P AP-SEi5 PROCEEDINGS OF THE SECOND INTERNATIONAL SYMPOSIUM ON DESIGN OF HYDRAULIC STRUCTURES / FORT COLLINS, COLORADO / 26-29 JUNE 1989 Design of Hydraulic

ructures 89 HYDRAULICS BRANCH St OFFICIAL FILE COPY

Edited by MAURICE L.ALBERTSON Department of Civil Engineering, Colorado State University, Fort Collins, USA T RAHIM A.KIA Mahab G. Consulting Eng., Tehran, Iran resently: Department of Civil Engineering, Colorado State University, ort Collins, USA

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Bureau of Reclamation HYDRAULICS BRANCH RI

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A.A.BALKEMA / ROTTERDAM / BROOKFIELD / 1989 Design of Hydraulic Structures 89, Albertson & Kia (eds) © 1989 Balkema, Rotterdam. ISBN 90 6191 898 7 The role of hydraulic modeling in development of innovative spillway concepts

Philip H.Burgi Bureau of Reclamation, Denver, Colo., USA

ABSTRACT: The use of hydraulic models to develop and verify the intricate design of waterways to pass flood flows has been closely associated with the development of hydraulic structures over the past 50 years. Since the mid-30's, the Bureau of Reclamation has used laboratory models to develop spillways for large dams such as Hoover, Grand Coulee, Glen Canyon, Yellowtail, and Morrow Point Dams. Documented reports and generalized design criteria have been developed to summarize the results of these investigations. In recent years, Reclamation has developed various innovative spillway concepts which have resulted in cost effective designs for hydraulic structures. This paper will summarize recent laboratory investigations for labyrinth, stepped, and fuse plug spillway concepts as well as retrofit concepts using aerators on spillways and downstream slope protection systems for overtopping low-head embankments.

INTRODUCTION

Physical model studies are used to investigate the anticipated performance of hydraulic structures. The model is usually a reduced size representation of the proposed hydraulic structure and is designed to investigate specific areas of concern related to the hydrodynamic performance of the waterways. Modeling laws based on theoretical analysis and laboratory experience have been developed which permit correct simulation of the particular hydrodynamic phenomena under investigation. Once the model laws are understood and proper consideration is given to their limiting range of application, successful laboratory investigations can be completed which will in fact simulate the performance of the full scale structure

In the early 1940's a question was asked of hydraulic researchers "Does the prototype act as the model predicted?" In 1944, the ASCE transactions (ASCE 1944) published case studies of model-prototype correlation. The papers resulted from a symposium held to assemble the results of a wide variety of studies in which actual comparisons had been made so that the engineer could judge the adequacy of hydraulic modeling as a design tool. Since the 1940's, there have been many model-prototype correlations to further assure the adequacy of physical laboratory models (Peterka 1954 ) and (Burgi 1988).

67 The hydraulic model plays a key role in the development of final design concepts for hydraulic structures. Although its most important role is to verify the adequacy of the design concept, it is also used to "fine tune" details such as pier shape, height of training walls, etc., which normally produce construction cost savings that more than offset the cost of the hydraulic model investigation. The cost of most model investigations can be equated to placing 100 - 300 m3 of concrete on the actual structure.

II. Rehabilitation and Modification to Correct Inadequate Spillway ' Capacity

With recent increases in the probable maximum flood (PMF), it has become imperative for the design engineer to provide more flood storage and/or larger capacity spillways to adequately pass the PMF. Innovative new design alternatives are under consideration to provide larger storage capacity and more cost effective spillway alternatives. In some cases, these new design concepts are used on existing structures where additional spillway capacity is needed. In other cases, the design concepts are applied to new hydraulic structures.

1. Labyrinth Spillways. - The labyrinth spillway is particularly well suited for a restricted length of spillway or in the rehabilitation of an existing spillway structure. The concept illustrated in figure 1 consists of repeated triangular or trapezoidal shapes which provide a developed crest length much longer than the spillway chute width. The ratio of the developed crest length for one cycle, 1, to the linear length of one labyrinth cycle, w, is defined as the length magnification, 1/w. The vertical geometry of the labyrinth is described by the spillway height, P, and the vertical aspect ratio, w/P.

