In recent years file and flooding has been occurring regularly in coastal towns all around the world monsoons storms cite clones and hurricane scores thousands of deaths and forced displacement of millions of people. Why is some cities more at risk than others what forces of nature lead to these disasters and is Global Warming the primary coops. To Hurricane Sandy devastated new york in two thousand and twelve scientists around the world intensified their efforts to identify the causes of these disasters. On october the twenty ninth two thousand and twelve Hurricane Sandy moved steadily closer to the east coast of the United States threatening new york city. Costs were alarming water levels were predicted to rise by five meters as a safety measure or public spaces and subways tunnels under bridges were close to the public. The man declared a state of emergency the city of new york evacuated three hundred seventy five thousand People Living in flooded bill areas. Back in the two thousand and five i say new york city. I was going to be flooded it was not a question of if but when i couldnt say exactly when and nobody else on this planet could say exactly when but i knew it was going to happen and it happened. Hospitals were evacuated fires broke out neighborhoods were stranded. The flood plunged the city into camps. From the planets perspective floods are routinely events we regard them as the most destructive natural disaster. Or coastal floods very widely and they cause tremendous damage and actually mortality i mean two hundred thousand people have been killed in the last thirty years from coastal floods alone. Theres been a lot of major coastal flood disasters over the last few years and in one thousand nine hundred one in bangladesh about one hundred thirty eight thousand people are estimated to have died in burma or in thousand eight hundred like them the grizz about one hundred thirty eight thousand people again were estimated to be killed and more recently in the philippines inside the typhoon hyaena six thousand people were killed and those are just a few examples even in the developed world people have died in Hurricane Katrina about two thousand people were killed in about eight hundred of those were in new orleans and inside clone sandy about two hundred people were killed more and more people are moving to cities globally now one half the people live in cities that happened fairly recently moving from human beings being a rural sort of species to being an urban species and most of all many of those cities are actually on the coast. No place in the world is safe from flooding but the sources of these cataclysms vary from region to region. In new york for example it was a special phenomenon that caused so much damage. The standing it was not the winds it was not the rain it was the storm surge the ocean coming up higher much higher than normal and washing ashore going into all the little harbors and the little rivers and flooding and finding the vulnerable low places and flooding all around and thats what was so bad. Out at sea violent winds of a hurricane push surface waters towards the coast the Sea Level Rises creating a destructive super wave called the storm surge. In Hurricane Sandys case other natural factors may decide to ation us. What is the stage of the tide when the hurricane hits and for sandy it hit high tide but also there was a full moon every two weeks theres an extra strong tide we say a spring tide and it just so happened that not only was the tide high but there was extra high tide due to the moon and then the storm hit and thats why the so was so. Damaging. What is the difference between a tsunami and a storm surge tsunami is caused by an undersea earthquake. Sixth floor is quite breaks a big earthquake it creates a big way that cripples a very high speed maybe seven hundred kilometers an hour and as a comes close to the land it gets higher and higher and stronger and it breaks and then it shoots short and creates a huge amount of destruction and death thats a tsunami. In new york the storm surge hit the city at night the extent of its destruction wasnt apparent until daylight. We saw a range of impacts really saw failures of our infrastructure system and how and really how it how our infrastructure is linked and the Power Systems were impacted our Transportation Systems were impacted with the tunnels being flooded our Telecommunications Systems ultimately went down we had gas lines because of a breakdown in supply chain for a look at Fuels Network and of course the impact on people and neighborhoods were just as severe. Its interesting how much damage there is in america during floods because they dont have good defenses. Always amazed that they dont. Have better defenses because they have the money. They have Technical Knowledge but they choose not to use it. People. Often so it was a very rare event it will never happen again i said no no no it will happen again and it will get worse and worse because as the Climate Changes and the sea rises very slowly but comes up. The danger will get more. In recent Years Research has lead scientists to better understand the parameters of extreme flooding according to specialists Global Warming well amplify these conditions in the future. But we have another problem which is probably going to be the worst of all which is Sea Level Rise due to Climate Change sea level has already risen by approximately twenty centimeters since the late Nineteenth Century and this rise has accelerated and it will accelerate further due to