Editing Lake Texcoco (section)

==Geography==
The [[Valley of Mexico]] is a basin with an average [[elevation]] of {{convert|2236|m|ft|0|abbr=on}} [[above mean sea level]] located in the southern highlands of [[Mexico]]'s [[Mexican altiplano|central ''altiplano'']]. Lake Texcoco formerly extended over a large portion of the southern half of the basin, where it was the largest of an interconnected chain of five major and several smaller lakes (the other main lakes being Lakes Xaltocan, [[Lake Zumpango|Zumpango]], [[Lake Chalco|Chalco]], and [[Lake Xochimilco|Xochimilco]]). Much of the lake was fed from groundwater aquifers; fresh water poured in from Lake Chalco and Xochimilco's freshwater springs, and the thermal springs of Zumpango and Xaltocan, as well as some in Texcoco itself, provided saline water.<ref>{{cite journal |last=Berres |first=Thomas E. |date=January 2000 |title=Climatic change and lacustrine resources at the period of initial Aztec development |journal=Ancient Mesoamerica |volume=11 |issue=11 |pages=27–38 |doi=10.1017/S0956536100111101 |jstor=26308028 |s2cid=162952844}}</ref> During periods of high water levels—typically after the May-to-October [[rainy season]]s—the lakes were often joined as one body of water, at an average elevation of {{convert|2242|m|ft|0|abbr=on}} above mean sea level. In the drier winter months the lake system tended to separate into individual bodies of water, a flow that was mitigated by the construction of [[Dike (construction)|dike]]s and causeways in the Late Postclassic period (1200–1521 CE) of [[Mesoamerican chronology]]. Lake Texcoco was the lowest-lying of all the lakes, and occupied the minimum elevation in the valley so that water ultimately drained towards it. The Valley of Mexico is a closed or [[endorheic basin]]. Because there is no outflow, [[evapotranspiration]] is estimated to be 72–79% of precipitation.<ref>{{cite journal |last1=Birkle |first1=Peter |date=December 1998 |title=The water balance for the Basin of the Valley of Mexico and implications for future water consumption |url=https://www.researchgate.net/publication/226329611 |journal=Hydrogeology Journal |volume=6 |issue=4 |pages=500–517 |bibcode=1998HydJ....6..500B |doi=10.1007/s100400050171 |access-date=2016-10-03 |s2cid=140202319}}</ref>