napoli 8-11-06-09
DESCRIPTION
This is the presentation about landsliding that I give almost three years ago at the IWL conference in Naples.TRANSCRIPT
Analysis of Saturated and Unsaturated Landslide Triggering through the Distributed Hydrological
Model GEOtop
First Italian Workshop on Landslides - Napoli 8-11 June, 2008
Riccardo Rigon, Silvia Simoni, Cristiano Lanni, Giuseppe Formetta
Monday, June 25, 12
Landslide an approach by GEOtop
R. Rigon, S. Simoni, C. Lanni, G. Formetta and A. Tarantino
2
... you know what I'm craving? A little perspective. That's it. ...Anton Egò
What’s for
•We tried to to have a model that could approach consistently the modeling of
water fluxes and head in a hillslope.
•To get landslide triggering ... well, and other processes.
•To be able to interpret field measures.
•And to cope the model with remote sensed data.
Monday, June 25, 12
Landslide an approach by GEOtop
R. Rigon, S. Simoni, C. Lanni, G. Formetta and A. Tarantino
3
snow, ice, permafrost
water cycle
shallow landslides
This is it !
Monday, June 25, 12
Landslide an approach by GEOtop
R. Rigon, S. Simoni, C. Lanni, G. Formetta and A. Tarantino
4Rigon et al., JHM, 2006, Bertoldi et al., JHM, 2006, Simoni, 2007, Endrizzi, 2007
http://www.geotop.org
The GEOtop project1. GEOtop is a distributed hydrological model, which integrates water and energy budget in complex terrain [Rigon et al. 2006].
2. It performs energy balance and water balance, computing energy fluxes between soil and atmosphere, subsurface and surface flows [ Bertoldi et al., 2006].
Monday, June 25, 12
Landslide an approach by GEOtop
R. Rigon, S. Simoni, C. Lanni, G. Formetta and A. Tarantino
5
Slope stability is assessed through the probabilistic and dynamic module GEOtop-FS [Simoni et al, 2007].
The GEOtop project
Data Assimilation
RadiationEnergyBudget
Vegetation
SubsurfaceFlows
SurfaceFlows
Snow&
Cryosphere
I/O
GEOtop 2010
Monday, June 25, 12
Landslide an approach by GEOtop
R. Rigon, S. Simoni, C. Lanni, G. Formetta and A. Tarantino
Liquid water
Soil particles
Frozen water
Air gas
Mass Volume
Ms Vs
Vag
Vi
Vlw
VspMsp
Mlw
Mi
Mag
The Basic, however, is the dynamics of
the soil water column
6
Monday, June 25, 12
Landslide an approach by GEOtop
R. Rigon, S. Simoni, C. Lanni, G. Formetta and A. Tarantino
Mass Budget of Condensed Water
The equation does not come alone. It fulfills some constraints:
⇤t (⇥lw�lw + ⇥i�i) +⇤ · (⇥lw⌃Jlw + ⇥i
⌃Ji)� ⇥lwslw � ⇥isi = 0
or
�r � �lw � ⇥se
�r � �lw + �i � ⇥s
7
Monday, June 25, 12
Landslide an approach by GEOtop
R. Rigon, S. Simoni, C. Lanni, G. Formetta and A. Tarantino
Mass Budget of Condensed Water
Some simplifications are readily made:
- The flux of ice is negligible, i.e.
- The source/sink of ice is also neglibile, i.e.
Thus the equation reduces to
⇥Ji � 0
si � 0
⇧t (⇥lw min(⇤se,max(�r, �lw)) + ⇥i min(max(0, �i), ⇤s) +⇤ · (⇥lw�Jlw)� ⇥lwslw = 0
8
Monday, June 25, 12
Landslide an approach by GEOtop
R. Rigon, S. Simoni, C. Lanni, G. Formetta and A. Tarantino
9
True: we also have to parametrize soil water retention curves and hydraulic conductivity [L T-1] (please do not call permeability [L2]).
