Napoli 8-11-06-09

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This is the presentation about landsliding that I give almost three years ago at the IWL conference in Naples.

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Napoli 8-11-06-09

  1. 1. Analysis of Saturated and Unsaturated Landslide Triggering through the Distributed Hydrological Model GEOtop Riccardo Rigon, Silvia Simoni, Cristiano Lanni, Giuseppe Formetta First Italian Workshop on Landslides - Napoli 8-11 June, 2008Monday, June 25, 12
  2. 2. Landslide an approach by GEOtop ... you know what Im craving? A little perspective. Thats 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. 2 R. Rigon, S. Simoni, C. Lanni, G. Formetta and A. TarantinoMonday, June 25, 12
  3. 3. Landslide an approach by GEOtop This is it ! snow, ice, permafrost water cycle shallow landslides 3 R. Rigon, S. Simoni, C. Lanni, G. Formetta and A. TarantinoMonday, June 25, 12
  4. 4. Landslide an approach by GEOtop The GEOtop project 1. 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]. Rigon et al., JHM, 2006, Bertoldi et al., JHM, 2006, Simoni, 2007, Endrizzi, 2007 http://www.geotop.org 4 R. Rigon, S. Simoni, C. Lanni, G. Formetta and A. TarantinoMonday, June 25, 12
  5. 5. Landslide an approach by GEOtop The GEOtop project Slope stability is assessed through the probabilistic and dynamic module GEOtop-FS [Simoni et al, 2007]. GEOtop 2010 I/O Data Subsurface Surface Assimilation Flows Flows Energy Snow Vegetation Radiation Budget & Cryosphere 5 R. Rigon, S. Simoni, C. Lanni, G. Formetta and A. TarantinoMonday, June 25, 12
  6. 6. Landslide an approach by GEOtop The Basic, however, is the dynamics of the soil water column Mass Volume Air gas Mag Vag Frozen water Mi Vi Ms Vs Liquid water Mlw Vlw Soil particles Msp Vsp 6 R. Rigon, S. Simoni, C. Lanni, G. Formetta and A. TarantinoMonday, June 25, 12
  7. 7. Landslide an approach by GEOtop Mass Budget of Condensed Water ⇤t (⇥lw lw ⌃ ⌃ + ⇥i i ) + ⇤ · (⇥lw Jlw + ⇥i Ji ) ⇥lw slw ⇥i si = 0 The equation does not come alone. It fulfills some constraints: r lw ⇥se or r lw + i ⇥s 7 R. Rigon, S. Simoni, C. Lanni, G. Formetta and A. TarantinoMonday, June 25, 12
  8. 8. Landslide an approach by GEOtop Mass Budget of Condensed Water Some simplifications are readily made: - The flux of ice is negligible, i.e. ⇥ Ji 0 - The source/sink of ice is also neglibile, i.e. si 0 Thus the equation reduces to ⇧t (⇥lw min(⇤se , max( r , lw )) + ⇥i min(max(0, i ), ⇤s ) + ⇤ · (⇥lw Jlw ) ⇥lw slw = 0 8 R. Rigon, S. Simoni, C. Lanni, G. Formetta and A. TarantinoMonday, June 25, 12
  9. 9. Landslide an approach by GEOtop 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 ) ⇥lw slw = 0 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) 9 R. Rigon, S. Simoni, C. Lanni, G. Formetta and A. TarantinoMonday, June 25, 12
  10. 10. Landslide an approach by GEOtop A Flash back ... into the geological/gemorphological community Two main contenders debated in the last decade about modeling shallow landslides. Just to personalize this, as it is common nowadays The West Coast guys The USGSes 10 R. Rigon, S. Simoni, C. Lanni, G. Formetta and A. TarantinoMonday, June 25, 12
  11. 11. Landslide an approach by GEOtop 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 11 R. Rigon, S. Simoni, C. Lanni, G. Formetta and A. TarantinoMonday, June 25, 12
  12. 12. Landslide an approach by GEOtop 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 12 R. Rigon, S. Simoni, C. Lanni, G. Formetta and A. TarantinoMonday, June 25, 12