the ongoing Global Warming. You know maybe too many people one meter of Sea Level Rise doesnt even sound much because on a calm day when you stand on the beach and you think ok waters one meter high it would make a difference when it really hits you is during a storm search because of course a storm surge already starts one meter higher than without the Sea Level Rise then and it actually runs up more than one meter higher because there are some effects like reduced friction in the higher sea level that make a storm surge run disproportionately higher when you start off with an elevated sea level due to Global Warming. The planet is warming up the levels of water in the oceans are constantly rising yet some regions of the world remain less affected than others this shows the pattern of Sea Level Rise since the year nine hundred ninety three and it shows that it has risen in most places but everywhere here in the eastern pacific we see an area where the sea level even has dropped in this period but on the other side here in the western pacific it has risen much more than average because obviously the trade winds have increased their pushing the water over here and piling it up on the east asian coast and. To reveal some coastal towns and cities can increase the risk of flooding thats particularly true of large cities situated on deltas like bangkok shanghai and new orleans. And these deltas are incredibly flat you could go one hundred kilometers and the elevation ups and downs would only be a few meters at most so theyre extremely flat so putting a setting on these flat lands is rather easy to do. This is a collection. Of many of the deltas of the world the delta. His are the land surface where the rivers water has brought the sediments to the coastline and accumulated in these large deposits we know that in the last thirty or so years sea level has been going up around three millimeters per year three millimeters per year is quite small. And so yes in the long term you know fifty years one hundred years you want to make sure youre sure lines are protected by closely studying deltas researches uncovered an unexpected phenomenon we would put instruments in the rivers we would put instruments in the coastal ocean we would be monitoring how the channels shifted around in all the sediments we found that the tide gauges suggested that the deltas were saying on average four times faster then the other areas and so we knew something was up something on that deltas was happening. Bangkok is an impressive city situated on the delta of the river crisscrossed by two thousand six hundred kilometers of canals it is an astonishing mix a combination of modern metropolis and a traditional village. The capital of thailand has grown considerably in just a few decades and the rate of growth has had substantial consequences. Thirty five years ago population of bangkok is perhaps lay four or five millions but right now is about ten million more than ten million so people need water lets look about thirty years ago you know to really clear and really clean so its ok to use you know in a rainwater and house something but you know. Getting weaker so it is difficult to use the rainwater you know for supply funding or for use or point any supply so people started rely on you know underground water. So when we have over pumping of the underground water the probe in start. Due to excessive pumping of water the city is sinking this phenomenon is called ground subsidence examples can be seen on many streets so this is the evidence. This here use actually. On the part. Of the foundation and in this area is actually on my foundation but this. Area used to be. Ok but now because of the previous water pumping. Ok everywhere in bangkok the ground moves and subsides. You know if it is evidence of cross fit it ok. You can see the barrier its not even if its like a way of this is because the barrier is a little kid over to foundation of the way over here in between a barrier if not on the foundation is in the foyer so its criteria for upside but how did it end of the highway is out of sight every year for years their department highway have just come here and feeling more at fault the concrete. The entire city is affected by this phenomenon of subsidence. Some areas were particularly affected during the terrible floods that hit thailand in two thousand and eleven the monsoon poured close to sixteen billion cubic meters of water onto the streets of bangkok that protected dykes burst and entire streets remained underwater for several months. Peoples houses will be looted damaged peoples cars will be washed away peoples fields will be flooded out cultural fields on the outskirts of bangkok at one point about twelve and a half percent of the land in thailand Agricultural Land was underwater. From north to south thailands rivers drain into the River Channel priam. Mountain waters from the north flow towards bangkok and the gulf of thailand the additional volume of monsoon rain waters is a major cause of flooding in the delta. If the tree falls of water we call the Three Sisters here the same time same place exactly the right moment when. The first is the waterfall the north. The second sister is water from the high tide that bird sister has water from the sky the end you imagine when the high tide take the place and the water from the north coming down here its already almost four point five opinion. At the mansion to give the rain come in the city. In two thousand and eleven the water level built up in the city and its infrastructure