Hydraulic Design Handbook

1.1 OVERVIEW

Since the Egyptians and Mesopotamians first successful efforts to control the flow ofwater thousands of years ago, a rich history of hydraulics has evolved. Sec. 1.2 contains abrief description of some ancient hydraulic structures that are found around the world.During the 20th century, many new developments have occurred in both theoretical andapplied hydraulics. A number of handbooks and textbooks on hydraulics have been pub-lished, as indicated in Fig. 1.1. From the viewpoint of hydraulic design, however, onlymanuals, reports, monographs, and the like have been published, mostly by governmentagencies. Unfortunately, many aspects of hydraulic design have never been published asa compendium. This Hydraulic Design Handbook is the first effort devoted to producinga comprehensive handbook for hydraulic design. The book covers many aspects ofhydraulic design, with step-by-step procedures outlined and illustrated by sample designproblems.

1.2 ANCIENT HYDRAULIC STRUCTURES

1.2.1 A Time Perspective

Although humans are newcomers to earth, their achievements have been enormous. It wasonly during the Holocene epoch (10,000 years ago) that agriculture developed (keep inmind that the earth and the solar system originated 4,600 million years ago). Humans havespent most of their history as hunters and food-gatherers. Only in the past 9,000 to 10,000years have humans discovered how to raise crops and tame animals. Such changes prob-ably occurred first in the hills to the north of present-day Iraq and Syria. The remains ofthe prehistoric irrigation works in Mesopotamia and Egypt still exist. Table 1.1 presents achronology of knowledge about water.

Figure 1.2 illustrates the chronology and locations of various civilizations rangingfrom India to Western Europe. This figure, from O. Neugebaurs book titled The ExactSciences in Antiquity, illustrates the Hellenistic period the era of ancient science,during which a form of science developed that spread later from Europe to India. This ancient science was dominant until the creation of modern science dominant inIsaac Newtons time.

CHAPTER 1INTRODUCTION

1.1

Larry W. MaysDepartment of Civil and Environmental Engineering

Arizona State University Tempe, Arizona

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Source: HYDRAULIC DESIGN HANDBOOK

1.2 Chapter One

FIGURE 1.1 A selected list of books on hydraulics published between 1900 to 1980.

Abbotts Computational Hydraulics (1980)

Fischer et al., Mixing in Inland andCoastal Waters (1979)

Grafs Hydraulics of Sediment Transport(1971)

Streeter and Wylies Hydraulic Transients(1967) U.S. Geological Surveys Roughness

Characteristics of Natural Channels (1967)Hendersons Open-Channel Flow (1966)

Daily and Harlemans Fluid Dynamics(1966)

Linsley and Franzinis Elements ofHydraulic Engineering (1964)

Leliavskys River and Canal Hydraulics(1965)

Morris and Wiggerts Applied Hydraulicsin Engineering (1963)

USBR Design of Small Dams (1960) 1960

1950

Chows Open-Channel Hydraulics (1959)U.S. Bureau of Reclamations HydraulicDesign of Stilling Basin and EnergyDissipators (1958)Stokers Water Waves (1957)Parmakiams Waterhammer Analysis(1955)

Leliavskys An Introduction to FluvialHydraulics (1955)Addisons Treastise on AppliedHydraulics (1954)Kings Handbook of Hydraulics (1954)

U.S. Bureau of Reclamations HydraulicLaboratory Practice (1953)Richs Hydraulic Transients (1951)Rouses Engineering Hydraulics (1950)

Freeze and Cherrys Groundwater (1979)

1970

1980



INTRODUCTION

Introduction 1.3

FIGURE 1.1 (Continued)

Allens Scale Models in HydraulicEngineering (1947)

Woodward and Poseys Hydraulics ofSteady Flow in Open Channels (1941)

ASCEs Hydraulic Models (1942) Davis and Sorersens Handbook ofApplied Hydraulics (1942)

Rouses Fluid Mechanics for HydraulicEngineers (1938)

Daughertys Hydraulics (1937)Muskats The Flow of HomogeneousFluids Through Porous Media (1937) Bakhmeteffs The Mechanics of Turbulent

Flow (1936)

1930

Bakhmeteffs Hydraulics of OpenChannels (1932)

Schoder and Dawsons Hydraulics (1927)

Le Contes Hydraulics (1926)

Hoyt and Grovers River Discharge(1916)

Hoskinss A TextBook on Hydraulics(1911)

1910

1900

Merrimans Treatise on Hydraulics (1904)

1940

1920

1950



INTRODUCTION

1.2.2 Irrigation Systems

1.2.2.1 Egypt and Mesopotamia. In ancient Egypt, the construction of canals was a majorendeavor of the Pharaohs beginning in Scorpios time. Among the first duties of provincialgovernors was the digging and repair of canals, which were used to flood large tracts of landwhile the Nile was flowing high. The land was checkerboarded with small basins defined bya system of dikes. Problems associated with the uncertainty of the Niles flows were recog-nized. During high flows, the dikes were washed away and villages were flooded, drowningthousands of people. During low flows, the land was dry and no crops could grow. In areaswhere fields were too high to receive water directly from the canals, water was drawn fromthe canals or from the Nile by a swape or shaduf (Fig. 1.3), which consisted of a bucket onthe end of a cord hung from the long end of a pivoted boom that was counterweighted at theshort end (de Camp, 1963). Canals continued to be built in Egypt throughout the centuries.

The Sumerians in southern Mesopotamia built city walls and temples and dug canalsthat were the worlds first engineering works. It also is of interest that these people, foughtover water rights from the beginning of recorded history. Irrigation was vital toMesopotamia, Greek for the land between the (Tigris and Euphrates) rivers. An ancientBabylonian curse was, May your canal be filled with sand (de Camp, 1963), and eventheir ancient laws dealt with canals and water rights. The following quotation fromapproximately the sixth century B.C., illustrates such a law (de Camp, 1963):

The gentleman who opened his wall for irrigation purposes, but did not makehis dyke strong and hence caused a flood and inundated a field adjoining his,shall give grain to the owner of the field on the basis of those adjoining.

Because the Tigris and Euphrates carried several times more silt per unit volume of waterthan the Nile did, flooding problems were more serious in Mesopotamia than in Egypt. Asa result the rivers in Mesopotamia rose faster and changed course more often.

1.4 Chapter One

TABLE 1.1 Chronology of Knowledge About Water

Prehistorical period Springs3rd 2nd millennium B.C. Cisterns3rd millennium B.C. Dams3 millennium B.C. WellsProbably very early Reuse of excrement as fertilizer2nd millennium B.C. Gravity flow supply pipes or channels and drains, pressure

pipes (subsequently forgotten)8th-6th c. B.C. Long-distance water supply lines with tunnels and bridges,

as well as intervention in and harnessing of karst water systems

6th c. B.C. at the latest Public as well as private bathing facilities, consisting of:bathtubs or showers, footbaths, washbasins, latrines or toilets, laundry and dishwashing facilities

6th c. B.C. at the latest Use of definitely two and probably three qualities of water:potable, subpotable, and nonpotable, including irrigationusing storm runoff, probably combined with waste waters

6th-3rd c. B.C. Pressure pipes and siphon systems

*Indicates an element discovered, probably forgotten, and rediscovered later.Indicates an educated guess.Source: Crouch, 1993.



INTRODUCTION

Introduction 1.5

FIGURE 1.2 Chronology and location of different civilizations ranging from India to Western Europe.(Neugebauer, 1993)

The irrigation systems in both Mesopotamia and the Egyptian Delta were of the basintype, opened by digging a gap in the embankment and closed by placing mud back intothe gap. (See Fig. 1.4 for a comparison of the irrigation works in Upper Egypt and inMesopotamia.) Water was hoisted using the swape, Mesopotamian laws required farmersto keep their basins and feeder canals in repair; they also required everyone else to wieldhoes and shovels when the rivers flooded or when new canals were required or old onesneeded repair (de Camp, 1963). Some canals may have been used for 1,000 years before



INTRODUCTION

1.6 Chapter One

FIGURE 1.3 Shadufs of the Amarna period, from the tomb of Nefer-Hotep at Thebes.Note irrigation of date palms and other orchard trees and the apparent tank or pool (lowerright). The water pattern in the lowest margin suggests lifting out of an irrigation canal.(Davies, 1933, pls. 46 and 47). Figure as presented in Butzer (1976).

they were abandoned and others were built. Even today, 4,000 to 5,000 years later, theembankments of the abandoned canals remain. In fact, these canal systems supported alarger population than lives there today. Over the centuries, Mesopotamian agriculturebegan to decline because of the salty alluvial soil. In 1258, the Mongols conqueredMesopotamia and destroyed its irrigation systems.



