Our method and how accurate the numbers are
How we know where the spring is from satellite imagery, how far you can trust the numbers, and their sources.
Open the «Where is the spring?» map · Original Arabic page: طريقتنا ودقة الأرقام
How far can you trust these numbers?
We say what we know and what we do not| What | How we know it | Its limits |
|---|---|---|
| Spring on the map | Two independent satellites (Terra and NOAA-20) must agree on each cell, and we exclude farms, the surroundings of villages and land that is green all year. | The cell is 500 m, so a narrow shaib does not show; we have not yet compared it with field photos. |
| Excluding farms and built-up areas | Land cover at 10 m resolution from ESA WorldCover 2021 (CC BY 4.0), with farm and oasis masks from satellite imagery. | Very small fields in the mountains or a new farm may slip through. |
| Landmark names | Desert Maps (maps_ksa@) and GeoNames (CC BY 4.0). Latin spellings: known forms where they exist, otherwise automatic transliteration (*). | The local name or its position may differ by hundreds of metres. |
| Reserves | Boundaries from OpenStreetMap (© OpenStreetMap contributors (ODbL)), and entry conditions from the websites of the reserve authorities and the National Center for Wildlife, checked on 3 October 2026 (22 Rabi' al-Akhir 1448 AH). | The boundaries are approximate and not the official boundaries, and for some reserves we have not verified the conditions, so we say so. Conditions may change; the authority’s website is the reference. |
| Access by car | Straight-line distance to the nearest paved road and the nearest dirt track drawn on OpenStreetMap (© OpenStreetMap contributors (ODbL)), data of 6 May 2026 (19 Dhu al-Qa'dah 1447 AH). | Open maps draw few desert tracks, so “no dirt track drawn” does not mean there is none. It does not mean the road suits your car. |
| Camping sites (Center’s guide) | The list, governorate and capacity from Camping and Caravan Guide 2025 — National Center for Vegetation Cover Development and Combating Desertification as published, reorganised by us and not endorsed by the Center, with the location from the guide’s map link for each site; checked on 4 October 2026 (23 Rabi' al-Akhir 1448 AH). Competent authority: National Center for Vegetation Cover Development and Combating Desertification. | Site data are from the 2025 Camping and Caravan Guide issued by the National Center for Vegetation Cover Development and Combating Desertification, reorganised by us and not endorsed by the Center. Permits are issued by the Center alone through the Nabati platform; DataPulse is a private entity that does not issue permits and is not affiliated with the Center. Check the site’s availability and conditions before you go. The guide is for 2025 and may change, and the capacity is the authority’s figure, not our count. The site Mutanazzah Tur Al Yazid* متنزه طور آل يزيد has no coordinates because its link in the guide duplicates another site’s, so we list it in the table and do not draw it on the map. |
| Meteorological information | We publish no meteorological information of any kind. Official meteorological information and alerts come from the National Center for Meteorology. | The Meteorology Law restricts publishing it to licensed parties. |
How accurate are we?
Of 120 spots (cells of about 500 m) picked at random from what the map showed as spring in four images from different seasons, we checked the land type with satellite imagery: 119 were natural open land, and one was something else.
We capture about half of the natural spring only (64 of 117 rawdahs and shaibs that really greened in satellite imagery): we miss very small rawdahs (under about 1 km²) and the surroundings of villages and hijrahs (about 1.5 km).
The full measurement and its limits are in the tool’s methodology; land cover is from ESA WorldCover 2021 (CC BY 4.0).
How we know, and the limits
- Method: the satellite measures the greenness of the land cell by cell. We compare its greenness now with the colour of the same land when dry (from ten years of imagery). What has clearly increased we call “starting to green”, then “spring”, then “strong spring”.
- Resolution: each cell on the map is about 500 m by 500 m. A rawdah, faydah or wadi shows; a narrow shaib does not. The cells are drawn with their true edges, without smoothing, so what you see is what the satellite measured.
- What is not desert spring: we exclude permanent greenery such as farms and oases, anything that does not look like the pattern of desert spring, and land that greens in summer year after year because it is most likely irrigated. Named rawdahs and faydahs are exempt from the “often green land” rule so that they are not counted as farms, unless there are fields near them that green every winter.
- Comparison with past years: from satellite imagery (MODIS, NASA) since 2002: one image per month on 1 km cells, classified the same way, so we know where the land greened in each month of each year, in which months each place usually greens, and in how many years it greened.
- Two satellites, not one: we count a cell as spring only if a second, independent satellite (NOAA-20) confirms it along with the Terra satellite.
- Farms: we exclude farms, wadi farms, oases, built-up areas, the surroundings of villages and hijrahs (about 1.5 km) and land that is green all year (shown in grey in the “Farms and permanent greenery” layer if you turn it on) so they are not counted as spring. A new farm may slip through; if you see a regular green shape, it is a farm.
- Using the map: “Desert places” shows only the places with spring around them, coloured by type; choose “All places” to see the rest or “Place names” to show names (landmark names from Desert Maps). The blue dot is your location, and the “My location” button on the map brings you back to it. When you open the page your browser asks permission to find your location; your location is used only on your device to calculate distance, and is not sent to us or stored.
- Timing: the image is the best reading of the last 8 days, so what greened two days ago may not show yet, and clouds delay the reading.
- Names: Place names are shown in Arabic as on the maps, with a Latin form: the known spelling where one exists (cities, reserves, regions and the best-known destinations), otherwise an automatic letter-by-letter transliteration marked *. Transliterations are approximate and may differ from local spellings; the Arabic name is the reference.
- Do not drive into a rawdah: driving vehicles into protected rawdahs and faydahs is a violation monitored by the Special Forces for Environmental Security, with fines of up to SAR 2,000, and some of the best-known rawdahs (such as King Abdulaziz Royal Reserve in As-Summan and Ad-Dahna) require a prior electronic permit. Leave your car on the road and walk.
- Before you go: greenness seen from space does not guarantee the condition of the place on the ground or permission to enter it. Some sites are reserves or private property, camping has its own regulations, and wadi beds are dangerous. The decision and its responsibility rest with you.
Sources: the NDVI greenness index from the Terra and Aqua (NASA MODIS) and NOAA-20 (VIIRS) satellites and true-colour imagery and the photo of each place (NASA HLS: Landsat and Sentinel-2; Contains modified Copernicus Sentinel data) through the NASA GIBS imagery service; monthly images since 2002 (MODIS/Aqua) for the comparison with past years; landmark names from Desert Maps (maps_ksa@) and GeoNames (CC BY 4.0); land cover to exclude farms and built-up areas from ESA WorldCover 2021 (CC BY 4.0; © ESA WorldCover project, Contains modified Copernicus Sentinel data (2021) processed by ESA WorldCover consortium); region boundaries and the base map © OpenStreetMap contributors; approximate reserve boundaries and the distance to paved roads and dirt tracks © OpenStreetMap contributors (ODbL); reserve entry conditions from the websites of the competent authorities (each authority’s link in the reserve window); camping and caravan sites and their capacity from Camping and Caravan Guide 2025 — National Center for Vegetation Cover Development and Combating Desertification (with each site’s location from the map link in the guide; reorganised by us and not endorsed by the Center). The classification, areas and comparisons are DataPulse calculations, not official figures.
The information is analytical to support decisions; it is not financial or investment advice. The decision and its responsibility rest with the user.