Dam collapses in Switzerland, kills 70

Dam collapses in Switzerland, kills 70



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On July 10, 1887, a dam breaks in Zug, Switzerland, killing 70 people in their homes and destroying a large section of the town.

The dam at Zug was 80 feet high and made of concrete. When the dam was built, concrete-making and setting techniques were not as advanced as they are today. The water pressure on the dam slowly eroded the concrete, finally causing it to collapse on July 10.

The resulting wall of water was so powerful that it picked up and washed away large farm animals. It uprooted trees and carried them downstream toward the town. Unsuspecting patrons at a cafe lost their lives when the roaring water and debris suddenly descended upon them. Rescue boats launched to assist people caught up in the sudden flood were ineffective, as some of those on the boats drowned when they capsized in the roiling waters.


List of hydroelectric power station failures

This is a list of major hydroelectric power station failures due to damage to a hydroelectric power station or its connections. Every generating station trips from time to time due to minor defects and can usually be restarted when the defect has been remedied. Various protections are built into the stations to cause shutdown before major damage is caused. Some hydroelectric power station failures may go beyond the immediate loss of generation capacity, including destruction of the turbine itself, reservoir breach and significant destruction of national grid infrastructure downstream. These can take years to remedy in some cases.

Where a generating station is large compared to the connected grid capacity, any failure can cause extensive disruption within the network. A serious failure in a proportionally large hydroelectric generating station or its associated transmission line will remove a large block of power from the grid that may lead to widespread disturbances.


Contents

In the early years of Los Angeles, the city's water supply was obtained from the Los Angeles River. This was accomplished by diverting water from the river through a series of ditches called zanjas. At that time, a private water company, the Los Angeles City Water Company, leased the city's waterworks and provided water to the city. Hired in 1878 as a zanjero (ditch tender), William Mulholland proved to be a brilliant employee, who, after doing his day's work, would study textbooks on mathematics, hydraulics and geology and taught himself engineering and geology. Mulholland quickly moved up the ranks of the Water Company and was promoted to Superintendent in 1886. [5]

In 1902, the City of Los Angeles ended its lease with the private water company and took control over the city's water supply. The city council established the Water Department with Mulholland as its Superintendent and when the city charter was amended in 1911, the Water Department was renamed the Bureau of Water Works and Supply. Mulholland continued as Superintendent and was named as its Chief Engineer. [5] [6]

Mulholland achieved great recognition among members of the engineering community when he supervised the design and construction of the Los Angeles Aqueduct, which at the time was the longest aqueduct in the world and uses gravity alone to bring the water 233 miles (375 km) from the Owens Valley to Los Angeles. [7] The project was completed in 1913, on time and under budget, despite several setbacks. Excluding incidents of sabotage by Owens Valley residents in the early years, the aqueduct has continued to operate well throughout its history and remains in operation today. [8]

It was during the process of building the Los Angeles Aqueduct that Mulholland first considered sections of San Francisquito Canyon as a potential dam site. He felt that there should be a reservoir of sufficient size to provide water for Los Angeles for an extended period in the event of a drought or if the aqueduct were damaged by an earthquake. In particular he favored the area between where the hydroelectric power plants Powerhouses No. 1 and No. 2 were to be built, with what he perceived as favorable topography, a natural narrowing of the canyon downstream of a wide, upstream platform which would allow the creation of a large reservoir area with a minimum possible dam. [9]

A large camp had been set up to house the workers near this area and Mulholland used his spare time becoming familiar with the area's geological features. In the area where the dam would later be situated, he found the mid and upper portion of the western hillside consisted mainly of a reddish colored conglomerate and sandstone formation that had small strings of gypsum interspersed within it. Below the red conglomerate, down the remaining portion of the western hillside, crossing the canyon floor and up the eastern wall, a drastically different rock composition prevailed. These areas were made up of mica schist that was severely laminated, cross-faulted in many areas and interspersed with talc. Although later many geologists disagreed on the exact location of the area of contact between the two formations, a majority opinion placed it at the inactive San Francisquito Fault line. Mulholland ordered exploratory tunnels and shafts excavated into the red conglomerate hillside to determine its characteristics. He also had water percolation tests performed. The results convinced him that the hill would make a satisfactory abutment for a dam should the need ever arise. [10]

A surprising aspect of the early geologic exploration came later when the need for a dam arose. Although Mulholland wrote of the perilous nature of the face of schist on the eastern side of the canyon in his annual report to the Board of Public Works in 1911, [11] it was either misjudged or ignored by the construction supervisor of the St. Francis Dam, Stanley Dunham. Dunham testified, at the Coroner's Inquest, that tests which he had ordered yielded results which showed the rock to be hard and of the same nature throughout the entire area which became the eastern abutment. His opinion was that this area was more than suitable for construction of the dam. [12]

The population of Los Angeles was increasing rapidly. In 1900 the population was slightly over 100,000. By 1910, it had become more than three times that number at 320,000, and by 1920 the figure reached 576,673. [13] This unexpectedly rapid growth brought a demand for a larger water supply. Between 1920 and 1926, seven smaller reservoirs were built and modifications were made to raise the height of its largest of the time, the Lower San Fernando, by seven feet, but the need for a still larger reservoir was clear. Originally, the planned site of this new large reservoir was to be in Big Tujunga Canyon, above the city now known as Sunland, in the northeast portion of the San Fernando Valley, but the high value placed on the ranches and private land which would be needed were, in Mulholland's view, an attempted hold-up of the city. He ceased the attempts at purchasing those lands and, either forgetful of or disregarding his earlier acknowledgement of geological problems at the site, [14] renewed his interest in the area he had explored twelve years earlier, the federally owned and far less expensive private land in San Francisquito Canyon. [9] [15]

The process of surveying the area and determining the location for the St. Francis Dam began in December 1922. Clearing of the site and construction began without any of the usual fanfare for a municipal project of this nature. The Los Angeles Aqueduct had become the target of frequent sabotage by angry farmers and landowners in the Owens Valley and the city was eager to avoid any repeat of these expensive and time-consuming repairs.

The St. Francis, sometimes referred to as the San Francisquito, was only the second concrete dam to be designed and built by the Bureau of Water Works and Supply. The first was the nearly dimensionally identical Mulholland Dam, on which construction had begun one year earlier. The design of the St. Francis was in fact an adaptation of the Mulholland Dam with certain changes which were made so as to suit the location. Most of the design profiles and computation figures of stress factors for the St. Francis came from this adaptation of the plans and formulas which had been used in the constructing of Mulholland Dam. This work was done by the Engineering department within the Bureau of Water Works and Supply. [16] [17]

In describing the shape and type of the St. Francis Dam the word curved is used although, by today's standards, due to the amount of curve in its radius, the dam would be considered arched and therefore making it of the gravity-arch design. It is not so called because the science of gravity-arch dams was still in its infancy and little was known in the engineering community about the arch effect, how it worked and how loads were transmitted, other than that it did help with stability and support. As such, the dam was designed without any of the additional benefits given by the arch action, which led to its profile being considered conservative given its size. [18] [19]

Annually, as did most other city entities, the Bureau of Water Works and Supply and the ancillary departments reported to the Board of Public Service Commissioners on the prior fiscal year's activities. From these we know that the preliminary studies of the area which became the site of the dam, and topographical surveys for the St. Francis reservoir and dam, were completed by June 1923. They called for a dam built to the elevation of 1,825 ft (556 m) above sea level, which is 175 ft (53 m) above the stream bed base. These early calculations for a reservoir created by the dam revealed it would have a capacity of approximately 30,000 acre⋅ft (37,000,000 m 3 ) [20] [21]

On July 1, 1924, the same day Mulholland was to submit his annual report to the Board of Public Service Commissioners, Office Engineer W. W. Hurlbut informed him that all of the preliminary work on the dam had been completed. In his report presented to the Board, Mulholland wrote that the capacity of the reservoir would be 32,000 acre-feet ( 39,000,000 m 3 ). Hurlbut, who also presented the Board with his annual report, Report of the Office Engineer gave a clarification for this change from the prior year's estimate. In his report he wrote that

. at the St. Francis Reservoir the dam site has been cleared and the foundation trench started. All concrete placing equipment has been contracted for and it is expected actual work of pouring the concrete will start in approximately ninety days. Additional topographic surveys have been completed and disclose a storage capacity of 32,000 acre feet at elevation 1825 feet above sea level.

