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Figure 5.17. (Left) Estimated mean annual runoff for the Huaihe River basin, China; (right) runoff mapped along the Huaihe River network,
China. From Yan et al.(
2011
).
5000
2500
long record
4000
2000
Estimated mean
over long period
3000
1500
2000
1000
1000
500
Mean over
long period
short record
0
0
1980
1985
1990
1995
2000
1000
2000
3000
Annual runoff (mm/yr) − long record
Figure 5.18. Illustration of using linear regression to estimate the mean runoff when a short runoff record is available, by using a longer record of
a hydrologically similar catchment.
1450 mm/yr, which is significantly different from the
original estimate of 1190 mm/yr.
only presented here in the context of the use of short records.
More details on process-based methods are presented next in
this chapter, and also in
Chapter 10
.
Rainfall
-
runoff modelling
A second, more complicated method, requiring a long pre-
cipitation record for the catchment of interest, involves the
calibration of a rainfall
5.4 Process-based methods of predicting annual
runoff in ungauged basins
5.4.1 Derived distribution methods
Where an acceptable model of a hydrological process is
available, and the probability distribution of the model
inputs is known,
runoff model to the short record, and
then running the model for the full period of the precipitation
record, to produce a longer runoff record whose mean and
inter-annual variability can then be calculated. Clearly, this
belongs to the process-based category of approaches, and is
-
it
is possible to integrate the model
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