Geology Reference
In-Depth Information
Considering model use, a major challenge is to
educate potential users in how to apply physical-
ly-based, spatially-distributed basin models most
advantageously. Some important points include:
●
the problems of data provision and parameter
uncertainty associated with such models must be
acknowledged but should not be taken to prevent
model use. Instead, users must learn how to inter-
pret outputs in the form of uncertainty envelopes.
This allows in any case a more realistic apprecia-
tion of the limitations of all types of sediment
model (not just physically-based) and provides a
means of quantifying the implications of making
decisions on the basis of imperfect data;
●
even in the absence of data it is possible to
apply physically-based models to explore prob-
lem areas and to carry out 'what if?' studies of
different potential courses of action;
●
satisfactory calibration and validation require
the incorporation of internal basin response data
and appropriate tests for a model's fitness for
purpose;
●
most reported model applications have been in
temperate and semi-arid regions. However, tropi-
cal regions are currently suffering from severe
problems of accelerated erosion related to land
use changes and demonstrations of model appli-
cability to these regions are therefore needed.
used in scenario studies and the exploration of
problem areas. As with other physically-based
models, uncertainties are associated with data
provision and parameterization; this uncertainty
should be accounted for in the modelling proce-
dure, for example with uncertainty envelopes (see
Chapter 5 for a case study), and users must learn
to interpret model output accordingly. As yet, a
new generation of models involving fundamental
developments in process understanding and solu-
tion technique has still to emerge. However,
there are a number of exciting opportunities for
enhancing existing capabilities, especially in the
areas of data provision, model parameterization
and process representation.
Acknowledgements
The continued evolution and application of
SHETRAN over the last two decades has depended
on the efforts of a team of researchers at Newcastle
University and other centres. These researchers
have been acknowledged in, or have been co-
authors of, previous publications. However, there
have been a number of important developments
over the last few years (not all associated with the
erosion model) and this author would particularly
like to acknowledge the work of Steve Birkinshaw,
Isabella Bovolo, Ahmed El-Hames, John Ewen
and Greta Moretti. The SHETRAN website is
maintained by Steve Birkinshaw.
14.9 Conclusion
Physically-based, spatially-distributed models
provide the strongest basis for predicting the
impacts of future changes in land use and climate
on soil erosion and sediment yield in river basins.
However, current computational constraints
limit their applicability to basins of a few thou-
sands of square kilometres. New models continue
to be developed but the basic process representa-
tion has shown only modest improvements over
the past two decades. SHETRAN remains a viable
and relevant model with particular advantages in
integrating a range of broad erosional processes.
Considerable experience has been accumulated
in its application at scales ranging from small ero-
sion plots to basins of 1500 km
2
and it has been
References
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Abbott, M.B., Bathurst, J.C., Cunge, J.A.,
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An introduction to the European Hydrological
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