Geoscience Reference
In-Depth Information
8
Beyond the Primer: Models for
Changing Risk
However the endeavour to produce such a theory [of flood hydrology] would be well worth-
while. It would improve our understanding of hydrologic phenomena, improve our decision
making in relation to water resources, and improve our standing among geophysicists. To
accomplish it, we require a broad background knowledge of our own subject and of cognate
disciplines and a real capacity to think both imaginatively and to work hard.
Jim Dooge, 1986
In view of the magnitude and ubiquity of the hydroclimatic change apparently now under
way, however, we assert that stationarity is dead and should no longer serve as a central,
default assumption in water-resource risk assessment and planning. Finding a suitable
successor is crucial for human adaptation to changing climate.
Chris Milly
et al.
2008
8.1 The Role of Rainfall-Runoff Models in Managing Future Risk
Catchment systems are not stationary systems; both their characteristics and the inputs which drive the
hydrology are changing over time (Milly
et al.
, 2008). There are two types of future risk that need
to be managed in catchment hydrology where rainfall-runoff models can play a useful role. The first
is the short-term forecasting problem of whether an important flood discharge with the potential to
pose a threat to life or property will occur. The second is the longer term seasonal or decadal prediction
problem of whether changes in catchment characteristics or climate might pose a threat to water resources
or flood and drought frequencies. Both of these problems are dependent on the inputs from weather
and climate prediction models, which are associated with significant uncertainties in their predictions,
including epistemic uncertainties. Managing these risks therefore requires consideration of a cascade of
uncertainties through multiple model components and seeking ways to constrain the resulting uncertainty
using forms of data assimilation wherever possible (e.g. Pappenberger
et al.
, 2005b).
