Geography Reference
In-Depth Information
a)
b)
100
100
D2H012
Sim. Lower
Sim. Upper
D2H003
Sim. Lower
Sim. Upper
10
10
1
1
0.1
0.1
0.01
0.01
0.001
0.001
0 0 0
30 50 60
% Time Equalled or Exceeded
0
70
80
90
100
0 0 0
30 50 60
% Time Equalled or Exceeded
0
70
80
90
100
c)
d)
1000
1000
D2H020
Sim. Lower
Sim. Upper
D2H005
Sim. Lower
Sim. Upper
100
100
10
10
1
1
0.1
0.1
0.01
0 0 0
30 50 60
% Time Equalled or Exceeded
0
70
80
90
100
0 0 0
30 50 60
% Time Equalled or Exceeded
0
70
80
90
100
e)
f)
1000
1000
100
100
10
10
D2H001
Sim. Lower
Sim. Upper
Midgley et al. (1994)
Sim. Lower
Sim. Upper
1
1
0.1
0.1
0 0 0
30 50 60
% Time Equalled or Exceeded
0
70
80
90
100
0 0 0
30 50 60
% Time Equalled or Exceeded
0
70
80
90
100
Figure 11.22. Results for the gauged sub-basins presented as 1-month flow duration curves for observed flows and the simulated upper and
lower bounds of the uncertainty ensembles.
that has been subject to any form of calibration is the
groundwater recharge parameters, and these have been
established to match the range of mean annual recharge
values given in DWAF ( 2005 ). The results are presented at
the sites of the gauging stations to determine whether the
local gauging data can be of any assistance in constraining
the parameter uncertainty ranges, or identifying where the
estimated parameter values are non-behavioural.
The records for D2H012 (1968 to 2010) are representa-
tive of present-day conditions in the northern headwaters.
However, the peak daily flow observations are truncated
and therefore the high flows are highly under-represented.
While there are a relatively small number of farm dams in
the upstream areas, it is assumed that the lowest flows will
have been affected by some abstractions. The balance of
the evidence suggests therefore that the simulations are
behavioural ( Figure 11.22a ). The records at D2H003
(1935 to 1954) pre-date the construction of a major reser-
voir (14.2 × 10 6 m 3 storage), while a second reservoir (5.6
×10 6 m 3
storage) has existed upstream since 1892. The
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