مهندسی سواحل

مهندسی سواحل

اسلاید 1: مهندسی سواحل

اسلاید 2: اهداف درستعاریف، مفاهیم و ترمینولوژیتاریخچه مهندسی سواحلرشته های مرتبط با مهندسی سواحلتعریف ساحل ، اجزا و قلمروساحل به عنوان یک بیوژئومورفولوژیکال سیستمطبقه بندی سواحلفرایندهای ساحلی (امواج، جزر و مد، جریانهای دریائی، باد و ...)بررسی فرایندهای غالب ساحلی (فرسایش، حمل و جابجائی رسوبات ورسوبگذاری)شناسائی لندفرمهای ساحلی و کاربری آنهااندازه گیری ، کمی سازی و پیش بینی تغییرات خط ساحلیراهبردها و راهکارهای حفاظت از سواحلآشنائی با تجهیزات و ماشین آلات لایروبی سواحل و بندرگاهها

اسلاید 3: تعریف مهندسی سواحلعلم مطالعه فرایندهای فعال در منطقه ساحلی و اثرات انها بر روی سواحل و سازه های ساحلی و برنامه ریزی برای حفاظت از انها

اسلاید 4: علوم مرتبط

اسلاید 5: تاریخچه مهندسی سواحلالف- مهندسی سواحل در دنیای باستان The history of coastal engineering reaches back to the ancient world bordering the Mediterranean Sea, the Red Sea, and the Persian Gulf. Coastal engineering, as it relates to harbors, starts with the development of maritime traffic, perhaps before 3500 B.C. Shipping was fundamental to culture and the growth of civilization, and the expansion of navigation and communication in turn drove the practice of coastal engineering. The availability of a large slave labor force during this era meant that docks, breakwaters, and other harbor works were built by hand and often in a grand scale similar to their monumental contemporaries, pyramids, temples, and palaces. Some of the harbor works are still visible today, while others have recently been explored by archaeologists. Most of the grander ancient harbor works disappeared following the fall of the Roman Empire. Earthquakes have buried some of the works; others have been submerged by subsidence, landlocked by silting, or lost through lack of maintenance. Recently, archaeologists, using modern survey techniques, excavations, and old documents, have revealed some of the sophisticated engineering in these old harbors. Technically interesting features have shown up and are now reappearing in modern port designs. Common to most ancient ports was a well-planned and effectively located seawall or breakwater for protection and a quay or mole for loading vessels, features frequently included in modern ports (Quinn 1972).-

اسلاید 6: Most ancient coastal efforts were directed to port structures, with the exception of a few places where life depended on coastline protection. Venice and its lagoon is one such case. Here, sea defenses (hydraulic and military) were necessary for the survival of the narrow coastal strips, and impressive shore protection works built by the Venetians are still admired. Very few written reports on the ancient design and construction of coastal structures have survived. A classic treatise by Vitruvius (27 B.C.) relating the Roman engineering experience, has survived (Pollio, Rowland, and Howe 1999). Greek and Latin literature by Herodotus, Josephs, Suetonius, Pliny, Appian, Polibus, Strabo, and others provide limited descriptions of the ancient coastal works. They show the ancients ability to understand and handle various complex physical phenomena with limited empirical data and simple computational tools. They understood such phenomena as the Mediterranean currents and wind patterns and the wind-wave cause-effect link. The Romans are credited with first introducing wind roses (Franco 1996).-

اسلاید 7: ب- مهندسی سواحل قبل از دوره رومیانMost ancient coastal efforts were directed to port structures, with the exception of a few places where life depended on coastline protection. Venice and its lagoon is one such case. Here, sea defenses (hydraulic and military) were necessary for the survival of the narrow coastal strips, and impressive shore protection works built by the Venetians are still admired. Very few written reports on the ancient design and construction of coastal structures have survived. A classic treatise by Vitruvius (27 B.C.) relating the Roman engineering experience, has survived (Pollio, Rowland, and Howe 1999). Greek and Latin literature by Herodotus, Josephs, Suetonius, Pliny, Appian, Polibus, Strabo, and others provide limited descriptions of the ancient coastal works. They show the ancients ability to understand and handle various complex physical phenomena with limited empirical data and simple computational tools. They understood such phenomena as the Mediterranean currents and wind patterns and the wind-wave cause-effect link. The Romans are credited with first introducing wind roses (Franco 1996).-

