Why Mexico City Has a Water Problem

look at this church since it was first built it has started to sink into the ground below and it's far from the only building like this in the city when that monument behind me was first built about a hundred years ago the base only had nine steps however since then the street around it has sunk so much that they've had to install another 13. this is mexico city the largest city in north america and the fifth biggest city in the world it is bigger than new york rainiers in portland and hires in denver well maybe not in both ways more than 20 million people call this mega city's metro area home but mexico city has one major problem water the city built upon what conquistadors once called the venice of the new world is sinking and the city that gets more rain than london or vancouver is in danger of running out of water so how did this all happen what are people doing to save the city that one out of every six mexicans call home and how did it beat new york to become the largest city on the continents this video is brought to you by paul agents if you're a high school student stick around to the end of the video to find out more mexico city has sunk by over 9 meters in some places over the last 100 years alone buildings across the mega city are bent and tilted by not insignificant margins this is more obvious when looking at older buildings like churches and monuments but even newer apartment buildings suffer from these effects that are often nauseating to live in here take a look at this map this is a map of buildings that were damaged during an earthquake in 2015 but this cluster of buildings over here is no coincidence trace the map out and we see what this area was before an entire city was built on top of it 500 years ago this area was not the sprawling megacity it is today and in fact most of it wasn't even dry land this is or rather was lake texcoco according to legend when the meshika or aztec people left their homeland of aslan seven hundred years ago the sun god withslopsly directed them toward a swampy island in the middle of this lake through the sign of an eagle eating a snake will perch atop a cactus which is what that thing on mexico's flag represents atop this unassuming island would form tenochtitlan capital of the new aztec empire the city would gradually span throughout its part of the lake through the use of small rectangular artificial islands known as chinampas within only two centuries tenochtitlan had grown large enough to support upwards of two hundred thousand people far larger than many of its contemporaries in europe unfortunately the aztec empire wasn't exactly the most liked kid on the block when aaron cortez and co showed up in 1521 the city would be besieged by the spanish forces and their native allies who would almost completely destroy the city and bury it under a new administrative center for a vastly different empire but cortes was the only one amongst the conquistadors who actually wanted to build their new city atop the old aztec capital most of the others wanted to build somewhere that you know actually made sense but this decision was cortez's alone to make and he ordered the new spanish city be built atop the ruins of tennoshilan in an attempt to erase its legacy from the newly built main square the zokolo the new mexico city extended outward in a typical spanish colonial trassa or city plan as the centuries passed however the city inched closer and closer to the lake since it was first founded the city has been regularly plagued by flooding an issue that still plagues the city to this day so the entrance is the metro stations are raised slightly like they do in southeast asia lake texaco and now mexico city sits within a vast plateau two kilometers above sea level and surrounded by mountains reaching over five kilometers into the air what this means is that mexico city is structured almost like a bowl with no natural way to drain excess water in the lake in fact as early as the 17th century leaders and residents of the city considered moving the capital somewhere like nearby puebla whose position had the unique distinction of actually making geographic sense but they didn't move the capital and instead embarked on a centuries-long project that is salway literally meaning drain conscripting thousands of indigenous workers to dig tunnels and trenches to drain water from the lake at first this project more or less failed miserably and it took another 200 years for the project to start again with some actual traction over the 19th and 20th centuries more channels were built as the lake was drained even further into the surrounding rivers this didn't just give the city more space to build on but also kept mosquitoes in sewage and therefore disease out of the area but then something else happened to the city it received even more humans in 1950 the city had a population of only 3.3 million but then people from all across mexico started to move in with the prospect of new jobs and new opportunities in the industrial sector now seven years later the population sieve close to 22 million and two things people generally need are water and shelter usually in the form of buildings but ironically for a city that gets more than a meter of rainfall a year many parts of the city don't have a stable supply of drinking water the city gets most of its water through underground aquifers normally these aquifers will be replenished by rain sinking through the soil until it reaches the aquifers however rain can't penetrate concrete like it can bear soil and as rainwater is pumped away to prevent the city from flooding the aquifers can't be replenished and so the soft soil above them begins to sink but this groundwater pumping doesn't explain all of the subsidence that has been plaguing the city the simple fact it was built on a dried lake bed at all is causing the city to sink i mean it's not the fact itself it's because it was built on you get what i mean the city is built atop super soft sand and soil which itself is more water than solid in some places and the buildings on top often have shallow foundations allowing them to sink possibly by up to 30 meters over the next 150 years now let that sink in for a moment oh right sorry something that helps us even less is earthquakes if we zoom out we can see that mexico city sits within a valley amidst the trans-mexican volcanic built a string of volcanoes stretching from coast to coast across central mexico perhaps the biggest example of this was the magnitude 8.1 earthquake that struck the city in 1985 killing more than 10 thousand people and causing hundreds of buildings to collapse as the sand below gave way this happened through a process that you've probably heard about on some of those nerd channels called liquefaction where the wet sand and soil starts to behave like a liquid when agitated say by an earthquake causing the buildings on top to sink like they were built on water but if mexico city was built on top of lake bed in an area that gets a lot of rain why are so many of its residents struggling to get water poor wastewater treatment old pipes that leak a thousand lasers of water a second and the symbol fact that the aquifers are being depleted mean that many in the outskirts of the mega city have to rely on water being delivered by trucks there are non-profits out there like izalo urbana who seek to help give mexico city residents the ability to store rainwater but well let's see could climate change be affecting anything of course climate change is affecting things the city has been facing increasingly severe droughts with researchers predicting the city will receive anywhere from 10 to 17 percent less rainfall by 2050 which will severely restrain the water supply for tens of millions of people and make wildfires even worse ultimately short of putting floaties on the city's buildings once any piece of land in the city sinks it cannot be on sunken or sunkens now i'm not going to go out and say it's over from mexico city and that the mexican government should finally make the move to puebla and that you shouldn't go to the city at all because seriously you 100 should the city isn't going to need to be evacuated or get swallowed into the earth or anything like that but it will need help going forward mexico city is not the only city in the world facing a major sinking problem jakarta is facing a very similar issue but mexico city's geographic and geological problems are quite unique amongst the major cities of the world so uh i guess it has that going for it polygense is a research academy for students looking for mentorship from top academics polygens pairs middle and high school students with top academics from some of those s-tier universities to work on any research project of your choosing and in your own way you can write a research paper if you're so inclined but if your inclination is at a different angle mentees have also made 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Channel: KhAnubis

Views: 57,537

Keywords: KhAnubis, education, educational, geography, geology, mexico, mexico city, ciudad de mexico, cdmx, how mexico city was built, how mexico city is sinking, why mexico city geography, aztec, spain, spanish empire, mexican history, tenochtitlan, documentary, largest city in north america

Id: uPytMQI-Y5M

Length: 10min 1sec (601 seconds)

Published: Sun Jul 17 2022