  13. 13. Landslide an approach by GEOtop 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 13 R. Rigon, S. Simoni, C. Lanni, G. Formetta and A. TarantinoMonday, June 25, 12
  14. 14. Landslide an approach by GEOtop 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 14 R. Rigon, S. Simoni, C. Lanni, G. Formetta and A. TarantinoMonday, June 25, 12
  15. 15. Landslide an approach by GEOtop A case study Rio Corda, Italy, Trentino •Area: 13.4 km2 •Min elevation: 924 m •Max elevation: 2890 m •Two main ephemeral stream •No steep, but hilly Oregon: an Alpine small catchment 15 R. Rigon, S. Simoni, C. Lanni, G. Formetta and A. TarantinoMonday, June 25, 12
  16. 16. Landslide an approach by GEOtop A case study Rio Corda, Italy, Trentino A landslide happened in June 2008 and we tried to reproduce that event 16 R. Rigon, S. Simoni, C. Lanni, G. Formetta and A. TarantinoMonday, June 25, 12
  17. 17. Landslide an approach by GEOtop A case study Rio Corda, Italy, Trentino We investigated the water pressures in the yellow point. 17 R. Rigon, S. Simoni, C. Lanni, G. Formetta and A. TarantinoMonday, June 25, 12
  18. 18. Landslide an approach by GEOtop A case study Rio Corda, Italy, Trentino A landslide happened in June 2008 and we tried to reproduce that Psi @ point 1 event 15 0.025 m 0.1 m 0.25 m 0.5 m 0.825 m 1.2 m water suction [mm] 1000 10 rain [mm/h] 0 -1000 5 -2500 0 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 time (days/month) 18 R. Rigon, S. Simoni, C. Lanni, G. Formetta and A. TarantinoMonday, June 25, 12
  19. 19. Landslide an approach by GEOtop A case study Rio Corda, Italy, Trentino A landslide happened in June 2008 and we tried to reproduce that Psi @ point 1 event 15 0.025 m 0.1 m 0.25 m 0.5 m 0.825 m 1.2 m water suction [mm] 1000 10 rain [mm/h] 0 -1000 5 -2500 0 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 time (days/month) 18 R. Rigon, S. Simoni, C. Lanni, G. Formetta and A. TarantinoMonday, June 25, 12
  20. 20. Landslide an approach by GEOtop A case study Rio Corda, Italy, Trentino A landslide happened in June 2008 and we tried to reproduce that Psi @ point 1 event 15 0.025 m 0.1 m 0.25 m 0.5 m 0.825 m 1.2 m water suction [mm] 1000 10 rain [mm/h] 0 -1000 5 -2500 0 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 time (days/month) 15.05.08 18 R. Rigon, S. Simoni, C. Lanni, G. Formetta and A. TarantinoMonday, June 25, 12
  21. 21. Landslide an approach by GEOtop A case study Rio Corda, Italy, Trentino A landslide happened in June 2008 and we tried to reproduce that Psi @ point 1 event 15 0.025 m 0.1 m 0.25 m 0.5 m 0.825 m 1.2 m water suction [mm] 1000 10 rain [mm/h] 0 -1000 5 -2500 0 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 time (days/month) 15.05.08 18 R. Rigon, S. Simoni, C. Lanni, G. Formetta and A. TarantinoMonday, June 25, 12
  22. 22. Landslide an approach by GEOtop A case study Rio Corda, Italy, Trentino A landslide happened in June 2008 and we tried to reproduce that Psi @ point 1 event 15 0.025 m 0.1 m 0.25 m 0.5 m 0.825 m 1.2 m water suction [mm] 1000 10 rain [mm/h] 0 -1000 5 -2500 0 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 time (days/month) 15.05.08 22.05.08 18 R. Rigon, S. Simoni, C. Lanni, G. Formetta and A. TarantinoMonday, June 25, 12
  23. 23. Landslide an approach by GEOtop A case study Rio Corda, Italy, Trentino We investigated the water pressures in the yellow point. Psi point 1 15 0.025 m 0.1 m 0.25 m 0.5 m 0.825 m 1500 1.2 m 10 water suction [mm] rain [mm/h] 500 −500 5 −1500 −2500 0 30/04 05/05 10/05 15/05 20/05 25/05 30/05 time (days/month) 19 R. Rigon, S. Simoni, C. Lanni, G. Formetta and A. TarantinoMonday, June 25, 12
