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Database Title

11.4 Landslide Database
Keywords
Type1.
Type 11.		 Geology, landslides, hazards
Abstract The landslide database is a hard copy and a digital database. It is a relational database of attributes including spatial elements for landslides. The digital information is organized in three main tables:
  • SLIDE-1 record per landslide with limited summary attributes
  • LSLIDE-polygons defining spatial data. There may be many records (polygons) per landslide. The polygons identifying the extent of the source are differentiated from those identifying the extent of the resultant debris
  • SAT-landslide attributes, usually many records per landslide.

All landslides in the GIS do not have the same level of information. Landslides in the GIS can be grouped into the following classes:

  • landslides with only spatial data in the database (53%)
  • landslide with only Large Landslide Database attributes (8%)
  • landslides with attributes from partially filled summary data forms(13%)
  • landslides with attributes from the completed summary data forms (26%)
Geographical Coverage It is intended that there be national coverage. At present there is about 40 percent coverage (for digitising data). The planned completion date for the North Island is June 2000. The planned completion date for the South Island is 2001.
Dataset start date. 1993
Dataset end date. Current
Status/currency. In progress
Update frequency. As new information becomes available/existing information is revised.
Maintenance. PGSF funding.

 

Technical Evaluation

  
Parameters- what is measured
  • landslide location
  • landslide size and volume
  • type of landslide
  • age of landslide(if known)
  • cause of landslide (if known)
  • geology and topography
Parameters- what is calculated N/A
Methods used to measure parameters The location and size of landslides is identified from aerial photograph interpretation. Depending on the size of the landslide, various other parameters are recorded on to the summary data form. The criteria for mapping and digitising landslides has changed over time. A checking process includes comparing data in the landslide GIS with that on the NZMS260 landslide sheets and summary data forms.
Secondary sources of data Data in the landslide GIS has come from three sources:
  • The Large Landslide Database(LLSDB). This database began in 1993 with the objective to catalogue all landslides in New Zealand with volumes > 1,000,000m3. Attribute information and location coordinates are in the SLIDE table.
  • Summary Data Forms. These were originally developed as part of the large landslide project. They have subsequently been modified. The data from these forms is in the SLIDE and SAT tables.
  • NZMS260 landslide sheets. Spatial information on landslides has been plotted by hand onto 1:50,000 topographical maps. While these started as part of the large landslide project, smaller landslides are also being recorded on the sheets. At present the spatial data in the landslide GIS does not contain all the different features presented on these landslide sheets. The landslide polygons are digitised and loaded into the LSLIDE polygon table.
Scale of use. Landslides are mapped at 1:50,000.
Number of records 4740(as at 15/9/99)
GIS compatibility. Yes
Available formats for users. Hard copy maps. Preferably digitised maps and data
Access constraints. The information is freely available but a fee is charged for the time it takes to compile the information.
Measurement Accuracy To be completed by database manager.
Completeness of dataset To be completed by database manager.
Positional accuracy To be completed by database manager.
Database steward IGNS
Database custodian IGNS
Database custodian contact person Graeme Hancox
Database custodian Contact
Address
Phone
Fax
Email		 P.O. Box 30 368
Lower Hutt
+64 4 570 1444
+64 4 570 1440
g.hancox@gns.cri.nz
References  
Date metadata record prepared. October 1999
Author of metadata record. Victoria Froude

 

Management Evaluation

  
Original purpose.
  • To obtain national coverage of landslides in New Zealand
  • To identify landslide risk in New Zealand
  • For landslide research purposes.
Relationships with classification systems. N/A
Relationships with other databases

The relationship with the former Large Landslide Database has already been described.

This database can be used with the Digital Terrain Model, Geological Map New Zealand, Digital Cadastral Database etc.
Known relationships with proposed EPIP indicators. N/A
Who uses this database? Database still in development.
Public awareness of the database N/A
Database strengths. There is systematic national coverage of landslides.
Database limitations.
  • The database is subjective. Most data is based on aerial photograph interpretation and the 1:50,000 capture scale for mapping.
  • There are many prehistoric landslides where there is little information on their timing. The geomorphic record can be up to 125,000 years in some places. It is more typically 20,000 years.
  • Many of the landslides in the database are prehistoric. This is because the focus has been on large landslides. The incidence of these in any year is low. The focus of the database is likely to expand to include a wider range of landslides.
  • The boundaries of landslides can be difficult to determine especially where landslides are now under vegetation.

 

What are the Current and Emerging Uses of the Database for:

  
Assisting with determining historic state/baseline. Landslides can be dated but this is difficult for prehistoric landslides because the resolution is diminished.
Assisting with determining current state/baseline. The database will identify the current extent of landslides above a minimum threshold.
Assisting with modeling possible future outcomes. It is intended that the information will be used to develop a model of landscape hazards including locations, frequency and size.
Risk assessment. It is intended that a model of landslide hazards in New Zealand will be developed.
Monitoring site selection and sample design. N/A
Aggregating and reporting data locally, regionally or nationally. Reporting can be at different levels.