I found the snowpack data at:
http://www.cnrfc.noaa.gov/ol.php?pr...e=precipValues&dataTable=false&mapBG=esriTopo
You can download KML files in Google Earth to get this:
Light blue line is Oroville basin; numbers are snowpack in water equivalent inches. Text labels are SWE (Snow Water Equivalent) at various stations.
Here's a color key:
Very roughly, fwiw:
~ 50% snow cover, 30 inches water average
- assume 80% yield
- 3600 sq mi drainage
=
1.1 2.3 million acre-feet (for reference the drawdown from 901 to date has been about 0.5 million ac-ft)
= about
7 14 days to run through spillway at current discharge rate of 80,000 cfs
But there is significant groundwater storage in this basin that is depleting, so lets say the current "base inflow" is close to that at ~20,000 cfs for the next few weeks. So that leaves about 60,000 cfs net discharge capacity for incoming rains and snowmelt. Per earlier discussion, about 1.2 inches of rain in a day will net maybe the equivalent of a a day of discharge at 90,000 cfs.
For perspective:
Assuming a net 60,000 cfs they can use to deplete storage or pass rain / snowmelt, and a seven day planning period, you have 0.5 million acre feet of flood storage, which would require about
70,000 cfs 35,000 cfs inflow to fill up in seven days for a total of
130,000 95,000 cfs net rain/snowmelt (above baseflow) over 7 days. This is
1.7 1.2 inches per day or
12 8.4 inches total rain / snowmelt average over the basin to refill to the brim of the emergency spillway.
I could make a case there is no issue for the upcoming storm, if something like 5 inches of rain occurs over the next 7 days and there isn't much snowmelt. In that case, maybe the reservoir level never even rises.
Or I could pay attention to some of the wilder weather models I am seeing (and perhaps misinterpreting), especially the ones with 10+ inches in the next 7 days with very warm heavy rains on Monday and say there could be a serious risk of overtopping the emergency spillway again. Rain on snow can be very bad, but I am not a California person and cannot say if that's a risk at this stage of the season.
Please don't read much into this - I am an amateur in hydrology, and have zero experience in California, and these are back of the envelope calcs with errors at best.
Another possibility is this storm just succeeds in building the snowpack and you get yet another wave in another week.