Geography Reference
In-Depth Information
concentration map for any of the water quality parameter can be created by
using following equations (Machiwal et al., 2011):
N
C
n
,
i
C
n
1
mean
,
i
N
(18)
where, C
mean,i
= mean annual concentration map of i
th
water quality parameter,
C
n,i
= annual concentration map of the i
th
parameter in n
th
year, and N = total
number of years of data availability.
In order to compute the median, first rank the annual observations from
'
'
C
) observation and then use
one of the following equations depending on the number of observations (N):
C
) observation to the largest (
the smallest (
'
C
C
median
,
i
(
N
1
2
, when N is odd
(19)
1
C
C
'
C
'
median
,
i
(
N
/
2
)
(
N
2
)
1
2
, when N is even
(20)
The spatial standard deviation map can be prepared from the following
expression (Machiwal et al., 2011):
N
C
C
n
,
i
mean
,
i
C
n
1
sd
,
i
N
1
(21)
where, C
sd,i
= spatially-distributed standard deviation map of the i
th
parameter.
Thereafter, the coefficient of variation maps for different parameters can
be developed using the following equation (Machiwal et al., 2011):
C
sd
,
i
C
%
100
cv
,
i
C
mean
,
i
(22)
Hydrologic variables with larger CV values are more variable than those
with smaller values. Wilding (1985) suggested a classification scheme for