Ideally the discharge ratio of the labyrinth spillway to a linear spillway, the flow magnification (QL/QN) should be directly related to the length magnification (Hinchliff and Houston, 1984). Therefore, if the developed spillway length for the labyrinth is three times greater than the linear length, the discharge capacity should be three times as great. This ideal condition is only true for low-head to crest- height ratios (H/P).

Figure 2 illustrates the decrease in flow magnification RAN) with the increase in head to crest height (H/P). The figure illustrates a 33 percent decrease in flow magnification as the upstream head approaches one-half the spillway height, P.

Several design guidelines are given in the paper. In general the importance of the vertical aspect ratio (w/P) and resultant nappe interference from cycles being placed too close together, increases as the head increases. It is generally recommended that the vertical aspect ratio be 2.5 or greater where a significant spillway head is expected.

Ute Dam is a good example of the successful use of a labyrinth spillway. The dam is owned by the New Mexico Interstate Stream Commission (NMISC) and was completed in 1963. It is located on the

68 Canadian River in central New Mexico. The existing 36.6-m-high embankment dam had a gated outlet works and a 256.0-m-wide free overflow spillway. It was desired to increase the reservoir storage to permit full storage allotment under the Canadian River Compact and to increase the spillway discharge capacity to 16 055 m3/s. The NMISC asked Reclamation to consider several alternatives to modify the existing Ute Dam. Appraisal designs and estimates for a traditional gated structure showed a minimum field cost of $34 million (1980 unit prices). After considering several alternatives, the most economical design was a labyrinth spillway combined with raising the dam for an estimated field cost of $10 million.

Numerous investigations were conducted in the laboratory to determine optimum ratios for the length magnification and vertical aspect ratio (Houston 1982). Both sectional flume studies and a 1:80 scale model of the full spillway, figure 3, were tested. The final design consisted of a 14-cycle spillway with a length magnification of 4 and a flow magnification of 2.4. The vertical aspect ratio of Ute is very small at 2.0. Figure 4 illustrates the nappe interference and resultant increased head loss for a discharge of 15 575 m3/s. In May 1987, a discharge of approximately 85 m3/s overtopped the newly placed spillway. The discharge was quite small and represented less than 1.0 percent of the design discharge.

2. Fuse Plug Spillways. - The fuse plug spillway is another cost- effective alternative to pass flood discharges. It is normally located on an auxiliary spillway where the fuse plug serves the same function as if gates were installed to restrict the spillway operation to floods of infrequent occurrence. "A fuse plug is an embankment designed to wash out in a predictable and controlled manner when the capacity in excess of the normal capacity of the service spillway and outlet works is needed." (Pugh and Gray 1984)

Model embankments 0.15 to 0.38 m high and 2.7 m long at scales of 1:10 and 1:25 were used by Reclamation to develop fuse plug spillway design guidelines (Pugh 1985). Laboratory discharges up to 0.61 m/s were used to determine lateral erosion rates, discharge coefficients, and design of embankment materials. Settling velocity adjustments and dimensionless unit sediment discharges were used to adjust the model sand grain size and/or model sediment density. The laboratory fuse plug embankment was designed with material zones similar to those found in most earth or rockfill dams.

A pilot channel (on the order of 1 meter wide) located high on the fuse plug is designed to wash out quickly once the reservoir level reaches the channel invert. An impervious core similar to that shown in figure 5 is designed into the fuse plug embankment. The core will break off in pieces from the weight of the water and embankment material. As the material downstream from the core is washed away, the core is left unsupported and breaks away. This results in a breach of the embankment at the pilot channel, but soon produces a controlled lateral erosion of the complete fuse plug as shown in figure 6.

