GOING WITH THE FLOW
IMPACTS OF CLIMATE CHANGE ON STORM INDUCED DEBRIS FLOWS IN HATZIC VALLEY, BC
Liz Sutton
Climate, Ocean, and Paleo-Environments (COPE) Laboratory
School of Resource and Environmental Management, Simon Fraser University
Climate change is expected to produce changes in precipitation patterns and these in turn could influence the potential for an increase of future debris flows (Dehn, Buma, &
Gasparetto, 2005). Increased storm events caused by climate change could present significant natural hazards to sensitive areas in terms of community infrastructure,
development sites, and public safety (Jakob & Weatherly, 2003).
INTRODUCTION
Debris flows are fast moving saturated sediment flows that are
triggered as a result of high volumes of precipitation.
Hatzic Valley and surrounding area have approximately 1350
residents inhabiting agricultural land and rural residential homes
(Stats Canada, 2006). The eastern side of Hatzic Valley is a
frequently active debris flow area, with the western side being less
so. Since 1980, 15 reported debris flows have resulted from five
specific storms causing damages to homes, roads, bridges, and
other infrastructure in the area.
Hatzic, BC
Vancouver
Mission
Abbotsford
U.S.A
RESEARCH FOCUS
This project focuses on three main research areas which will
address:
1)  Local debris flow initiation variables
2)  Potential effects of climate change on meteorological variables
of debris flows
3)  Application of the research results to emergency preparedness
and planning
DATA
Meteorological data collected by Environment Canada is currently
being used to identify conditions of past storms which triggered
debris flows. Environment Canada Mission West Abbey (MWA)
station is the closest station to Hatzic Valley with a record extending
from 1962 to present. In January of 2010 a HOBO data logger was
installed to collect in situ meteorological data from an active debris
flow site along the eastern slope of Hatzic Valley. Comparison of the
MWA and COPE HOBO-1 will be used to determine if there is a
significant difference in meteorological conditions based on the
location of the station.
METHODS
Storms that produced debris flows will be compared with similar storms
which did not produce flow events in order to isolate which
meteorological variables are most influential in debris flow initiation.
Meteorological mechanisms which have been found to contribute to
debris flows are antecedent precipitation, as well as intensity and
duration of storms. Antecedent precipitation will be measured in 1,2,3,
and 4 week totals, while intensity/duration events will be assessed by
rate of rainfall over the duration of the storm. Physical variables
including geology, soils, slope, and topography will be considered within
the specific local setting. Previous studies in other areas of BC suggest
that discriminate function analysis and cluster analysis are appropriate
analytical tools.
Day
of
storm
Source: Environment Canada
 Figure 2.
Pattison Creek in
Hatzic Valley, an
active creek for
debris flows and
floods.
Figure 1. Study Area: Hatzic Valley debris flows locations
PROJECT RATIONALE
The primary research goal is to identify climatic and geomorphic
variables which have historically initiated debris flows in Hatzic
Valley in order to develop criteria for forecasting events under
similar conditions. Meteorological variables are being considered
within the context of climate change to determine whether debris
flow inducing storm conditions are likely to increase or decrease in
the future.
THANKS TO:
Figure 3. COPE
HOBO-1 was
deployed January
2010 to collect
meteorological
data near Pattison
Creek.

Days
before
storm
(antecedent)
Figure 4. week antecedent precipitation
for January 29, 2004 storm initiating
debris flow at Carratt Cr. And Field Cr.
Figure 5 Local historical precipitation trends
from Agassiz CDA, the longest running MET
station in the Fraser Valley
A CHANGING CLIMATE
Total annual precipitation between 1900 and 1998 has increased
by 22% on average across British Columbia which is consistent
with a general increase in precipitation throughout the Pacific
Northwest (Pacific Climate Impacts Consortium, 2007).
A study of the effects of climate change on the frequency of slope
failures in south-west BC shows that antecedent precipitation is
expected to increase by 10% by the end of the 21st century (Jakob
and Lambert, 2009). Based on these findings, it is plausible that the
frequency of debris flows in south-west BC will increase over time
which will have implications for land-use and public safety planning.