3 ms·

Before-and-after photos show California storm's insane impact on water levels

28 points by andrewfromx 10y ago

javiramos 10y ago
I felt scared for the pedestrian crossing the bridge in second 0:28!
- runlevel1 10y ago
  Me too. Those trusses don't look like they were designed for that kind of lateral force. I'd be interested to hear a civil engineer's take.
gumby 10y ago
This is a poor article. First of all, its numbers are way off. I plotted last Tuesday's data ( http://cdec.water.ca.gov/cgi-progs/products/rescond.pdf http://cdec.water.ca.gov/cgi-progs/products/rescond.pdf for current levels) and the total reservoir levels added up to be 101% of typical years (ranging from well below at New Melones, which is still low, to abnormally high for some of the smaller ones like Folsom. The total water level was still less than 2/3 total capacity (actually 63%). This is exciting but doesn't get us out of the woods. Those historical levels have of course been trending down due to low water levels. Just look at those pictures of the floating docks on Folsom: all that grassy, treeless area around the lake is empty reservoir! We don't want them completely full since there would be no buffer for later filling. What you want is full for a given point in the season. There are two other problems. One is that we have another reservoir system: the snowpack. We just got a couple of meters of accumulation which is great, but it was preceded by a rain that washed a lot of water out of the snowpack and into the reservoirs. We depend on that snowpack to modulate the water release into the year for two reasons; one is it's a free buffer. The other is that as it trickles down rather than gushing down it percolates into the aquifers, which are historically low. Some of them are irrecoverable (under the Central Valley the water was laid down 20,000 years ago; when it is sucked out the ground sinks so the water can't be replaced) but many are also natural reservoirs that need to be recharged. If we get an earlier sprint and overall warmer conditions that water will rush across the land and into the sea rather than into the ground. So this is great news, no question, but that article doesn't tell a useful story.

28 points by andrewfromx 10y ago

javiramos 10y ago

I felt scared for the pedestrian crossing the bridge in second 0:28!

runlevel1 10y ago
Me too. Those trusses don't look like they were designed for that kind of lateral force. I'd be interested to hear a civil engineer's take.

gumby 10y ago

This is a poor article. First of all, its numbers are way off. I plotted last Tuesday's data ( http://cdec.water.ca.gov/cgi-progs/products/rescond.pdf http://cdec.water.ca.gov/cgi-progs/products/rescond.pdf for current levels) and the total reservoir levels added up to be 101% of typical years (ranging from well below at New Melones, which is still low, to abnormally high for some of the smaller ones like Folsom. The total water level was still less than 2/3 total capacity (actually 63%). This is exciting but doesn't get us out of the woods. Those historical levels have of course been trending down due to low water levels. Just look at those pictures of the floating docks on Folsom: all that grassy, treeless area around the lake is empty reservoir! We don't want them completely full since there would be no buffer for later filling. What you want is full for a given point in the season. There are two other problems. One is that we have another reservoir system: the snowpack. We just got a couple of meters of accumulation which is great, but it was preceded by a rain that washed a lot of water out of the snowpack and into the reservoirs. We depend on that snowpack to modulate the water release into the year for two reasons; one is it's a free buffer. The other is that as it trickles down rather than gushing down it percolates into the aquifers, which are historically low. Some of them are irrecoverable (under the Central Valley the water was laid down 20,000 years ago; when it is sucked out the ground sinks so the water can't be replaced) but many are also natural reservoirs that need to be recharged. If we get an earlier sprint and overall warmer conditions that water will rush across the land and into the sea rather than into the ground. So this is great news, no question, but that article doesn't tell a useful story.