اسلاید 8: The earliest were rock cut, in that natural features like offshore reefs were adapted to give shelter to craft riding at anchor.b. In the second group, vertical walls were built on convenient shallows to serve as breakwaters and moles. Harbors of this type were in protected bays, and often the walls connected with the defenses of a walled town (for example, ancient Tyre on the Lebanese coast). Often these basins were closeable to traffic using chains to prevent the entry of enemy ships (Franco 1996). c. The third group were harbors that were imposed on even unpromising coasts by use of Romaninnovations such as the arch and improved hydraulic cement. Projects like this required the engineering, construction, and financing resources of a major empire.-

اسلاید 9: All ancient ports had one thing in common: they had to be kept clear of silt at a time when mechanical dredging was unknown. This was accomplished by various means. One was by designing the outer parts of the harbor so that they deflected silt-bearing currents. The second was by allowing a controlled current to flow through the port or by flushing it out when necessary by means of channels. For example, at Sidon, a series of tanks (like swimming pools) were cut into the harbor side of a natural rock reef. The tanks filled with clear water that was held in place with sluice gates. When the gates were opened, currents of clear water would flush the inner harbor. Documentary and archaeological evidence show that both Tyre and Sidon were flourishing and powerful ports from the Bronze Age through the Roman era and must therefore have been kept clear of silt for over a thousand years (Frost 1963). Another method of preventing silt consisted of diverting rivers through canals so that during part or much of the year, the flow would enter the sea at location well away from the harbor. -

اسلاید 10: The origins of breakwaters are unknown. The ancient Egyptians built boat basins with breakwaters on the Nile River at Zosers (Djoser) step pyramid (ca. 2500 B.C.) (Inman 2001). The Minoans constructed a breakwater at Nirou Khani on Crete long before the explosion of Santorini (Thera) in ca. 1500 B.C. The breakwater was small and constructed of material taken from nearby dune rock quarries (Inman 1974, Figure 4). In the Mediterranean, size and sophistication of breakwaters increased over time as the Egyptian, Phoenician, Greco-Macedonian, and Roman civilizations developed and evolved. Breakwaters were built in China but generally at a later date than in the Mediterranean. Probably the most sophisticated man-made harbor of this era was the first harbor of Alexandria, Egypt, builtwest of Pharos Island about 1800 B.C. by the Minoans. The main basin, built to accommodate 400 ships about 35 m in length, was 2,300 m long, 300 m wide and 6-10 m deep. Large stone blocks were used in the many breakwaters and docks in the harbor. Alexander the Great and his Greek successors rebuilt the harbor (300-100 B.C.) in monumental scale. The Island of Pharos was joined to the mainland by a 1.5 km breakwater with two openings dividing two basins with an area of 368 hectares (910 acres) and 15 km of quay front. Alexandria is probably best known for the 130m-high lighthouse tower used to guide ships on a featureless coast to the port from 50 km at sea. The multi-storied building was built with solid blocks of stone cemented together with melted lead and lined with white stone slabs. Considered one of the Wonders of theAncient World, it eventually collapsed due to earthquakes between 1326 and 1349 (Franco 1996, Empereur 1997). -

اسلاید 11: Another feature of the Greek harbors was the use of colossal statues to mark the entrances. Colossal statues of King Ptolemy, which stood at the base of the lighthouse, have been found with the lighthouse debris. Historians report the most famous harbor statue was the 30 m high Colossus of Rhodes, which stood on the breakwater heads. Three ancient windmill towers are still surviving upon the Rhodes breakwater (Franco 1996). Frost (1963) notes that the Greeks had used hydraulic cement long before the Romans.ج- مهندسی سواحل در رم باستانThe Romans introduced many revolutionary innovations in harbor design. They learned to build walls underwater and constructed solid breakwaters to protect exposed harbors. They used metal joints and clamps to fasten neighboring blocks together and are often credited with discovering hydraulic cement made with pozzolanic ash obtained from the volcanic region near Naples, which hardens underwater. Frost (1963) notes that the Greeks had used hydraulic cement long before the Romans. The Romans replaced many of the Greek rubble mound breakwaters with vertical and composite concrete walls -

