Geography Reference
In-Depth Information
having continuous or linear (strip) distributions. In this
case the diagrams belong to a linear spatial element: a river
channel. The diagrams are traced on both sides of a chan-
nel. The width of the diagrams is changed smoothly along
the length of the river; at inflow points they fork,
depending on the contributing discharge.
We distinguished three scales of water discharge: more
than 500 m 3 /s, 50
Q , m 3 /sec
A
700
600
I
II
500
400
III
50 m 3 /s. Mapping
begins where the average long-term discharge is more than
5m 3 /s, as a smaller discharge is difficult to map and would
overload the map. At a more detailed scale, a more detailed
elaboration of the rivers for smaller discharge is possible.
500 m 3 /s and 5
300
-
-
IV
200
V
100
250 M
0
0
500
1000
1500
2000
Figure 11.13. R elation between average annual runoff, Q m , and the
total entropy, M ð A Þ , for the Yenisei Basin.
Discussion
With this method, it is possible to determine the discharge
at any cross-section that allows optimisation of economic
and security measures. It is possible to determine the water
budgets of surface water resources in terms of landscape,
natural-economic, ecological and administrative divisions.
Using this method, we prepared the water content maps of
the Lower Angara region and the Irkutsk region (Korytny
and Ilyichyova, 2005 ).
classes (see Figure 11.13 ). The predominant platform
regime of runoff and river network formation in the Angara
River basin was responsible for three groups. In the Lena
River basin, five groups were identified; each of the groups
is characterised by the specific character of the hydrology
and geological structure. The rivers of the Baikal catch-
ment basin are organised into four groups.
Thus, the local dependencies of the average runoff on
entropy combine rivers that are in similar or identical
conditions of runoff formation, with the set of hydrological
and structural parameters inherent in this group only. High
values of
11.5 PREDICTING SPATIAL PATTERNS
OF INTER-ANNUAL RUNOFF
VARIABILITY IN THE CANADIAN
PRAIRIES
j. w. pomeroy, k. shook, xing fang and
t. brown
, the angle of inclination, are characteristic for
well-developed and humid river systems lying, usually, in
deeply incised high-mountain landscapes on rock with
steep gradients, and with large amounts of atmospheric
precipitation feeding the runoff. Extremely low values of
the angle of inclination are typical for a river network of
weakly differentiated uplands and valleys, usually, with a
low density of channel network, low values of atmospheric
precipitation, and with a small runoff that follows the
overall gradient of the basin. In intermediate cases the
dominant role can be played by any one of the factors of
runoff and hydraulic network formation, namely, exposure
of the mountain ranges relative to the moisture-carrying
streams, age and composition of earth materials, the pres-
ence of karst etc. Thus, the local relationships Q
α
The issue from societal and hydrological perspectives
Western Canada contains a vast semi-arid to sub-humid
agricultural region known as the Canadian Prairies. Large
fractions of the Canadian Prairies are not normally hydro-
logically connected to any large-scale drainage system, and
most of the large rivers in the region obtain the majority of
their flow from the Rocky Mountains rather than locally
( Pomeroy et al., 2007a ). Whilst the large rivers are gauged,
the smaller streams in the Canadian Prairies are often
ephemeral and ungauged. The streams are often part of
poorly developed drainage basins that feed and are com-
posed of numerous small post-glacial depressions. Though
they do not normally contribute to river flow, these depres-
sions can become important wetlands for migratory water-
fowl that use them as habitat during the spring, summer
and autumn (Smith et al., 1964 ). On-farm water supplies
are also provided by natural depressions and man-made
'
f(M)
can be used to determine the mean water discharge of river
systems that have not been studied to date.
¼
Results
Structural information, obtained for the entire topological
space, makes it possible to carry out a detailed mapping of
the water availability in the river systems. We present this
in the form of an along-the-channel scale band (distribution
diagram) (see Figure 11.14 ). This method is called
'
local-
, which are fed by local runoff and runoff due to
the lack of suitable groundwater on many farms (Pomeroy
dugouts
'
ised diagrams
'
; it is a method of mapping phenomena
Search WWH ::




Custom Search