11-14-2023, 12:09 PM
Water, like many other resources, is subject to supply and demand. Something has to give. Building more housing in the areas with no water means that water usage has to stop elsewhere -- generally agriculture.
Sites reservoir: "This will be an off-stream reservoir, siphoning water off the nearby Sacramento River.
The idea is to take the water during high river flows — particularly during flood threats — and hold it until river water is low."
Hmmm.... Rivers run the easiest route downhill. I guess this "siphoning" (a term which I suspect is not used in the technical sense) is going to require pumping. To pump enough water out during high river flows to significantly affect flooding will require really big pumps (and lots of power). It will also require large aqueducts to move the water fast enough to the reservoir.
Note this reservoir is downstream of the Shasta dam. The USGS indicates the highest water flow in downtown Sacramento was 108,800 cu ft/sec in 1986 (while still 3 feet below flood stage -- but this flow might flood other portions of the river). In March 2023, my estimate from the river stage readings is that the maximum flow was about 90,000 cu ft/sec. The maximum flow rate in 2017 & 2018 was just under 80,000 cubic feet/sec, and obviously much lower until early 2023.
Say the Sacramento River has 14 days of "high river flows" a year. If they're only taking water out during that time and think they'll fill the reservoir, they'd need to move 100,000 acre-feet a day = 54,000 cfs, about 2/3 the average flow of Niagra Falls. Obviously, they're not really planning to fill the reservoir during a 2-week period, but this calculation is just to give a feel for how much it would take to reduce the flow of the Sacramento during a flood.
So, I question whether they're planning to do New Orleans-style (45,000 cfs) pumping "particularly during flood threats". I suspect that is a politician talking. Judging from the 1986 & 1987 flow information, 1,200 cfs was equivalent to 3.6" difference in the height of the river.
Sites reservoir: "This will be an off-stream reservoir, siphoning water off the nearby Sacramento River.
The idea is to take the water during high river flows — particularly during flood threats — and hold it until river water is low."
Hmmm.... Rivers run the easiest route downhill. I guess this "siphoning" (a term which I suspect is not used in the technical sense) is going to require pumping. To pump enough water out during high river flows to significantly affect flooding will require really big pumps (and lots of power). It will also require large aqueducts to move the water fast enough to the reservoir.
Note this reservoir is downstream of the Shasta dam. The USGS indicates the highest water flow in downtown Sacramento was 108,800 cu ft/sec in 1986 (while still 3 feet below flood stage -- but this flow might flood other portions of the river). In March 2023, my estimate from the river stage readings is that the maximum flow was about 90,000 cu ft/sec. The maximum flow rate in 2017 & 2018 was just under 80,000 cubic feet/sec, and obviously much lower until early 2023.
Say the Sacramento River has 14 days of "high river flows" a year. If they're only taking water out during that time and think they'll fill the reservoir, they'd need to move 100,000 acre-feet a day = 54,000 cfs, about 2/3 the average flow of Niagra Falls. Obviously, they're not really planning to fill the reservoir during a 2-week period, but this calculation is just to give a feel for how much it would take to reduce the flow of the Sacramento during a flood.
So, I question whether they're planning to do New Orleans-style (45,000 cfs) pumping "particularly during flood threats". I suspect that is a politician talking. Judging from the 1986 & 1987 flow information, 1,200 cfs was equivalent to 3.6" difference in the height of the river.