The results of these laboratory studies are used by Reclamation to design full scale fuse plugs, such as the 9.7-m-high, 1370-m-long Twin

69 Buttes Dam fuse plug. The approach channel for the Twin Buttes fuse plug is relatively long and shallow and filled with mesquite (Klumpp 1988). The long approach channel and mesquite affect the head loss and resultant discharge capacity of the auxiliary spillway. Figure 7 shows a decrease in the maximum discharge capacity of 4.0 percent caused by the mesquite.

3. Embankment Protection to Permit Overtopping. - The thought of flood flow over an embankment is very frightening to most engineers. However, in recent years there has been increased interest in investigating various protective systems for the downstream slopes of low embankments (under 15 meters) which may be overtopped during extreme flood events. Various modeling techniques have been used from the full scale tests conducted at Jackhouse Dam by the United Kingdom's Construction Industry Research and Information Association (CIRIA) (Hewlett 1987) to the Reclamation laboratory studies (Dodge 1989). More recently, full scale tests using a 1.83-m-high embankment in a 1.22-m-wide and 18.30-m-long test flume were conducted for four government agencies (Federal Highway Administration, Bureau of Reclamation, Soil Conservation Service, and Tennessee Valley Authority) by Simons, Li, and Associates (Clopper and Chen 1988).

A wide variety of protective systems have been investigated. They include various classes of vegetation (grasses), jute, fiberglass, nylon mat, various concrete blocks, concrete blocks with cables, gabions, various geosynthetic materials, and soil cement. The use of roller- compacted concrete (RCC) steps as embankment slope protection has also been tested in the laboratory (Houston 1988) and placed in the field (Moler 1987). Critical velocities and shear stresses are summarized for a number of these systems (Clopper and Chen 1988). One major and obvious conclusion of these investigations is that the protection systems must be in contact with the underlying embankment. Once the bond is broken, the system's ability to protect the embankment is seriously compromised.

These hydraulic investigations have added considerably to our understanding of design and installation considerations for protective systems on embankments. They have provided significant qualitative data to assist in the selection of protective systems for low embankments. The future engineering challenge related to embankment protection deals with the extrapolation of present knowledge to high embankments. As the size of design floods continues to increase, there is increased pressure to consider these protective systems as alternatives to the more costly traditional spillway designs. What will be the role of hydraulic modeling in this new challenge?

4. Spillway Aerators. - Spillway aerators are another innovative design which were developed and verified using hydraulic models. Cavitation damage to spillways occurred as early as 1944, when the newly completed Boulder Dam (now Hoover Dam) tunnel spillways were placed in operation. A 1 to 60 scale model was constructed by the Bureau of Reclamation and a number of devices were studied to introduce air between the high velocity water jet and the concrete tunnel liner (Bradley 1945). The studies were eventually discontinued when no successful method to introduce air was found.

70 After the 1967 damage in the Yellowtail Dam tunnel spillway in Montana, a model study was used to develop a conical nozzle (ramp) and aerator slot to introduce air just upstream of the vertical bend (Colgate 1971). This design was installed in the prototype tunnel and verified with field tests conducted in June 1969. The serious damage to the two Glen Canyon Dam tunnel spillways in 1983, figure 8, resulted in additional model investigations to further improve the aerator design proposed at Glen Canyon Dam (Pugh 1984). Design methods were also developed to identify when spillway aerators are needed on high-head dams. This analysis resulted in the installation of aerators on Reclamation's five highest tunnel spillways - Hoover, Glen Canyon, Yellowtail, Flaming Gorge, and Blue Mesa Dams, and permitted a rational method to determine which of Reclamation's 20 tunnel spillways required aerators.

The repair criteria for damaged concrete surfaces downstream from the aerator at Glen Canyon, Hoover, and Flaming Gorge Dam spillway tunnels were relaxed. Savings of several million dollars were realized by this relaxed surface tolerance criteria (Burgi and Eckley 1987).