INTRODUCTION

Introduction 1.7

FIGURE 1.4 Comparative irrigation networks in Upper Egypt and Mesopotamia. A. Example of linear,basin irrigation in Sohag province, ca. AD 1850. B. Example of radial canalization system in the lowerNasharawan region southeast of Baghdad, Abbasid (A.D. 8831150). Modified from R. M. Adams (1965,(Fig. 9) Same scale as Egyptian counterpart) C. Detail of field canal layout in B. (Simplified from R. M.Adams, 1965, Fig. 10). Figure as presented in Butzer (1976).

The Assyrians also developed extensive pubic works. When Sargon II invaded Armeniain 714 B.C., he discovered the gant (Arabic) or kariz (Persian), a system of tunnels usedto bring water from an underground source in the hills down to the foothills (Fig. 1.5).Sargon destroyed the system in Armenia but brought the concept back to Assyria. Over thecenturies, this method of irrigation spread across the Near East into North Africa and is



INTRODUCTION

still used. Sargons son Sennacherib also developed waterworks by damming the TebituRiver and using a canal to bring water to Nineveh, where the water could be used for irri-gation without the need for hoisting devices. During high water in the spring, overflowswere handled by a municipal canebrake that was built to develop marshes used as gamepreserves for deer, wild boar, and birds. When this system was outgrown, a new canal 30mi long was built, with an aqueduct that had a layer of concrete or mortar under the upperlayer of stone to prevent leakage.

1.2.2.2 Prehistoric Mexico. During the earliest years of canal irrigation in Mexico,the technology changed little (Fig. 1.6) and the method of flooding tended to be hap-hazard. The technological achievements were relatively primitive until about 600 or500 B.C., and few of the early systems remain. Whereas the earlier systems were con-structed of loosely piled rocks, the later ones consisted of storage dams constructed ofblocks that were mortared together. Some spillways were improved, and floodgateswere used in some spillways. (Some dams could be classified as arch dams.) Thecanals were modified to an extent during this time: Different cross-sectional areas were

1.8 Chapter One

FIGURE 1.5 Details of the gant system. (Biswas, 1970).



INTRODUCTION

Introduction 1.9

FIGURE 1.6 Regional chronology and dates of developments in various aspects of canal irrigationtechnology in Mexico. (Doolittle, 1990)

used, some were lined with stone slabs, and the water for irrigation of crops was morecarefully controlled.

Between 550 and 200 B.C., the irrigation-related features and the entire canal systemswere significantly improved. The channelization of stream beds, the excavation of canals,and the construction of dams were probably the most significant improvements. However,the technology stopped improving after 200 B.C., and no significant developmentsoccurred for approximately 500 years. Around 300 A.D., a few new improvements wereinitiated, but the technology remained essentially the same through the classic period(A.D., 200 800/1000) and early postclassical period (A.D. 800/10001300). Figure 1.7 isa map of fossilized canals in the Tehuacan Valley in Mexico.



INTRODUCTION

1.2.2.3 North America. The canal irrigation systems in the Hohokam and Chacoregions stand out as two major prehistoric developments in the American Southwest(Crown and Judge, 1991). The two systems expanded over broad geographic areas of sim-ilar size (the Hohokam in Arizona and the Chacoans in New Mexico). Although they weredeveloped at similar times, they apparently functioned independently. Because the twosystems evolved in different environments, their infrastructures also differed considerably.

The Hohokam Indians inhabited the lower Salt and Gila River valleys near Phoenix,Arizona. Although the Indians of Arizona began limited farming nearly 3000 years ago,construction of the Hohokam irrigation systems probably did not begin until the first fewcenturies A.D. Who originated the idea of irrigation in Arizona, whether the technologywas developed locally or it was introduced from Mexico, is unknown. Figure 1.8 illus-trates the extensive system in the Phoenix area, and Fig. 1.9 provides a schematic of thedetails of its major components.

In approximately 1450 A.D., the Hohokam culture declined, possibly for a combinationof reasons: flooding in the 1080s, hydrologic degradation in the early 1100s, and therecruitment of laborers by surrounding populations. The major flood in 1358 ultimatelydestroyed the canal networks, resulting in movement of the people. Among the PimaIndians, who were the successors of the Hohokam Indians, use of canals was either limited or absent. Although the prehistoric people who lived outside the area of Hohokam

1.10 Chapter One

FIGURE 1.7 Map of fossilized canals on the Llano de la Taza in the Tehuacan Valley.(Woodbury and Neely, 1972, as presented in Doolittle, 1990)



INTRODUCTION

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1.11

INTRODUCTION



1.12 Chapter One

FIGURE 1.9 Schematic representation of the major components of a Hohokam irrigation system in the Phoenix Basin. (Masse, 1991)

culture also constructed irrigation systems, none approached the grand scale of theHohokam systems.

In the ninth century, the Anasazi people of northwestern New Mexico developed acultural phenomenon, the remains of which currently consist of more than 2400archaeological sites and nine towns, each containing hundreds of rooms, along a 9-mistretch. The Chacoan irrigation system is situated in the San Juan Basin in northwest-ern New Mexico. The basin has limited surface water, most of it discharge fromephemeral washes and arroyos. Figure 1.10 illustrates the method of collecting anddiverting runoff throughout Chaco Canyon. The water collected from the side canyonthat drained from the top of the upper mesa was diverted into a canal by either an earth-en or a masonry dam near the mouth of the side canyon (Vivian, 1990). These canalsaveraged 4.5 m in width and 1.4 m in depth; some were lined with stone slabs and oth-ers were bordered by masonry walls. The canals ended at a masonry head gate, wherewater was then diverted to the fields in small ditches or to overflow ponds and smallreservoirs.



INTRODUCTION

Introduction 1.13

1.2.3 Dams

The Sadd-el-Kafara dam in Egypt, situated on the eastern bank of the Nile near Heluanapproximately 30 km south of Cairo, in the Wadi Garawi, has been referred to as the worldsoldest large dam (Garbrecht, 1985). The explorer and geographer George Schweinfurthrediscovered this dam in 1885, and it has been described in a number of publications sincethat time (see Garbrecht, 1985). It was built between 2950 and 2690 B.C. Although the Jassdrinking-water reservoir in Jordon and the diversion dams on the Kasakh River in Russia areprobably older, they are much smaller than the Sadd-el-Kafara (Dam of the Pagans).

It is unlikely that the Sadd-el-Kafara dam was built to supply water for drinking or irri-gation because the dam lies too far from the alabaster quarries situated upstream to havesupplied the labor force with drinking water. Furthermore, there is a vast supply of waterand fertile land in the nearby Nile valley. The apparent purpose of the dam was to protectinstallations in the lower wadi and the Nile valley from frequent, sudden floods. The damwas destroyed during construction by a flood; consequently, it was never completed. Todate, the dams abutments still exist.

FIGURE 1.10 Hypothetical reconstruction of the Rincon4 North watercontrol system in Chaco Canyon. Similar systems were located at themouths of all northern side conyons in the lower 15 m of Chaco Canyon.(Adapted by Ron Beckwith from Vivian, 1974, Fig. 9.4)



INTRODUCTION

The dam had an impervious core consisting of rubble, gravel, and weathered materi-al. On both the upstream and downstream sides, the core was bordered by sections ofrockfill that supported and protected the core. The diameter of the stones ranged from 0.1to 0.6 m. One remarkable construction feature is the facing of the section of rockfillwhere parts of the facing on the upstream side are still well preserved. The dam had anapproximate crest length of 348 ft and a base length of 265 ft and was built straightacross the wadi at a suitably narrow point, with a maximum height of 32 ft above the valley bed. See Smith (1971) and Upton (1975) for more on dams.