اسلاید 12: The Romans introduced many revolutionary innovations in harbor design. They learned to build walls underwater and constructed solid breakwaters to protect exposed harbors. They used metal joints and clamps to fasten neighboring blocks together and are often credited with discovering hydraulic cement made with pozzolanic ash obtained from the volcanic region near Naples, which hardens underwater. Frost (1963) notes that the Greeks had used hydraulic cement long before the Romans. The Romans replaced many of the Greek rubble mound breakwaters with vertical and composite concrete walls . These monolithic coastal structures could be built rapidly and required little maintenance. In In most cases, rubble or large stone slabs were placed in front of the walls to protectagainst toe scour. The Romans developed cranes and pile drivers and used them extensively in their construction. This technology also led them to develop dredges. Another advanced technique used for deep-water applications was the watertight floating cellular caisson, precursor of the modern day monolithic breakwater. some cases wave reflection may have been used to prevent silting. They also used low, water-surface breakwaters to trip the waves before they reached the main breakwater. The peculiar feature of the vertical wall breakwater at Thapsus (Rass Dimas, Tunisia) was the presence of vents through the wall to reduce wave impact forces. This idea is used today in the construction of perforated caisson breakwaters (Franco 1996). Using some of these techniques, the Romans built sophisticated breakwaters at Aquileia, Italy (ca. 180 B.C.),and at Caesarea, Israel (ca. 20 B.C.). -

اسلاید 13: ج- مهندسی سواحل در رم باستانThe Romans introduced many revolutionary innovations in harbor design. They learned to build walls underwater and constructed solid breakwaters to protect exposed harbors. They used metal joints and clamps to fasten neighboring blocks together and are often credited with discovering hydraulic cement made with pozzolanic ash obtained from the volcanic region near Naples, which hardens underwater. Frost (1963) notes that the Greeks had used hydraulic cement long before the Romans. The Romans replaced many of the Greek rubble mound breakwaters with vertical and composite concrete walls . These monolithic coastal structures could be built rapidly and required little maintenance. In In most cases, rubble or large stone slabs were placed in front of the walls to protectagainst toe scour. The Romans developed cranes and pile drivers and used them extensively in their construction. This technology also led them to develop dredges. Another advanced technique used for deep-water applications was the watertight floating cellular caisson, precursor of the modern day monolithic breakwater. some cases wave reflection may have been used to prevent silting. They also used low, water-surface breakwaters to trip the waves before they reached the main breakwater. The peculiar feature of the vertical wall breakwater at Thapsus (Rass Dimas, Tunisia) was the presence of vents through the wall to reduce wave impact forces. This idea is used today in the construction of perforated caisson breakwaters (Franco 1996). Using some of these techniques, the Romans built sophisticated breakwaters at Aquileia, Italy (ca. 180 B.C.),and at Caesarea, Israel (ca. 20 B.C.). -

اسلاید 14: ج- مهندسی سواحل در رم باستان The southwestern breakwater at Caesarea contained a forebreakwater that acted as a submerged reef that trips the wave causing it to break and dissipate energy before encountering the main breakwater (Inman 2001). The largest manmade harbor complex was the imperial port of Rome; the maritime town at the mouth of the Tiber River was named Portus (The Port). It is now some four km from the sea, partly buried under Rome-Fiumicino airport. Despite its importance to the capital of the empire, (300,000 tons/year of wheat from Egypt and France), the harbor always suffered siltation from the river. Trajan, who also built the ports of Terracina and Centumcellae, built Portus inner hexagonal basin. The port of Centumcellae was built just to serve his villa at a site with favorable rocky morphology. A grandiose engineering project between 107-106 B.C. created a sheltered bathing and boating retreat. Slaves from all parts of the empire excavated a harbor and hauled in massive stones to create an artificial harbor to dampen the force of the waves. After the decline of Portus, it became, and remains, the Port of Rome. After remaining unchanged for over 1,000 years, the inner Roman Basin, which was dredged from rock (200,000 m3 or 260,000 yd3), is still in use. Roman engineers also constructed harbors in northern Europe along the main waterways of the Rhine and Danube and in Lake Geneva. They became the first dredgers in the Netherlands to maintain the harbor at Velsen. Silting problems here were solved when the previously sealed solid piers were replaced with new open- piled jetties. In general, the Romans spread their technology throughout the western world. Their harbors became independent infrastructures, with their own buildings and storage sheds as opposed to the pre-Roman fortified city-enclosed harbors. -

