Published on 30 September 2024

swissEO VHI

The Vegetation Health Index (VHI) shows the current health status of vegetation as observed by satellites.

This index consists of two components and assesses, in addition to the condition of the plants (local biophysical conditions; Vegetation Condition Index, or VCI), the climatic conditions (temperature; Thermal Condition Index, or TCI). The current values are compared and related to the corresponding values from the climate reference period from 1991 to 2020. The combination of VCI and TCI in the VHI allows for the evaluation of the vegetation condition. When plants wilt prematurely or change color, and temperatures are unusually high at the same time, the VHI value decreases. A low VHI value indicates vegetation stress, such as during a drought period or in the case of disease infestation. The lower the VHI value, the higher the stress and the greater the potential damage to the vegetation.
The VHI is a relative measure that is only meaningful when comparing the same conditions. For example, the VHI is not meaningful for a farming plot where different crops are grown each year. Similarly, managed forests with wood removal may show a relatively lower or drier value, as less biomass remains. However, the remaining trees might be just as healthy as they were during the climate reference period.

Schematic representation of the composition of the Vegetation Health Index (VHI) from the Vegetation Condition Index (VCI) and the Thermal Condition Index (TCI). Both indices classify the current value (NDVIcurrent or Tcurrent) relative to the conditions of the corresponding period during the climate reference period (1991-2020).

Data visualisation and availability

The latest dataset can be displayed in the BGDI map viewer via https://map.geo.admin.ch/?layers=ch.swisstopo.swisseo_vhi_v100 . In the WMS of the BGDI, the dataset can be shown using the layer «ch.swisstopo.swisseo_vhi_v100».

The VHI has been produced retroactively for every day since April 2017 and is published continuously with a time lag of currently around three days. In addition, historical VHI data (January 1991 – March 2017) calculated using Landsat 5, 7 and 8 data is available. This data has a spatial resolution of 30 m and is summarised in monthly data sets (dated on the first day of each month).

To display older datasets in the BGDI map viewer, an URL parameterization must be applied. In the following link, <id> is replaced by the date of the data capture in the format ‘yyyy-mm-dd’ (example: 2025-01-01)
.

https://map.geo.admin.ch/index.html?layers=WMS||vhi_v100_<id>t235959||https://wms.geo.admin.ch/?item=<id>t235959||ch.swisstopo.swisseo_vhi_v100||1.3.0

For example, for the dataset from 21th of September 2024:

https://map.geo.admin.ch/index.html?layers=WMS||vhi_v100_2024-09-21t235959||https://wms.geo.admin.ch/?item=2024-09-21t235959||ch.swisstopo.swisseo_vhi_v100||1.3.0

Additional information

• Technical details

  • Coordinate system: CH1903+ LV95 (EPSG:2056)
  • Resolution: 10 m (since April 2017) / 30 m (1991-2017)
  • Temporal resolution: Daily update (using data from the last seven days) / Monthly (for historical VHI data prior to 2017)
  • Data format: Cloud Optimized GeoTIFF (COG)
  • Interfaces: STAC, WMS
  • Source code used for production: https://github.com/swisstopo/topo-satromo/

• Product contents

  The “swissEO VHI” product contains ten elements, all of which can be downloaded directly:*

  • FOREST-10M: This raster contains the VHI values masked for the forest areas of Switzerland with a resolution of 10 m. (Preview, Sample)
  • FOREST-WARNREGIONS-CSV: CSV file with the average VHI value and the percentage availability of valid values over the forest areas per warning region. (Sample)
  • FOREST-WARNREGIONS-GEOJSON: GeoJSON file with the average VHI value and the percentage availability of valid values over the forest areas per warning region. Also included are the coordinates of the warning regions and their bounding box. (Sample)
  • FOREST-WARNREGIONS-PARQUET: Parquet file with the average VHI value and the percentage availability of valid values over the forest areas per warning region. Also included are the coordinates of the warning regions and their bounding box. (Sample)
  • VEGETATION-WARNREGIONS-CSV: CSV file with the average VHI value and the percentage availability of valid values over the vegetation areas per warning region. (Sample)
  • VEGETATION-WARNREGIONS-GEOJSON: GeoJSON file with the average VHI value and the percentage availability of valid values over the vegetation areas per warning region. Also included are the coordinates of the warning regions and their bounding box. (Sample)
  • VEGETATION-WARNREGIONS-PARQUET: Parquet file with the average VHI value and the percentage availability of valid values over the vegetation areas per warning region. Also included are the coordinates of the warning regions and their bounding box. (Sample)
  • METADATA: JSON file with all necessary information for each element of the product. (Sample)
  • VEGETATION-10M: This raster contains the VHI values masked for the entire vegetated area of Switzerland with a resolution of 10 m. (Sample)
  • THUMBNAIL: A reduced JPEG image of the dataset for quicker preview. (Preview)