Dam building in the Americas began in the pre-Colombian period in the civilizationsof Central and South America: the Aztecs in Mexico, the Mayans in Guatemala andYucatan, and the Incas in Peru. Where as old-world civilizations developed in the valleysof the big rivers, the Nile River, the Euphrates and the Tigris Rivers, the Indus River, andthe Yellow River, most of the early civilizations in the New World were not river civiliza-tions. In South America, the civilizations appeared in the semiarid highlands and the aridcoastal valleys traversed by small rivers. In Central America, the Mayans, the Aztecs, andthe predecessors of the Aztecs were not river civilizations.

The Mayans did not practice irrigation; however, they did provide efficient water supplies to several of their large cities. They developed the artificial well (cenote), the under-ground cistern (chultun), and the large open reservoir (aguado). The Mayans failure todevelop irrigation may have accelerated their decline. In the Yucatan, the aguados are stillfound in some places, but the cenote was the major source of water for drinking and bathing.

1.2.4 Urban Water Supply and Drainage Systems

Knossos, approximately 5 km from Herakleion, the modern capital of Crete, was amongthe most ancient and unique cities of the Aegean and Europe. The city was first inhabitedshortly after 6000 B.C. and, within 3000 years, it had became the largest NeolithicSettlement in the Aegean (Neolithic age, circa 57002800 B.C). During the Bronze age(circa 28001100 B.C.), the Minoan civilization developed and reached its culmination asthe first Greek cultural miracle of the Aegean world.

The Minoan civilization has been subdivided into four periods: the prepalatial period(28001900 B.C.), the protopalatial period (19001200 B.C.), the neopalatial period(17001400 B.C.), and the postpalatial period (14001100 B.C.). During the prepalatialperiod, a settlement at Knossos; was leveled to erect a palace. Little is known about theold palace because it was destroyed in approximately 1700 B.C. A new palace was con-structed on leveled fill from the old palace. During the neopalatial period, Knossos was atthe height of its splendor. The city covered an area of 75,000 to 125,000 m2 and had a pop-ulation estimated to be on the order of tens of thousands.

The irrigation and drainage systems at Knossos were most interesting. An aqueductsupplied water through tubular conduits from the Kounavoi and Archanes regions andbranched out into the city and the palace. Figure 1.11 shows the type of pressure conduitsused within the palace for water distribution. The drainage system consisted of two sepa-rate conduits: one to collect the sewage and the other to collect rain water (Fig. 1.12).Unfortunately, the Mycenean palace was destroyed by an earthquake and fire in approxi-mately 1450 B.C., as were all the palatial cities of Crete.

Anatolia, also called Asia Minor, which is part of the Republic of Turkey, has been thecrossroads of many civilizations during the past 10,000 years. During the last 4000 years,going back to the Hittite period (2000200 B.C.) many remains of ancient urban water-supply systems have been found, including pipes, canals, tunnels, inverted siphons, aque-ducts, reservoirs, cisterns, and dams. (see Ozis, 1987 and Ozis and Harmancioglu, 1979).

1.14 Chapter One



INTRODUCTION

Introduction 1.15

FIGURE 1.11 Water distribution pipe in Knossos, Crete. (Photograph by L.W. Mays)

FIGURE 1.12 Urban drainage system in Knossos, Crete. (Photograph by L.W. Mays)



INTRODUCTION

An example of one such city is Ephesus, which was founded during the 10th centuryB.C. as an Ionian city out of the Temple of Artemis. In the sixth century B.C., the city set-tled near the temple, and subsequently was reestablished at its present site, where it devel-oped further during the Roman period. Water was supplied to Ephesus from springs at dif-ferent sites. Cisterns also supplied well water to the city. Water for the great fountain, builtbetween 4 and 14 A.D., was diverted by a small dam at Marnss and was conveyed to thecity by a system 6 km long consisting of one large and two small clay pipe lines. Figure1.13 shows the type of clay pipes used at Ephesus to distribute water.

1.16 Chapter One

FIGURE 1.13 Water distribution pipe in Ephesus, Turkey. (Photograph by L. W. Mays)



INTRODUCTION

The latrine, or public toilet shown in Fig. 1.14, was built in the first century A.D. atEphesus. The toilets were placed side by side with no partitions. In the middle was asquare pond, and the floors were paved with mosaics.

The Great Theatre at Ephesus, the citys largest and most impressive building, had aseating capacity for 24,000 people. Built in the Hellenistic period, the theatre was not onlya monumental masterpiece but during the early days of Christianity, one major con-frontation between Artemis and Christ took place there. Of notable interest from a water-resources viewpoint is the theatres intricate drainage system. Figure 1.15 shows adrainage channel in the floor of the theatre.

Public baths also were a unique feature in ancient cities: for example, the Skolacticabaths in Ephesus had a salon and central heating; a hot bath (caldarium), a warm bath(tepidarium), and a cold bath (frigidarium); and a dressing room (apodyterium). In thesecond century A.D., the first building had three floors. In the fourth century, a womannamed Skolacticia modified the baths, making them accessible to hundreds of people.There were public rooms and private rooms, and people who wished to could stay formany days. Hot water was provided by a furnace and a large boiler.

Perge is another ancient city in Anatolia that had a unique urban water infrastructure.The photographs in Fig. 1.16 illustrate the Majestic Fountain (nymphaion), which con-sisted of a wide basin and a richly decorated architectural facade. Because of its architec-ture and statues, the fountain was one of Perges most magnificent edifices. A water chan-nel ran along the middle, dividing each street and bringing life and coolness to the city.The baths of Perge were magnificent. The first photograph in Fig. 1.17 shows one of thebaths of Perge; the second photograph illustrates the storage of water under the floor tokeep the water warm. Like the baths in other ancient cities in Anatolia, the baths of Pergehad a caldarium, a tepidarium, and a frigidarium.

Introduction 1.17

FIGURE 1.14 A latrine, or public toilet, built at Ephesus, Turkey, in the first century B.C.(Photograph by L. W. Mays)



INTRODUCTION

The early Romans devoted much of their time to useful public works projects, includ-ing roads, harbor works, aqueducts, temples, forums, town halls, arenas, baths, and sew-ers. The prosperous early Roman bourgeois typically had a 12room house, with a squarehole in the roof to let rain in and a cistern beneath the roof to store the water. Althoughthe Romans built many aqueducts, they were not the first to do so. King Sennacherio builtaqueducts, as did the Phoenicians and the Helenes. The Romans and Helenes neededextensive aqueduct systems for their fountains, baths, and gardens. They also realized that

1.18 Chapter One

FIGURE 1.15 A drainage channel on the floor of the Great Theater at Ephesus,Turkey. (Photograph by L. W. Mays)



INTRODUCTION

Introduction 1.19

FIGURE 1.16 Two views of the Majestic Fountain (nymphaion) in Perge, Anatolia, Turkey.(Photographs by L. W. Mays)

water transported from springs was better for their health than river water and that springwater did not need to be lifted to street level as did river water. Roman aqueducts werebuilt on elevated structures to provide the needed slope for water flow. Knowledge of pipe



INTRODUCTION

1.20 Chapter One

FIGURE 1.17A View of the baths at Perge, Anatolia, Turkey. (Photographs by L.W. Mays)

makingusing bronze, lead, wood, tile, and concretewas in its infancy, and the difficultyof making strong large pipes was a hinderance. Most Roman piping was made of lead, andeven the Romans recognized that water transported by lead pipes was a health hazard.

The source of water for a typical Roman water supply system was a spring or a dugwell, which usually was equipped with a bucket elevator to raise the water. If the well



INTRODUCTION

water was clear and of sufficient quantity, it was conveyed to the city by aqueduct. Also,water from several sources was collected in a reservoir, then conveyed by an aqueduct ora pressure conduit to a distributing reservoir (castellum). Three pipes conveyed the water:one to pools and fountains, one to the public baths for public revenue, and one to privatehouses for revenue to maintain the aqueducts (Rouse and Ince, 1957). Figures 1.18 and1.19 illustrate the layout of the major aqueducts of ancient Rome. Figure 1.20 shows theRoman aqueduct in Segovia, Spain, which is probably among the most interesting ofRoman remains in the world. This aqueduct, built during the second half of the first cen-tury A.D. or the early years of the second century, has a maximum height of 78.9 m. SeeVan Deman (1934) for more details on Roman aqueducts.