III. Stepped Spillways Associated with Roller-Compacted Concrete Dam Construction

The concept of the stepped spillway is not new, but has gained renewed interest in recent years with the use of RCC technology in dam construction. The economical use of RCC depends on the uninterrupted placement of concrete and the compatible design of spillways, outlet works, and other dam appurtenance.

In recent years, there have been a number of RCC dams constructed but very few have used the stepped spillway concept. Galesville Dam has a free overflow spillway section of smooth enriched RCC. Elk Creek Dam has a gated overflow spillway with conventional smooth concrete section.

The stepped spillway concept takes advantage of the normal RCC placement depths of 0.6 to 1.0 meter. The step dimensions are related to the slope of the downstream face of the dam. For low head dams or low unit discharges, the downstream natural face of the RCC may be sufficient. The Kirville Dam in Texas, figure 9, is an example of a low head dam which in 1985 underwent a 4.3-meter depth of overtopping (Smith 1986). For high head dams or high unit discharges facing elements of conventional concrete may be required. Reclamation's Upper Stillwater Dam is an example of a high head dam with conventional concrete facing elements.

Upper Stillwater Dam. - Upper Stillwater Dam is located at the 2440 meter elevation in the Uinta Mountains in the state of Utah. The 88-meter-high gravity dam was completed in 1987 and includes 1.15 million m3 of RCC and 70 000 m3 of slip formed facing concrete.

A short construction period due to the low air temperatures during most of the year required dam construction methods which emphasized concrete placement speed. Horizontal slip formed facings were used to place

71 conventional concrete on the vertical upstream face and the sloped downstream face. Each facing element is 0.9-meter high and the lower one-third of the element overlaps the previously placed element. this results in 0.6-meter-high steps on the downstream face of the dam, figure 10. The major benefit of the stepped spillway is the resulting energy dissipation from flow tumbling down the spillway face. A high percentage of the energy is dissipated before reaching the stilling basin, thus significantly reducing the basin length. Three laboratory models (1:5, 1:10, and 1:15) were used to determine the crest design of the 60-meter-high and 183-meter-wide stepped spillway. The models were also used to study details of the entrance conditions, height of training walls, pressure on the steps, and adequacy of energy dissipation to design the stilling basin. Model scales were chosen based on detail needed for the crest design (1:15 and 1:10) and the need for a full height sectional model (1:15). The availability of existing flumes and pump capacity were also determining factors. These model scales were highly desirable and permitted very accurate predictions of prototype performance.

For the design discharge of 425 m3/s (2.32 m3/s/m) and H = 1.07 meters, the aerated turbulent flow tumbled uniformly down the stepped face with 75 percent reduction in energy. During the course of the study the design unit discharge was increased from 2.32 to 11.6 m3/s/m. This larger design discharge required a head of 3.0 meters. With only minor modifications to the crest end piers, the addition of two steps on the crest, and reinforcement of the RCC end sill in the stilling basin, the design was determined to be adequate for the increased total discharge of 2095 m3/s. Figure 11 illustrates the 11.6 m3/s/m unit discharge in the 1:15 scale model.

Figure 12 illustrates the final design of the spillway face. The required stilling basin length for the stepped spillway was 9.14 meters, a reduction of 85 percent over that computed for a traditional hydraulic jump basin.

SUMMARY

Hydraulic modeling has played a significant and essential role in the development of hydraulic structures around the world. Mankind's confidence to build water resources projects such as Hoover, Grand Coulee, Itapu, Tarbella, Kariba, and many other large hydraulic structures has been supported by the verification tests performed in hydraulic laboratories all around the world. In recent years, Reclamation has continued to rely on hydraulic models to develop and verify innovative spillway concepts for hydraulic structures.

BIBLIOGRAPHY

ASCE, Transactions of the American Society of Civil Engineers, Vol 109, 1944. Peterka, A. J. 1954. Spillway Tests Confirm Model-Prototype Conformance, Bureau of Reclamation, Engineering Monograph No. 16.

