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THE ROLE OF DEBRIS FLOWS IN LONG TERM DENUDATION AND LANDSCAPE EVOLUTION
OF THE CENTRAL APPALACHIANS
L. Scott Eaton, Ph.D.L. Scott Eaton, Ph.D.Department of Geology and Environmental Department of Geology and Environmental
ScienceScienceJames Madison UniversityJames Madison University
Death Valley, CA
~ 140 fatalities
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Blue Ridge Mountains, VA
Rapidan Storm,June 1995
775 mm
Research Question:Research Question:
In the Appalachians, are debris flows a In the Appalachians, are debris flows a
significant process in the significant process in the transportation of transportation of
sediment from sediment from mountainous terrain to mountainous terrain to thethe
floodplains?floodplains?
What is the frequency of debris flows?What is the frequency of debris flows?
How much sediment is transported How much sediment is transported during an event?during an event?
What are the long term erosion What are the long term erosion (denudation)(denudation) rates in the central rates in the central Appalachians?Appalachians?
frequency of debris flowsfrequency of debris flows
DEBRIS FLOW FREQUENCY IN THE RAPIDAN BASIN
from Eaton and others, 2003
Sediment Transport and Denudation
0.398 km2
Before After
? ?
?
13, 364 m3
0.398 km2
Volume = 13, 364 m3
Area 0.398 km2 or 398,000 m2 = 0.034 m
= 3.4 cm
Summary of Basin Denudation of Blue Ridge Systems
Event
BasinBasin Area (km2)
Volume ofSediment Eroded
(m3)
Mean Basin
Denuda-tion (cm)
HurricaneCamille
Willis Cove
4.08 173,488 4.25
HurricaneCamille
Ginseng Hollow
1.75 88,727 5.07
HurricaneCamille
Polly Wright Cove
2.47 87,707 3.55
Rapidan Flood
Jenkins Hollow
0.398 13,364 3.36
Rapidan Flood
Teal Hollow 0.123 2,492 2.03
Long Term and Episodic Denudation
0
1
2
3
4
5
6
7
8
9
10
Nelson County Madison County
Den
ud
atio
n (
cm) Long Term
Episodic
3,500 Years 1 Day
2,500Years 1 Day
HurricaneCamille
RapidanStorm
A Model of A Model of AppalachianAppalachian
Landscape EvolutionLandscape Evolution
BEFORE…..
AFTER…..
HIGH “M”LOW (f)
LOW “M”HIGH (f)