اسلاید 15: ج- مهندسی سواحل در رم باستانThey developed and properly used a variety of design concepts and construction techniques at different coastal cites to suit the local hydraulic and morphological conditions and available materials (Franco 1996). The Romans also introduced to the world the concept of the holiday at the coast. The ingredients for beach holidays were in place: high population density coupled with a relatively high standard of living, a well-established economic and social elite, and a superb infrastructure of roads. From the end of the republic to the middle of the second century of the empire, resorts thrived along the shores of Latium and Capania, and an unbroken string of villas extended along the coast from the seashore near Rome to the white cliffs of Terracina. Fine roads connected these resorts to the capital, allowing both the upper crust and the masses to descend from sultry and vapor-ridden Rome to the sea. For five hundred years, the sybaritic town of Baiae reigned as the greatest fashionable beach resort of the ancient world. Seneca the Younger called Baiae a (Lencek and Bosker 1998). -

اسلاید 16: د- مهندسی سواحل در دوران جدیدAfter the fall of the Western Roman Empire, a long hiatus in coastal technology and engineering prevailed throughout most of the European world with a few exceptions. Little is recorded on civil engineering achievements during the Dark and Middle Ages. The threat of attack from the sea caused many coastal towns and their harbors to be abandoned. Many harbors were lost due to natural causes such as rapid silting, shoreline advance or retreat, etc. The Venice lagoon was one of the few populated coastal areas with continuous prosperity and development where written reports document the evolution of coastal protection works, ranging from the use of wicker faggots to reinforce the dunes to timber piles and stones, often combined in a sort of crib work. Protection from the sea was so vital to the Venetians, that laws from 1282 to 1339 did not allow anyone to cut or burn trees from coastal woods, pick out mussels from the rockrevetments, let cattle upon the dikes, remove sand or vegetation from the beaches or dunes, or export materials used for shore protection (Franco 1996). Of necessity, Byzantium had become a sea power, sending forth fleets of merchant ships and multi-oared dromonds (swift war vessels) throughout the Black Sea and Mediterranean. When the weary soldiers of the first crusades reached Byzantiums capital city, Constantinople, in 1097, they were amazed and awed by its magnificence, sophistication, and scientific achievements. -

اسلاید 17: In England, coastal engineering works date back to the Romans, who recognized the danger of floods and sea inundation of low-lying lands. On the Medway, for example, embankments built by the Romans as sea defense remained in use until the 18th century (Palmer and Tritton Limited 1996). The low-lying lands, consisting of recently-deposited alluvial material, were exceeding fertile but were also vulnerable to flooding from both runoff and storm surges. In the Middle Ages, the Church became instrumental in reclaiming and protecting many marshes, and monks reclaimed portions of the Fylde and Humber estuaries. In 1225, Henry III constituted by Charter a body of persons to deal with the question of drainage (Keay 1942). Across the North Sea, the Friesland area of the Netherlands had a large and wealthy population in the period 500 - 1000 A. D., and increasing need for agricultural land led to building of sea dikes to reclaim land that previously was used for grazing (Bijker 1996). Water boards developed in response to the need for a mutual means to coordinate and enforce dike maintenance. These boards represent some of the earliest democratic institutions in the Netherlands. Engineering and scientific skills remained alive in the east, in Byzantium, where the Eastern Roman empire survived for six hundred years while Western Rome decayed. Of necessity, Byzantium had become a sea power, sending forth fleets of merchant ships and multi-oared dromonds (swift war vessels) throughout the Black Sea and Mediterranean. When the weary soldiers of the first crusades reached Byzantiums capital city, Constantinople, in 1097, they were amazed and awed by its magnificence, sophistication, and scientific achievements. -

اسلاید 18: Constantinople was built on the hills overlooking the Golden Horn, a natural bay extendingnorth of the Bosporus. Marble docks lined the waterfront, over which passed the spices, furs, timber, grain, and the treasures of an empire. A great chain could be pulled across the mouth of the Golden Horn to prevent intrusion by enemy fleets. A series of watch towers extended along the length of the Sea of Marmara, the Bosphoros, and the south shore of the Black Sea, and the approach of an enemy fleet could be signaled to the emperor within hours by an ingenious code using mirrors by day and signal fires by night (Lamb 1930). The Renaissance era (about XV - XVI centuries) was a period of scientific and technologic reawakening, including the field of coastal engineering. While the standards for design and construction remained thosedeveloped primarily by the Romans, a great leap in technology was achieved through the development of mechanical equipment and the birth of the hydraulic sciences including maritime hydraulics (Franco 1996). The Italian School of Hydraulics was the first to be formed and the only one to exist before the middle of the 17th century (Rouse and Ince 1963). -