Irrigation was not a major concern because of the terrain and the intermittent rivers.However, the Romans did, drain marshes to obtain more farmland and to eliminate the badair, or harmful spirits, rising from the marshes because they believed it caused disease(de Camp, 1963). The disease-carrying mechanism was not the air, (or spirits) but themalaria-carrying mosquito. Empedocles, the leading statesman of Acragas in Sicily dur-ing the Persian War in the fifth century B.C., drained the local marshes of Selinus toimprove the peoples health (de Camp, 1963).

The fall of the Roman Empire extended over a 1000-year period of transition calledthe Dark Ages during which the concepts of science related to water resources probablyretrogressed. After the fall of the Roman Empire, clean water, sanitation, and public healthdeclined in Europe. Historical accounts tell of incredibly unsanitary conditions: pollutedwater, human and animal wastes in the streets, and water thrown out of windows ontopassersby. As a result, various epidemics ravaged Europe. During the same period, theIslamic cultures on the periphery of Europe religiously mandated high levels of personalhygiene, highly developed water supplies, and adequate sanitation systems. For furthenreading see Needham (1959) Payne (1959), Reynolds (1970) Robbins (1946), Sarton(1952-59) and Wittfogel (1956).

Introduction 1.21

FIGURE 1.17B View of the baths at Perge, Anatolia, Turkey. (Photographs by L.W. Mays)



INTRODUCTION

1.22 Chapter One

FIGURE 1.19 The area of Spes Vetus showing the courses of the major aqueducts entering thecity above ground. (From R. Lanciani, Forma Urbis Romae), as presented in Evans (1993).

FIGURE 1.18 Termini of the major aqueducts in ancient Rome. (Evans, 1993)



INTRODUCTION

1.3 DEVELOPMENT OF HYDRAULICS

The historical development of hydraulics as a modern science has been described byBiswas (1970), Rouse (1976), and Rouse and Ince (1963). More recently, the book titled,The Science of Water (Levi, 1995) presents an excellent history of the foundation of modern hydraulics. The reader is referred to these excellent books for details on the devel-opment of hydraulics.

1.4 FEDERAL POLICIES AFFECTING HYDRAULIC DESIGN

Federal legislation contains policies that can affect the design of various types ofhydraulic structures. These policies are listed in Appendix 1.A, where they are categorizedinto the following sections: environment, health, historic and archeological preservation,and land and water usage. The appendix also lists the abbreviations used in the policies,(adapted from AASHTO, 1991).

1.5 CONVENTIONAL HYDRAULIC DESIGN PROCESS

Conventional procedures for hydraulic design are basically iterative trial-and-error proce-dures. The effectiveness of conventional procedures depends on an engineers intuition,experience, skill, and knowledge of hydraulic systems. Therefore, conventional proceduresare closely related to the human element, a factor that could lead to inefficient results for thedesign and analysis of complex systems. Conventional procedures are typically based on

Introduction 1.23

FIGURE 1.20 Roman aqueduct in Segovia, Spain. (Photograph by L.W. Mays)



INTRODUCTION

using simulation models in a process of trial and error to arrive at an optimal solution. Figure1.21 presents a depiction of the conventional procedure for design and analysis. For exam-ple, determining a least-cost pumping scheme for an aquifer dewatering problem wouldrequire one to select the required pump sizes and the site where the aquifer would be dewa-tered. Using a trial set of pump sizes and sites, a groundwater simulation model is solved todetermine whether the water levels are lower than desired. If the pumping scheme (pumpsize and site) does not satisfy the water levels, then a new pumping scheme is selected andsimulated. This iterative process is continued, each time to determine the cost of the scheme.

Optimization eliminates the trial-and-error process of changing a design and resimu-lating it with each new change. Instead, an optimization model automatically changes thedesign parameters. An optimization procedure has mathematical expressions that describe

1.24 Chapter One

Data collection to describe system

Estimate initial design of system

Analyze system design using simulation

Check results of simulation to check performance

Compute cost or benefits

Change designIs design

satisfactory?

Are costs orbenefits ok?

Yes

Yes

No

No

Stop

FIGURE 1.21 Conventional procedure for hydraulic design and analysis. (Mays and Tung, 1992)



INTRODUCTION

the system and its response to the system inputs for various design parameters. Thesemathematical expressions are constraints in the optimization model. In addition, con-straints are used to define the limits of the design variables, and the performance of thedesign is evaluated through an objective function, which could be used to minimize costs.

An advantage of the conventional process is that engineers use their experience and intuition to make conceptual changes in the system or to change or add specifications. Theconventional procedure can lead to nonoptimal or uneconomical designs and operation poli-cies. Also, the conventional procedure can be extremely time consuming. An optimizationprocedure requires the engineer to identify the design variables explicitly, the objective func-tion of the measure of performance to be optimized, and the constraints for the system. Incontrast to the decision-making process in the conventional procedure, the optimization pro-cedure is more organized because a mathematical approach is used to make decisions. Referto Mays and Tung (1992) for more detail.

1.6 ROLE OF ECONOMICS IN HYDRAULIC DESIGN

1.6.1 Engineering Economic Analysis

Engineering economic analysis is an evaluation process that can be used to compare alter-native hydraulic designs and then apply a discounting technique to select the best alterna-tive. To perform this analysis, the engineer must understand several basic concepts, suchas equivalence of kind, equivalence of time, and discounting factors.

One first step in economic analysis is to find a common unit of value, such as mone-tary units. Through the use of common value units, alternatives of rather diverse kinds canbe evaluated. The monetary evaluation of alternatives generally occurs over a number ofyears. Each monetary value must be identified by amount and time. Because the timevalue of money results from the willingness of people to pay interest for the use of money,money at different times cannot be directly combined or compared; first, it must be madeequivalent through the use of discount factors, which convert a monetary value at one dateto an equivalent value at another date.

Discount factors are described using the following notations: i is the annual interestrate, n is the number of years, P is the present amount of money, F is the future amountof money, and A is the annual amount of money. Consider an amount of money P that isto be invested for n years at an interest rate of i percent. The future sum F at the end of nyears is determined from the following progression:

Amount at beginning Plus Amount at Period of year interest end of year

Year 1 P iP (1+i)PYear 2 (1+i)P iP(1+i) (1+i)2PYear 3 (1+i)2P iP(1+i)2 (1+i)3P

Year n (1+i)n1P iP(1+i)n1 (1+i)nP

The future sum is then

F P(1 i)n (1.1)and the single-payment compound amount factor is

Introduction 1.25



INTRODUCTION

FP (1 i)

n FP, i%, n

(1.2)

This factor defines the number of dollars that accumulate after n years for each dollarinitially invested at an interest rate of i percent. The single-payment present worth factor(P/F, i%, n) is simply the reciprocal of the single-payment compound amount factor.Table 1.2 summarizes the various discount factors.

Uniform annual series factors are used for equivalence between present (P) and annu-al (A) monetary amounts or between future (F) and annual (A) monetary amounts.Consider the amount of money A that must be invested annually (at the end of each year)to accumulate F at the end of n years. Because the last value of A in the nth year is with-drawn immediately on deposit, it accumulates no interest. The future value F is

F A (1 i)A (1 i)2 A (1 i)n1 A (1.3)

1.26 Chapter One

TABLE 1.2 Summary of Discounting Factors

Type of Discount Factor Symbol Given* Find FactorSingle-payment factors:

Compound-amount factorFP, i%, n

P F (1 i)n

Present-worth factorPF, i%, n

F P (1 1

i)n

Uniform annual series factors:

Sinking-fund factorAF, i%, n

F A (1 ii)n 1

Capital-recovery factorAP, i%, n

P A (1i(

1 i)n

i

)n1

Series compound-amount AF

, i%, n A F

(1 ii)n 1

factor

Series present-worth factorPA, i%, n

A P (1

i

(1i

)ni

)n1

Uniform gradient seriesfactors:

Uniform gradient seriesG

P,i%,n

G Ppresent-worth factor*The discount factors represent the amount of dollars for the given amounts of $1 for for P, F, A and G.Source: Mays and Tung, 1992.

