Geology Reference
In-Depth Information
16.7
Applicability to Climate Change
for these future scenarios (e.g. Nearing
et al
.,
2005; Elliot, 2006; see also Chapter 15).
The WEPP model is the physically-based engine
behind the interfaces that have been described.
The climate input into the WEPP model includes
daily precipitation amounts and maximum and
minimum temperatures. These files are generally
generated with a stochastic climate generator
CLIGEN (Nicks
et al
., 1995) that is accessed by
all of these interfaces. This interface allows incor-
poration of future climate scenarios into any
WEPP technology.
The general approach to incorporate future cli-
mate scenarios for all of these applications is
through the online 'RockClime' interfaces (Scheele
et al
., 2001). This interface allows users to access
current climate station data from the CLIGEN
database containing about 2600 stations, modify
that climate for remote areas within the US using
the PRISM monthly precipitation database (Daly
et al
., 1994), and further adjust the maximum and
minimum temperatures, monthly precipitation
amount, and number of wet days in a month to
match future climate scenarios. Future tempera-
tures and precipitation values are readily available
from numerous sources (e.g. http://forest.mos-
cowfsl.wsu.edu/climate/). Research is ongoing to
determine the distribution of wet days in future
climates.
It is generally predicted that future climates
will be warmer, and in many areas, wetter in the
winter months. This means that snowpack in the
northern hemisphere will be less developed, and
snowmelt or rain-on-snow events less severe,
whereas runoff associated with large precipitation
events may increase. Warmer summers will also
likely lead to increased evapotranspiration and
lower soil water contents, resulting in lower
runoff from summer storms, unless those storms
are more severe. Whatever the effect, the altered
climate coupled with the WEPP technology will
be able to predict the risk of a given amount of
erosion from a single event, or from a year for any
current or future climate. The biggest limitation
is the ability to describe the future climate. The
WEPP technologies are already providing average
annual predictions and single storm predictions
16.8 Summary
This chapter described the need for risk-based
modelling to predict soil erosion associated with
forest management disturbances and wildfires.
It presented four different WEPP interfaces and
demonstrated how they could be used for erosion
risk analysis following a wildfire. These included
a Windows interface, two online interfaces, and
a GIS interface. In the examples provided, the
online ERMiT tool, which considers a range of
fire severities, and the WEPP Windows inter-
face, estimated lower erosion rates than the
Disturbed WEPP interface, which could only
provide an annual estimate and not a single
storm prediction. Each of the models predicted
erosion rates within the wide range of those
measured in field experiments in the modelled
area. The WEPP model is well suited for making
such risk-based predictions for current and
future climate scenarios.
Acknowledgement
This chapter was written and prepared by US
Government employees on official time, and
therefore it is in the public domain and not sub-
ject to copyright.
References
Cochrane, T.A. & Flanagan, D.C. (1999) Assessing water
erosion in small watersheds using WEPP with GIS
and digital elevation models.
Journal of Soil and
Water Conservation
54
: 678-85.
Daly, C., Neilson, R.P. & Phillips, D.L. (1994) A statisti-
cal-topographic model for mapping climatological
precipitation over mountainous terrain.
Journal of
Applied Meteorology
33
: 140-48.
Doerr, S.H., Shakesby, R.A. & Walsh, R.P.D. (2000) Soil
water repellency: its causes, characteristics and
hydro-geomorphological significance.
Earth-Science
Review
15
: 33-65.