اسلاید 19: Leonardo da Vinci (1465-1519), with his well-known experimental method, based on the systematic observation of natural phenomenon supported by intellectual reasoning anda creative intuition, could be considered the precursor of hydrodynamics, offering ideas and solutions oftenmore than three centuries ahead of their common acceptance. Some of his descriptions of water movement are qualitative, but often so correct, that some of his drawings could be usefully included in a modern coastal hydrodynamics text. The quantitative definition and mathematical formulation of the results were far beyond the scientific capabilities of the era. Even so, da Vinci was probably the first to describe and test several experimental techniques now employed in most modern hydraulic laboratories. To visualize the flow field, he used suspended particles and dyes, glass-walled tanks, and movable bed models, both in water and in air.The movement from kinematics to dynamics proved impossible until the correct theory of gravitation was developed, some two centuries latter by Sir Issac Newton (Fasso 1987). The variety of hydro kinematics problems dealt with in da Vincis notebooks is so vast that it is not possible to enumerate them all in this brief review. In the 36 folios (sheets) of the Codex Leicester (1510), he describes most phenomena related to maritime hydraulics. Richter (1970) provides an English translation of da Vincis notebooks (Franco 1996). The scientific ideas of the Italian Renaissance soon moved beyond the confines of that country, to the European countries north of the Alps. -

اسلاید 20: ه- عصر مهندسی عمران و فعالیتهای نظامی(ارتش)After the Renaissance, although great strides were made in the general scientific arena, little improvement was made beyond the Roman approach to harbor construction. Ships became more sea-worthy and global navigation became more common. With global navigation came the European discovery of the Americas, Australia, New Zealand, Indonesia, and other areas of the world, soon followed by migration and colonization. Trade developed with previously unreachable countries and new colonies. France developed as the leader in scientific knowledge. The French Genie officers, who, along with their military task, were also entrusted with civilian public works, are reportedly the direct ancestors of modern civil engineers. Sebastien le Prestre de Vauban (1633-1707) was a builder of numerous fortresses and perfected the system of polygonal and star shaped fortifications. His most eminent public works project was the conversion of Dunkirk into an impregnable coastal fortress. Apart from the construction of several forts, there were extensive harbor and coastal works, including the excavation of canals and harbor basins, the construction of two long jetties flanking the entrance channel, and the erection of storehouses and workshops. -

اسلاید 21: A great lock, a masterpiece of civil engineering, was built at the entrance to the Inner Harbor. Vauban himself designed and supervised the lock construction. Unfortunately, no more than 30 years after its completion, the fortress was destroyed as a consequence of the Spanish War of Succession. Vaubans projects providea good example of engineering methods and lucidity. They consisted of an explanatory memorandum, several drawings, and a covering letter. The memorandum had four sections: (1) general background of the scheme;(2) detailed descriptions of the different parts, with references to the drawings; (3) cost estimates; (4) features and advantages of the work. It was during this time that the term Ingenieur was first used in France, as a professional title for a scientifically-trained technician in public service. -

اسلاید 22: While France enjoyed a leading position in Europe with regard to exact sciences and their applications to technical problems, a social and economic revolution later known as the Industrial Revolution was taking place in England. The riding-horse and the packhorse gave way to the coach, the wagon and the barge. Hard roads and canals replaced the centuries old soft roads and trails, dusty in dry weather and mud-bound during rains (Straub 1964). Steam power allowed industry to be concentrated in factories that required continuous supply of raw materials and export of manufactured goods.In the 18th and 19th centuries, advances in navigation and mathematics, the advent of the steam engine, the search for new lands and trade routes, the expansion of the British Empire through her colonies, and other influences, all contributed to the revitalization of sea trade and a renewed interest in port works. As the volume of shipping grew, more vessels were needed and as the dimensions of the new vessels became larger, increased port facilities were necessary. Ports of the world experienced growing pains for the first time since the Roman era, and, except for the interruption caused by two world wars, port needs continue to grow (Quinn 1972). -

اسلاید 23: سپاه مهندسان ارتش آمریکا:Since the formation of the United States, Army engineers and the Corps of Engineers have been responsible for or intimately associated with a wide variety of civil projects and improvements to waterways, ports, and navigation systems. The following paragraphs summarize the history of the U.S. Army Corps of Engineers (USACE) and outline some of the Corps early efforts in coastal and navigation improvements. The origins of the USACE date to June of 1775, at the beginning of the American War of Independence, when the Second Continental Congress authorized General Washington to assign a chief engineer for the grand army (Parkman 1978). General Washington selected Colonel Richard Gridley, a seasoned artilleryman, who had been preparing a line of fortifications around Boston during the early weeks of the war. -