(1 i)n 1 (1 ni i)i2(1 i)n

A A A A A

A A A A A

A A A A A

A A A A A

G 2G 3G (n-1)G

P G = $1

P A = $1

P F = $1

P = $1

F = $1

A = $1 F

P = $1 F



INTRODUCTION

Multiply Eq. (1.3) by (1 i); then subtract Eq. (1.3) from the result to obtain the uni-form annual series sinkingfund factor:

AF (1 i

i)n 1

AF, i%, n

(1.4)The sinking-fund factor is the number of dollars A that must be invested at the end of

each of n years at i percent interest to accumulate $1. The series compound amount fac-tor (F/A) is simply the reciprocal of the sinking-fund factor (Table 1.3), which is the num-ber of accumulated dollars if $1 is invested at the end of each year. The capital-recoveryfactor can be determined by simply multiplying the sinking fund factor (A/F) by the sin-gle-payment compound-amount factor (Table 1.2):

AP, i%, n

AF

FP (1.5)

This factor is the number of dollars that can be withdrawn at the end of each of n yearsif $1 is invested initially. The reciprocal of the capital-recovery factor is the series present-worth factor (P/A), which is the number of dollars initially invested to withdraw $1 at theend of each year.

A uniform gradient series factor is the number of dollars initially invested to withdraw$1 at the end of the first year, $2 at the end of the second year, $3 at the end of the thirdyear, and so on.

1.6.2 Benefit-Cost Analysis

Water projects extend over time, incur costs throughout the duration of the project, andyield benefits. Typically, the costs are large during the initial start-up period of construc-tion, followed by operation and maintenance costs only. Benefits typically build up to amaximum over time, as depicted in Fig. 1.22. The present values of benefits (PVB) andcosts (PVC) are as follows:

PVB b0 (1b

1

i) (1 b2

i)2 (1 bn

i)n (1.6)and

PVC c0 (1c

1

i) (1 c2

i)2 (1 cn

i)n (1.7)

Introduction 1.27

Benefits (B)and

Costs (C)

B

C

Time

FIGURE 1.22 Illustration of how benefits (B) and costs (C) build up over time. (Mays andTung, 1992)



INTRODUCTION

The present value of net benefits is

PVNB PVB PVC (b0 c0) (b(1

1

c

i)1)

((b12

ic

)22

)

((b1n

ic

)n

n

) (1.8)

To carry out benefit-cost analyses, rules for economic optimization of the projectdesign and procedures for ranking projects are needed. The most important point in plan-ning a project is to consider the broadest range of alternatives. The range of alternativesselected is typically restricted by the responsibility of the water resource agency, the plan-ners, or both. The nature of the problem to be solved also may condition the range of alter-natives. Preliminary investigation of alternatives can help to rule out projects because oftheir technical unfeasibility or costs.

Consider the selection of an optimal, single-purpose project design, such as the con-struction of a flood-control system or a water supply project. The optimum size can bedetermined by selecting the alternative so that the marginal or incremental current valueof costs, PVC, is equal to the marginal or incremental current value of the benefits,PVB, (PVB PVC.)

The marginal or incremental value of benefits and costs are for a given increase in thesize of a project:

PVB (1

b1i) (1

b2i)2 (1

bni)n (1.9)

and

PVC (1

c1i) (1

c2i)2 (1

cni)n (1.10)

When selecting a set of projects, one rule for optimal selection is to maximize the cur-rent value of net benefits. Another ranking criterion is to use the benefit-cost ratio (B/C),PVB/PVC:

CB

= PP

VV

CB

(1.11)This method has the option of subtracting recurrent costs from the annual benefits or

including all costs in the present value of cost. Each option will result in a different B/C,ratio, with higher B/C ratios when netting out annual costs, if the ratio is greater than one.The B/C ratio is often used to screen unfeasible alternatives with B/C ratios less than 1from further consideration.

Selection of the optimum alternative is based on the incremental benefit-cost ratios,B/C, whereas the B/C ratio is used for ranking alternatives. The incremental benefit-cost ratio is

CB (1.12)

where PVB(Aj) is the present value of benefits for alternative Aj. Figure 1.23 is a flowchartillustrating the benefit-cost method.

1.6.3 Estimated Life Spans of Hydraulic Structures

The Internal Revenue Service bulletin gives estimated average lives for many thousandsof different types of industrial assets. The lives (in years) given for certain elements ofhydraulic projects are listed in Table 1.3. Although such estimates of average lives may behelpful, they are not necessarily the most appropriate figures to use in any given instance.

PVBAj PVB

Ak

PVC Aj

PVCAk

1.28 Chapter One



INTRODUCTION

Introduction 1.29

Compute B/C Ratio of EachAlternative

Keep Alternatives With B/C > 1

Rank Alternatives in Order ofIncreasing Cost

Compare Two Least-CostlyAlternatives

Compute Incremental B/C RatioB/C

Select NextAlternative to

Compare

Select NextAlternative to

Compare

Choose Less Costly Alternative Choose More Costly Alternative

BC > 1

YesNo

FIGURE 1.23 Flowchart for a benefit-cost analysis. (Mays and Tung, 1992)

TABLE 1.3 Lives (in years) for Elements of Hydraulic ProjectsBarges 12 Penstocks 50Booms, log 15 Pipes:Canals and ditches 75 Cast ironCoagulating basins 50 2-4 in. 50Construction equipment 5 4-6 in. 65Dams: 8-10 in. 75

Crib 25 12 in. and over 100Earthen, concrete, or masonry 150 Concrete 20-30Loose rock 60 PVC 40Steel 40 Steel

Filters 50 Under 4 in. 30Flumes: Over 4 in. 40

Concrete or masonry 75 Wood staveSteel 50 14 in. and larger 33



INTRODUCTION

1.7 ROLE OF OPTIMIZATION IN HYDRAULIC DESIGN

An optimization problem in water resources can be formulated in a general framework interms of the decision variables (x), with an objective function to optimize

f(x) (1.13)subject to constraints

g(x) 0 (1.14)and bound constraints on the decision variables

x

x x (1.15)where x is a vector of n decision variables (x1, x2, , xn), g(x) is a vector of m equationscalled constraints, and x

and x represent the lower and upper bounds, respectively, on the

decision variables.Every optimization problem has two essential parts: the objective function and the set

of constraints. The objective function describes the performance criteria of the system.Constraints describe the system or process that is being designed or analyzed and can bein two forms: equality constraints and inequality constraints. A feasible solution of theoptimization problem is a set of values of the decision variables that simultaneously sat-isfies the constraints. The feasible region is the region of feasible solutions defined by theconstraints. An optimal solution is a set of values of the decision variables that satisfiesthe constraints and provides an optimal value of the objective function.

Depending on the nature of the objective function and the constraints, an optimizationproblem can be classified as (1) linear vs. nonlinear, (2) deterministic vs. probabilistic, (3)static vs. dynamic, (4) continuous vs. discrete, or (5) lumped parameter vs. distributedparameter.

Linear programming problems consist of a linear objective function, and all constraintsare linear, whereas nonlinear programming problems are represented by nonlinear equa-tions: that is, part or all of the constraints or the objective functions or both are nonlinear.

Deterministic problems consist of coefficients and parameters that can be assignedfixed values, whereas probabilistic problems consist of uncertain parameters that areregarded as random variables.

1.30 Chapter One

TABLE 1.3 (Continues)Wood 25 3-12 in. 20

Fossil-fuel power plants 28 Pumps 18-25Generators: Reservoirs 75

Above 3000 kva 28 Standpipes 501000-3000 kva 25 Tanks:50 hp-1000 kva 17-25 Concrete 50Below 50 hp 14-17 Steel 40

Hydrants 50 Wood 20Marine construction equipment 12 Tunnels 100Meters, water 30 Turbines, hydraulic 35Nuclear power plants 20 Wells 40-50*Alternating-current generators are rated in kilovolt-amperes (kva).Source: Linsley et al., 1992.