is well unable to accommodate it. In the past bangkok had networks of canals and natural waterways that would. Serve as natural drainage for water flowing from the north through bangkok to the gulf of thailand with more people and how seeing construction infrastructure all of those networks of canals and river waste and waterways pretty much blocked disappear. You have the International Airport where you have the necessary estates built in floodways i think if you look at the root cause they say open land use. To accommodate its growing population new housing was built in areas which provided drainage for the city after monsoons urbanization has transformed the landscape of bangkok rendering the city more vulnerable to flooding. We realize that the flooding is actually in some area where there was a you know factories that you think are water pumping out. And then we start to do the morning during the day in the area and we found that thirty years ago they didnt rate is about ten centimeters per year which is quite a lot so then we are starting to enforce not to use underground water not to use underground water and the. Rate is Getting Better from ten centimeters to say when there are five and up to now. Is completely we have about three centimeter for a year. In bangkok. Pumping is limited so the factory is really moved out. And due to the pumping because the allow at that area is needed as. Creating the you know the intrusion of the sea water. As the Sea Level Rises the coastal lands of bangkok are sinking the waters of encroached by five kilometers in twenty years no one imagined a city could sink at such a right sections of the coastline of bangkok have disappeared it. Is the tiny capital the only city threatened or is it just one among many others. If we go around the world we see the really substance. Is mainly an issue in asian cities bangkok is maybe a classical example where the center of the city has sunk two or three meters in the Twentieth Century making it much more prone to flooding tokyo has sunk up to four meters in the Twentieth Century not the entire city but the bit of the city built on the delta around the port has gone though up to four meters asarco in japan has gone down three meters tianjin gone down two meters shanghai has subsided three meters jakarta in indonesia has subsided four meters and is still subsiding very fast today manila probably a meter of calcutta and aca were not really sure but theyre almost certainly going down and then places like new Orleans New Orleans has subsided up to three meters and is continuing to subside vancouver in canada areas there have subsided in excess of a meter and so all these cities ive named have become much more vulnerable to coastal flooding because of this substance without any consideration of other changes. Everywhere in the world citizens sinking because of excessive pumping of groundwater for big cities situated on down to other factors can worsen this subsidence the ground under these regions has a natural tendency to compact in the past rivers brought new sediments to partly compensate for this subsidence dams built by man of upset this delicate balance. Sometimes when we had dams put in eventually that sediment was. No longer able to get to the coals it was all being sequestered behind the dams in the reservoirs and then the shoreline was shift landward and weve been building one large dam on earth every day on average for the last one hundred thirty hundred forty years and you see in one thousand nine hundred there were just a very few dams and you will see and read where new dams are forming first in the u. S. Japan and india. So the issue of dams is very much part of the story. By diverting river waters with dams and pumping greater quantities of ground water man has upset the balance of Natural Forces yet the growth of more huge cities seems inevitable. Located on the Yangtze Delta shanghai symbolizes the race for Economic Development with twenty three Million People it is the most populated city in china. It is about is Chinese Success and ams to become the leading Financial Hub in asia. Shanghai continues to grow. Its expansion seems limitless in spite of the threats from nature. Life in this city has always been mocked by the time i fangirl the word which alarms the population is the chinese term for a tropical typhoon which brings violent winds and torrential rains periodic late wreaking havoc on the city. If the Sea Level Rises the most direct impact on shanghai comes from coastal waters once the maximum water level is reached in the city is flooded from heavy rain or upstream flooding the drainage system wont be able to handle the excess water. High is faced with a huge problem in cases of massive flooding all strong tides its canals will be unable to evacuate such as surplus of water in an effort to mina. Mines the damage the chinese built the barrier. To entry and. Here we have a flood gate its meant to prevent the one poor title waters from entering the river. Plus of the normal it lies on the riverbed so it doesnt spoil the landscape it rises every morning and order to block the high tides when at the end of the house. This mobile dike protects an area that has sunk by more than three meters in one hundred years due to excessive pumping of water from the water table. Beginning in one thousand nine hundred twenty is chinese all floridians have been measuring the steady sinking of the city. To study the phenomenon shanghai established a ground subsidence institute the only one of its kind in the