Construction of the dam itself began five weeks later, in early August, when the first concrete was poured. [22] [23]

In March 1925, prior to Mulholland's report to the Board of Public Service Commissioners, Office Engineer Hurlbut again reported to Mulholland on the progress of the St. Francis Dam and reservoir. He stated the reservoir would now have a capacity of 38,000 acre-feet ( 47,000,000 m 3 ) and that the dam's height would be 185 feet (56 m) above stream bed level. Hurlbut wrote, in an explanation of these changes that was presented to the Board of Public Service Commissioners, that

Additional surveys and changes in the plans for this reservoir have disclosed the fact that at crest elevation of 1835 feet above sea level the reservoir will have a capacity of 38,000 acre-feet. [24] [25]

This 10-foot (3.0 m) increase in the dam's height over the original plan of 1923 necessitated the construction of a 588-foot (179 m) long wing dike along the top of the ridge adjacent to the western abutment in order to contain the enlarged reservoir. [26]

A distinctive aspect of the St. Francis Dam was its stepped downstream face. While the height of each step was a constant 5 feet (1.5 m), the width of each step was unique to its respective elevation above sea level. This width varied between 5.5 feet (1.7 m) near the stream bed base at 1,650 feet (500 m) and decreased to 1.45 feet (0.44 m) at an elevation of 1,816 feet (554 m), the base of the spillways and upright panels. [27]

When completed on May 4, 1926, the stairstep faced dam rose to a height of 185 feet above the canyon floor. Both faces leading up to the crest were vertical for the final 23 feet (7.0 m). On the downstream face, this vertical section was fashioned into 24 feet (7.3 m) wide sections. A portion of these made up the spillway, which consisted of 11 panels in total divided into two groups. Each spillway section had an open area that was 18 inches (46 cm) high and 20 feet (6.1 m) wide for the overflow to pass. The dam also had five 30-inch (76 cm) diameter outlet pipes through the center section which were controlled by slide gates attached to the upstream face.

Water began to fill the reservoir on March 12, 1926. [28] It rose steadily and rather uneventfully, although several temperature and contraction cracks did appear in the dam and a minor amount of seepage began to flow from under the abutments. In accord with the protocol for design, which had been established by the engineering department during construction of the Mulholland dam, no contraction joints were incorporated. [29] The most notable incidents were two vertical cracks that ran down through the dam from the top. One was approximately fifty-eight feet west of the outlet gates and another about the same distance to the east. Mulholland, along with his Assistant Chief Engineer and General Manager Harvey Van Norman, inspected the cracks and leaks and judged them to be within expectation for a concrete dam the size of the St. Francis.

At the beginning of April, the water level reached the area of the inactive San Francisquito Fault line in the western abutment. Some seepage began almost immediately as the water covered this area. Workers were ordered to seal off the leak, but they were not entirely successful and water continued to permeate through the face of the dam. A two-inch pipe was used to collect this seepage and was laid from the fault line down to the home of the dam keeper, Tony Harnischfeger, which he used for domestic purposes. Water that collected in the drainage pipes under the dam to relieve the hydrostatic uplift pressure was carried off in this manner as well. [30]

In April 1927 the reservoir level was brought to within ten feet of the spillway, and during most of May the water level was within three feet of overflowing. There were no large changes in the amount of the seepage that was collected and, month after month, the pipe flowed about one-third full. This was an insignificant amount for a dam the size of the St. Francis, and on this subject Mulholland said, "Of all the dams I have built and of all the dams I have ever seen, it was the driest dam of its size I ever saw." The seepage data recorded during the 1926–1927 period shows that the dam was an exceptionally dry structure. [30]

On May 27 the problems in the Owens Valley escalated once again with the dynamiting of a large section of the Los Angeles Aqueduct, part of the California Water Wars. A second incident took place a few days later which destroyed another large section. In the days that followed, several more sections of the aqueduct were dynamited which caused a complete interruption of the flow. The near-full reservoir behind the St. Francis Dam was the only source of water from the north and withdrawals began immediately. [31]

During this time, the Los Angeles Sheriff's Department received an anonymous phone call that a carload of men were on their way from Inyo County with the intention of dynamiting the St. Francis Dam and "to get some officers on the way as quick as possible." [32] [31] Within minutes, all personnel of the Bureaus of Power and Light and Water Works and Supply either working or residing within the canyon had been notified. Cars carrying dozens of officers from both the Los Angeles Police and Sheriff's Department rushed to the area. Although no sign of the threat that brought all this about materialized, for many days after the canyon resembled an armed camp. [31]

The Daily Record of High Water Elevations of the St. Francis Dam shows that between May 27 and June 30 alone, 7000 to 8000 acre-feet of water was withdrawn. Through June and July the Owens Valley fight continued, as did interruptions in the flow from the aqueduct. This in turn caused continued withdrawals from the reservoir. [31]

In early August, opposition to Los Angeles' water projects collapsed after the indictment of its leaders for embezzlement. The city subsequently sponsored a series of repair and maintenance programs for aqueduct facilities that stimulated local employment. [33] [34]

Once again, the St. Francis reservoir level rose, although not without incident. Late in the year a fracture was noticed which began at the western abutment and ran diagonally upwards and toward the center section for a distance. As with others, Mulholland inspected it, judged it to be another contraction crack and ordered it filled with oakum and grouted to seal off any seepage. At the same time another fracture appeared in a corresponding position on the eastern portion of the dam, starting at the crest near the last spillway section and running downward at an angle for sixty-five feet before ending at the hillside. It too was sealed in the same manner. Both of these fractures were noted to be wider at their junction with the hillside abutments and narrowed as they angled toward the top of the dam. [35]

The reservoir continued to rise steadily until early February 1928, when the water level was brought to within one foot of the spillway. During this time though, several new cracks appeared in the wing dike and new areas of seepage began from under both abutments. [36]

Near the end of February, a notable leak began at the base of the wing dike approximately 150 feet (46 m) west of the main dam. It was discharging about 0.60 cubic feet per second (4.5 U.S. gallons, or 17 liters, per second) and was inspected by Mulholland who judged it to be another contraction or temperature crack and left it open to drain. During the first week of March, it was noticed that the leak had approximately doubled. Due in part to some erosion taking place, Mulholland ordered an eight-inch (20.3 cm) concrete drain pipe to be installed. The pipe led the water along the dike wall, discharging it at the west abutment contact with the main dam. [37]

This gave the hillside a very saturated appearance, and the water flowing down the steps of the dam where it abutted the hill caused alarm among the canyon residents and others traveling on the road 700 feet (210 m) to the east, as at that distance it appeared the water was coming from the abutment. On March 7, 1928, the reservoir was three inches below the spillway crest and Mulholland ordered that no more water be turned into the St. Francis. [38]

On the morning of March 12, while conducting his usual inspection of the dam, the dam keeper discovered a new leak in the west abutment. Concerned not only because other leaks had appeared in this same area in the past but more so that the muddy color of the runoff he observed could indicate the water was eroding the foundation of the dam, he immediately alerted Mulholland. After arriving, both Mulholland and Van Norman began inspecting the area of the leak. Van Norman found the source and by following the runoff, determined that the muddy appearance of the water was not from the leak itself but came from where the water contacted loose soil from a newly cut access road. The leak was discharging 2 to 3 cubic feet (15 to 22 U.S. gallons, or 57 to 85 liters) per second of water by their approximation. Certainly their concern was heightened not only given its location but more so in that at times the volume being discharged was inconsistent, they later testified at the Coroner's Inquest. Twice as they watched, an acceleration or surging of the flow was noticed by both men. [39] [40] Mulholland felt that some corrective measures were needed although this could be done at some time in the future. [41]

For the next two hours Mulholland, Van Norman and Harnischfeger inspected the dam and various leaks and seepages, finding nothing out of the ordinary or of concern for a large dam. With both Mulholland and Van Norman convinced that the new leak was not dangerous and that the dam was safe, they returned to Los Angeles. [41] [42]

Two and a half minutes before midnight on March 12, 1928, the St. Francis Dam catastrophically failed.

There were no surviving eyewitnesses to the collapse, but at least five people passed the dam less than an hour before without noticing anything unusual. The last, [43] [44] Ace Hopewell, a carpenter at Powerhouse No. 1 , rode his motorcycle past the dam about ten minutes before midnight. He testified at the Coroner's Inquest that he had passed Powerhouse No. 2 without seeing anything there or at the dam that caused him concern. He stated that at approximately one and one-half miles (2.4 km) upstream he heard above his motorcycle's engine noise, a rumbling much like the sound of "rocks rolling on the hill." He stopped and got off, leaving the engine idling, and smoked a cigarette while checking the hillside above him. The rumble that had caught his attention earlier had begun to fade behind him. Assuming that it might have been a landslide, as these were common in the area, and satisfied that he was in no danger, he continued on. At the Bureau of Power and Light at both Receiving Stations in Los Angeles and the Water Works and Supply at Powerhouse No. 1 there was a sharp voltage drop at 11:57:30 p.m. [45] Simultaneously, a transformer at Southern California Edison's Saugus substation exploded, a situation investigators later determined was caused by wires up the western hillside of San Francisquito canyon about ninety feet above the dam's east abutment shorting. [46] [27]

Given the known height of the flood wave, and that within seventy minutes or less after the collapse the reservoir was virtually empty, the failure must have been sudden and complete. Seconds after it began, little of what had been the dam remained standing, other than the center section and wing wall. The main dam, from west of the center section to the wing wall abutment atop the hillside, broke into several large pieces, and numerous smaller pieces. All of these were washed downstream as 12.4 billion gallons (47 million m³) of water began surging down San Francisquito Canyon. The largest piece, weighing approximately 10,000 tons (9,000 metric tons) was found about three-quarters of a mile (1.2 km) below the dam site. [47]