INTRODUCTION

Static problems do not explicitly consider the variable time aspect, whereas dynamicproblems do consider the variable time. Static problems are referred to as mathematicalprogramming problems, and dynamic problems are often referred to as optimal controlproblems, which involve difference or differential equations.

Continuous problems have variables that can take on continuous values, whereas withdiscrete problems, the variables must take on discrete values. Typically, discrete problemsare posed as integer programming problems in which the variables must be integer values.

Lumped problems consider the parameters and variables to be homogeneous through-out the system, whereas distributed problems must account for detailed variations in thebehavior of the system from one location to another.

The method of optimization used depends up the type of objective function, the typeof constraints, and the number of decision variables. Optimization is not covered in thishandbook, but it is discussed in detail in Mays and Tung (1992).

1.8 ROLE OF RISK ANALYSIS IN HYDRAULIC DESIGN

1.8.1 Existence of Uncertainties

Uncertainties and the consequent related risks in hydraulic design are unavoidable.Hydraulic structures are always subject to a probability of failure in achieving theirintended purposes. For example, a flood control project may not protect an area fromextreme floods. A water supply project may not deliver the amount of water demanded.This failure may be caused by failure of the delivery system or may be the result of thelack of supply. A water distribution system may not deliver water that meets quality stan-dards although the source of the water does. The rationale for selecting the design andoperation parameters and the design and operation standards are questioned continually.Procedures for the engineering design and operation of water resources do not involve anyrequired assessment and quantification of uncertainties and the resultant evaluation of arisk.

Risk is defined as the probability of failure, and failure is defined as an event that caus-es a system to fail to meet the desired objectives. Reliability is defined as the complementof risk: i.e., the probability of nonfailure. Failures can be grouped into either structuralfailures or performance failures. Water distribution systems are a good example. A struc-tural failure, such as broken pipe or a failed pump, can result in unmet demand. In addi-tion, an operational aspect of a water distribution system, such as the inability to meetdemands at required pressure heads, is a failure despite the lack of a structural failure inany component in the system. Uncertainty can be defined as the occurrence of events thatare beyond ones control. The uncertainty of a hydraulic structure is an indeterministiccharacteristic and is beyond rigid controls. In the design and operation of these systems,decisions must be made under various kinds of uncertainty.

The sources of uncertainties are multifold. First, the ideas of natural uncertainties,model structure uncertainties, model parameter uncertainties, data uncertainties, andoperational uncertainties will be discussed. Natural uncertainties are associated withthe random temporal and spatial fluctuations that are inherent in natural processes.Model structural uncertainties reflect the inability of a simulation model or design pro-cedure to represent the systems true physical behavior or process precisely. Modelparameter uncertainties reflect variability in the determination of the parameters to beused in the model or design. Data uncertainties include inaccuracies and errors in mea-surements, inadequacy of the data gauging network, and errors in data handling and

Introduction 1.31



INTRODUCTION

transcription. Operational uncertainties are associated with human factors, such as con-struction, manufacture, deterioration, and maintenance, that are not accounted for in themodeling or design procedure.

Uncertainties fall into four major categories: hydrologic uncertainty, hydraulic uncer-tainty, structural uncertainty, and economic uncertainty. Each category has various com-ponent uncertainties. Hydrologic uncertainty can be classified into three types: inherent,parameter, and model uncertainties. Various hydrologic events, such as streamflow orrainfall, are considered to be stochastic processes because of their observable natural,(inherent) randomness. Because perfect hydrologic information about these processes islacking, informational uncertainties about the processes exist. These uncertainties arereferred to as parameter uncertainties and model uncertainties. In many cases, modeluncertainties result from the lack of adequate data and knowledge necessary to select theappropriate probability model or from the use of an oversimplified model, such as therational method for the design of a storm sewer.

Hydraulic uncertainty concerns the design of hydraulic structures and the analysisof their performance. It arises mainly from three basic sources: the model, the con-struction and materials, and the operational conditions of flow. Model uncertaintyresults from the use of a simplified or an idealized hydraulic model to describe flowconditions, which in turn contributes to uncertainty when determining the design capac-ity of hydraulic structures. Because simplified relationships, such as Mannings equa-tion, are typically used to model complex flow processes that cannot be described ade-quately, resulting in model errors.

Structural uncertainty refers to failure caused by structural weakness. Physical failuresof hydraulic structures can be caused by saturation and instability of soil, failures causedby erosion or hydraulic soil, wave action, hydraulic overloading, structural collapse, mate-rial failure, and so forth. An example is the structural failure of a levee system either inthe levee or in the adjacent soil; the failure could be caused by saturation and instabilityof soil. A flood wave can cause increased saturation of the levee through slumping. Leveesalso can fail because of hydraulic soil failures and wave action.

Economic uncertainty can arise from uncertainties regarding construction costs,damage costs, projected revenue, operation and maintenance costs, inflation, projectlife, and other intangible cost and benefit items. Construction, damage, and operationor maintenance costs are all subject to uncertainties because of fluctuations in the rateat which construction materials, labor costs, transportation costs, and economic loss-es, increase and the rate at which costs increase in different geographic regions. Manyother economic and social uncertainties are related to inconvenience losses: for exam-ple, the failure of a highway crossing caused by flooding, which results in traffic-related losses.

The objective when analyzing uncertainties is to incorporate the uncertainties system-atically into the evaluation of loading and resistance. The most commonly used method isthe first-order analysis of uncertainties. This method is used to determine the statistics ofthe random variables loading and resistance, which are typically defined through the useof deterministic models but have uncertain parameter inputs. Chapter 7 provides details ofthe first-order analysis of uncertainties.

1.8.2 Risk-Reliability Evaluation

1.8.2.1 Load resistance The load for a system can be defined as an external stress to thesystem, and the resistance can be defined as the capacity of the system to overcome the external load. Although the terms load and resistance have been used in structural

1.32 Chapter One



INTRODUCTION

engineering, they definitely have a place in the types of risk analysis that must be per-formed for engineering projects involving water resources.

If we use the variable R for resistance and the variable L for load, we can define a fail-ure as the event when the load exceeds the resistance and the consequent risk is the prob-ability that the loading will exceed the resistance, P(L R). A simple example of this typeof failure would be a dam that fails because of overtopping. The risk would be the proba-bility that the elevation of the water surface in a reservoir exceeds the elevation of the topof the dam. In this case, the resistance is the elevation of the top of the dam, and the load-ing is the maximum elevation of the water surface of a flood wave entering the reservoir.

Because many uncertain variables define both the resistance and loading, both areregarded as random variables. A simple example would be to use the rational equation Q CiA to define the design discharge (loading) for a storm sewer. The loading L Qis a function of three uncertain variables: the runoff coefficient C, the rainfall intensity i,and the drainage area A. Because the three variables cannot be determined with completecertainty, they are considered to be random variables. If the resistance is defined usingMannings equation, then the resistance is a function of Mannings roughness factor, thepipe diameter, and the slope (friction slope). The two main contributors to uncertainty inthis equation would be the friction slope and the roughness factor i.e., random variables.Thus, the resistance is also is a random variable because it is a function of the other tworandom variables.

It is interesting to note that in the example of the storm sewer, both the loading and theresistance are defined by deterministic equations: the rational equation and Manningsequation. Both equations are considered to have uncertain design parameters that result inuncertain resistance and loading. Consequently, they are considered to be random vari-ables. In the storm sewer example, as in many types of hydraulic structures, the loadinguncertainty is actually the hydrologic uncertainty and the resistance uncertainty is thehydraulic uncertainty.

