years quite small. and so yes in the long term you know fifty years a hundred years you want to make sure you're sure lines are protected by closely studying deltas research has uncovered an unexpected phenomenon we would put instruments in the rivers we put instruments in the coastal ocean we would be monitoring hard the channels shifted around and other sediments we found that the tide gauges suggested that the deltas were sinking on average four times faster then the other areas and so we knew something was up something on that belt as was happening. bangkok is an impressive city situated on the delta of the champ 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 relation of bangkok is perhaps lay four or five millions but right now is about ten million more than ten million so people need water let's look about thirty years ago you know to really clear and really clean so it is ok to use you know in a rainwater and store in his house something no doubt but you know some polish and coming. getting bigger so it is difficult to use the rainwater you know for supply for i didn't king or for us or for the only supply so people that started rely on

you know underground water. so when we have. been on the underground water. due to excessive pumping of water the city is sinking this phenomenon is called ground subsidence examples can be seen on many streets. every day. here use actually. on the park. and in this area. to area. but now. the previous. ok everywhere in bangkok the ground moves subsides.

every bit. a. barrier it's not even if it's like a way of because the barrier is a little kid. over here in between a barrier if not on the foundation is in the foyer. side. of the highway is out of sight every year for years their department highway had 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. to protect the dikes burst entire streets remained underwater for several months. people's houses will be damaged people's cars will be washed away people's fields will be flooded at 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 thailand's rivers drain into the river channel preying on. 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 off what do we call the three states to hit the same time same place exactly the right moment when probably. the first is water fallen off the second if water from the high tide that but this water from the sky the end you imagine when the high tide. water from the north coming down here it's already almost four point five feet you think. that the mayor didn't give their income in the city. in two thousand and eleven the water level built up in the city and its infrastructures were unable to accommodate it.

in the past bangkok pad networks of canals and natural waterways that would. serve as natural drainage or 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 remove waste and waterways pretty much blocked all disappear. you have international airport where you have enough for estates built in flood ways 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 their flooding is actually occurring in some area where there was a you know factory that new figure out water pumping out. and then we start to do the morning during the day in each area and we found that thirty years ago. we didn't rate is about ten centimeters per year which is quite a lot so then we are starting to inforce not to use underground water not to use a new car water and. it is getting better from ten centimeter to say when five and up to now. is completely we have about three centimeter for a year. in bangkok for our water pumping is limited

so the factory is fairly near the shoreline and due to the pumping because at that area is needed as a sub site ok creating the you know the intrusion are the sea water in. 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 wrecked sections of the coastline of bangkok have disappeared. into the tiny capital the only city threatened or is it just one among many others. if we go around the world we see that really. this 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 but the entire city but the bit of the city built on the delta around the port is gone then up to four meters a sucker in japan has gone down three meters t.n.g. in gone down two meters shanghai has subsided three meters jakarta in indonesia subsided four meters and is still subsiding very fast today manila probably a meter of calcutta and aca we're not really sure but they're 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 i've named have become much more vulnerable to

coastal flooding because of the substance without any consideration of other changes. everywhere in the world cities are 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 settlements to partly compensate for the subsidence dams built by man have upset his 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 we've 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 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 ems to become the leading financial hub in asia .

china high continues to grow. its expansion seems limitless in spite of the threats from nature. of life in this city has always been mocked by the time fang the word which alarms the population is the chinese term for a tropical typhoon which brings violent winds and torrential rains periodic leap wreaking havoc on the city. will heighten missiles if the sea level rises the most direct impact on shanghai comes from coastal waters once the maximum water level is reached and the city is flooded from heavy rains or upstream flooding the drainage system won't be able to handle the excess water. shanghai is

faced with a huge problem in cases of massive flooding all strong tides its canals will be unable to evacuate such a surplus of water in an effort to. minus the damage the chinese built a barrier. to filling up. here we have a flood gate it's meant to prevent the one poor title waters from entering the river. consider so normal and it lives on the river bed so it doesn't spoil the landscape it rises every morning in order to block the high tides well i doubt that it houses. 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 s. chinese authorities 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. shall issue dilution and that fish dishes africa's at sea yet until the one nine hundred sixty s. too much ground water was removed in shanghai. only to mention this led to a severe increase in subsidence. dimensionality we're told this three d. model shows how subsidence occurred at different times. late that you mentioned here you can see what happened between the one nine hundred sixty s. and two thousand and ten and the dimension we can see that subside lots of been worsening steadily until the implementation of efficient measures to slow it down

bushy and keep its evolution under control. that ali. it was only in one thousand 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. dimity ashit on some say it's a reverse of boat you want. it poses a significant threat to shanghai skyscrapers i'm sure they aren't and it also has an impact on urban infrastructures only in china. the offensive side and it was established in one thousand nine hundred eighty one in shanghai that they've measured a lot of elevation of two to three meters.