Mowing dates

Province of North Holland

Processing satellite imagery to identify whether grasslands are mowed during the breeding season of protected bird species.

Last change on 4th of July 2024, at 13:31 (CET) | Publication Standard 1.0

• Publication category: Impactful algorithms
• Impact assessment: Field not filled in.
• Status: In use

General information

Theme

Nature and Environment

Begin date

2021

Contact information

[e-mail]

Responsible use

Goal and impact

More targeted, efficient and transparent monitoring of grassland mowing which is important for protected bird species. Positive outcomes are verified by policy officers and physical observations. No direct grant decision is made based on algorithm outcomes, but there is an increased likelihood of contacting stakeholders.

Considerations

Automated signalling of cut grass makes monitoring more targeted, efficient and transparent than random physical observations in the field.

Human intervention

All positive outcomes are weighed and verified by policy staff and physical observations. Furthermore, no grant decision will ever be made directly based on the algorithm's results. Stakeholders will always be contacted first.

Risk management

There is a chance that an algorithm will lead to 'false positive' outcomes. Normally, the NDVI value will not simply drop abruptly for healthy uncut grass. Nevertheless, something may go wrong with the imaging of the grassland, for example due to atmospheric effects or fertilisation of the land. This is taken into account by including multiple moments of measurement in human consideration of outcomes and by always testing with physical observations.

Legal basis

North Holland province must monitor agreements made on mowing behaviour once grants are made

Operations

Data

The images are from ESA's Sentinel-2 satellites. These images are public and available for anyone to download from a historically built database. Each image contains multiple 'layers' including three layers of visible light (red, green, blue), infrared and near-infrared light, and a classification layer in which ESA's own algorithms classify pixels. The Sentinel-2 satellites take images of the Netherlands every five days. Processing of these images and analysis of the plots takes place annually.

Technical design

A vegetation index is calculated from satellite images: the Normalised Difference Vegetation Index (NDVI). If NDVI values of a plot of land suddenly drop sharply, it is a signal that the grass present may have been cut. Using simple decision rules, we determine for each plot whether a limit has been reached, within or outside the breeding season. The results are visualised on a map in an interactive reporting tool.

External provider

Internally developed