1.8.2.2 Composite risk The discussion about the hydrologic and hydraulic uncertaintiesbeing the resistance and loading uncertainties leads to the idea of a composite risk. Theprobability of failure defined previously as the risk, P(L R), is actually a composite risk.If only the hydrologic uncertainty, in particular the inherent hydrologic uncertainty, wereconsidered, then this would not be a composite risk. In the conventional design processesof water resources engineering projects, only the inherent hydrologic uncertainties havebeen considered. Essentially, a large return period is selected and is artificially consideredas the safety factor without any regard to accounting systematically for the various uncer-tainties that actually exist.

1.8.2.3 Safety factor The safety factor is defined as the ratio of the resistance to load-ing, R/L. Because the safety factor SF R/L is the ratio of two random variables, it alsois a random variable. The risk can be written as P(SF 1) and the reliability can be writ-ten as P(SF 1). In the example of the storm sewer, both the resistance and the loadingare considered to be random variables because both are functions of random variables.Consequently, the safety factor for storm sewer design would also be a random variable.

1.8.2.4 Risk assessment Risk assessment requires several phases or steps, which canvary for different types of water resources engineering projects: (1) identify the risk ofhazard, (2) assess load and resistance, (3) perform an analysis of the uncertainties, (4)quantify the composite risk, and (5) develop the composite risk-safety factor relationships.1.8.2.5 A model for risk-based design The risk-based design of hydraulic structurespotentially promises to be the most significant application of uncertainty and risk analy-

Introduction 1.33



INTRODUCTION

sis. The risk-based design of hydraulic structures integrates the procedures of economics,uncertainty analysis, and risk analysis in design practice. Such procedures can considerthe tradeoffs among risk, economics, and other performance measures in the design ofhydraulic structures. When risk-based design is embedded in an optimization framework,the combined procedure is called optimal risk-based design. This approach to design isthe ultimate model for the design, analysis, and operation of hydraulic structures andwater resource projects that hydraulics engineers need to strive for in the future. Chapter7 provides detailed discussions on risk-reliability evaluation.

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1.34 Chapter One



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Introduction 1.35



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Supply Paper No. 1849, Arlington, VA, 1967.Van Deman, E.B., The Building of Roman Aqueducts, Carnegie Institute of Washington, 1934.Vivian, R.G., Conservation and Diversion: Water-Control Systems in the Anasazi Southwest, in

Irrigation Impact on Society, Anthropological papers of the University of Arizona, No. 25, T.Downing and M. Gibson, eds., pp. 95112, University of Arizona, Tucson, 1974.

Vivian, R.G., The Chacoan Prehistory of the San Juan Basin, Academic Press, San Diego, CA,1990.

Wittfogel, K.A., The Hydraulic Civilization: Mans Role in Changing the Earth, University ofChicago Press, Chicago, 1956.

Woodburg, R.B. and J.A. Neely, Water Control Systems of the Tehuacan Valley, in ThePrehistory of the Tehuacan Valley: Vol. 4, Chronology and Irrigation, R.S. MacNeish and F.Johnson, eds., pp. 81153, University of Texas Press, Austin, 1972.

Woodward, S.M., and C.J. Posey, Hydraulics of Steady Flow in Open Channels, John Wiley &Sons, New York, 1941.

1.36 Chapter One



INTRODUCTION

Introduction 1.37

A.1 POLICIES BY CATEGORY

A.1.1 Environment

National Environmental Policy Act: 42 U.S.C. 43214347 (P.L. 91190 and 9481).Reference - 23 CFR 770772, 40 CFR 15001508, CEQ Regulations, Executive Order11514 as amended by Executive Order 11991 on NEPA responsibilities. The purpose is toconsider environmental factors through a systematic interdisciplinary approach beforecommitting to a course of action.Section 4(f) of the Department of Transportation Act: 23 U.S.C. 138, 49 U.S.C. 303 (P.L.10017, 97449, and 86670), 23 CFR 771.135. The purpose is to preserve publiclyowned public parklands, waterfowl and wildlife refuges, and all historic areas.Economic, Social, and Environmental Effects: 23 U.S.C. 109(h) (P.I. 91605), 23U.S.C. 128, 23 CFR 771. The purpose is to assure that possible adverse, economic,social, and environmental effects of proposed highway projects and their locations arefully considered and that final decisions on highway projects are made in the best over-all public interest.Public Hearings: 23 U.S.C. 128, 23 CFR 771.111. The purpose is to ensure adequateopportunity for public hearings on the social, economic, and environmental effects ofalternative project locations and major design features as well as the consistency of theproject with local planning goals and objectives.Surface Transportation and Uniform Relocation Assistance Act of 1987: Section 123(f)Historic Bridges 23 U.S.C. 144(o) (P.L. 100-17). The purpose is to complete an invento-ry of on-and-off system bridges to determine their historic significance and to encouragethe rehabilitation, reuse, and preservation of historic bridges.

A.1.2 Health

Safe Drinking Water Act: 42 U.S.C. 300f300;f-6 (P.L. 93523 and 99339), FHPM6733, 23 CFR 650, Subpart E, 40 CFR 141, 149. The purpose is to ensure publichealth and welfare through safe drinking water.Solid Waste Disposal Act, as amended by the Resource Conservation and Recovery Actof 1976: 42 U.S.C. 6901, et seq., see especially 42 U.S.C. 69616964 (P.L. 89272,91512, and 94580), 23 CFR 751, 40 CFR 256300. The purpose is to provide for therecovery, recycling, and environmentally safe disposal of solid wastes.

APPENDIX 1. AINTRODUCTION



INTRODUCTION

1.38 Chapter One

A.1.3 Historic and Archeological Preservation

Section 106 of the National Historic Preservation Act, as amended: 16 U.S.C. 470f (P.L.89665, 91243, 9354, 94422, 94458, 96199, 96244, and 96515), Executive Order11593, 23 CFR 771, 36 CFR 60, 36 CFR 63, 36 CFR 800. The purpose is to protect, reha-bilitate, restore, and reuse districts, sites, buildings, structures, and other objects signifi-cant in American architecture, archeology, engineering, and culture.Section 110 of the National Historic Preservation Act, as amended: 16 U.S.C. 470h2(P.L. 96515), 36 CFR 65, 36 CFR 78. The purpose is to protect national historic land-marks and record historic properties before demolition.Archeological and Historic Preservation Act: 16 U.S.C. 469469c (P.L. 93291) (Moss-Bennett Act), 36 CFR 66 (draft). The purpose is to preserve significant historical andarcheological data from loss or destruction.Act for the Preservation of American Antiquities: 16 U.S.C. 431433 (P.L. 59209), 36CFR 251.5064, 43 CFR 3. Archeological Resources Protection Act: 16 U.S.C. 470aa11(P.L. 9695), 18 CFR 1312, 32 CFR 229, 36 CFR 296, 43 CFR 7. The purpose is to pre-serve and protect paleontologic resources, historic monuments, memorials, and antiquitiesfrom loss or destruction.American Indian Religious Freedom Act: 42 U.S.C. 1996 (P.L. 95341). The purpose isto protect places of religious importance to American Indians, Eskimos, and NativeHawaiians.

A.1.4 Land and Water Usage

Wilderness Act 16 U.S.C. 11311136. 36 CFR 251, 293, 43 CFR 19, 8560, 50 CFR 35.The purpose is to preserve and protect wilderness areas in their natural condition for useand enjoyment by present and future generations.Wild and Scenic Rivers Act: 16 U.S.C. 12711287, 36 CFR 251, 261, 43 CFR 8350. Thepurpose is to preserve and protect wild and scenic rivers and immediate environments forthe benefit of present and future generations.Land and Water Conservation Fund Act (Section 6(f)): 16 U.S.C. 46014 to 111 (P.L.88578). The purpose is to preserve, develop, and assure the quality and quantity of out-door recreation resources for present and future generations.Executive Order 11990, Protection of Wetlands, DOT Order 5660. 1A, 23 CFR 777. Thepurpose is to avoid direct or indirect support of new construction in wetlands whenever apracticable alternative is available.Emergency Wetlands Resources Act of 1986: 16 U.S.C. 3901 note (P.L. 99645). The pur-pose is to promote the conservation of wetlands in the U.S. to maintain the public bene-fits they provide.National Trails Systems Act: 16 U.S.C. 12411249, 36 CFR 251, 43 CFR 8350. The pur-pose is to provide for outdoor recreational needs and encourage outdoor recreation.Rivers and Harbors Act of 1899: 33 U.S.C. 401, et seq., as amended and supplemented,23 CFR part 650, Subpart H, 33 CFR 114115. The purpose is to protect navigable watersin the U.S.Federal Water Pollution Control Act (1972), as amended by the Clean Water Act (1977 &1987): 33 U.S.C. 12511376 (P.L. 92500, 95217, 1004), DOT Order 5660.1A, FHWA