  24. 24. Landslide an approach by GEOtop A case study Rio Corda, Italy, Trentino Method in Simoni et al., HP, 2008 20 R. Rigon, S. Simoni, C. Lanni, G. Formetta and A. TarantinoMonday, June 25, 12
  25. 25. Landslide an approach by GEOtop A case study Rio Corda, Italy, Trentino Method in Simoni et al., HP, 2008 20 R. Rigon, S. Simoni, C. Lanni, G. Formetta and A. TarantinoMonday, June 25, 12
  26. 26. Landslide an approach by GEOtop A simple comparison between GEOtop and SHALSTAB Rio Corda, Italy, Trentino 21 R. Rigon, S. Simoni, C. Lanni, G. Formetta and A. TarantinoMonday, June 25, 12
  27. 27. Landslide an approach by GEOtop A simple comparison between GEOtop and SHALSTAB Rio Corda, Italy, Trentino 22 R. Rigon, S. Simoni, C. Lanni, G. Formetta and A. TarantinoMonday, June 25, 12
  28. 28. Landslide an approach by GEOtop A simple comparison between GEOtop and SHALSTAB Rio Corda, Italy, Trentino Top Index - Saturated Top Index - Not saturated GEOtop -Saturated 26.9 15.04 GEOtop Not Saturated 15.04 43.02 23 R. Rigon, S. Simoni, C. Lanni, G. Formetta and A. TarantinoMonday, June 25, 12
  29. 29. Landslide an approach by GEOtop A simple comparison between GEOtop and SHALSTAB Rio Corda, Italy, Trentino 24 R. Rigon, S. Simoni, C. Lanni, G. Formetta and A. TarantinoMonday, June 25, 12
  30. 30. Landslide an approach by GEOtop Conjectures on the differences Rio 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. 25 R. Rigon, S. Simoni, C. Lanni, G. Formetta and A. TarantinoMonday, June 25, 12
  31. 31. Landslide an approach by GEOtop A theoretical investigation to assess these behavior 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.  Geometry  Soil Type  Antecedent Soil Moisture Conditions  Rainfall intensities and volumes Different Values of these features are chosen as described below 26 R. Rigon, S. Simoni, C. Lanni, G. Formetta and A. TarantinoMonday, June 25, 12
  32. 32. Landslide an approach by GEOtop A theoretical investigation to assess these behavior Lanni et al., 2009, in preparation 27 R. Rigon, S. Simoni, C. Lanni, G. Formetta and A. TarantinoMonday, June 25, 12
  33. 33. Landslide an approach by GEOtop A theoretical investigation to assess these behavior Lanni et al., 2009, in preparation 27 R. Rigon, S. Simoni, C. Lanni, G. Formetta and A. TarantinoMonday, June 25, 12
  34. 34. Landslide an approach by GEOtop Boundary Conditions  On the sides  On the sides AB, BC, CD, DE AF, EF (switch of the b.c.) Omogeneous Neumann Boundary Neumann or Dirichlet Boundary Conditions, Conditions depending from moisture conditions at the 28 first soil layer R. Rigon, S. Simoni, C. Lanni, G. Formetta and A. TarantinoMonday, June 25, 12
  35. 35. Landslide an approach by GEOtop Computer Experiment Set-up  Two cases analyzed: steep and gentle slope i. STEEP SLOPE, when the angle of tan φ the slope is bigger than the = 0.7 frictional angle of the soil tan α1 ii. GENTLE SLOPE, when the angle of the slope is smaller (or is the tan φ same) than the frictional angle = 1.0 € tan α 2 of the soil 29 R. Rigon, S. Simoni, C. Lanni, G. Formetta and A. TarantinoMonday, June 25, 12
  36. 36. Landslide an approach by GEOtop The Computer Experiment Set-up  Two cases analyzed: sandy soil and sandy-silt soil SANDY SOIL % sand = 80 S1 % silt = 20 o φ = 35 −4 K sat = 10 m /s € € % sand = 40 SANDY-SILT SOIL € % silt = 60 S2 o € φ = 30 K sat = 10−6 m /s € € Through physical properties and soil texture it is possible to € get the shape parameters of the van Genuchten model using Vereecken PTF€ (1989) 30 R. Rigon, S. Simoni, C. Lanni, G. Formetta and A. TarantinoMonday, June 25, 12
