OVERKILL
$100 Site Donor 2021
For some perspective, just the James Bay Project alone (from the Wikipedia page):
The establishment of reservoirs containing large amounts of standing water has the ability to produce local climate changes. Alteration of annual precipitation patterns, increased abundance of low stratus clouds and fog, and warmer autumns and cooler springs, leading to a delay in the beginning and end of the growing season, have all been observed in the vicinity of the project's major reservoirs. The doubling of the freshwater input into James Bay during the winter decreases the salinity of the seawater, thereby increasing the freezing point of the bay. The resultant increased ice content at the northern section of the project in the winter has cooled warm air currents more than usual, bringing harsher Arctic weather, including strong winds and less precipitation, to south-central Quebec. The tree line at the southern edge of the development has shifted noticeably southward since the project's construction.
Following construction of the project, the area's water flow was substantially modified. In the James Bay area in general, the average monthly surface runoff rate in the winter increased by 52%, doubling the total freshwater input, while that of the summer months decreased by 6%. The James Bay area's water flow is most affected by the hydroelectric project from January to April because rivers have their lowest runoff rates in the winter months when freezing occurs. Additionally, runoff rates in the damming system can be altered to meet power needs, which are highest in the winter and lowest in the summer, thereby more completely reversing the natural water flow cycle. As evidenced by the 500% increase in its winter runoff, the La Grande River is the pillar of the James Bay project's hydroelectric capacity, with the runoff increasing from an average yearly amount of 1,700 m3/s to 3,400 m3/s, and from 500 m3/s to 5,000 m3/s in the winter. This immense harnessing of the area's energy at La Grande was made possible by reducing the Eastmain River's water flow at its mouth by 90% and by reducing that of the Caniaspiscau River's by 45%, and then by diverting these rivers into La Grande. Not only does this alter the runoff amount of the Eastmain and the Caniaspiscau Rivers, but also their drainage location, since prior to having been directly merged with La Grande, these rivers’ drainage locations were separate from the La Grande River. The summer runoff rate of La Grande increased by 40%, making the average annual runoff rate 91% greater than its natural rate.
I would expect that the damming of the Yangtze River with the Three Gorges dam, which also produced a giant reservoir and altered water flows would have a similar impact.
The establishment of reservoirs containing large amounts of standing water has the ability to produce local climate changes. Alteration of annual precipitation patterns, increased abundance of low stratus clouds and fog, and warmer autumns and cooler springs, leading to a delay in the beginning and end of the growing season, have all been observed in the vicinity of the project's major reservoirs. The doubling of the freshwater input into James Bay during the winter decreases the salinity of the seawater, thereby increasing the freezing point of the bay. The resultant increased ice content at the northern section of the project in the winter has cooled warm air currents more than usual, bringing harsher Arctic weather, including strong winds and less precipitation, to south-central Quebec. The tree line at the southern edge of the development has shifted noticeably southward since the project's construction.
Following construction of the project, the area's water flow was substantially modified. In the James Bay area in general, the average monthly surface runoff rate in the winter increased by 52%, doubling the total freshwater input, while that of the summer months decreased by 6%. The James Bay area's water flow is most affected by the hydroelectric project from January to April because rivers have their lowest runoff rates in the winter months when freezing occurs. Additionally, runoff rates in the damming system can be altered to meet power needs, which are highest in the winter and lowest in the summer, thereby more completely reversing the natural water flow cycle. As evidenced by the 500% increase in its winter runoff, the La Grande River is the pillar of the James Bay project's hydroelectric capacity, with the runoff increasing from an average yearly amount of 1,700 m3/s to 3,400 m3/s, and from 500 m3/s to 5,000 m3/s in the winter. This immense harnessing of the area's energy at La Grande was made possible by reducing the Eastmain River's water flow at its mouth by 90% and by reducing that of the Caniaspiscau River's by 45%, and then by diverting these rivers into La Grande. Not only does this alter the runoff amount of the Eastmain and the Caniaspiscau Rivers, but also their drainage location, since prior to having been directly merged with La Grande, these rivers’ drainage locations were separate from the La Grande River. The summer runoff rate of La Grande increased by 40%, making the average annual runoff rate 91% greater than its natural rate.
I would expect that the damming of the Yangtze River with the Three Gorges dam, which also produced a giant reservoir and altered water flows would have a similar impact.
