A View from the Back of the Envelope top

Volume rate
m3/s
Scale of some things
Volume
Time
How fast volume flows/shifts/accumulates/drains/etc.
Rough Draft
m3/s
...
10-9 microliter/s
10-8
10-7 3 m3/yr
10-6 milliliter/s | gallon/hr
10-5 ft3/hr | blood through adult brain
10-4 gallon/min | faucet | through adult heart
10-3 liter/s | 2 ft3/min
10-2 2 gal/s | 100 gal/min
10-1 3 ft3/s | 1/2 m storm drain
100 m3/s
101 4m2 open channel w 0.2% slope
102 3 109 m3/yr
103 water use - US non-agricultural | Colorodo river
104 water use - US agricultural / World non-agricultural | World&US powerplant cooling
105 3 1012 m3/yr | US runoff / evaporation / precipitation | water use - World agricultural
106 world land runoff / precipitation / evapotranspiration
107 world sea precipitation / evaporation
108
109
...

Conversions

unit m3/s
ft3/s 10-2 × 2.832
gallon/s 10-2 × 0.3785
liter/s 10-3 × 1.000
ft3/min 10-3 × 0.472
gallons/min (gpm) 10-4 × 0.6308
ft3/hr 10-5 × 0.7866
gallons/hr (gph) 10-6 × 1.051
milliliter/s 10-6 × 1.000
m3/yr 10-8 × 3.169
microliter/s 10-9 × 1.000
10 ×
10 ×

Notes

Currently in pre-first-draft state...
faucet  rain/meter^2  drop/s  evap/m^2
heart breath(500cft/day?)
world petrol consump (1Ggal?)
a thunderstorm
open channel flow example [Lindeburg p19-4] 0.002 slope,
 finished concrete n=0.012, 2.5m wide, 1.6m deep => 377ft3/s,
 10.7m3/s  0.002 is 2m/km
20 in concrete storm drain on 0.001 slope and 2/3 full
 does 2.5ft3/s, 7.0 × 10-2m

From [Cow p239]: in 10^12 m^3/yr
 US(excl.Ak&Ha) runoff 1.65, evapotranspiration 3.95, precipitation 5.6,
 world runoff 46, evapotranspiration from land 62, sea evaporation 456,
   precip sea 410, precip land 108
in 10^9 m^3/yr, water used by humans
                        withdraw  consume  (world US)
 municipal&domestic  220  42  74  10
 mining & manufact.  390  52  40   6
 electric pwr plant cool 620 180   8   2.6
 irrigation&livestock 2100 205  1100 125
oom buckets:
       1-9  USindC WUSpwrC
     10-90  WmuniC USmuniWC USindW WindC    USmuni+indC
   100-900  WmuniW WindW WUSpwrW USagriWC   Wmuni+indC
 1000-9000  WagriWC
Have not dealt cleanly w W/C distinction in pot scale above?  Esp re pwr

my kitchen faucet 10s/liter
wells 1-2000 gal/min
Water-saving showerheads use 2 to 3 gpm while conventional showerheads use 4 to 5 gpm.
Hoover is 29Macre-ft, holds ~2 yrs of Colorodo.
  So river at Hoover is 0.44 acreft/s, or 1/2 × 103 m3/s.

Blood flow through whole brain (adult) = 750 ml/min src.  I.e. 1.25e-5 m^3/s.

A View from the Back of the Envelope
Comments encouraged. - Mitchell N Charity <mcharity@lcs.mit.edu>