اسلاید 24: Military operations during the war underscored the need for an efficient body of engineers, and in March of 1779, the Continental Congress finally authorized a separate and distinct corps of engineers, to be commanded by Louis LeBègue Du Portail, an officer recruited by the American mission in France. The corps was a vital unit of the Continental Army until disbanded in November 1783 with the arrival of peace. When war between France and England broke out in the 1790s Congress authorized President Washington to begin construction of a system of fortifications along the coast. In 1802, in anticipation of the European belligerents signing a treaty of peace, Congress cut back and reorganized the army and created a separate corps of engineers, limited at that time to sixteen officers (Parkman 1978). The Act of March 16, 1802 had other far-reaching consequences, as it provided further that the Corps was to constitute the personnel of a military academy at West Point. Congress had recognized the almost complete absence of trained military and civil engineers in the United States, and, in effect, established a national college of engineering. West Point was the only school in the country to graduate engineers until 1824, when Rensselaer Polytechnic Institute was formed. Quickly becoming the growing nations primary source of engineering expertise, the Corps first concentrated on constructing and maintaining strategically-placed coastal fortifications to repel naval attacks. But soon it became concerned with civil functions as it planned and executed the nationalinternal improvement program initiated in the 1820s (Maass 1951). -

اسلاید 25: Until the early 1800s, little maintenance or improvement was done to harbors or rivers, and maintaining navigability of waterways was considered the responsibility of the states or private interests. What little the Federal government had done was carried out by the Treasury Department, which had assisted navigation by erecting lighthouses, beacons, buoys, and public piers. In 1818, John C. Calhoun, then Secretary of War, recommended that the Corps of Engineers be directed to improve waterways navigation and other transportation systems because these civil works would facilitate the movement of the Army and its materials while contributing to national economic development (USACE 1978). Congress accepted Calhounsrecommendations and passed the landmark General Survey Act, which President James Monroe signed into law on April 30, 1824. It directed the President to use Army engineers to survey roads and canals. By the mid-1820s Corps of Engineers officers were busy surveying the Ohio and lower Mississippi Rivers and the Great Lakes, identifying navigation impediments, and proposing improvements and new routes. Only a month later, on May 24, 1824, President Monroe signed the first Rivers and Harbors Act, which authorized the President to appropriate Federal monies to improve navigation on the Ohio and Mississippi Rivers. By 1829, Army engineers were using steam-powered snagboats to remove snags and floating trees and to dig out sandbars that impeded river traffic. Subsequent acts authorized a wide variety of internalimprovements and assigned Army engineers to direct and manage these projects. Work soon began on a number of challenging locations that were deemed critical for the growth of a growing nation.

اسلاید 26: Hazardous navigation conditions on the Great Lakes also called for the rapid improvement of harbors. With the passage of the Rivers and Harbors Act, Congress voted a $20,000 appropriation for deepening the channel at the harbor of Presque Isle (at Erie, Pennsylvania) on Lake Erie (Drescher 1982). Signaling the beginning of federal involvement in the development of harbors on the Great Lakes, the USACE now maintains over 600 navigation projects throughout these waterways. One of the USACEs first civil projects on an ocean coast was repairing Long Beach at Plymouth, Massachusetts. The beach was a long, narrow sand spit that formed the towns harbor. Constantly endangered by waves and wind, it had been a subject of concern to the citizens of the town as early as 1702, when they made it a crime to fell its trees or fire the grass. The congressional appropriation of $20,000 on May 26, 1824, to repair Plymouth Beach in the state of Massachusetts, and thereby prevent the harbour at that place from being destroyed initiated the Corps civil works mission in New England. Corps officers supervised local agents, who built a cribwork breakwater along the beachs outer shore and erected brushfences and planted grass to stabilize the sand. Similar projects were undertaken at nearby Duxbury and other beaches in New England (Parkman 1978). The pattern whereby Corps specialists supervise local contractors has continued to this day for most civil works projects.Over the succeeding century and a half, the USACEs role in civil works grew dramatically, in step with the growth of the nations population and economy. To adequately cover this interesting story in the CEM would risk doubling its size, so readers are referred to a series of books that document the history of each district (Table I-3-1).

