Data Quality Assurance & Control (QA/QC)
Validation, spatial quality checks, field verification, error correction and checklists.
Spatial Data Quality Checks
Each dataset is checked for completeness, internal consistency and comparability before it is published. The checks below are for the 2021 National Forest Resources Assessment; the portal shows the cautions next to the figures they affect.
5,226,192 haCounty Forest Cover sheetUsed in the portal as the official 2021 forest cover
5,178,154 haLand use and forest types sheetsUsed only for those breakdowns
48,038 haGap between the two12 counties differ by more than 2,000 ha
Mandera
−171,997
Turkana
+81,875
Kajiado
+54,412
Kilifi
+50,275
Wajir
+37,754
Marsabit
−27,165
Baringo
−14,992
Kwale
+8,030
Kitui
+4,703
Garissa
+4,291
Samburu
+4,139
Tana River
+3,670
County Forest Cover sheetLand use sheet (forest land)Hectares of forest, 2021
Checks
| Check | Result |
|---|---|
| Tree cover is at least forest cover in every county | Pass |
| Sum of county forest equals the national total (5,226,192 ha) | Pass |
| Land use and forest types sheets agree with the County Forest Cover sheet | Differ by 48,038 ha nationally; Mandera, Turkana, Kajiado, Kilifi and Wajir differ most |
| Mangrove area is consistent with mangrove assessments (about 61,000 ha) | Only 14,134 ha as a separate type: most mangroves seem counted as natural forest |
| Plantation areas match the KFS plantation records | Some look misplaced (for example 7 ha in Nakuru) |
| Counties below the 10% tree cover target | 10: Busia, Isiolo, Kisumu, Machakos, Mandera, Marsabit, Siaya, Taita Taveta, Uasin Gishu, Wajir |
| 2021 is comparable with 2010–2018 | No: different imagery (WorldView vs Landsat) |
2021 was mapped from WorldView imagery; all other years from Landsat. The 2021 figures are therefore not directly comparable with 2010–2018.
Source: 2021 National Forest Resources Assessment, Kenya Forest Service (WorldView very high-resolution imagery).