INTRODUCTION

Notices N5000.3 and N5000.4, FHPM 6733, 23 CFR 650, Subpart B, E, 771, 33 CFR209, 40 CFR 120, 122125, 128131, 133, 125136, 148, 230231. The purpose is torestore and maintain the chemical, physical, and biological integrity of the nation's watersthrough prevention, reduction, and elimination of pollution.Executive Order 11988, Floodplain Management, as amended by Executive Order 12148,DOT Order 5650.2, FHPM 6732, 23 CFR 650, Subpart A, 771. The purpose is to avoidthe long and short-term adverse impacts associated with the occupancy and modificationof floodplains and to restore and preserve the natural and beneficial values served byfloodplains.National Flood Insurance Act: (P.L. 90448), Flood Disaster Protection Act: (P.L. 93234)42 U.S.C. 40014128, DOT Order 5650.2, FHPM 6732, 23 CFR 650, Subpart A, 771,44 CFR 5977. The purpose is to identify flood-prone areas and provide insurance and torequire the purchase of insurance for buildings in special flood-hazard areas.Marine Protection Research and Sanctuaries Act of 1972, as amended: 33 U.S.C.14011445 (P.L. 92532, 93254, 96572), 33 CFR 320, 330, 40 CFR 220225,227228, 230231. The purpose is to regulate the dumping of materials into U.S.ocean waters.

Water Bank Act: 16 U.S.C. (P.L. 91559, 96182), 7 CFR 752. The purpose is to preserve,restore, and improve wetlands of the U.S.Coastal Zone Management Act of 1972: 16 U.S.C.1 14511464 (P.L. 92583, 94370,96464), 15 CFR 923, 926, 930931, 23 CFR 771. The purpose is to preserve, protect,develop, and (when possible) restore and enhance the resources of the coastal zone.Coastal Barrier Resource Act, as amended: 16 U.S.C. 35013510, 42 U.S.C. 4028 (P.L.97348), Great Lakes Coastal Barrier Act of 1988 (P.L. 100707), 13 CFR 116 SubpartsD, E, 44 CFR 71, 205 Subpart N. The purpose is to minimize the loss of human life,wasteful expenditures of federal revenues, and the damage to fish, wildlife, and other nat-ural resources.Farmland Protection Policy Act of 1981: 7 U.S.C. 42014209 (P.L. 9798, 99198), 7CFR 658. The purpose is to minimize impacts on farmland and maximize compatibilitywith state and local farmland programs and policies.Resource Conservation and Recovery Act of 1976 (RCRA), as amended: 42 U.S.C. 690,et seq. (P.L. 94580, 98616), 40 CFR 260271. The purpose is to protect human healthand the environment; prohibit open dumping; manage solid wastes; and regulate the treat-ment, storage transportation, and disposal of hazardous waste.Comprehensive Environmental Response, Compensation, and Liability Act of 1980(CERCLA), as amended: 42 U.S.C. 96019657 (P.L. 96510), 40 CFR 300, 43 CFR 11.Superfund Amendments and Reauthorization Act of 1986 (SARA) (P.L. 99499). Thepurpose is to provide for liability, compensation, cleanup, and emergency response whenhazardous substances have been released into the environment and to provide for thecleanup of inactive hazardous waste disposal sites.Endangered Species Act of 1973, as amended: 16 U.S.C. 15311543 (P.L. 93205,94359, 95632, 96159, 97304), 7 CFR 355, 50 CFR 17, 23, 2529, 81, 217, 222,225227, 402, 424, 450453. The purpose is to conserve species of fish, wildlife, andplants facing extinction.Fish and Wildlife Coordination Act: 16 U.S.C. 661666c (P.L. 85624, 8972, 95616.The purpose is to conserve, maintain, and manage wildlife resources.

Introduction 1.39



INTRODUCTION

2.1 INTRODUCTION

The need to provide water to satisfy basic physical and domestic needs; use of mar-itime and fluvial routes for transportation and travel, crop irrigation, flood protec-tion, development of stream power; all have forced humanity to face water from thebeginning of time. It has not been an easy rapport. City dwellers who day after daysee water flowing from faucets, docile to their needs, have no idea of its idiosyn-crasy. They cannot imagine how much patience and cleverness are needed to han-dle our great friend-enemy; how much insight must be gained in understanding itsarrogant nature in order to tame and subjugate it; how water must be enticed toagree to our will, respecting its own at the same time. That is why a hydraulicianmust first be something like a water psychologist, thoroughly knowledgeable of itsnature. (Enzo Levi, The Science of Water: The Foundations of Modern Hydraulics,ASCE, 1995, p. xiii.)

Understanding the hydraulics of pipeline systems is essential to the rational design,analysis, implementation, and operation of many water resource projects. This chapterconsiders the physical and computational bases of hydraulic calculations in pressurizedpipelines, whether the pipelines are applied to hydroelectric, water supply, or wastewatersystems. The term pressurized pipeline means a pipe system in which a free water surfaceis almost never found within the conduit itself. Making this definition more precise is dif-ficult because even in a pressurized pipe system, free surfaces are present within reser-voirs and tanks and sometimes for short intervals of time during transient (i.e.,unsteady) eventscan occur within the pipeline itself. However, in a pressurized pipelinesystem, in contrast to the open-channel systems discussed in Chapter 3, the pressureswithin the conveyance system are usually well above atmospheric.

Of central importance to a pressurized pipeline system is its hydraulic capacity: that is,its ability to pass a design flow. A related issue is the problem of flow control: how designflows are established, modified, or adjusted. To deal adequately with these two topics, this chapter considers head-loss calculations in some detail and introduces thetopics of pumping, flow in networks, and unsteady flows. Many of these subjects are treat-ed in greater detail in later chapters, or in reference such as Chaudhry and Yevjevich (1981).

Rather than simply providing the key equations and long tabulations of standard values, this chapter seeks to provide a context and a basis for hydraulic design. In addi-tion to the relations discussed, such issues as why certain relations rather than others areused, what various equations assume, and what can go wrong if a relation is used incor-

CHAPTER 2HYDRAULICS OF

PRESSURIZED FLOW

Bryan W. KarneyDepartment of Civil Engineering

University of Toronto,Toronto, Ontario,

Canada

2.1



Source: HYDRAULIC DESIGN HANDBOOK

rectly also are considered. Although derivations are not provided, some emphasis is placedon understanding both the strengths and weaknesses of various approaches. Given the virtually infinite combinations and arrangements of pipe systems, such information isessential for the pipeline professional.

2.2 IMPORTANCE OF PIPELINE SYSTEMS

Over the past several decades, pressurized pipeline systems have become remarkablycompetitive as a means of transporting many materials, including water and wastewater.In fact, pipelines can now be found throughout the world transporting fluids through everyconceivable environment and over every possible terrain.

There are numerous reasons for this increased use. Advances in construction techniques and manufacturing processes have reduced the cost of pipelines relative toother alternatives. In addition, increases in both population and population density havetended to favor the economies of scale that are often associated with pipeline systems. Theneed for greater conservation of resources and, in particular, the need to limit lossescaused by evaporation and seepage have often made pipelines attractive relative to open-channel conveyance systems. Moreover, an improved understanding of fluid behavior hasincreased the reliability and enhanced the performance of pipeline systems. For all thesereasons, it is now common for long pipelines of large capacity to be built, many of whichcarry fluid under high pressure. Some of these systems are relatively simple, composedonly of series-connected pipes; in others systems, the pipes are joined to form complexnetworks having thousands of branched and interconnected lines.

Pipelines often form vital links in the process chain, an

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Hydraulic Design Handbook