For the first we use the van Genucthen (1980) scheme for the second Mualem (1976)
Mass Budget of Condensed Water
If the ice is neglected, for the present case, the conventional Richard’s equation is obtained
⇧t (⇥lw min(⇤se,max(�r, �lw))) +⇤ · (⇥lw�Jlw)� ⇥lwslw = 0
Monday, June 25, 12
Landslide an approach by GEOtop
R. Rigon, S. Simoni, C. Lanni, G. Formetta and A. Tarantino
A Flash back ...
Two main contenders debated in the last decade about modeling shallow landslides. Just to personalize this, as it is common nowadays
10
into the geological/gemorphological community
The West Coast guys The USGSes
Monday, June 25, 12
Landslide an approach by GEOtop
R. Rigon, S. Simoni, C. Lanni, G. Formetta and A. Tarantino
11
A Flash back ... into the geological/gemorphological community
Bill and Dave assert that shallow landslides can be approximately explained by saturation excess hydrology, lateral flow, and infinity slope stability. They produced the widely used and cited SHALSTAB model.
Montgomery and Dietrich, 1994
Monday, June 25, 12
Landslide an approach by GEOtop
R. Rigon, S. Simoni, C. Lanni, G. Formetta and A. Tarantino
12
A Flash back ... into the geological/gemorphological community
Dick Iverson (S. Baum, J. Godt) insists that the transient vertical effects counts in building a sufficient pore pressure to destabilize hillslope. This broughto TRIGRS
Iverson, 2000; Baum et al., 2002
Monday, June 25, 12
Landslide an approach by GEOtop
R. Rigon, S. Simoni, C. Lanni, G. Formetta and A. Tarantino
13
A Flash back ... with intrusion of hydrologists
One Italian gang tried to reconcile the fighters observing that all
of that above derives from the Richards equation with various
degree of simplifications, and proposed a linear simplified
theory with analytical solutions available that superimpose the
SHALSTAB theory with Iverson’s one, to be convoluted to
precipitations. D’Odorico et al., WRR, 2005; Cordano and Rigon, WRR, 2008
Monday, June 25, 12
Landslide an approach by GEOtop
R. Rigon, S. Simoni, C. Lanni, G. Formetta and A. Tarantino
14
A Flash back ... with intrusion of hydrologists
I.M.H.O., the linear theory works close to saturation but has some
problems of parameter characterizations in more unsaturated
cases, which caused some headaches to us.
To make a long story short, we did our best with simplified
theories*, but finally we had to observe that going directly to a
numerical non linear model was the right and conceptually
simpler choice.
*I am pretty sure that Frattini and Crosta, 2009 does it better
Monday, June 25, 12
Landslide an approach by GEOtop
R. Rigon, S. Simoni, C. Lanni, G. Formetta and A. Tarantino
15
•Area: 13.4 km2
•Min elevation: 924 m
•Max elevation: 2890 m
•Two main ephemeral stream
A case studyRio Corda, Italy, Trentino
•No steep, but hilly Oregon: an Alpine small catchment
Monday, June 25, 12
Landslide an approach by GEOtop
R. Rigon, S. Simoni, C. Lanni, G. Formetta and A. Tarantino
16
A case studyRio Corda, Italy, Trentino
A landslide happened in June 2008 and we tried to reproduce that event
Monday, June 25, 12
Landslide an approach by GEOtop
R. Rigon, S. Simoni, C. Lanni, G. Formetta and A. Tarantino
17
A case studyRio Corda, Italy, Trentino
We investigated the water pressures in the yellow point.
