Parent Layer: Ground Stability

Name: Landslide Susceptibility

Display Field: DESCRIPT

Type: Feature Layer

Geometry Type: esriGeometryPolygon

Description: EXECUTIVE SUMMARY GNS Science (GNS) has been commissioned by Rotorua District Council (RDC) to describe landslide hazards within the Rotorua district. The project has assessed landslides throughout the district in order to differentiate areas where the landslide hazard is similar. The report and accompanying map explain and show the variation in relative landslide susceptibility throughout the district. This information will help RDC develop policies and rules for dealing with landslide hazards in the new district plan. The landslide susceptibility map prepared using the methodology outlined in this report is in good agreement with the known landslide information in the Rotorua district. The agreement between the susceptibility model and historical landslide data provides confidence that the relative landslide susceptibility displayed on the map effectively discriminates relative landslide hazard. Two rainfall events generated multiple landslides over a 14 year period between 1996 and 2010. Analysis of rainfall data indicates that 200 mm of rainfall in 24 hours is the threshold for causing multiple landslides. Given that the rainfall events were limited in their extent in the district and a threshold of 200 mm of rain in 24 hours (approximately a 1-in-20 year return period event based on HIRDS data), to have two multiple landslide generating rainstorms (greater than 20-year return period storms) in 14 years matches rainfall data (the rainfall and landslide datasets were collected independently). The landslide damage caused by the 2004 Rotoehu earthquake is equivalent to MM8 in the epicentral area around Lakes Rotoehu and Rotoma. The 1987 Edgecumbe earthquake caused landslide damage equivalent to MM6 in the same area. In Rotorua City MM8 intensity has a return period of about 2500 years but for areas east of the city MM8 has a return period of 500 years. Thus the landslide distribution in the epicentral area of the Rotoehu earthquake is an analog for the type of landslide damage that might be expected during MM8 shaking in Rotorua city, which is expected to occur an average once every 2500 years. Large pre-existing landslides have been searched for by systematically examining vertical aerial photographs. No pre-existing large landslides have been identified in the Rotorua district. Based on the lack of evidence for large landslides in these terrains nationally, there is no large, pre-existing landslide hazard in the Rotorua district. First-time landslides not triggered by high-intensity rainfall or earthquake-shaking occur occasionally. Some of these occur in association with rainfall but there are often other contributing factors such as recent slope modification. GNS Science Consultancy Report 2010/82

Service Item Id: ab638295e74843ddaaaa0705b8223b95

Copyright Text:

Default Visibility: true

MaxRecordCount: 2000

Supported Query Formats: JSON, geoJSON, PBF

Min Scale: 0

Max Scale: 0

Supports Advanced Queries: true

Supports Statistics: true

Has Labels: false

Can Modify Layer: true

Can Scale Symbols: false

Use Standardized Queries: true

Supports Datum Transformation: true

Extent:

XMin: 1861320.2139999997
YMin: 5725753.9861
XMax: 1917204.4497999996
YMax: 5796075.3774
Spatial Reference: 2193  (2193)

Drawing Info:

Renderer:
Unique Value Renderer:
Field 1: DESCRIPT
Field 2: N/A
Field 3: N/A
Field Delimiter: ,
Default Symbol:
N/A
Default Label: N/A
UniqueValueInfos:
• Value: very low
  Label: Very low
  Description: N/A
  Symbol:
  Style: esriSFSSolid
  Color: [158, 187, 215, 255]
  Outline:
  Style: esriSLSNull
  Color: [110, 110, 110, 255]
  Width: 0
• Value: low
  Label: Low
  Description: N/A
  Symbol:
  Style: esriSFSSolid
  Color: [199, 215, 158, 255]
  Outline:
  Style: esriSLSNull
  Color: [110, 110, 110, 255]
  Width: 0
• Value: moderate
  Label: Moderate
  Description: N/A
  Symbol:
  Style: esriSFSSolid
  Color: [245, 245, 122, 255]
  Outline:
  Style: esriSLSNull
  Color: [110, 110, 110, 255]
  Width: 0
• Value: high
  Label: High
  Description: N/A
  Symbol:
  Style: esriSFSSolid
  Color: [245, 202, 122, 255]
  Outline:
  Style: esriSLSNull
  Color: [110, 110, 110, 255]
  Width: 0
• Value: very high
  Label: Very high
  Description: N/A
  Symbol:
  Style: esriSFSSolid
  Color: [255, 127, 127, 255]
  Outline:
  Style: esriSLSNull
  Color: [110, 110, 110, 255]
  Width: 0
Transparency: 25
Labeling Info:

Advanced Query Capabilities:

Supports Statistics: true
Supports OrderBy: true
Supports Distinct: true
Supports Pagination: true
Supports TrueCurve: true
Supports Returning Query Extent: true
Supports Query With Distance: true
Supports Sql Expression: true
Supports Query With ResultType: false
Supports Returning Geometry Centroid: false
Supports Binning LOD: false
Supports Query With LOD Spatial Reference: false
Supports Percentile Statistics: true
Supports Having Clause: true
Supports Count Distinct: true
Supports Time Relation: true
Supports Sql Format: false
Supports Query Analytic: true
Supports Query With Current User: true

HasZ: false

HasM: false

Has Attachments: false

HTML Popup Type: esriServerHTMLPopupTypeAsHTMLText

Type ID Field: null

Fields:

• OBJECTID ( type: esriFieldTypeOID, alias: OBJECTID )
• VALUE ( type: esriFieldTypeSmallInteger, alias: VALUE )
• DESCRIPT ( type: esriFieldTypeString, alias: DESCRIPT, length: 10 )
• Shape ( type: esriFieldTypeGeometry, alias: Shape )
• Shape.STArea() ( type: esriFieldTypeDouble, alias: Shape.STArea() )
• Shape.STLength() ( type: esriFieldTypeDouble, alias: Shape.STLength() )

Supported Operations:   Query   Query Attachments   Query Analytic   Generate Renderer   Return Updates

  Iteminfo   Thumbnail   Metadata