  * All sample data and previews refer to the latest product update

• Detailed product information

  The «swissEO VHI» product is based on remote sensing data with different spectral, radiometric, spatial, and temporal resolutions from polar-orbiting and geostationary satellites. The optical data (Sentinel-2), processed in the "swissEO S2-SR" product, has a spatial resolution of 10 m and covers the Switzerland entirely approximately every five days. For the ‘swissEO S2-SR’ product, the masks supplied (cloud and terrain shadows) are used, whereby all clouds and cloud shadows are masked. In addition, pixels with an illumination angle of more than 65° are identified as potentially problematic and masked accordingly, as the reflection values can no longer be reliably interpreted due to the extreme oblique illumination. Thermal data (Meteosat) are available daily for all of Switzerland, and the spatial resolution is 0.02° (approx. 1'720 m). Pixels with cloud cover are already masked out. The two data sources are aggregated into one product in the VHI and provided with a resolution of 10 m. The «swissEO VHI» is updated daily, using the most recent data available for each grid cell over the past seven days.

  Since the VHI was developed for vegetated areas, a corresponding mask is applied. Based on the categories of the Swiss Habitat Map, «swissEO VHI» only includes values for 10 m pixels that are fully covered by vegetation. «swissEO VHI» consists of two products:

  • VHI for all vegetation (Categories: 2 - shores and wetlands, 4 - grasslands, 5 - herbaceous edges, tall forb communities, and shrubs, 6 - forests, 8 - plantations, fields, and crops)
  • VHI for forested areas (Category: 6 – forests)

  For the Principality of Liechtenstein, the corresponding categories from the CLC+Backbone dataset were used. Since the VHI for all vegetation includes areas that are temporarily strongly influenced by human/anthropogenic activities (agriculture) and not solely by meteorological/hydrological drought stress, the VHI for forest areas is more suitable as an indicator for drought monitoring. Thus, the VHI for forest areas is primarily used for generating values for the warning regions of the Federal Drought Platform.

  The «swissEO VHI» was developed in collaboration with MeteoSwiss for the Federal Drought Platform. The data foundation for the vegetation values is based on optical satellite data from the European Space Agency (ESA – Sentinel-2) for current values processed in the «swissEO S2-SR» product and the National Aeronautics and Space Administration (NASA – Landsat 5, 7, 8) for the values of the climate reference period. Land surface temperature data are obtained from the European Organization for the Exploitation of Meteorological Satellites (EUMETSAT – Meteosat First and Second Generation) as LST_METEOSAT_V002, which is calculated by their Climate Monitoring Satellite Application Facility (CM SAF) and provided by MeteoSwiss.

• Additional content information

  • swissEO VHI - Additional content information

    PDF300.87 kB25 March 2025

Access to raw data

The data can be accessed via the STAC Collection «ch.swisstopo.swisseo_vhi_v100» in the STAC interface of BGDI:

• Browser and download interface: swissEO VHI: Vegetation Health Index (admin.ch)
• Download API documentation: REST Interface: Spatial Temporal Asset Catalog API (admin.ch)
• Google Earth Engine: VHI Image Collection (since April 2017) [projects/satromo-prod/assets/col/VHI_SWISS] / VHI Image Collection (1991-2020) [projects/satromo-prod/assets/col/VHI_HIST_SWISS]
• Accessing STAC via Python - Introduction (Jupyter Notebook)
• Image processing using Python with STAC (Jupyter Notebook)
• Streaming swissEO products in QGIS

Terms of use

swissEO may be used, distributed and made accessible. Furthermore,it may be enriched and processed and also used commercially. A reference to the source is mandatory. In the case of digital or analogue representations and publications, as well as in the case of dissemination, the following source references must be attached in any case:

© swisstopo, Contains modified Copernicus Sentinel data [Year]

Further information on the terms of use can be found on the terms of use webpage.