1
Water Balance
1.
Continuity equation for a hydrologic system
I - O = S/t
in volume/time or
It - Ot = S in volume
I is Inflow; O is outflow; S is the change of storage
within the hydrologic system, for a specific period of
time, t.
Inflow, I
S
Storage, S
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1
Exam Three
Sample question
1. Determine the diameter of concrete pipe needed to deliver water at a flow rate of 3 m 3/s from a
reservoir with a water surface elevation of 70 m to a reservoir with a water surface elevation of 40
m. The pipe is 2000 m lon
Prob. 10.33 Analytical methods
Month Inflow
1
Oct
Nov
Dec
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
(cfs)
2
130
70
50
41
30
95
230
195
100
65
85
157
300
346
Inflow Outflow Outflow Monthly Cumul
Cumul
Volume
Volume
diff.
Diff.
Deficit
(cfs-day) (cfs) (cf
1
Hydrologic Cycle
Our world is represented by the cycle.
It is the center of hydrology.
Subjects (topics) to be covered in this course revolve around
this center (cycle): surface and groundwater hydrology and
hydraulics.
The total volume of water on,
P (in), i (in/hr)
Rain-fan Hyetograph:
Cumulative Mass (P) and Intensity (i)
who
m. . 1
:(in/hr) -F(in)
14
12
"2-6410
0
'10 '20 30 46 50 .60 10 39 99 100110 12013914015018i
t(min) Atlw Mm
Jo Jami
if)?! (:gmw W 8 .m .D ,cmmom E m Emgmxm we maa mummmgamommws$5me
ag wmmwwm
EMEV momm
QB mm aw 9m ON 2 w w w
I. . J. t z" m H u 1 M
3
mmw
cm
Emu, Q35:
m
mega W W
5.53% w M
(Lg/cfw_5g lgsumm uogmgmaxd
LEM/g %Z@CWJ/O j?
7 gm f! cfw_3&4
M g 71% 1?: y. x 2 f
@4er 2; Asa: ,3 cfw_a Wm /Wi :5 M wWWfi QWW
W 03994373 m/wg
z i x
M, iymim Mad 5W :2 cfw_WM 5:; ffia" fm
magi WWW/Mm
W E W-mm 056 S
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A? cfw_:5 5
10.33 Graphic methods
Month Inflow
(cfs)
1
Oct
Nov
Dec
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
2
130
70
50
41
30
95
230
195
100
65
85
157
300
346
Inflow Outflow Outflow Cumul
Cumul
Diff. of
Volume
Volume inflow outflow
cumul
(cfs-day) (cfs) (cfs-day)