Evaluating and Mapping the Stability of Slopes in Napa County with a GIS-based Model Dongyuan Wang Ph.D candidate in geotechnical engineering The University of Texas at Austin December 7, 2000
Jan 05, 2016
Evaluating and Mapping the Stability of Slopes in Napa County
with a GIS-based Model
Dongyuan Wang
Ph.D candidate in geotechnical engineering
The University of Texas at Austin
December 7, 2000
Outline Outline Objective Background Data Preparation SINMAP Model Implementing SINMAP Outputs of SINMAP Discussions Acknowledgement
ObjectivesObjectives
Make the evaluation results visualized and accessible to the people.
Through this showcase, explore the feasibility of applying GIS in geotechnical engineering;Show how to evaluate and map the stability of slopes with SINMAP, a GIS-based model.
BackgroundBackground
Why Napa County?
•Development require more Lands;
•Landslide is one of main natural disasters plaguing the people in every country.
Why slope stability?
Why GIS?
Landslides in USALandslides in USA
Landslides in USALandslides in USA
Data Preparation(1) Data Preparation(1) DEMs: from USGS website
Only part of Napa CountySDTS GridScale:1:24000UTM projection
Soils: from USDA website SSURGOUseful files: comp,layer,
mapunit“Unifiled” field in “layer”
Data Preparation (2)Data Preparation (2)
Landslides: from USGS websiteIn geographic coordinates systemConvert it to UTM;Landslide PointsAdd “type” filed to
the shapefile
SINMAP SINMAP
An ArcView extension to calculate and map stability index of slopes based upon geographic information, primarily on DEMs.
Theoretical BasisInfinite slope model Topographic wetness index, R/T ratioDistribution: Uniform
Implementing SINMAP (1)Implementing SINMAP (1) Model Parameters
Gravity constant: 9.81 m/s2
Soil Density: 2000 kg/m3 Water Density: 1000 kg/m3·
Number of points in SA Plot: 2000 Calibration Parameters
T/R ratio: 2000-3000 m Dimensionless cohesion: 0.0-0.25
Angle of internal friction: 30-45 degrees
Lower wetness line percentage: 10%
Select DEM Grid Calibration area
Use “comp” file in soil date to create a calibration area; Clip “unifiled” field in “layer” to “comp” manually.Add landslide points;
Analyze Stability by adjusting calibration parameters
Implementing SINMAP(2)Implementing SINMAP(2)
Outputs (1) Outputs (1)
Outputs(2)Outputs(2)
DiscussionsDiscussions
1. Can we apply GIS in geotechnical engineering ?
2. Does SINMAP work well ?
3. Future work ?
AcknowledgementAcknowledgement Dr. Maidment at UT Dr. Tarbonton, Bob Pack and Craig Goodwin
at USU