Somewhat similarly, the dam portion east of the center section had also broken into several larger and smaller pieces. Unlike the western side, most of these ended lying near the base of the standing section. The largest fragments fell across the lower portion of the standing section, coming to rest partially on its upstream face. Initially, the two remaining sections of the dam remained upright. As the reservoir lowered, water undercut the already undermined eastern portion, which twisted and fell backwards toward the eastern hillside, breaking into three sections. [47]

The dam keeper and his family were most likely among the first casualties caught in the initially 140 feet (43 m) high flood wave, which swept over their cottage about a quarter of a mile (400 m) downstream from the dam. The body of a woman who lived with the family was found fully clothed and wedged between two blocks of concrete near the base of the dam. This led to the suggestion she and the dam keeper may have been inspecting the structure immediately before its failure. Neither his nor his six-year-old son's bodies were found. [48]

Five minutes after the collapse, the then 120-foot-high (37 m) flood wave had traveled one and one-half miles ( 2.4 km ) at an average speed of 18 miles per hour (29 km/h), destroying the heavy concrete Powerhouse No. 2 there and taking the lives of 64 of the 67 workmen and their families who lived nearby. This cut power to much of Los Angeles and the San Fernando Valley. It was quickly restored via tie-lines with Southern California Edison Company, but as the floodwater entered the Santa Clara riverbed it overflowed the river's banks, flooding parts of present-day Valencia and Newhall. At about 12:40 a.m. Southern California Edison's two main lines into the city were destroyed by the flooding, re-darkening the areas that had earlier lost power, and spreading the outage to other areas served by Southern California Edison. Nonetheless power to most of the areas not flooded was restored with power from Edison's Long Beach steam electric generating plant. [49]

Near 1:00 a.m. the mass of water, then 55 ft (17 m) high, [50] followed the river bed west and demolished Edison's Saugus substation, cutting power to the entire Santa Clara River Valley and parts of Ventura and Oxnard. At least four miles of the state's main north–south highway was under water and the town of Castaic Junction was being washed away. [51]

The flood entered the Santa Clarita valley at 12 mph (19 km/h). Approximately five miles downstream, near the Ventura–Los Angeles county line, a temporary construction camp the Edison Company had set up for its 150-man crew on the flats of the river bank was hit. In the confusion, Edison personnel had been unable to issue a warning and 84 workers perished. [52]

Shortly before 1:30 a.m. , a Santa Clara River Valley telephone operator learned from the Pacific Long Distance Telephone Company that the dam had failed. She called a California Highway Patrol officer, then began calling the homes of those in danger. The CHP officer went from door to door warning residents about the imminent flood. At the same time, a deputy sheriff drove up the river valley, toward the flood, with his siren blaring, until he had to stop at Fillmore. [44]

The flood heavily damaged the towns of Fillmore, Bardsdale, and Santa Paula, before emptying both victims and debris into the Pacific Ocean 54 miles (87 km) downstream south of Ventura at what is now the West Montalvo Oil Field around 5:30 a.m. , at which point the wave was almost two miles ( 3 km ) wide and still traveling at 6 mph (9.7 km/h).

Newspapers across the country carried accounts of the disaster. The front page of the Los Angeles Times ran four stories, including aerial photos of the collapsed dam and the city of Santa Paula. A Times Flood Relief Fund was set up to receive donations, mirrored by similar efforts by other publications. [ citation needed ] In a statement Mulholland said, "I would not venture at this time to express a positive opinion as to the cause of the St. Francis Dam disaster. Mr. Van Norman and I arrived at the scene of the break around 2:30 a.m. this morning. We saw at once that the dam was completely out and that the torrential flood of water from the reservoir had left an appalling record of death and destruction in the valley below." [53] Mulholland stated that it appeared that there had been major movement in the hills forming the western buttress of the dam, adding that three eminent geologists, Robert T. Hill, C. F. Tolman and D. W. Murphy, had been hired by the Board of Water and Power Commissioners to determine if this was the cause. It was noted that no tremors had been reported at seismograph stations, ruling out an earthquake as the cause of the break. [ citation needed ]

There were at least a dozen separate investigations into the collapse. With unprecedented speed, eight of these had begun by the weekend following the collapse. Almost all of these involved investigative panels of prominent engineers and geologists. The more notable of these groups and committees were those sponsored by California governor C. C. Young, headed by A. J. Wiley, the renowned dam engineer and consultant to the U.S. Bureau of Reclamation's Boulder (Hoover) Dam Board the Los Angeles City Council, which was chaired by the Chief of the Reclamation Service, Elwood Mead the Los Angeles County coroner, Frank Nance and Los Angeles County District Attorney Asa Keyes. Others were convened: the Water and Power Commissioners started their own inquiry, as did the Los Angeles County Board of Supervisors who hired J. B. Lippincott. The Santa Clara River Protective Association employed the geologist and Stanford University professor emeritus, Dr. Bailey Willis, and eminent San Francisco Civil Engineer and past president of the American Society of Civil Engineers, Carl E. Grunsky. There were others, such as the railroad commission and several political entities who only sent investigators or representatives. [54]

Although they were not unanimous on all points, most commissions quickly reached their respective conclusions. The governor's commission met on March 19 and submitted their 79-page report to the governor on March 24, five days later, and only eleven days after the early-morning March 13 flood. Although this may have been sufficient time to answer what they had been directed to determine, they had been deprived of the sworn testimony at the Coroner's Inquest which was scheduled to be convened March 21, the only inquiry that took into consideration factors other than geology and engineering. [55]

The need for nearly immediate answers was understandable, having its roots in the Swing–Johnson Bill in Congress. This bill, which had first been filed in 1922, and failed to be voted on in three successive Congresses, was again before Congress at the time. This bill ultimately provided the funding for constructing the Hoover Dam. Supporters and responsible leaders alike realized the jeopardy in which the bill then stood. Although the water and electricity from the project were needed, the idea of the construction of such a massive dam of similar design, which would create a reservoir seven hundred times larger than the St. Francis, did not sit well with many in light of the recent disaster and the devastation. [56] The bill was passed by Congress, and signed into law by President Coolidge on December 21, 1928. [57] [58]

The governor's commission was the first to release its findings, titled Report of the Commission appointed by Governor C. C. Young to investigate the causes leading to the failure of the St. Francis dam near Saugus, California. The report became the most widely distributed analysis. Along with most of the other investigators, they perceived the new leak as the key to understanding the collapse, although the commission believed that "the foundation under the entire dam left very much to be desired." The report stated, "With such a formation, the ultimate failure of this dam was inevitable, unless water could have been kept from reaching the foundation. Inspection galleries, pressure grouting, drainage wells and deep cut-off walls are commonly used to prevent or remove percolation, but it is improbable that any or all of these devices would have been adequately effective, though they would have ameliorated the conditions and postponed the final failure." [59] They placed the cause of the failure on the western hillside. "The west end," the commission stated, "was founded upon a reddish conglomerate which, even when dry, was of decidedly inferior strength and which, when wet, became so soft that most of it lost almost all rock characteristics." The softening of the "reddish conglomerate" undermined the west side. "The rush of water released by failure of the west end caused a heavy scour against the easterly canyon wall . and caused the failure of that part of the structure." There then "quickly followed . the collapse of large sections of the dam." [60]

The committee appointed by the Los Angeles City Council, for the most part concurred in attributing the collapse to "defective foundations", and wrote, "The manner of failure was that the first leak, however started, began under the concrete at that part of the dam which stood on the red conglomerate this leak increased in volume as it scoured away the foundation material already greatly softened by infiltrated water from the reservoir which removed the support of the dam at this point and since no arch action could occur by reason of the yielding conglomerate abutment, made failure of the dam inevitable." Likewise, they concluded the failure most likely followed a pattern similar to that which was proposed by the governor's commission, although they did acknowledge that "the sequence of failure is uncertain." [61]

The committee ended their report with, ". having examined all the evidence which it has been able to obtain to date reports its conclusions as follows:


Worst Bridge Disasters In History

Angers Bridge

Angers Bridge, also known the Basse-Chaîne Bridge, was a suspension bridge constructed over the Maine River located in Angers, France. The bridge was designed by Joseph Charley and Bordilion and was constructed between 1836 and 1839. The bridge collapsed on April 16, 1850 when a troop of French soldiers were marching across. The collapsed bridge claimed the lives of 226 people. The bridge stretched over 335 feet with two wire cables that carried a deck 24 feet wide and towers that were made of cast iron columns 17.9 feet tall.