Monday, June 25, 12
Landslide an approach by GEOtop
R. Rigon, S. Simoni, C. Lanni, G. Formetta and A. Tarantino
18
A case studyRio Corda, Italy, Trentino
A landslide happened in June 2008 and we tried to reproduce that event
Psi @ point 1
time (days/month)
wa
ter
su
ctio
n [m
m]
30/04 03/05 06/05 09/05 12/05 15/05 18/05 21/05 24/05 27/05 30/05 02/06 05/06 08/06 11/06
-2500
-1000
01000
0.025 m0.1 m0.25 m0.5 m0.825 m1.2 m
05
10
15
rain
[m
m/h
]Monday, June 25, 12
Landslide an approach by GEOtop
R. Rigon, S. Simoni, C. Lanni, G. Formetta and A. Tarantino
18
A case studyRio Corda, Italy, Trentino
A landslide happened in June 2008 and we tried to reproduce that event
Psi @ point 1
time (days/month)
wa
ter
su
ctio
n [m
m]
30/04 03/05 06/05 09/05 12/05 15/05 18/05 21/05 24/05 27/05 30/05 02/06 05/06 08/06 11/06
-2500
-1000
01000
0.025 m0.1 m0.25 m0.5 m0.825 m1.2 m
05
10
15
rain
[m
m/h
]Monday, June 25, 12
Landslide an approach by GEOtop
R. Rigon, S. Simoni, C. Lanni, G. Formetta and A. Tarantino
18
A case studyRio Corda, Italy, Trentino
A landslide happened in June 2008 and we tried to reproduce that event
Psi @ point 1
time (days/month)
wa
ter
su
ctio
n [m
m]
30/04 03/05 06/05 09/05 12/05 15/05 18/05 21/05 24/05 27/05 30/05 02/06 05/06 08/06 11/06
-2500
-1000
01000
0.025 m0.1 m0.25 m0.5 m0.825 m1.2 m
05
10
15
rain
[m
m/h
]
15.05.08
Monday, June 25, 12
Landslide an approach by GEOtop
R. Rigon, S. Simoni, C. Lanni, G. Formetta and A. Tarantino
18
A case studyRio Corda, Italy, Trentino
A landslide happened in June 2008 and we tried to reproduce that event
Psi @ point 1
time (days/month)
wa
ter
su
ctio
n [m
m]
30/04 03/05 06/05 09/05 12/05 15/05 18/05 21/05 24/05 27/05 30/05 02/06 05/06 08/06 11/06
-2500
-1000
01000
0.025 m0.1 m0.25 m0.5 m0.825 m1.2 m
05
10
15
rain
[m
m/h
]
15.05.08
Monday, June 25, 12
Landslide an approach by GEOtop
R. Rigon, S. Simoni, C. Lanni, G. Formetta and A. Tarantino
18
A case studyRio Corda, Italy, Trentino
A landslide happened in June 2008 and we tried to reproduce that event
Psi @ point 1
time (days/month)
wa
ter
su
ctio
n [m
m]
30/04 03/05 06/05 09/05 12/05 15/05 18/05 21/05 24/05 27/05 30/05 02/06 05/06 08/06 11/06
-2500
-1000
01000
0.025 m0.1 m0.25 m0.5 m0.825 m1.2 m
05
10
15
rain
[m
m/h
]
22.05.0815.05.08
Monday, June 25, 12
Landslide an approach by GEOtop
R. Rigon, S. Simoni, C. Lanni, G. Formetta and A. Tarantino
19
A case studyRio Corda, Italy, Trentino
We investigated the water pressures in the yellow point.
Psi point 1
time (days/month)
wate
r suction [m
m]
30/04 05/05 10/05 15/05 20/05 25/05 30/05
−2500
−1500
−500
500
1500
0.025 m0.1 m0.25 m0.5 m0.825 m1.2 m
05
10
15
rain
[m
m/h
]
Monday, June 25, 12
Landslide an approach by GEOtop
R. Rigon, S. Simoni, C. Lanni, G. Formetta and A. Tarantino
20
A case studyRio Corda, Italy, Trentino
Method in Simoni et al., HP, 2008
Monday, June 25, 12
Landslide an approach by GEOtop
R. Rigon, S. Simoni, C. Lanni, G. Formetta and A. Tarantino
20
A case studyRio Corda, Italy, Trentino
Method in Simoni et al., HP, 2008
Monday, June 25, 12
Landslide an approach by GEOtop
R. Rigon, S. Simoni, C. Lanni, G. Formetta and A. Tarantino
21
A simple comparison between GEOtop and SHALSTABRio Corda, Italy, Trentino
Monday, June 25, 12
Landslide an approach by GEOtop
R. Rigon, S. Simoni, C. Lanni, G. Formetta and A. Tarantino
22
A simple comparison between GEOtop and SHALSTABRio Corda, Italy, Trentino
Monday, June 25, 12
Landslide an approach by GEOtop
R. Rigon, S. Simoni, C. Lanni, G. Formetta and A. Tarantino
23
A simple comparison between GEOtop and SHALSTABRio Corda, Italy, Trentino
Top Index - Saturated Top Index - Not saturatedGEOtop -Saturated 26.9 15.04
GEOtop Not Saturated 15.04 43.02
Monday, June 25, 12
Landslide an approach by GEOtop
R. Rigon, S. Simoni, C. Lanni, G. Formetta and A. Tarantino
24
A simple comparison between GEOtop and SHALSTABRio Corda, Italy, Trentino
Monday, June 25, 12
Landslide an approach by GEOtop
R. Rigon, S. Simoni, C. Lanni, G. Formetta and A. Tarantino
25
Conjectures on the differencesRio Corda, Italy, Trentino
Differences are due to:
•Non stationarity of the response
•Downslope reinfiltration of surface water
•The treatment of surface water in GEOtop that set a boundary conditions for
the water table elevation at the channel network
This is apparent, for instance, after Cordano and Rigon, 2008.
