Environmental Engineering Reference
In-Depth Information
Fig. 3.32 Automated sampler for collecting stream water samples at a prescribed time interval.
(a) A field sampler with the sample intake in a pool above a V-notch weir. (b) The same sampler
showing the control unit and 24 sample bottles inside the sampler body (Photos by Masaki
Hayashi)
straightforward for some terms; for example,
<
P
>
is given by the total amount of
precipitation divided by
t
2
t
1
. However, assumptions may have to be made for
averages of other terms. For example, if continuous surface inflow data are avail-
able but only two values of concentration are available, a reasonable approximation
is to use an arithmetic mean for concentration
<
C
Si
S
i
>
ð
C
Si
1
þ
C
Si
2
Þ
=
2
<
S
i
>
(3.52)