Veligonda Railway Bridge

The Veligonda Railway Bridge collapsed on October 29, 2005 near the town of Veligonda, India when a small rail bridge was swept away by flash floods. The nighttime train was full of passengers visiting their families for the holiday of Diwali. The rail line was swept away when a humongous irrigation tank ruptured resulting in floods down the railway lines. The train derailed on the broken section claiming the lives of 114 passengers and injuring more than 200. The area had been experiencing heavy rainfall before the accident thus some the roads were destroyed which profoundly hampered rescue attempts.

Point Ellice Bridge

The Point Ellice Bridge disaster occurred on May 26, 1896 in Victoria, British Columbia when a streetcar cramped with 143 holidaymakers crashed on Point Ellice and collapsed into the upper harbor. The 143 passengers were on their way to attend Queen Victoria's birthday celebrations when the accident happened claiming the lives of 55 men, women, and children.The accident was marked as one of the worst transit disasters to occur in British Columbia. However, only the left side passengers of the streetcar were able to escape death. The tramway operator was found at fault on June 12, 1896 due to irresponsibility since the tramcar was loaded with a heavier weight than the bridge could support. Victoria's City Council was also found at fault regarding negligence since the bridge was also not well maintained and safety limits were not properly observed. The bridge's design and construction were also discovered to be poor thus playing a role in the disaster.

Whangaehu River Rail Bridge

The Tangiwai disaster occurred on December 24, 1953 at exactly 22:21 hours when the Whangaehu River Bridge collapsed crashing an express passenger train at Tangiwai, New Zealand.The train was on its way to Auckland from Wellington when the disaster occurred. The train and the first of its six carriages crashed into the river claiming the lives of 151 passengers. The disaster was caused due to the collapsing of the Tephra Dam that was holding back Mount Ruapehu's Crater Lake which burst destroying the piers at Tangiwai Bridge just a moment before the train reached the bridge. The Tangiwai disaster is one of the worst rail accidents to ever occur in New Zealand.


Water Warning: The Looming Threat of the World’s Aging Dams

Tens of thousands of large dams across the globe are reaching the end of their expected lifespans, leading to a dramatic rise in failures and collapses, a new UN study finds. These deteriorating structures pose a serious threat to hundreds of millions of people living downstream.

Who would want to live downstream of the 125-year-old Mullaperiyar Dam, nestled in a seismic zone of the Western Ghats mountains in India? The 176-foot-high relic of British imperial engineering cracked during minor earthquakes in 1979 and 2011. According to a 2009 study by seismic engineers at the Indian Institute of Technology, it might not withstand a strong earthquake larger than 6.5 on the Richter scale.

Three million people live downriver of the dam. But their demands for it to be emptied are held up by a long-running legal case in the nation’s Supreme Court between Kerala, the state under threat, and Tamil Nadu, the state upstream that operates the dam to obtain irrigation water and hydropower.

Or how about living below the Kariba Dam, built by the British on the Zambezi River in Southern Africa 62 years ago? Back then, it was seen as Africa’s equivalent of the Hoover Dam. But in 2015, engineers found that water released through its floodgates had gouged a hole more than 260 feet deep in the river bed, causing cracks and threatening to topple the concrete dam, which is 420 feet high and holds back the world’s largest artificial lake.

Downstream are some 3.5 million people, as well as another giant dam, the Cahora Bassa in Mozambique, that engineers fear would probably break if hit by floodwater from a Kariba failure. Despite the urgency, the $300-million repair work won’t be finished until 2023 at the earliest.

Both dams exemplify the potentially dangerous mix of structural decay, escalating risk, and bureaucratic inertia highlighted in a pioneering new study into the growing risks from the world’s aging dams, published in January by the United Nations University (UNU), the academic and research arm of the UN. It warns that a growing legacy of crumbling dams past their design lives is causing a dramatic increase in dam failures, leaks, and emergency water releases that threaten hundreds of millions of people living downstream. Meanwhile, safety inspectors cannot keep up with the workload.

The 20th century was a boom time for dam builders. The peak, particularly in Asia, was from the mid-1950s to mid-1980s, when dams were in vogue to generate hydroelectricity and store water to irrigate crops and keep taps flowing, as well as to smooth out river flow to prevent flooding and improve navigation.

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But the boom is over. “A few decades ago, a thousand large dams were being built each year now it is down to a hundred or so,” report co-author Vladimir Smakhtin of the UNU’s Institute of Water, Environment, and Health in Hamilton, Canada told Yale Environment 360. Most sites sought by dam engineers, such as in narrow valleys, have been plugged. Dams now barricade the majority of the world’s rivers, and can store the equivalent of a sixth of their total annual flow. Meanwhile, environmental and social concerns about flooding land and wrecking river ecosystems have grown, and there are many alternatives for generating low-carbon energy, says Smakhtin.

A helicopter drops sandbags onto the 188-year-old Toddbrook Dam in England after a spillway collapse forced a nearby town to evacuate in 2019. Leon Neal/Getty Images

So the world’s stock of large dams, defined as those higher than 15 meters (49 feet), is aging fast. The World Bank estimated last year that there are already 19,000 large dams more than 50 years old, which the UNU study concludes is the typical lifespan before it needs major repairs or removal.

Britain and Japan have the oldest dams, averaging 106 and 111 years old respectively. U.S. dams average 65 years. But China and India, the epicenters of the mid-20th century dam-building craze, are not so far behind, with average ages of their 28,000 large dams now 46 and 42 years respectively. “By 2050, most of humanity will live downstream of large dams built in the 20th century” that are “at increasing risk of failure,” the UNU report says.

This burgeoning legacy of aging dams poses ever-growing safety risks, as their structures become more fragile and climate change increases stresses on them by increasing extreme river flows, says Smakhtin. The report finds a steep increase in the rate of dam failures since 2005. There is no global database, says co-author Duminda Perera, also of UNU. But he found reports of more than 170 failures between 2015 and 2019, whereas prior to 2005 the average was below four per year.

Just last month, Zambia’s Kandesha Dam, built in the 1950s, collapsed in heavy rains, displacing thousands of people. Last June, a 55-year-old irrigation dam in China’s Guangxi region gave way, after its 492-foot wall was swamped in heavy rain. A month earlier, two old dams in Michigan collapsed during heavy rain — the 96-year-old Edenville Dam on the River Tittabawassee unleashed a flood that demolished the 94-year-old Sanford Dam downstream.

In August 2019, one of Britain’s oldest dams almost failed. Around 1,500 inhabitants of the town of Whaley Bridge were ordered out of their homes after the flood spillway on the 188-year-old Toddbrook Dam, built to supply water to a canal, collapsed in heavy rains, spilling water that began to eat away at the dam itself, raising fears that the structure would collapse and engulf the town.

In 2017, a spillway collapsed at the 50-year-old Oroville Dam in California’s Sierra Nevada foothills. It caused the evacuation of around 180,000 people. The 770-foot dam is the highest in the U.S. and, after repairs to the spillway, remains critical to the state’s water supply.

Dam engineers say the greatest threats for the coming decades are probably in China and India. Both countries have in the past suffered dam failures that killed tens of thousands. In 1979, the disintegration of the Machchhu Dam in Gujarat, India, during a flood, killed as many as 25,000 people.

Four years before, the Banqiao Dam in Henan, China, burst, sending a wave of water 7 miles wide and 20 feet high downriver at 30 miles per hour. It killed an estimated 26,000 people directly, including the entire population of the town of Daowencheng. As many as 170,000 more died during an ensuing famine and epidemics. The disaster has been called the deadliest structural failure in history. It was kept a state secret for many years.

Water is released from the Sanmenxia Dam in Henan Province, China in 2019 to prevent the dam from overflowing. Sun Meng/VCG via Getty Images

Both these disasters involved young dams, aged 20 and 23 years respectively. Still, their demise suggests there may be many more ticking timebombs from that era.

China has around 24,000 large dams. Many date from the days of the Cultural Revolution, when Maoist ideology trumped engineering prowess in the dash for economic development. A third of the country’s dams were “considered to be of high-level risk because of structural obsolescence and/or lack of proper maintenance,” a 2011 analysis by Meng Yang, now of the Huazhong University of Science and Technology, found.

In India, the director of the Central Water Commission, Jade Harsha, warned in 2019 that the country would have more than 4,000 large dams above the age of 50 by 2050. More than 600 are already half a century old. Dams that India’s first Prime Minister Jawaharlal Nehru in 1954 called “the temples of India, where I worship,” are now aging edifices whose safety Harsha now sees as “blind spots in India’s water policies.”

The World Bank agrees. Last December, it announced a $250-million loan to India for an ongoing project to “strengthen dam safety,” with better inspections and management of the country’s large dams, which hold back 240 million acre-feet of water — starting with 120 of the country’s aging dam fleet.

Martin Wieland, chair of the committee on seismic aspects of dam design at the Paris-based International Commission on Large Dams, the leading body of dam professionals, told Yale e360 that “many dams could last much longer than 50 or 100 years if well designed, well-constructed, and well-maintained and monitored. The oldest concrete dam in Europe, the Maigrauge Dam [in Switzerland] was completed in 1872 and is expected to reach 200 years.” But, he said, “the safety of a dam may deteriorate very fast.” He suggested a large part of the growing risk was “not aging, but the increased number of people downstream.”