  37. 37. Landslide an approach by GEOtop The Computer Experiment Set-up Initial Conditions ψ (z) = ψ bottom + γ w ⋅ ( 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 31 R. Rigon, S. Simoni, C. Lanni, G. Formetta and A. TarantinoMonday, June 25, 12
  38. 38. Landslide an approach by GEOtop The Computer Experiment Set-up The above prescriptions turn into: 0.45 0.55 tan φ (γ wψ ) (γ wψ b ) FS = + tan φ tan α γ ⋅ h ⋅ sin α ⋅ cos α € 0.35 (steep) 0.05 (gentle) for CI1 0.7 if steep slope case 0.40 (steep) 0.10 (gentle) for CI2 1.0 if gentle slope case 0.50 (steep) 0.20 (gentle) for CI3 32 R. Rigon, S. Simoni, C. Lanni, G. Formetta and A. TarantinoMonday, June 25, 12
  39. 39. Landslide an approach by GEOtop The Computer Experiment Set-up  In unsaturated medium the total stress is defined as: σ = (σ − ua ) + χ (ψ )( ua − uw ) Bishop (1959) χ valued according to Khalili & Kabbaz empirical relation (1998) € ⎡ u − u ⎤−0.55 χ = ⎢ a w ⎥ if ( ua − uw ) b < ( ua − uw ) b ⎣( ua − uw ) b ⎦ χ =1 if ( ua − uw ) b ≥ ( ua − uw ) b where:€ (ua − uw ) b [ FL−2 ] € € is the air-entry value matrix suction 33 € R. Rigon, S. Simoni, C. Lanni, G. Formetta and A. TarantinoMonday, June 25, 12
  40. 40. Landslide an approach by GEOtop Some Results work in progress Soil Type Slope Initial Conditions Rainfall Duration Behavior Coarse Steep Wet Short 1D Coarse Steep Wet Long 1D Coarse Steep Dry Long 2D · · · · · Fine Gentle Wet Any 1D 1D means that soil failure happens above the bedrock 2D means that soil failure happens at the bedrock Probably this also affect the position in the hillside where the failure can happen. 34 R. Rigon, S. Simoni, C. Lanni, G. Formetta and A. TarantinoMonday, June 25, 12
  41. 41. Landslide an approach by GEOtop Some Further Results Results work in progress by I. Pretto and C. Lanni 35 R. Rigon, S. Simoni, C. Lanni, G. Formetta and A. TarantinoMonday, June 25, 12
  42. 42. Landslide an approach by GEOtop Some Further Results Results work in progress by I. Pretto and C. Lanni In real life the water table has a curvature due to the channal drainage 36 R. Rigon, S. Simoni, C. Lanni, G. Formetta and A. TarantinoMonday, June 25, 12
  43. 43. Landslide an approach by GEOtop Beyond GEOtop: The complete GEOFRAME framework Eclipse RCP uDig PostGIS JGrass Postgres J-Console Engine GIS engine OpenMI Web The Horton services UIBuilder Machine WMS Models WFS-T H2 spatial WPS GRASS BeeGIS www.slideshare.net/GEOFRAMEcafe/geoframe-a-system-for-doing-hydrology-by-computer 37 R. Rigon, S. Simoni, C. Lanni, G. Formetta and A. TarantinoMonday, June 25, 12
  44. 44. Landslide an approach by GEOtop First Steps into GEOFRAME: First Componentization Next year Meteo Energy Water I/O + + Forcings Budget Budget The first version 38 R. Rigon, S. Simoni, C. Lanni, G. Formetta and A. TarantinoMonday, June 25, 12
  45. 45. Landslide an approach by GEOtop First Steps into GEOFRAME: Second Componentization Next year Meteo Energy Water I/O Forcings Budget Budget The second version 39 R. Rigon, S. Simoni, C. Lanni, G. Formetta and A. TarantinoMonday, June 25, 12
  46. 46. Landslide an approach by GEOtop Further splitting will follows I/O Data Subsurface Surface Assimilation Flows Flows Energy Snow Vegetation Radiation & Budget Cryosphere 40 R. Rigon, S. Simoni, C. Lanni, G. Formetta and A. TarantinoMonday, June 25, 12
  47. 47. Hoping that Bill, Dick Dave, forgive me! Thank you for your attention Free GIS: www.jgrass.org Free Hydrological Model: www.geotop.org Search also GEOFRAME Cafe on SlideshareMonday, June 25, 12

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