72 Burgi, P. H. 1988. Proceedings International Symposium on Model- Prototype Correlation of Hydraulic Structures, American Society of Civil Engineers, New York. Hinchliff, D. L. & K. L. Houston 1984. Hydraulic Design and Application of Labyrinth Spillways, United States Committee on Large Dams. Houston, K. L. 1982. Hydraulic Model Study of Ute Dam Labyrinth Spillways, Bureau of Reclamation, GR-82-7. Houston, K. L. 1987. Hydraulic Model Studies of Upper Stillwater Dam Stepped Spillway and Outlet Works, Bureau of Reclamation, REC-ERC- 87-6. Hansen, K. D. 1987. Roller Compacted Concrete Worldwide, Water Power and Dam Construction Handbook. Houston, K. L. & A. T. Richardson 1988. Energy Dissipation Characteristics of a Stepped Spillway for an RCC Dam, Beijing, International Symposium on Hydraulics for High Dams. Moler, W. A. 1987. Spring Creek Dam is Ready for the PMF: A Case Study, Proceedings ASCE National Conference on Hydraulic Engineering, p. 676-681. Burgi, P. H. & M. S. Eckley 1987. Repairs at Glen Canyon Dam, ACI Concrete International: Design and Construction, March 1987, p. 24- 31. Pugh, C. A. & E. W. Gray 1984. Fuse Plug Embankments in Auxiliary Spillways - Developing Design Guidelines and Parameters, United States Committee on Large Dams. Pugh, C. A. 1985. Hydraulic Model Studies of Fuse Plug Embankments, Bureau of Reclamation, REC-ERC-85-7. Klumpp, C. C. 1988. Hydraulic Model Study of Twin Buttes Dam Fuse Plug Spillway, Bureau of Reclamation, REC-ERC-88-2. Dodge, R. A. 1988. Overtopping Flow on Low Embankment Dams - Summary Report of Model Tests, Bureau of Reclamation, REC-ERC-88-3. Hewlett, H.W.M., L. A. Borman & M. E. Bramley 1987. Design of Reinforced Grass Waterways, Construction Industry Research and Information Association, London. Clopper, P. E. & Y. H. Chen 1988. Minimizing Embankment Damage During Overtopping Flow, FHWA-RD-88-181, Federal Highway Administration. Bradley, J. N. 1945. Study of Air Injection into the Flow in the Hoover Dam Spillway Tunnels, Bureau of Reclamation, HYD-186. Colgate, D. 1971. Hydraulic Model Studies of Aeration Devices for Yellowtail Spillway Tunnel, Bureau of Reclamation, REC-ERC-71-48. Pugh, C. A. 1984. Modeling Aeration Devices for Glen Canyon Dam, Proceedings of ASCE Hydraulics Division Specialty Conference, p. 412- 416. Smith, L. 1986. RCC Dam Survives Texas Flood, Engineering News Record, April 24, 1986, p. 28-29.

73 a

PROFILE

PLAN

LEGEND

a = Half length of labyrinth apex b = Length of labyrinth wall H = Total upstream head over crest (less than Ho) Ho = Design head 1 = Developed length of one labyrinth cycle = 4a + 2b L = Total developed length of spillway 1/w = Length magnification n = Number of spillway cycles in plan P = Spillway height (crest height) ' QL = Discharge over labyrinth spillway QN = Discharge over linear spillway QL/QN = Flow magnification (measure of spillway performance) W = Width of linear spillway w = Width of one labyrinth spillway cycle w/P = Vertical aspect ratio « = Angle of sidewalls to main flow direction

Figure 1. - General plan and section of labyrinth spillway (Hinchliff and Houston 1984)

74 5

10

0 o v. -z

10 - - Crest Shop el

2

t 7H__FI - EI l m

H/P

Figure 2. - Design curves with quarter-round upstream face, trapezoidal form weir (Hinchliff and Houston 1984),

Figure 3. - 1:80 scale model of Ute Dam labyrinth spillway (Houston 1982).