Dams are mostly made of earth, masonry, or concrete. They can fail because of decaying concrete, cracking, seepage, hidden fissures in surrounding rocks, or buckling under their own weight. They can suffer lining failures, earthquakes, sabotage, or being washed away when floods breach their crests. Regular inspections are vital, says Wieland.

But there is growing concern worldwide about a lack of inspectors capable of assessing the risk from aging dams, leading to backlogs of inspections and hazards that are missed. An investigation after the failure of the Oroville Dam in the United States found that past inspections had failed to spot structural flaws. As Wieland puts it: “Not everything is visible or measurable.”

Many old dams are now being abandoned as their reservoirs fill with sediment dropped by the rivers they barricade. An international study in 2014 headed by G. Mathias Kondolf of the University of California, Berkeley, estimated that more than a quarter of the total sediment flow of the world’s rivers is being trapped behind dams.

On the Yellow River in China, the world’s siltiest river, the Sanmenxia Dam filled in just two years. India’s reservoirs are losing almost 1.6 million acre-feet of water-storage capacity each year due to sediment build-up, according to officials.

The accumulation of sediment makes dams less useful, but sometimes also makes them more dangerous. This is because with less reservoir space, the dams are at greater risk of being overwhelmed during heavy rains. To save their structures, operators are more likely to make abrupt emergency releases down spillways at the height of floods.

After Hurricane Mitch ripped through Central America in 1998, several hundred people died in their beds in the Honduran capital of Tegucigalpa when a “wall of water” rushed through the city’s poor riverside communities. Investigators from the U.S. Geological Survey concluded that the “wall” appeared when operators of the city’s two main dams made emergency releases at the height of the flood. The two dams were built only in the 1970s, but had lost much of their capacity to siltation.

Workers assess damage following the collapse of a spillway at the 50-year-old Oroville Dam in California in 2017. Florence Low / California Department of Water Resources

Meanwhile, climate change, which is bringing more extreme floods to many places, and aging dams threaten to be a lethal combination. “Old dams were designed and built on the basis of hydrological records in a pre-climate change era,” says Smakhtin. “Now things are different, and this is worrying.”

What should be done? Some aging dams remain safe, but all will require much more rigorous inspection as they grow older, experts say, often followed by expensive repairs. Many more will need to be reengineered to cope with extreme river flows different from those envisaged when they were first built.

But the UNU report points to a growing legacy of dams that cease to serve much purpose — either because of siltation or because there are alternative sources of electricity — and are retained mostly because removing them is expensive and technically difficult. This is both a safety threat and a tragedy for river ecosystems that could be restored by their removal.

The U.S. is the world leader in decommissioning dams, with more than a thousand removed over the past 30 years. But even so, its dams removed to date have mostly been small, usually less than 16 feet in height. An exception was the 87-year-old Glines Canyon Dam in Olympic Park, Washington, removed in 2014. At 210 feet, the dam was the largest ever taken down. The task took two decades to plan and execute. But thousands more such removals are likely to be necessary to prevent an upsurge of dam disasters, says Smakhtin.

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“Some dams are so big it is difficult to imagine how to approach the problem,” he says. “Look at the Kariba dam. It is absolutely huge, and by mid-century, it will be a hundred years old. Hopefully there will by then be technology to decommission it. But right now we don’t know how to do it.”


Top 15 Worst Dam Disasters Ever

Human civilization has progressed a great deal in all scientific fields during its journey from the Stone Age to the scientific era. However, with all its achievements, mankind is far from infallible. Dams are created by highly talented engineers with claims that these buildings are built to stay for centuries to come. However, time and again dams have collapsed and some of them have resulted in major disasters. Here is a list of 15 of the world’s worst dam disasters ever:

15. Kelly Barnes Dam Disaster – United States (1977)

Kelly Barnes dam was located in Stephens County, Georgia. It was specifically designed to serve as a reservoir for the production of hydroelectricity. The dam was modified many times based upon the requirements but was never declared to be in the safest possible state. On November 6, 1977, after a series of heavy rain and floods, the dam failed.

The walls were believed to be strong but the rain severely affected them and so about 777090 m 3 of water was released which traveled several miles and caused immense structural damage.

14. Lower Otay Dam Disaster – United States (1916)

The Lower Otay Dam constructed on Otay River is situated in San Diego County, California, United States. Its purpose was to serve as a large water reservoir.

In January 1916, after a heavy rain spell hit on the southern region of California, the dam topped up and started releasing water. Unfortunately, no proper rescue measures were taken and the reservoir emptied causing great damage in the nearby areas.

13. Edersee Dam Destruction – Germany (1943)

The Edersee dam was built over the Eder River in northern Hesse, Germany. The dam was completed in 1914 with the purpose of satisfying the electrical power needs of the area.

The dam was running fine until May 17, 1943, when it got bombed by the British Lancaster bombers because of World War II. The bombs completely destructed the dam structure and within minutes the whole reservoir turned empty. The water that flew the nearby areas caused major structural damage.

12. Shakidor Dam Failure – Pakistan (2005)

Shakidor Dam was constructed in 2003 near Pasni, Balochistan province, Pakistan. It was a small-scale dam and was constructed for providing water for irrigation.

Due to excessive rainfall and floods in February 2005 in the region, the dam collapsed and released a massive amount of water, and carried away a large number of nearby areas straight into the Arabian Sea.

11. The Buffalo Creek Flood – United States (1972)

In 1972, Pittston Coal Company built a small dam for the storage of the coal slurry impoundment. It was located on a hillside in Logan Country, West Virginia, USA. The constructors defined the state of the dam to be satisfactory and it was believed to be completely fit for storing a large amount of coal waste.

On February 26, 1972, the dam collapsed unexpectedly and a total of 500000 m 3 of coal slurry completely destroyed the surroundings. All the 16 coal mining hamlets in Buffalo Creek Hollow were affected by the 30 ft. high waves of black wastewater.

10. Mill River Dam Collapse – United States (1874)

Mill River dam was built on the Mill River in Williamsburg, Massachusetts, United States. The constructing party of the dam went through severe challenges to construct the dam. A lot of major changes to be made in the design of the dam were denied because of improper funding and hence the dam was believed by the engineers not to stand for long. No action was taken, however.

In May 1874, while the water reservoir was full, the dam failed and 600 million gallons of water were released instantaneously which completely destroyed four nearby towns.

9. Gleno Dam Failure – Italy (1923)

The Gleno dam was situated in the Valle di Scalve in the Northern Province of Bergamo, Italy. The dam was initially planned to be a gravity dam but later, due to financial issues, it was made as a multiple-arch dam. Due to the poor construction methodologies, the arches were fairly weaker than how they should’ve been.

The foundations of the dam were also believed to be made of the same weak material but nothing was done to make it stronger.

On December 1, 1923, the dam cracked spilling over 4.5 million m 3 of water in the surrounding areas which were completely eradicated from the map, all because of poor judgment and lack of proper funds.

8. Malpasset Dam Disaster – France (1959)

The Malpasset Dam was built on the Reyran River located on the French Riviera in the southern portion of France. In 1959, some cracking noises were heard near the dam wall but due to the technical inability, they couldn’t be properly analyzed.

On December 2, 1959, the dam was breached and the entire wall collapsed into pieces. Waves of over 40 meters started flowing across the nearby areas causing heavy fatalities and structural damage.

7. Mina Plakalnitsa Dam Collapse – Bulgaria (1966)

The Mina Plakalnitsa Dam was situated in Vratsa, Bulgaria. The purpose of its make was to control floods and to produce electric power.

In 1966, due to unexplained reasons, the dam collapsed releasing about 450000 m 3 of a mixture of water and mud into the nearby village of Zgorigrad. The water speed and height was enough to completely eradicate a major portion of the village. The death toll as reported by the local news agency was 107 but unofficial estimates put it over 500.

6. Saint Francis Dam Tragedy – United States (1928)

St. Francis Dam was built in 1926. It was located in the San Francisquito Canyon. Due to the geological instability of the canyon walls, cracks started appearing in the walls of the dam. They were surely taken care of but not completely as most of the damages were considered to be ‘normal’ by the engineers and they didn’t decide to give time to that.

However, on March 12, 1928, the walls of the dam couldn’t hold the water and it collapsed and over 47 billion liters of water started flowing down the canyon. Waves of about 43 meters in height started moving towards the nearby areas and caused great damage.

5. Pantano De Puentes Dam Failure – Spain (1802)

The Pantano de Puentes dam (meaning Bridges of Marsh) is situated in Lorca Spain. Little is known about the history and construction of this dam. In 1802, due to heavy rain in the area, the dam’s water level began to rise. Although emergency measures were taken, there seems to be no way how this rain and the flood could have been controlled.

The dam failed and released a considerable amount of water which swiftly spread in the nearby areas causing the destruction of over 1800 houses and 40000 trees.