Monday, June 25, 12
Landslide an approach by GEOtop
R. Rigon, S. Simoni, C. Lanni, G. Formetta and A. Tarantino
26
A theoretical investigation to assess these behavior
Geometry
Soil Type
Antecedent Soil Moisture Conditions
Rainfall intensities and volumes
The aim is to investigate the role of some factors that control the processes
of pore-water pressure redistribution and, hence, the factor of safety (FS) of
the slope.
Different Values of these features are chosen as described below
Monday, June 25, 12
Landslide an approach by GEOtop
R. Rigon, S. Simoni, C. Lanni, G. Formetta and A. Tarantino
27
A theoretical investigation to assess these behavior
Lanni et al., 2009, in preparation
Monday, June 25, 12
Landslide an approach by GEOtop
R. Rigon, S. Simoni, C. Lanni, G. Formetta and A. Tarantino
27
A theoretical investigation to assess these behavior
Lanni et al., 2009, in preparation
Monday, June 25, 12
Landslide an approach by GEOtop
R. Rigon, S. Simoni, C. Lanni, G. Formetta and A. Tarantino
28
Boundary Conditions
On the sides AB, BC, CD, DEOmogeneous Neumann Boundary
Conditions
On the sides AF, EF (switch of the b.c.)Neumann or Dirichlet Boundary Conditions,
depending from moisture conditions at the
first soil layer
Monday, June 25, 12
Landslide an approach by GEOtop
R. Rigon, S. Simoni, C. Lanni, G. Formetta and A. Tarantino
29
Computer Experiment Set-up
Two cases analyzed: steep and gentle slope
i. STEEP SLOPE, when the angle of the slope is bigger than the frictional angle of the soil
ii. GENTLE SLOPE, when the angle of the slope is smaller (or is the same) than the frictional angle of the soil
€
tanφ'tanα1
= 0.7
€
tanφ'tanα2
=1.0
Monday, June 25, 12
Landslide an approach by GEOtop
R. Rigon, S. Simoni, C. Lanni, G. Formetta and A. Tarantino
30
Two cases analyzed: sandy soil and sandy-silt soil
Through physical properties and soil texture it is possible toget the shape parameters of the van Genuchten model usingVereecken PTF (1989)
SANDY SOIL
S1
€
φ'= 35o
€
% sand = 80
€
% silt = 20
€
Ksat =10−4m /s
SANDY-SILT SOIL
S2
€
φ'= 30o
€
% sand = 40
€
% silt = 60
€
Ksat =10−6m /s
The Computer Experiment Set-up
Monday, June 25, 12
Landslide an approach by GEOtop
R. Rigon, S. Simoni, C. Lanni, G. Formetta and A. Tarantino
31
€
ψ(z) =ψbottom + γw ⋅ H − z( )
Chosen so as to obtain the following values of initial safety factor of the slope:
FS=1.05 for CI1 initial condition
FS=1.10 for CI2 initial condition
FS=1.20 for CI3 initial condition
The Computer Experiment Set-upInitial Conditions
Monday, June 25, 12
Landslide an approach by GEOtop
R. Rigon, S. Simoni, C. Lanni, G. Formetta and A. Tarantino
32
0.7 if steep slope case1.0 if gentle slope case
0.35 (steep) 0.05 (gentle) for CI10.40 (steep) 0.10 (gentle) for CI20.50 (steep) 0.20 (gentle) for CI3
€
FS =tanφ 'tanα
+γwψ( )0.45 γwψb( )0.55
γ ⋅ h ⋅ sinα ⋅ cosαtanφ'
