Atlas · Tanzania / Methodologies
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METHODOLOGIES

The official yearly series (1985–2025)

The authors' country statistics file supplies an extent figure for every year; Atlas loads it alongside the seven mapped years.

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Intermediate 1 min read time seriesofficial statisticsannualGlobal Mangrove Watch

Atlas keeps seven full polygon maps per country in its database (1996, 2000, 2005, 2010, 2015, 2020, 2025) to save space, but the Global Mangrove Watch authors also publish a yearly statistics table for every year from 1985 to 2025.

Atlas stores that table inside each country's latest dataset (field official_annual_ha) and draws it on the Mangrove Change page as the "Every year" chart.

How the two relate. The seven mapped years are Atlas' own measurements of the polygons; the 41-year line is the authors' figure. The two differ by a constant 2.3%, so the shapes match and only the level differs.

All 41 yearly maps are downloaded and archived on the server even though only seven are loaded into the database. They can be loaded on request (about 0.4 GB of database space each).

Limits. The yearly series is a statistic, not a map; you cannot see where change happened from it.

Related reading

Using the Mangrove Change page

Pick a country in the header, read the KPIs and charts, then scroll to the Africa-wide table.

Why Atlas totals are 2.3% higher than the official figures

Atlas measures polygons on the ellipsoid; the authors publish a "corrected area". The gap is a constant 2.3% in every country.

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