4. Vajont Dam Failure – Italy (1963)

The Vajont dam, situated in the valley of the Vajont River is among the tallest dams in the world. The dam is though not used but still stands in its perfect form as it never structurally collapsed. The area was often hit by minor earthquakes but it never affected the dam. In October 1963, while the reservoir was being filled with water, an earthquake hit the area and a landslide of about 260 million m 3 collapsed into the reservoir.

In just 45 seconds, the whole of the area immersed into the water, and about 50 million m 3 of water was released from the dam in form of a 250 meters high wave which completely annihilated the nearby villages.

3. South Fork Dam Disaster – United States (1889)

South Fork Dam is situated near South Fork, Pennsylvania United States. The dam’s water was often reported to be leaking at certain portions however to solve the issue, all the engineers did, was filling up the cracked patches with mud and straw. This served the purpose for that time but was definitely not a permanent solution.

However, immense rainfall in May 1889, caused the bases of the dam to weaken. Moreover, the dam was not designed to hold this much water that the rain was adding. So the dam collapsed and over 20 million tons of water was released on May 21, 1889, and it ran several miles downstream. The total damage was estimated to be around $17 million.

2. Machchhu II Dam Collapse – India (1979)

The Machchhu-2 dam was situated on the Machhu river burst. It was located near the small town Morvi in the Rajkot district of Gujarat, India. In August 1979, due to excessive rain and massive flooding, the walls of the dam started to weaken. Due to no appropriate emergency measures, this issue was certainly something no one could control.

Within twenty minutes of the flood, waves of about 10 meters in height started flowing over the nearby areas. In mere minutes, the whole town was gone. This disaster is also known as the Morvi Dam Failure.

1. Banqiao Dam and Shimantan Reservoir Dam Disaster – China (1975)

Soon after the completion of the dam in 1952, cracks started appearing in the sluice gates. The issue was handled on a serious basis under the supervision of Soviet civil engineers and the gates were soon repaired. They used to call the dam ‘Iron Dam’ as it was believed to never take any damage in the future.

In August 1975, after the collision of the Super Typhoon Nina and a cold front, more than a year’s rain fell within 24 hours. The water level in the dam began to rise, and the sediment sluice gates were unable to handle all the water pressure which made the gates collapse instantaneously. As a result, a total of 1.7 billion m 3 of water was released in total at an average velocity of 31 mph which even devastated the land situated thousands of square kilometers away from it.

Disasters are always caused by a chain of mistakes and unfortunate events and the same is true if we analyze the history of dam failures. With the advancement of technology and with the advent of new precautionary measures, dam failures will minimize with time and hopefully, many possible worst dam disasters can be avoided. Did we miss any notable dam-related tragedy in our list of the worst dam disasters of all time? Let us know in the comments below!


Dam collapses in Switzerland, kills 70 - HISTORY

By Eric Fish

On the night of Aug 8, 1975, a line of people frantically piled sandbags atop Henan Province&rsquos Banqiao Dam while being battered by the worst storm ever recorded in the region. They were in a race with the rapidly rising Ru River to save the dam and the millions of people that lay sleeping downstream. It was a race they were about to lose.

Just after 1:00 am, the sky cleared and stars emerged from behind the storm clouds. There was an eerie calm as someone yelled, &ldquoThe water level is going down! The flood is retreating!&rdquo

There was little chance to enjoy that calm. One survivor recalled that a few seconds later it &ldquosounded like the sky was collapsing and the earth was cracking.&rdquo The equivalent of 280,000 Olympic-sized swimming pools burst through the crumbling dam, taking with it entire towns and as many as 171,000 lives.

Today if you ask Chinese outside of Henan what they know about the Banqiao Dam collapse, you&rsquore not likely to hear much. What may have been the deadliest structural failure of all time occurred in an era when the state quickly covered the scale of such catastrophes.

In 2005, 30 years after the collapse, historical records began to open and scholars sought to re-examine the event yet the majority of Chinese are still unaware of the disaster&rsquos scale and the missteps that led to it. As China now embarks on another binge of rapid dam development, some worry that factors which led to Banqiao&rsquos collapse are re-emerging.

The dam was completed in 1952 as part of a campaign to &ldquoHarness the Huai River&rdquo and its tributaries after severe flooding in previous years. During the 1950s, over 100 dams and reservoirs were built just in Zhumadian Prefecture of Henan Province along with Banqiao. When the Great Leap Forward began in 1958, the campaign was held up as a national model to &ldquogive primacy to water accumulation for irrigation."

A hydrologist named Chen Xing warned that an overbuilding of dams and reservoirs could raise the water table in Henan beyond safe levels and lead to disaster. After the Great Leap Forward, many of the projects were re-examined and renovated, but dams continued to go up quickly. From the 1950s to the 1970s, about 87,000 reservoirs were built across the country.

More than 100 additional dams went up in Zhumadian in the 1960s, joining those that had gone up in the previous decade. They created reservoirs that claimed huge tracts of land previously reserved for flood diversion. The irresistible benefits of the dams ultimately drowned out the voices urging restraint.

Today, China is on the cusp of another dam-building binge.

By 2020, the country intends to increase its total energy capacity by nearly 50 percent at the same time it tries to raise the non-fossil fuel proportion of that energy from 9 to 15 percent. With nuclear development being slowed in the wake of Japan&rsquos 2011 Fukushima disaster, dams have been left to do most of the heavy lifting. The 12 th five-year plan calls for the hydropower producing equivalent of seven Three Gorges Dams to be built by 2015.

Nowhere is the aggressive dam push raising more eyebrows than in Southwest China, where dozens of major projects are gearing up. On three river systems &ndash the Nu (Salween), the Lancang (Mekong), and the Yangtse watershed &ndash there are altogether 32 major dams completed. But in coming years those are likely to be joined by over 100 more .

In January, the State Council lifted a ban on major dam projects in the region that was enacted on environmental concerns under Premier Wen Jiabao in 2004. The move has been long awaited by dam developers, some of whom have referred to the last decade as &ldquolost time.&rdquo

While most worries associated with the planned projects focus on environmental effects and dislocation of local residents, serious safety concerns have also been raised. A report by the environmental group Probe International last year said that of the 130 proposed dams on these and other rivers in the region, &ldquo48.2 percent are located in zones of high to very high seismic hazard.&rdquo

The report continues, &ldquoBy constructing more than 130 large dams in a region of known high seismicity, China is embarking on a major experiment with potentially disastrous consequences for its economy and its citizens&rdquo

Earthquakes are only one of the concerns in the mountainous region with unstable terrain. In 2010, a geographically similar part of Gansu Province was hit by landslides that killed nearly 1,500 people. A prolonged drought followed by heavy rains were the official causes of the disaster, but experts like Sichuan-based geologist Fan Xiao believed these factors were exacerbated by deforestation, mining and a binge of dam building that had occurred in the preceding years &ndash issues that also plague Southwest China&rsquos river valleys.

At the time of the landslides, Fan Xiao told South China Morning Post, &ldquoLocal authorities have ignored daunting warnings about the severe consequences of dam-building and viewed dams as their key source of taxation.&rdquo

While officials may see dams as a clean and efficient way to boost local economies, they sometimes also see them as opportunities to line their own pockets.

In recent years the term &ldquotofu construction&rdquo has come into vogue, referring to structures built with substandard materials and unqualified contractors as a result of corruption. Since 2007, China has had at least 19 major bridge collapses resulting in over 140 total deaths. In one case, a collapsed bridge was found to have been built by a blind contractor .

While China&rsquos high-profile Three Gorges Dam was being built there were nearly 100 reported instances of corruption, bribery and embezzlement associated with the project. Most were related to resettlement funds for displaced residents, but at least 16 cases were directly related to construction.

Old dams raise even greater worries. Thousands that were built prior to Reform & Opening Up are still in use, many of which are badly in need of renovation. The central government has said that more than 40,000 dams are at risk of breach and allotted 62 billion yuan to repair them. But that appears to be coming up short and local governments have been unwilling or unable to make up difference.

&ldquoThere are so many endangered dams,&rdquo Zhou Fangping from the Water Resources Department of Guangdong Province told China Economic Weekly in 2011. &ldquoWe have so many rivers to manage and so many irrigation and water conservancy projects. If there&rsquos only one project, we can handle it, but there are so many. So the result is either we promise to complete all the projects but we don&rsquot actually meet the targets, or we finish them all but with sub-standard quality.&rdquo

The China Economic Weekly piece reported that about 15,900 new small-sized dams would be built by the central government by the end of 2013 and 25,000 by local governments before the end of 2015.

As recently as Feb 2 this year, a small dam in Xinjiang collapsed , flooding 70 homes and killing one man. According to a statement by a Water Resources Ministry official in 2006, in a given year around 68 (mostly small) dikes like this collapse in China.

Soon after the Banqiao Dam was completed in 1952, cracks began to emerge. So from 1955-56, the structure was reinforced using Soviet specifications (which the Water Resources Ministry would later admit were inappropriate for the region). After renovations, Banqiao was dubbed the &ldquoIron Dam&rdquo to reflect its newfound invincibility.

