . .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. 2 1. Spillwayand pier tests. 3 2. Deflector and vertical bend tests. .. .. .. .. 5 3. Outlet works and tunnel junction tests . .. .. .. .. .. .. .. .. .. .. .. 6 4. Stillingbasin tests. .. .. .. .. 6 5. Spillway air tests .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. 8 The 1950Spring Flood. .. .. .. .. 11 Model-Prototype Comparison Tests. .. .. .. .. .. .. .. .. .. .. .. .. 12 1. Spillwaycapacity. 12 2. Spillway performance--Free and submerged discharges .. .. .. .. 14 3. Spillwayair demand. 19 4. Stilling basin performance . .. .. .. .. .. .. .. .. .. .. .. .. .. 21 5. Erosion downstream from stilling basin .. .. .. .. .. .. .. .. .. .. .. .. .. .. 24 6. Tail-water elevations . .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. 27 7. Rivererosion. 29 8. Inspection of structure following 1950 and 1951 floods. 29 SHADEHILL DAM STUDIES .. .. .. .. .. .. .. .. .. .. .. .. 30 Description of the Project .. .. .. .. .. .. .. .. .. .. .. .. .. .. 30 Summary of Model Tests .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. 35 1. The model .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. 35 2. Spillway air tests .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. 35 3. Stillingbasintests. 35 1952SpringFlood. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. 35 ModelPrototypeComparisonTests. 41 1. Spillwaycapacity. .. .. .. .. .. .. .. .. .. 41 2. Spillway performance--submerged and free discharges .. .. .. .. 41 3. Vortex action and effect of ice. .. .. .. .. .. .. .. .. .. .. .. .. .. .. 45 4. Vibration. 49 i 5. Debris. 50 5. Tunnel air demand .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. 50 7. Spillway head loss .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. ~ .. 51 8. Stilling basin performance .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. 52 9. Tail-waterelevations. .. .. .. .. ~ 52 10. Erosion below the stilling basin . .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. e 58 fuspection of the Prototype after the Flood .. .. .. .. .. .. .. .. 62 " ACKNOWLEDGMENTS. .. .. .. .. .. .. .. 62 ii LIST OF FIGURES Number Description Page 1 Index and vicinity maps .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. 2 2 Plan and sections of spillway and outlet worksat HeartButteDam. 3 3 Laboratory model of spillway and outlet works for Heart Butte Dam. 3 4 Heart Butte spillway model tests at a discharge of 3,750 cfs . 4 5 Entrance details of spillway and outlet worksat HeartButteDam. 5 6 Flow through vertical bend in Heart Butte spillway model .. .. .. .. 6 7 Tests of junction of spillway and outlet tunnels for Heart Butte Dam. 7 8 Stilling basin details for spillway and outlet works at Heart Butte Dam. 8 9 Testing Heart Butte stilling basin model at a discharge of 5, 600 cfs . .. .. .. .. 9 10 Hydrographs of April 1950 flood on Heart River. .. .. .. .. 10 11 Reservoir elevations and hydraulic data of 1950 flood at Heart Butte Dam. 11 12 Spillway discharge capacity curve for Heart Butte Dam .. .. .. .. .. 12 13 Discharge comparison of Heart Butte modelandprototype. 12 14 Performance of spillway and outlet works at Heart Butte Dam. 13 15 Reservoir at el. 2073.8, crest submerged 9. 3 ft., discharge 3,250 cfs. 14 16 Operation of Heart Butte spillway with piers submerged. .. .. .. .. .. .. .. .. .. 15 17 Reservoir at el. 2074.0, discharge 3,260 cfs .. .. .. .. .. .. 16 18 Reservoir at el. 2071, discharge 3,090 cfs. 16 19 Reservoir at el. 2068.6, discharge 1,600 cfs .. .. .. .. .. .. .. .. .. 17 20 Reservoir at el. 2070.0, discharge 2,650 cfs, 36 inches of ice on the water. .. .. .. .. 18 21 Spillway air vent system at Heart Butte Dam .. .. .. .. 19 22 Air demand curves for model and prototype for varying discharges. 20 23 Outflow 3, 250 cis, stilling basin operating efficiently 21 24 Performance of the stilling basin at a discharge of 3,600 cfs . 22 iii Number Description Page ')~ ~0 Performance of the stilling basin at a discharge of 3, 600 cfs. 23 26 Profiles of comparative discharges of model and prototype spillway . 24 ~,?"' Profiles of comparative discharges of model and prototype spillway. 24 28 Comparative cross sections of river channel before and after 1950flood. 