75 Figure 4. - Ute Dam labyrinth spillway with 15 575 m3/s (Houston 1982)

Fw

PILOT CHANNEL

IMPERVIOUS CORE

Figure 5. - Flow through the pilot channel showing the mode of failure of the impervious core (Pugh and Gray 1984)

76 Figure 6. Photographs showing washout process (Pugh and Gray 1984).

77 TWIN BUTTES DAM MODEL STUDY 2000.0 ~- DISCHARGE RATING CURVE

1995.0

1990.0

1985.0 With mesquite friction F d u

Ithout ZO 1980.0 mesquite F a friction w J 1975.0. W a---d Without mesquite friction 1970.0 O--0 With mesquite friction NOTE: Includes discharge through ogee service spillway and outlet works 1965.0 r as shown in the curve on figure 2.

1960.0 0.00 0.10 0.20 0.30 0.40 0.50 0.60 0.70 0.80 0.90 1.00 1.10 1.20 r 1.30 1.40 1.50 1.60 1.70 1.60

,DISCHARGE, x 10"' ftl/s

Figure 7. - Fuse plug spillway rating curves with and without mesquite friction (Klumpp 1988). 1 ft = 0.305 m, 1 ft3/s = 0.028 m3/s.

78 Figure 8. - View looking downstream across the 10.7-m-deep hole in the invert liner of the left tunnel spillway at Glen Canyon Dam (Burgi and Eckley 1987).

79 Figure 9a. - Kirville Dam - 4.3-m overtopping.

Figure 9b. - Kirville Dam after overtopping event.

80 Maximum water surface EL. 8182.00 (2493.9) conventional concrete crest 25.3 (7.7m)

Crest El. 8172.00 (2490.8m)

EI. 8183.50 (2488.2m) \ Axis of dam EI. 8184.00 S-0.02 f (2488.2m)

2.0 (0.81m) V -Facing k elements

RCC Alts I Figure 10. - Upper Stilllwater Dam spillway crest (Houston and Richardson 1988).

Figure 11. - 11.6 m3/s/m unit discharge on the 1:15 scale model of Upper Stillwater spillway (Houston 1987). 1 m3/s/m = 10.8 ft3/s/ft.

81 0 So 0.3 w2go 03A 0530 3] 11•I!

031 E. 946 00 OSI' ]•00. OS SO'

.2]

• Nw •FIF EI S.3200 S

TA-P +F•E• •y. ~..O~O~y~• E3+

Ofi SCALE .M FEET

SOIIIN E. M3200 tnFt ulE~ •

f

J 0 W SO SO b SO

scut M.11

Figure 12. - Section of preliminary and final spillway designs (Houston 1987). 1 ft = 0.305 m.