However, on Aug 5, 1975, a typhoon collided with a cold front over Henan and dropped the area&rsquos average yearly rainfall in less than 24 hours. The 106 cm of rain that fell that day dwarfed the 30 cm daily limit the dam&rsquos designers had anticipated. Witnesses said that the area was littered with birds that had been pummeled to death by the intense rainfall.

In an effort to mitigate downstream floods that were already severe, Banqiao was ordered not to fully open its sluice gates early in the storm. Then communication lines were knocked out, leaving operators guessing as to how the situation outside was unfolding.

By the time the gates were fully opened, it was too late. Water was rising faster than it could escape. The hydrologist who had warned that the region&rsquos dam building binge was dangerous had also recommended 12 sluice gates be included on Banqiao. In the end, only five had been installed, and even those were partially blocked by accumulated silt when the storm hit.

When the dam collapsed it sent a 50 km/hour tidal wave crashing toward the valley below that would take out 62 other dams like dominos. In minutes, entire villages with thousands of people were wiped off the map.

In a 2010 CCTV documentary, one survivor recalled that moment saying, &ldquoI didn&rsquot know where I was &ndash just floating around in the water, screams and cries ringing in my ears. Suddenly, all the voices died down, leaving me in deadly silence.&rdquo

During the six hours the Banqiao Reservoir took to empty, an estimated 26,000 people were killed, many of whom were sleeping. The downed communication lines had thwarted any chance of a large scale evacuation. Some managed to cling to life by holding onto trees or standing on rooftops, but many of those who survived the initial onslaught would soon wish they hadn&rsquot.


The storm that toppled Banqiao blindsided the dam&rsquos designers, who had only built it to withstand a 1-in-1,000-year flood. For whatever design flaws the structure had, it might have survived if it weren&rsquot for the 1975 flood that was designated a 1-in-2,000 year event.

Today however, such designations are quickly becoming misnomers. What were once considered freak weather occurrences are transitioning to routine events. At a 2012 press conference on coping with urban flood disasters, Wu Zhenghua, a researcher with the Beijing Meteorological Bureau, warned that climate change will bring more frequent heavy precipitation to China.

One of the most dangerous implications is that areas already prone to flooding are likely to see more extreme storm events that local infrastructure isn&rsquot prepared for. These are precisely the areas in Central and Southwest China that are making major dam pushes.

If the big storm ever does hit, a complete communication breakdown like the one that hit Banqiao is very unlikely, thanks to improved technology. But there&rsquos still potential for dangerous communication issues.

Katy Yan, China Program Coordinator of International Rivers, an international conservation group, warns that multiple companies sometimes operate different dams on the same river. &ldquoLack of communication and coordination between these companies and between different water and energy users can often lead to problems, especially during a major drought period,&rdquo she says.

But perhaps the greatest danger of a dam break isn&rsquot the initial disaster itself, but the aftermath.

When the Banqiao reservoir had emptied and the waters had settled on the morning after the collapse, the horror was only beginning. Because dikes had gone unmaintained for years and flood diversion zones had been repurposed, the water had nowhere to drain. Roads were washed out and rescue workers had no way to maneuver. Survivors were left to wait on rooftops or huddled together on small patches of dry land.

They stripped tree branches of leaves and wrangled floating livestock carcasses to eat. Food was airdropped, but much fell in the water and was lost or eaten after it had rotted. Disease spread quickly while people battled hunger and the summer heat. For every person that had been swept to their death in the initial tsunami, it&rsquos estimated at least five died from the famine and plague that followed.

The cascade of dams that had been built on the Huai River and its tributaries to reduce flood risks ultimately made the flooding deadlier and the rescue effort more difficult. The Probe International report warns that this development model is being used again today in China&rsquos southwest and it could have equally disastrous consequences.

&ldquoIf one dam fails, the full force of its ensuing tsunami will be transmitted to the next dam downstream, and so on, potentially creating a deadly domino effect of collapsing dams,&rdquo the report says. &ldquoA cascade of catastrophic dam failures would almost certainly cause an unprecedented number of casualties and deaths in major downstream population centers, such as Chengdu, and along these major river valleys.&rdquo

If such a collapse were to occur today, it could be made more devastating by the chemical industry that&rsquos taken hold along rivers. Li Zechun from the Chinese Academy of Engineering Sciences was present for the aftermath of the Banqiao disaster. In 2005, he told People&rsquos Daily that &ldquoOnce the chemical plants are flooded, the contamination to the environment is immeasurable.&rdquo

And while China&rsquos relief capability has made huge strides since 1975, rescuing those affected from a disaster could still be a major problem. The winding roads on steep mountainsides surrounding rivers in Southwest China experience routine blockages from landslides even without serious rainstorms. After roads were destroyed in the 2008 Sichuan Earthquake, many who&rsquod survived the initial tremors died from blood loss, shock and exposure while stranded in the following days. China&rsquos total helicopter fleet &ndash which was barely one-thousandth the size of the U.S.&rsquos &ndash simply couldn&rsquot be everywhere it was needed.

However, Lu Youmei, the former head of China Three Gorges Corporation who oversaw the Three Gorges Dam project from 1993-2003, says there&rsquos little to worry about in regards to dam safety.

In his Beijing office, the jovial 79-year-old responds to concerns he&rsquos heard many times before. &ldquoEvery dam is considered and designed carefully based on hydrology and the most severe flood in history,&rdquo he said. &ldquoAnd every dam should be able to bear the highest possible level earthquake.&rdquo

He explains that the dam sites are carefully studied to ensure they&rsquore not directly on fault lines. He also points out that the Banqiao Dam was built from clay, whereas new large dams are made with concrete and much more modern technology.

He adds that changing weather patterns are indeed a concern, but one that can easily be addressed. &ldquoIt&rsquos a very slow process maybe 100 years,&rdquo he said about climate change. &ldquoIt is possible that some dams will have no water or too much water in the future. If that happens, we can reconstruct. This isn&rsquot a problem.&rdquo

As for corruption, Lu says that &ldquotofu construction&rdquo isn&rsquot an issue with dam projects either. The corruption cases that were found with the Three Gorges Dam construction mainly involved overpaying contractors, he says, and small and medium-sized dams involve private funding now, which hedges against corruption.

&ldquoI don&rsquot believe there&rsquos no corruption at all,&rdquo he says. &ldquoBut overall, the situation is healthy.&rdquo

Indeed, few experts have voiced serious concerns that a Banqiao-type event could occur again in China. The disaster resulted from a perfect storm of factors that was finally capped by a literal perfect storm during the height of Mao-era China&rsquos overconfidence in its engineering campaigns.

&ldquoCompared with the 1970s, safety measures have certainly improved,&rdquo said Peter Bosshard, policy director of International Rivers. &ldquoBut still, corners are being cut and the environment has become riskier. The geography has become riskier with the move upstream and the risks of climate change are just compounding the natural risks.&rdquo

But whether the concerns are over safety or the environment, they&rsquore unlikely to further thwart the opportunity that developers have been waiting nearly a decade for.

&ldquoWe must proceed,&rdquo Zhang Jinxuan, director of the Nujiang National Development and Reform Commission told the EO in 2011. &ldquoThe resources here are too good. Not to develop is not an option."


PUBLIC INPUT

Immediately after the Federal Investigative Board was formed on November 8, 1977, efforts were undertaken to obtain maximum public involvement. On November 10, a news release announced formation of the Board and solicited old photographs and first-hand knowledge about the dam and its construction history.

On November 14, a second news release was issued by the Board setting up a two-day public meeting at the Georgia Baptist Assembly on November 17-18 in an effort to encourage local people to provide any first-hand knowledge about the incidents leading up to the failure, copies of old photos, details about earlier construction features of the dam, observations on visits to the dam site, or any other knowledge which may provide a broad-based background. Copies of a public notice were sent by mail to every household and business firm in Toccoa and Toccoa Falls.

Attendance at the public meeting was sparse, except for news media, and limited information was produced by the public meeting.

Interviews were conducted by the Investigative Board following the public meeting with a number of local citizens who indicated various degrees of knowledge about the structure. Telephone interviews were conducted with people as far away as California and Texas in an effort to locate historical data about the dam.


Dam collapses in Switzerland, kills 70 - HISTORY

Hundreds of dam failures have occurred throughout U.S. history. These failures have caused immense property and environmental damages and have taken thousands of lives. As the nation’s dams age and population increases, the potential for deadly dam failures grows.

No one knows precisely how many dam failures have occurred in the U.S., but they have been documented in every state. From January 2005 through June 2013, state dam safety programs reported 173 dam failures and 587 "incidents" - episodes that, without intervention, would likely have resulted in dam failure.

This map is based on a (non-comprehensive) list of dam failures compiled by ASDSO. It was prepared by James S. Halgren with the National Weather Service, National Oceanic and Atmospheric Administration. The map demonstrates that dam failures are not particularly common but they do continue to occur. Locations are approximate.