اسلاید 27: Presently, USACE officers and a large contingent of non-military government employees maintain a navigation system of more than 40,000 km (25,000 miles) and 219 locks and dams connecting large regions of the country. Of the nations top 50 ports active in foreign waterborne commerce, over 90 percent require regular dredging (Waterborne Commerce Statistics Center 1999). Over 300 million cubic meters of dredged material are removed from navigation channels each year. In 1997, the USACE contracted for the dredging of about half this total (157 million m3, see Figure I-3-1) at coastal sites only. This does not include inland waterways (Hillyer 1996). Most inlets and harbors used for commercial navigation in the United States are protected and stabilized by hard structures. The USACE built most of the structures and is responsible for maintaining even a larger number since the Federal Government assumed responsibility for some state and local projects. Figure I-3-2 summarizes the locations of the Federal projects (Hillyer 1996). Many U.S. coastal urban and recreational centers are protected by erosion control and storm damage reduction projects constructed cooperatively by the USACE, state, and local governments (Figure I-3-3). Although most of the 83 congressionally authorized shore protection projects are in densely developed areas, some were constructed primarily for recreation and are associated with public or park beaches (Sudar et al.1995).

اسلاید 28: The Coastal System

اسلاید 29: Coasts can be studied in several different ways dependent upon their classification:Erosional or depositionalSediment type (clastic: shingle and sand; or muddy)Submergent or emergentTectonic settingProcess-based: wave dominated, tide dominated and wind dominated - the agents of erosionThe Study of Coasts

اسلاید 30: Wave Dominated Tide Dominated Wind DominatedShore PlatformsMudflatsSand DunesCliffsSandflatsBeachesSalt MarshesSpits, TombolosMangrovesDeltasDeltasHighLowEnergy(French, 1997)Questions & AnswersCause and EffectKnowledge & Understanding

اسلاید 31: The Coastal SystemWAVESWINDTIDESGEOLOGICAL STRUCTURECliffs and Shore PlatformsCoral ReefsBeachesSand DunesMudflatsDominantLess DominantMarineTerrestrialCoarserFinerMATERIALSENERGY(Hansom, 1988)

اسلاید 32:

اسلاید 33: Coastal Systems:coastal systems vary primarily in response to wave intensity and tidal currents breaking waves (and resultant currents) provide most of the systemic energy several additional factors also influence coastal processes and landforms original geology of the coastline relative erodibility of regional bedrock sea level variations (global and local tectonic or glacio-eustatic changes) coastal systems typically characterized as erosional or depositional erosional or depositional nature of any coastline varies with the systemic energy سیستم ساحلی

اسلاید 34: Littoral Zone

اسلاید 35: Fig. 10-1

اسلاید 36:

اسلاید 37: قلمرو محدوده های مختلف در ساحل-)Offshore Zoneالف – کرانه دور یا پیش کرانه (دورترین بخش به خط ساحلی- عمق آب دریا در این منطقه غالبا بیشتر از نصف طول امواج وارده - امواج نمی توانند در این محدوده شکسته شوند و روی بستر تاثیر مورفولوژیک داشته باشند ب – منطقه مجاور ساحلی: (Near Shore Zone )- دراین محدوده امواج وارده به ساحل متحمل بیشترین تغییرات می گردند - جابجایی رسوبات به طور واقعی در همین منطقه صورت می گیرد. -این محدوده در مطالعات ژئومورفولوژی ساحلی از اهمیت خاصی برخوردار است- شامل سه محدوده مستقل با مسخصات ویژه میباشد (منطقه شکست ، منطقه خیزاب ، منطقه یورش امواج) ج – منطقه پس کرانه (Backshore Zone)این منطقه در سطحی بالاتر از آنچه که برای امواج دریا قابل حصول باشد قرار گرفته و تنها در هنگام طوفان های شدید آنهم اگر با مد یا آب بالای استثنائی ( بالاترین مد ) همراه باشند تحت تاثیر مستقیم امواج قرار می گیرد

اسلاید 38: طبقه بندی سواحلCoastal Classification-معروف ترین سیستم های طبقه بندی سواحلطبقه بندی ژئوتکتونیکی زوس ( Suess) 1888 طبقه بندی ژنتیکی جانسون ( 1919 )، طبقه بندی تکتونیکی کوتون ( Cotton – 1952 ) طبقه بندی شپارد Shepard ( 1963 ) طبقه بندی والنتین ( 1953 ) طبقه بندی ژئومورفولوژیکی اینمن و نورستورم (1971)

