Empirical Landslide Modeling

Finn Krogstad

UW Forest Engineering

May 30, 1990

Overview

• Why Empirical Modeling?

• A simple example

• Logistic Regression

• Results

Why Empirical Modeling?

• Most landslide models show where landslides will be, but not how many.

• If we want to evaluate operations or landscape plans, we need to know how many landslides will result from our plan.

A simple example

Q: How many landslides will a high hazard area produced?

A: Count the fraction that have slid already, and apply this to the proposed action.

low mod high

No-cut pln=yln/nln pmn=ymn/nmn phn=yhn/nhn

clearcut plc=ylc/nlc pmc=ymc/nmc phc=yhc/nhc

hchcmcmclclc pNpNpNY

Regression

• The familiar form

• can also be thought of as

• Allows any mapable variables of interest

• Already coded in ArcInfo

• Output in Probability of Landsliding

iharviroadicurveislopebasei harvaroadacurveaslopeaap exp1/1

iiii harvharv

roadroad

curvecurve

slopeslopebasei bbbbbp

Hazard Mapping

• Using just slope and curvature, we can create a hazard map, much like SMORPH.

• This map can guide our design

Operational Assessment

• Calculate cell probabilities before and after the operation, subtract, and sum the differences (E(ls)=.364).

before after difference

Landscape Evaluation

• Same as the Operational evaluation, but on a larger scale.