25 29 Detail cross sections of river channel before and after 1950flood. 25 30 Erosion of the excavated channel downstream from the stilling basin. 26 31 Comparison of measured and computed tail water elevations. 27 32 Flow conditions at junction of excavated and natural channels. 28 33 Loss of bank material through erosion during 1950flood. 29 34 River channel erosion, compare with figure 23 . 30 35 Cast of eroded area in. vertical bend. 31 36 Cast of another eroded area . .. 32 37 General plan and sections of spillway at ShadehillDam. 33 38 Details of spillway intake for Shadehill Dam . 34 39 Details of spillway stilling basin at Shadehill Dam. 36 40 ShadehillDamspillwaymodel. 37 4J Test of Shadehill spillway model at a discharge of 5,000cfs. 38 42 Reservoir elevations and hydraulic data of the 1952 flood at Shadehill Dam. 39 43 Hydrographs of the 1952 flood at Shadehill Dam 40 44 Discharge capacity curve of the service spillwayat ShadehillDam. 42 45 Comparison of the discharges of the model and prototype spillways at Shadehill Dam. 43 46 Transition from submerged to free flow at Shader..ill Dam spillway. 44 47 Vortex of submerged spillway flow at Shadehill Dam. 45 48 Effect of ice on vortex action of the Shadehill spillway. 46 48 Vortex action was continuous above el. 2284.9 in Shadehillspillway. 47 iv Number DescriDtion. Page 50 Vortex action at reservoir e1. 2283.6 was sporadic. 48 51 No vortex visible at reservoir e1. 2277.8 and below . 48 52 Air demand and spillway discharge curves for ShadehillDam. 49 53 Air flow in tunnel was insufficient to deflect a trickle of water. 50 54 Overall head loss through Shadehill service spillwaystructure. 51 55 Comparison of water surface profiles of model and prototype spillways. 53 56 Water surface profiles of Shadehill spillway, 1, 300 to 3, 950 cfs ................ 54 57 Shadehill spillway stilling basin dischargL'1g4, 400cfs. 55 58 Shadehill spillway stilling basin discharging 4, 600 cis. .. & . .. .. .. 56 59 Computed and actual tail water curves for service spillway at Shadehill. 57 60 Flood erosion and repairs to spillway outlet channel following 1952 flood. .. .. .. .. 59 61 Channel erosion caused by 1952 flood at Shadehill. 60 62 Erosion of excavated channel banks by 1952 flood atShadehill. 61 v INTRODU CTlON the morning-glory during submerged dis- charge, the erosion of the downstTeam rive::-- There is a general need for dab which banks, and the effectiveness of the riprap can be used to compare the perform.ance of used on the excavated cham'el banks, The models and prototypes and extend the range results of inspections of the spillway tun- of usefulness of hydraulic models as all aid nels and structures following the floods are in design. Ordinarily, prototype data are also given. difficult to obtain and usually the model data are not in the prototype range of heads or HEART BUTTE DAM STUDIES discharges, which makes direct comparison difficult. Also, several years may elapse Descriution of Pro,lec". between model tests and the time the proto- type is subjected to large flows. The Heart Heart Butte Dam is on the Ileart River Butte and Shadehill Spillways, however, op- 60 miles west of Bismarck, North Dakota, erated during the first flood season following and is part of the Heart Hive::- Unit of the their completions and almost immediately IVIissOIlri River Basill Pr'ojed (figure 1). 'T'he after the hydraulic model tests were made. dam is of compacted eartl1 fill with arockrip- With the test data on the models still fresh rap cover, rises 135 feet above str-ear:: bcd, it was possible to obtain prototype data on and is 1, 860 feet long. It Serves both Lrriga- short notice that could be compared with tion a..'1dflood-control purposes, At maximurn model tests. water-surfaceeievatlOn the reservoir wiE contain 392,500 acre-feet of water collected This monograph compares the perform- from a drainage area of 1,810 square mile's. ances of both the Heart Butte and Shadehill Dam. morning glory spillway models with the Figure 2 shows plan and sections of the performances of the prototype structures. nood-control spillway and of the outlet works, The results of these comparisons add further which, as the transparent model in figure 3 proof to