world. Dilution and that. Africa has until the one nine hundred sixty s. Too much ground water was removed in shanghai. Only this led to a severe increase in subsidence. You mentioned earlier dont have this three d. Model shows how subsidence occurred at different times. Of the late that you mentioned here you can see what happened between the one nine hundred sixty s. And two thousand and ten and you mention you can see that subside lots of them worsening steadily after that until the implementation of efficient measures to slow it down and keep its evolution under control but how they got there that only a country. It was only in the one nine hundred sixty is that laws were created to regulate the pumping of water the chinese were the first to recognize the scale of the subsidence. Subsidence is a reversible once. It poses a significant threat high skyscrapers. And it also has an impact on urban infrastructures. Sense of side and it was established in one thousand nine hundred eighty one in shanghai that theyve measured a lot of elevation of two to three meters. To allow me to go. To keep watch on this change the city built an extensive surveillance network. Through the storm. This is our ground subsidence Monitoring Network for shanghai. Its made up of thirty seven land subsidence monitoring stations. Here in one of the. This is where we monitor the evolution of ground subsidence in the different layers at various steps. Today the measurements occur it out fully automatic lay out the Real Time Monitoring of the different soil layers makes it possible to observe the variations of subsidence more than two hundred meters below the surface today we extract less than ten million tons of water every year as a consequence our level of subsidence remains under six millimeters. Since one thousand nine hundred sixty six pumping from the water tables has been strictly regulated in shanghai yet to ground subsidence continues at a rate of six millimeters per year. Some blame is being put on its many buildings some scientists believe the weight of the huge new skyscrapers is in. Creasing ground subsidence. No expert is willing to comment on this at present. Yet the information has been officially published by the institute for ground subsidence in shanghai. In recent years with the launching of large scale urban construction land subsidence has accelerated. In spite of the possible consequences buildings continue to be built this chinese dream seems unstoppable. Elsewhere in the country new urban centers are developing. All of these Development Plans ignore the warnings and they run the risk of causing ground subsidence as in shanghai. In japan the greater tokyo area has a population of thirty seven million. It is the biggest urban center in the world. It is also among the coastal cities threatened by flooding. For more than a century the japanese have struggled to protect their cities against flooding. In ninety ten we had a very big tie front which cam up here and there we got a very serious for out the government of the time decided to excavate this diversion. They were to get rid of the frog. So therefore their story about bomb was cos rocket zero point five zero eight thousand or the other saw the soaring award i can top this. That because the area behind the river was concrete to a rule. In the past buffer zones provided a method of diverting from waters into arable fields then jus to a lack of. Living space in the middle of the Twentieth Century people settled on these fields thereby creating the koto district just as in bangkok and shanghai pumping of groundwater has led to the subsidence for more than one hundred twenty square kilometers in the center of tokyo without. Thats a sign saying that there were you know. Was that so the current say was there ever was here. And now im standing on this. So this and. There is a risk. So this was cause rather than just. The risk. Thanks to the roads that are enacted in nine ten seven days ground subsidence due to excessive pumping of groundwater had stopped so there was no worry about father subsidence but the round subsided there was no hope that we can get the original ground the rubble recovered. For more than forty years the japanese have attempted to contain ground subsidence caused by mans activities and science has identified another cause of subsidence. Japan is regularly hit by earthquakes. On the surface the damage can be considerable. But deeper in the earthquakes also generate an amazing geological phenomenon. Liquefaction. The first comes a big shock. Than it is for the by ricky fox breaker faction is a phenomena that a chorus and rosary deposited the sand. We have. Rosery deposit sounds. A wrong the coast the rhine or why then mom made the rounds so we have grandeur of poverty upset which is not strong and the fabric is completely fair to voice what. Was a big fuss quick cross face rule is probably. Rosies it strikes at the camp break. Once they swear at ricky fires they pressurize the water and sand both of their ways to this office. So they sufis or wont fall into this eerie to fire the zone. So well a sea of huge amount of sun the jet. And we want to get the redo. After removing the sun must we see the ground subsidence a bit. Well you can see here on all of these awards on a tear and you can see here or you know growing there ever was place and the sun poseidons here must have been. A couple of the towns sound to me just sums and act that. Carries a on as i use ample of. Induced rick if i action can say crisis. This tool a mob force for