اسلاید 39: انواع سیستمهای طبقه بندی بر اساس دو عامل شکل و فرایند ساحلی ( فرم و پروسه ) انئاع:الف – طبقه بندی سواحل بر اساس تغییرات سطح آب دریا .( جانسون - 1919 و والنتین 1953) سواحل از آب خارج شدهEmergence) )SUBMERGENCE سواحل غوطه ورب – طبقه بندی بر اساس تغییرات ساختار (تکتونیکی) زمین شناسی(نوردستروم( 1971) - سواحل تصادمی که در مناطق همگرایی صفحه های تکتونیکی شکل می گیرند. کوه های ساحلی آند در آمریکای جنوبیسواحل با لبه دنباله دار در مناطقی که دو صفحه تکتونیکی از هم فاصله می گیرند سواحل کارولینا در آمریکای شمالی و سواحل دریای سرخسواحل حاشیه ای دریا، شامل اغلب مناطق دلتاهای آبرفتی یا رودخانه ای سواحلی که در مناطق استقرار صفحات تکتونیکی پایدار واقعند ( مانند سواحل هند و استرالیا ))ج – طبقه بندی سواحل بر اساس نوع فرایند های ساحلی (دیویس 1980 و تانر 1960)محیط هایی با امواج طوفانی کوچک و بزرگ از همه جهات، سواحل صخره ای و سکو های ساحلی محیط های ساحلی با امواج آرام، لند فرم های ماسه ای نهشته گذاری شده محیط های ساحلی نسبتا محصور و حفاظت شده که فعالیت امواج توسط پوشش یخ در عرض های جغرافیایی بالا به شدت محدود شده

اسلاید 40: فرایندهای ساحلیCoastal ProcessesWind, Waves, Tide, CurrentsSediment MovementCoastal FormDynamic over Space & TimeWeathering, Erosion, & DepositionEquilibrium

اسلاید 41: Weathering & ErosionWhat is?Weathering: Breakdown of rock (Geology) to form sediment in situWeathering is a set of physical, chemical and biological processes that alter the physical and chemical state of rocks and soil at or near the earths surface. Rock and soil is altered physically by disintegrating and chemically by decomposing. Nearly all weathering involves water, mostly directly: frost shattering, wetting and drying, salt weathering, and all chemical weathering is in solution. That is, weathering is climatically driven and thus the term weathering. Because weather and climate occur at the earths surface, the intensity of weathering decreases with depth and most of it occur within less than a metre of the surface of soil and rock. Erosion:Transport of weathered material from one location to another...The wearing away of land or the removal of beach and/or dune sediments by wave action, tidal currents, wave currents, drainage, or wind. Erosion includes, but is not limited to, horizontal recession and scour and can be induced or aggravated by human activities.

اسلاید 42: طبقه بندي سواحلCoastal Classification

اسلاید 43: معروف ترین سیستم هاي طبقه بندي سواحل عبارتند:طبقه بندی زوس 1888 ، طبقه بندي ژنتیکی جانسون ( 1919 )، طبقه بندي تکتونیکی کوتون 1952طبقه بندي شپارد 1963طبقه بندي والنتین ( 1953 )طبقه بندي ژئومورفولوژیکی اینمن و نورستورم (1971)

اسلاید 44: الف – طبقه بندي سواحل بر اساس تغییرات سطح آب دریا :جانسون - 1919 و والنتین 1953سواحل از آب خارج شده: Emergence سواحل غوطه ور: SUBMERGENCE

اسلاید 45: ب – طبقه بندي بر اساس تغییرات ساختار (تکتونیکی) زمین شناسی:نوردستروم 19711- سواحل تصادمی که در مناطق همگرایی صفحه هاي تکتونیکی شکل می گیرند2- سواحل با لبه دنباله دار در مناطقی که دو صفحه تکتونیکی از هم فاصله می گیرند تشکیل می شوند3- سواحل حاشیه اي دریا که گروه بسیار متنوعی از اشکال ساحلی همراه با بسیاري از ویژه گیهاي سواحلداراي لبه دنباله دار را شامل می شوند و اغلب مناطق دلتاهاي آبرفتی یا رودخانه اي را در بر می گیرند.4- سواحلی که در مناطق استقرار صفحات تکتونیکی پایدار واقعند ( مانند سواحل هند و استرالیا )

اسلاید 46: ج – طبقه بندي سواحل بر اساس نوع فرایند هاي ساحلی

اسلاید 47: The Coastal System