GIS LANDSLIDES ANALYSIS ii

GIS LANDSLIDES ANALYSISRoadway between USC Wrigley Institute and Two Harbors

Catalina Island, CA.

M.Sc. GIS Program – GEOG 587 class

Presented by: Edmundo M. Zevallos

April 3rd. 2011

GIS LANDSLIDES ANALYSIS

A Landslide is a Mass movements under influences of gravity.

Roadway between USC Wrigley Institute and Two HarborsCatalina Island, CA.

A Landslide is a Mass movements under influences of gravity. Occurs as a result of diverse disturbing and destabilizing

processes, for example of climatic or anthropological origin. The stability of slopes is determined by the geometry of surfaces

and slip-horizons.

Introduction

p

In regard to spatial landslide analysis, GIS is an important tool to carry out data input, handling, visualization, combination, query, analysis.

Ability of the GIS to incorporate the spatially varying data of Hypothesis:

Ability of the GIS to incorporate the spatially varying data of ground elevation, soil properties, slope, etc. in the engineering analysis of the slope stability.

USC MARINE CAMPUS-TWO HARBORS GIS LANDSLIDES ANALYSIS

Roadway between USC Wrigley Institute and Two Harbors

ROADWAY• An analysis of landslide in an specific area of the Catalina Island.

• Study Area located in the north west part (section third) of the island


• Study Area located in the north west part (section, third) of the island.

• In the East-West existing roadway between the USC Wrigley Institute facility and the town of Two Harbors.

Research following a spatially-distributed data with a geo-reference to real world.

USC Wrigley Institute

ExistingRoadway

Area of Analysis

Two Harbors

y


Raster-based GIS was applied in order to analyze the spatial distribution of landslides


distribution of landslides. Parameters established in a map: 1.- slope

2.- Geology3.- Geomorphology4.- drainage/scour network5.- Road network

Four possible landslides spot were inventoried in the study. Followed by a field work inventory in the North East side of the

existing roadway. Three types of landslides were identified in the study area

Abstract

Three types of landslides were identified in the study area1.- scour2.- rock falls3.- flows

The landslides are distributed:1 id f l (15% t 50%) di t ( f 1)1.- on a wide range of slope (15% to 50%) gradient (ref.1)2.- Two constant geological (ref 2) setting: - Catalina Schist

- Volcanic. This paper will demonstrates the ability of the GIS to incorporate

the spatially varying data of: - ground elevation, soil properties, etc. p y y g g , p p ,in the engineering analysis of the slope stability.


The management of spatial-data is pivotal for this analysis, due:


1. - The unique capability of GIS: to workTo captureTo store

Manage the data 2. - The handle of data referenced: by vast spatial

O hi di t

GIS and Landslide analysis

Or geographic coordinates

3. - Its ability to incorporate appropriate engineering models

In the case of the landslide analysis in here, this analysis demands:1. - Collection of data, 2. - Storage of data 3 Use of the data for the analysis handled in the GIS3. - Use of the data for the analysis handled in the GIS environment.





GPS device Reported Number of Description

Collection of data

GPS device Reported accuracy

Number of points taken

Description of points

Nomad (Trimble)

5 mt 5 points Drainage Structures and Possible Slide

GPS devices were used and their

of dataland location

630 pointGPS Setup to logging

results different accuracy.

interval every 5 seconds2,120 pointsGPS setup to logginglogging interval every 1 meter

Geo XH (Trimble)

45 cm 18 points( )



Storage of data and processingArcMap Layers:

ArcMap storage of Data and analysis

spatially-distributed data and geo-reference to real world.

g y

Critical area along road

+

Typical Drainage structure

Typical possible Landslide spot



GPS Pathfinder OfficeCreation of Data Dictionary editor

Dat

a C

olle

ctor

de

vice

Creation of Data Dictionary editor

ArcMap storage of Data and spatial analysis

Storage of data and processing

(cont.)

Sratigraphy thickness

Thickness

Slope

US Geological SurveyMetadata of Catalina Island

521

poly

gons

4,



F l ti f T i l l d lid l i

A slope stability analysis combined with risk

Formulation of Typical landslide analysis

A slope stability analysis combined with risk analyses is proposed to carry out.

The area under investigation is geoprocessed in ArcMap, and marked with more than 4,000 point elevationselevations.

It could observe that the hill is sloping downward towards northwest.

The slide has occurred at the upper regions.

Various man-made features are also present, like roads and only three drainage structures, a

t f lli i th d lstream falling in the downslope.



Formulation of Typical landslide analysis (cont.)

The steps involved in the landslide hazard it generates a mapping given as flow chart.

The formulation of the work is described.

The methodology gyproposed would be able to develop the hazard map, and perform decision analysis



ColoredContours Triangles ColoredTriangles surfaces

DTMDigital Terrain ModelModel

Plan View of Existing RoadPlan View of Existing Road

Profile of Existing Road



Conclusions

1) I studied the distribution / characterization of landslides in the study area through: - Photointerpretation- Geomorphologic surveyGeomorphologic survey

2) This area of study is characterized by two stratigraphic-structural units: - Mostly Miocene volcanic rocks- Tertiary subvolcanic rocks- Tertiary subvolcanic rocks

3) This research shows that in the area of the analysis there are two types of landslides: - slow earth flow their landslide masses are quite small

k f ll i li t f ti- rock falls occur in limestone formations

4) Morphometric characteristics, play an important role in landsliding processes.

5) Can be determined through the analysis of the digital terrain model.



Conclusions (cont.)

6) The application of this method would be useful to locate potential unstable areas, and so to predict the occurrence of future landslides.

7) Since the slides has occurred at the upper regions and hence short-term remediation will be an immediate solution in the form of relief wells.

8) The analysis using: - Hydrologic models could be incorporated in the Arc View- Stability models

9) GIS-based techniques are the best approach to the study of landslide tibilit b th ll th t f l th isusceptibility because they allow the management of several themes concerning

instability factors.

10) Geographic Information Systems (GIS) is being exploited widely in many engineering problems which involves spatial data managementengineering problems, which involves spatial data management.



Thank you for your attention

Any questions?



References

Soil Survey of Catalina Island, California. USDA (2008) USGS - Soils data for the Conterminous United States

Derived from the NRCS State Soil Geographic (STATSGO) D t B (2001)Data Base. (2001)

Landslide analysis in Geographic Information Systems, G.L. Babu (1998)

Soils data for the Conterminous United States Derived from Soils data for the Conterminous United States Derived from the NRCS State Soil Geographic (STATSGO) Data Base. (1995) USGS.

Technology

GIS LANDSLIDES ANALYSIS ii