an underground water tank. And all project having a big horrible and it can get through. To be dished it out and a lake of fire the soil so they still sane scame up to the ground or of all so men wow this haunting the solar house subsiding maybe the zero point five meters or a little roger so therefore this is choice in the hollow target of the regular function. And a underground pipes john because why is unable there are many. Things. As they are after the earthquake just not to forget the same as it happened here due to a fraction. With liquefaction of the ground earthquakes increased subsides making the city and more vulnerable to flooding. The areas threatened by subsidence in the event of a big earthquake as shown in red on the map the port of tokyo is particularly at risk it includes an Industrial Zone with chemical factories scientists are understandably worried about this extremely vulnerable site what happens if the body experiences an earthquake a tsunami or a storm. In this. Area. It is zero because it was core sucked at one hundred. Or seventy years ago. And also that there is no countermeasures against a faction of the ground but this. Crane with area there are so many Chemical Industry factories located in the area so for the case of some such i think the ground i believe that although there are baby. Born crowding and there are a lot of tanks and storage of can cover the areas in the area. So it is necessary to protect the levy some can get my carry out this Industrial Area in it could aim at the area of talking about it but when my view we are not ready we are not prepared. To see his rising climatic events are increasingly violent and big coastal urban areas are sinking subsidence is increasing the risk of flooding. All over the world the lives of many people are now threatened by these impending environmental disasters. So that led us to think well where what other cities are vulnerable to these kinds of problems. So what we did was we actually took a study of all the cities around the world and we looked at one hundred thirty six cities that in two thousand and five had more the Million People that were coastal with a port and we looked at how many people live in the hundred year flood playing so thats the area that would flood have a one percent chance of flooding every year and we found this four hundred Million People in two thousand and five living in these two hundred thirty six cities and forty million so ten percent of them lived in lived in those areas and we found that certain cities had very large areas in the floodplain a quarter of these one hundred thirty six cities are actually sinking and when i say things sometimes it goes down ten twenty centimeters per year or a meter every five or ten years so these are huge changes. Some regions are sinking faster than others one example is the coastline of the u. S. State of louisiana. Is the mississippi Delta New Orleans is located in this area in here and most of the land surface has been disappearing over the last thirty years and our projections ours this will disappear in the next ten twenty thirty years it will be gone and so. When this disappears water from a hurricane can more readily impact the city of new orleans so the cities on the delta are at risk all of them. I mean without question and theyre part of the list of one hundred thirty six areas at risk if we look at the Twentieth Century in many ways that probably for many cities the substance has been much much more important than climate into Sea Level Rise because were talking about meters of change when the sea has risen maybe seventeen twenty centimeters in the Twentieth Century in the twenty First Century we expect much more climate into three level rise and climate and you see the rise will affect every coastal city not just the ones that have subsiding so we expect we expect Sea Level Rise in the twenty First Century to be much much more important than it has been historically substance and Sea Level Rise are making things worse in the same direction so you may solve the problem of energy. You still have the problem so these two have independent drivers they both relate to humans but theyre independent of one another. Rising sea levels ground subsidence and disappearance of flood zones and natural conditions facing mankind at the beginning of the twenty First Century flooding threatens our coastal cities what can be done ecologically to stop this dramatic spiral and protect our urban centers everywhere in the world engineers architects and politicians are attempting to address this challenge. The ducted by rebels at the age of eleven forced to marry at fourteen released at twenty two evelyn story is fairly common in uganda tens of thousands of children are kidnapped abused and forced to become child soldiers and their trauma continues even after they retire because communities often reject the children of terror young rebel captives in uganda. In fifteen d. W. Your children like chocolate. You cant live without your smartphone. You buy your tomatoes in the supermarket. As we go about our daily life human rights fall from the last thing on the worlds. Invisible hands. Slavery in the twenty First Century. Starting december second on d w. This is news live from berlin Zimbabwes President Robert Mugabe faces the end of his nearly four decade rule the countrys ruling party is expelled mugabe at the fleeter thousands of zimbabweans are demanding his immediate resignation but so far mugabe is written
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