82 New & recent publications Breusers, H.N.C. & AJ.Raudkivi 90 6191 983 5 Scouring-hydraulic Structures Design Manual, 8 Albertson, M.L. &Rahim A.Kia (eds.) 90 6191 958 4 (Published for International Association for Hydraulic Research) Design of hydraulic structures 89 -Proceedings of the 2nd 1990,25 cm, c.190pp., Hfl.95 /$45.00/£27 international symposium, Colorado State University, Fort Scouring occurs naturally as part of the morpholoc changes of Collins, 26-29June 1989 rivers & as the resultof man-made structures. The developmentof 1989,23 cm, 504 pp., Hfl.120/$55.00/£34 river valleys reveals such activity through millenia, long before 61 papers covering new developments and creative interdisciplin- man's efforts had any appreciable impact on them. In recent times, ary approaches in all possible aspects of hydraulic structure de- the addition of many types of structures has greatly altered river sign. Hydrology, floods & risks; Computers, simulation & optimi- regimes, & significant impacts on the transport & deposition of zation; Modelling, testing & analysis; Foundations & materials; sediment have resulted Most structures increase these processes, Storage & conveyance; Erosion & sediment control; Spillways & at least locally & often to the detriment of the river regimes. The energy dissipation; Intakes & energy loss; Irrigation, drainage & designer must therefore seek to understand the scouring process & navigation; Hydropower, Pumps & valves; Operation, manage- to study the consequences of a given structure & its effect on the ment & rehabilitation. Author & subject index. Editors: Colorado larger processes of river morphology. Topics: Basic concepts of State University, Fort Collins. soil erosion & sediment transport; Scour in rivers & river constric- tions; Scour around spur dikes & abutments; Scour at bridge piers; Kollonan, P.A., J.Lindenberg & K.W.Pilarczyk (eds.) Scour by jets, at high-head structures & culvert outlets; Scour Modelling soil-water-structure interactions -Proceedings of below low-head structures. the international symposium, Delft, 29.08-02.09.1988 1988, 25 cm, 514pp., Hit. 125/$57.00/£36 9061918154 Wessels, A.C.E. (ed.) 90 6191 645 3 Topics on soil-water-structure interactions: General introduction Measuring techniques in hydraulic research -Proceedings of of the processes & screening of the fields of interaction; Different the international symposium on measuring techniques in hydrau- ways of computation modelling & scale modelling; Use & useful- lic research, IAHR Section, Delft,22 24 April 1985 ness of models for the designer. Topics on interactions: Wave & 1986, 25 cm, 288 pp., 1111.95 /$45.00 /£27 current induced behaviour of the seabed (near pipelines & fixed Practical application of measuring techniques. 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(coordinator-editor) 90 6191 643 7 topics including: the quality of the water we drink; the waste we Swirling flow problems at intakes (Hydraulic structures produce & its disposal; what happens to acid rain; the search for design manual, 1) (Published for the International Association for new raw materials; the development of traditional sources of ener- Hydraulic Research). gy such as oil, coal, & gas; and the search for alternative sources of 1987, 25 cm,168 pp., Hfl.85 / $38.00 /£24 energy such as geothermal power. 199 papers provide an up-to- Fundamentals of vortex intake flow; Results of theoretical & ex- date picture of research in hydrogeochemistry.199 papers. Editor. perimental work; Prediction of critical submergence; Modelling British Geological Survey, Wallingford of vortices & swirling flows; Design recommendations; Intake strucurres; Pump sumps; Vortex-flow intakes. Garbrecht, Giinther(ed.) 90 6191 621 6 Hydraulics and hydraulic research : A historical review Inter- national Association for Hydraulic Research 1935-1985 Mailer, Andreas (ed.) 9061917824 (Jubilee volume published for the International Association for Discharge and velocity measurements - Proceedings of a short Hydraulic Research) course, Zarich, 26-27August 1987 (Published for the Interna- 1987,28 cm, 377 pp., Hfl.165/$75.00/£47 tional Association for Hydraulic Research). One of the very few books on the history of hydrology, hydraulics 1988,25 cm, 216 pp., 1111.95 /$45.00/£27 & water utilization. 32 authors from 16 different countries give a Discharge measurements & their calibration; Point measurements comprehensive portrait of hydraulics & hydraulic research. 33 of velocities; Measurement of velocity fields; Needs for further contributions with 114 photos. Editor. Braunschweig Technical developments. Editor. E.T.H., Zurich. University, Germany. 90 6191 958 4 Alluvial river problems -Proceedings of the third international Franciss, Fernando Olavo 90 6191 550 3 workshop on alluvial river problems (TIWARP), University of Soil and rock hydraulics-Fundamentals, numerical methods Roorkee, 2-4 March1989 (No rights India) and techniques of electrical analogs 1989,22 x 28 cm, 337 pp., Hfl.95 / $45.00 /£27 1985,23 cm, 184 pp., Hfl.120/$55.00/£34 Scour and its protection; Morphological calculations; Resistance A textbook for geologists, mining & civil engineers. Soil & mck of alluvial streams; Sediment transport; Sediment yield and con- hydraulics describes mathematically the physical phenomena trol; River improvement works; Coastal sedimentation & estua- related to water seepage through soil & rock masses. rine hydraulics; Sediment measurement; Appendices; 32 papers.

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