The large red dot on the Gulf Coast represents the New Orleans levee failures resulting from Hurricane Katrina. A few other levee failures are included on this illustration. If levee failures from the 1993 Midwest Floods were included, more failures would be indicated in the center of the map.

The following is an excerpt from the American Society of Civil Engineers' 2017 Infrastructure Report Card detailing the importance of public safety and proper maintenance:
"In order to improve public safety and resilience, the risk and consequences of dam failure must be lowered. Progress requires better planning for mitigating the effects of failures increased regulatory oversight of the safety of dams improving coordination and communication across governing agencies and the development of tools, training, and technology. Dam failures not only risk public safety, they also can cost our economy millions of dollars in damages. Failure is not just limited to damage to the dam itself. It can result in the impairment of many other infrastructure systems, such as roads, bridges, and water systems. When a dam fails, resources must be devoted to the prevention and treatment of public health risks as well as the resulting structural consequences."

The Causes of Dam Failures


Dam failures are most likely to happen for one of five reasons:

1. Overtopping caused by water spilling over the top of a dam. Overtopping of a dam is often a precursor of dam failure. National statistics show that overtopping due to inadequate spillway design, debris blockage of spillways, or settlement of the dam crest account for approximately 34% of all U.S. dam failures.
Click Here for Video Example [YouTube]

2. Foundation Defects, including settlement and slope instability, cause about 30% of all dam failures.
Click Here for Video Example [YouTube]

3. Cracking caused by movements like the natural settling of a dam.

4. Inadequate maintenance and upkeep.
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5. Piping is when seepage through a dam is not properly filtered and soil particles continue to progress and form sink holes in the dam. [See an animation of a piping failure.] Another 20% of U.S. dam failures have been caused by piping (internal erosion caused by seepage). Seepage often occurs around hydraulic structures, such as pipes and spillways through animal burrows around roots of woody vegetation and through cracks in dams, dam appurtenances, and dam foundations.
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Causes of Dam Failure Incidents, 2010-2019**

** From the ASDSO Dam Incident Database, dam failure incidents for the years 2010 through 2019. Incident data mostly obtained from the state dam safety programs and/or media reports. The incident data is not inclusive of all dam safety incidents.

Learning From The Past: A Snapshot of Historic U.S. Dam Failures


Before Dam Safety Laws
At 7:20 a.m. on May 16, 1874, the 43-foot-high Mill River Dam above Williamsburg, Massachusetts failed, killing 138 people, including 43 children under the age of ten. This failure was the worst in U.S. history, up to that time.

Fifteen years later, on May 31, 1889, this tragedy was replayed on a larger scale in Pennsylvania. Over 2,200 people - more than one in five residents of Johnstown - perished in the flood caused by the failure of South Fork Dam, nine miles upstream.

Many more failures - in Arizona, Tennessee, Oregon, North Carolina, Texas, Virginia, West Virginia, and elsewhere across the U.S. - occurred around the turn of the century, and some early state dam safety legislation was passed.

The failure of St. Francis Dam, in March 1928, was a landmark event in the history of state dam safety legislation, spurring legislation not only in California, but in neighboring states as well. However, most states had no substantive dam safety laws prior to a series of dam failures and incidents that occurred in the 1970s.


Most Read

The National Weather Service said poor communications in the area prevented an accurate record of rainfall. But a spokesman said one station north of Toccoa reported 5.25 inches of rain in the 24 hours that ended at 7 a.m. (New York TIme) yesterday.

Water and natural gas supplies to the community were cut off and electric power curtailed. A state of emergency was declared.

Officials said that the flood jammed houses, mobile homes and cars against the bridge over the creek. If the debris had not piled up there, slowing the wave of water, the damage and death toll might have been much greater, they said.

In western North Carolina, five persons died in flooding. The dead included a mother and two children swept from their mobile home. Dozens of highways were reported flooded and about 30 secondary bridges were washed out after thunderstorms dumped more than five inches of rain in six hours.


Today in History

Today is Monday, May 31, the 151st day of 2021. There are 214 days left in the year. This is Memorial Day.

Today’s Highlight in History:

On May 31, 1921, a race riot erupted in Tulsa, Oklahoma, as white mobs began looting and leveling the affluent Black district of Greenwood over reports a Black man had assaulted a white woman in an elevator hundreds are believed to have died.

In 1578, the Christian catacombs of ancient Rome were accidentally discovered by workers digging in a vineyard along the Via Salaria.

In 1790, President George Washington signed into law the first U.S. copyright act.

In 1859, the Big Ben clock tower in London went into operation, chiming for the first time.

In 1889, some 2,200 people in Johnstown, Pennsylvania, perished when the South Fork Dam collapsed, sending 20 million tons of water rushing through the town.

In 1935, movie studio 20th Century Fox was created through a merger of the Fox Film Corp. and Twentieth Century Pictures.

In 1962, former Nazi official Adolf Eichmann was hanged in Israel a few minutes before midnight for his role in the Holocaust.

In 1970, a magnitude 7.9 earthquake in Peru claimed an estimated 67,000 lives.

In 1977, the Trans-Alaska oil pipeline, three years in the making despite objections from environmentalists and Alaska Natives, was completed. (The first oil began flowing through the pipeline 20 days later.)

In 1989, House Speaker Jim Wright, dogged by questions about his ethics, announced he would resign. (Tom Foley later succeeded him.)

In 2009, Dr. George Tiller, a rare provider of late-term abortions, was shot and killed in a Wichita, Kansas, church. (Gunman Scott Roeder was later convicted of first-degree murder and sentenced to life in prison with no possibility of parole for 50 years.) Millvina Dean, the last survivor of the 1912 sinking of the RMS Titanic, died in Southampton, England at 97.

In 2014, Sgt. Bowe Bergdahl, the only American soldier held prisoner in Afghanistan, was freed by the Taliban in exchange for five Afghan detainees from the U.S. prison at Guantanamo Bay, Cuba. (Bergdahl, who’d gone missing in June 2009, later pleaded guilty to endangering his comrades by walking away from his post in Afghanistan his sentence included a dishonorable discharge, a reduction in rank and a fine, but no prison time.)

In 2019, a longtime city employee opened fire in a municipal building in Virginia Beach, Virginia, killing 12 people on three floors before police shot and killed him officials said DeWayne Craddock had resigned by email hours before the shooting.

Ten years ago: Angered by civilian casualties, Afghan President Hamid Karzai said he would no longer allow NATO airstrikes on houses. Former Bosnian Serb military commander Ratko Mladic (RAHT’-koh MLAH’-dich) was placed in a U.N. detention unit in the Netherlands to await trial on genocide charges.

Five years ago: A jury found former suburban Chicago police officer Drew Peterson guilty of trying to hire someone to kill the prosecutor who helped to convict him in the killing of his third wife, Kathleen Savio.

One year ago: Tens of thousands of protesters again took to the streets across America, with peaceful demonstrations against police killings overshadowed by unrest officials deployed thousands of National Guard soldiers and enacted strict curfews in major cities. Protesters in Washington, D.C., started fires near the White House amid increasing tensions with police, who fired tear gas and stun grenades. In tweets, President Donald Trump blamed anarchists and the media for fueling violence. The White House said it had sent to Brazil more than 2 million doses of a malaria drug touted by Trump as potentially protecting against the coronavirus scientific evidence had not backed up those uses of the drug. The privately-owned spacecraft SpaceX delivered two NASA astronauts to the International Space Station. Artist Christo, known for massive public arts projects that often involved wrapping large structures in fabric, died in New York at 84.

Today’s Birthdays: Actor-director Clint Eastwood is 91. Singer Peter Yarrow is 83. Humanitarian and author Terry Waite is 82. Singer-musician Augie Meyers is 81. Actor Sharon Gless is 78. Football Hall of Famer Joe Namath is 78. Broadcast journalist/commentator Bernard Goldberg is 76. Actor Tom Berenger is 71. Actor Gregory Harrison is 71. Actor Kyle Secor is 64. Actor Roma Maffia (ma-FEE’-uh) is 63. Actor/comedian Chris Elliott is 61. Actor Lea Thompson is 60. Singer Corey Hart is 59. Actor Hugh Dillon is 58. Rapper DMC is 57. Actor Brooke Shields is 56. Country musician Ed Adkins (The Derailers) is 54. TV host Phil Keoghan is 54. Jazz musician Christian McBride is 49. Actor Archie Panjabi is 49. Actor Merle Dandridge (TV: “Greenleaf”) is 46. Actor Colin Farrell is 45. Rock musician Scott Klopfenstein (Reel Big Fish) is 44. Actor Eric Christian Olsen is 44. Rock musician Andy Hurley (Fall Out Boy) is 41. Country singer Casey James (TV: “American Idol”) is 39. Actor Jonathan Tucker is 39. Rapper Waka Flocka Flame is 35. Actor Curtis Williams Jr. is 34. Pop singer Normani Hamilton (Fifth Harmony) is 25.