The Computer Experiment Set-up
The above prescriptions turn into:
Monday, June 25, 12
Landslide an approach by GEOtop
R. Rigon, S. Simoni, C. Lanni, G. Formetta and A. Tarantino
33
In unsaturated medium the total stress is defined as:
€
σ = σ − ua( ) + χ ψ( ) ua − uw( ) Bishop (1959)
The Computer Experiment Set-up
χ valued according to Khalili & Kabbaz empirical relation (1998)
€
χ =ua − uwua − uw( )b
⎡
⎣ ⎢
⎤
⎦ ⎥
−0.55
if ua − uw( )b < ua − uw( )b
€
χ =1
€
if ua − uw( )b ≥ ua − uw( )b
€
ua − uw( )b FL−2[ ]where:
is the air-entry value matrix suction
Monday, June 25, 12
Landslide an approach by GEOtop
R. Rigon, S. Simoni, C. Lanni, G. Formetta and A. Tarantino
34
Some Results
1D means that soil failure happens above the bedrock
2D means that soil failure happens at the bedrock
work in progress
Soil Type Slope Initial Conditions Rainfall Duration BehaviorCoarse Steep Wet Short 1DCoarse Steep Wet Long 1DCoarse Steep Dry Long 2D· · · · ·Fine Gentle Wet Any 1D
Probably this also affect the position in the hillside where the failure can happen.
Monday, June 25, 12
Landslide an approach by GEOtop
R. Rigon, S. Simoni, C. Lanni, G. Formetta and A. Tarantino
35
Some Further Results Resultswork in progress by I. Pretto and C. Lanni
Monday, June 25, 12
Landslide an approach by GEOtop
R. Rigon, S. Simoni, C. Lanni, G. Formetta and A. Tarantino
36
Some Further Results Resultswork in progress by I. Pretto and C. Lanni
In real life the water table has a curvature due to the channal drainage
Monday, June 25, 12
Landslide an approach by GEOtop
R. Rigon, S. Simoni, C. Lanni, G. Formetta and A. Tarantino
37
PostGISPostgres
Webservices
WMSWFS-TWPS
Beyond GEOtop: The complete GEOFRAME framework
OpenMI
J-Console Engine
JGrass
uDigEclipse RCP
H2 spatial
UIBuilder
GRASS
GIS engine
The Horton Machine
Models
BeeGIS
www.slideshare.net/GEOFRAMEcafe/geoframe-a-system-for-doing-hydrology-by-computer
Monday, June 25, 12
Landslide an approach by GEOtop
R. Rigon, S. Simoni, C. Lanni, G. Formetta and A. Tarantino
Next year
38
First Steps into GEOFRAME: First Componentization
WaterBudget
EnergyBudget
MeteoForcings
The first version
+ + I/O
Monday, June 25, 12
Landslide an approach by GEOtop
R. Rigon, S. Simoni, C. Lanni, G. Formetta and A. Tarantino
Next year
39
I/OWaterBudget
EnergyBudget
MeteoForcings
The second version
First Steps into GEOFRAME: Second Componentization
Monday, June 25, 12
Landslide an approach by GEOtop
R. Rigon, S. Simoni, C. Lanni, G. Formetta and A. Tarantino
40
Further splitting will follows
I/O Data Assimilation
RadiationEnergyBudget
Vegetation
SubsurfaceFlows
SurfaceFlows
Snow&
Cryosphere
Monday, June 25, 12
Hoping that Bill, Dick Dave, forgive me!Thank you for your attention
Free GIS: www.jgrass.orgFree Hydrological Model: www.geotop.org
Search also GEOFRAME Cafe on Slideshare
Monday, June 25, 12