International Charter Space and Major Disasters rapid-mapping workflow
The International Charter on Space and Major Disasters routes satellite tasking and derived maps to civil protection authorities within hours of activation. This page explains the mechanics: who triggers it, what data arrives, and where the workflow breaks down.
Sensors
- Sentinel-1 IW (C-band SAR): 5 x 20 m ground range resolution in Interferometric Wide swath mode, 250 km swath, 6-day repeat at the equator (1-3 days with both satellites). Cloud-penetrating and night-capable, making it the primary flood-extent sensor under overcast post-disaster skies. Freely available via Copernicus Dataspace.
- Sentinel-2 MSI: 10 m resolution in visible and near-infrared bands, 5-day revisit with both satellites. Excellent for post-event optical damage assessment and burn scar delineation when skies clear, but rendered unusable by the cloud cover that typically accompanies floods and cyclones.
- ALOS-2 PALSAR-2 (L-band SAR): L-band penetrates vegetation canopy more effectively than C-band, resolving flooded forest and rice paddy inundation that Sentinel-1 misses. Spotlight mode reaches 1-3 m resolution; standard stripmap is 10 m at 70 km swath. JAXA is a Charter member and routinely tasks ALOS-2 within 24 hours of activation.
- Maxar WorldView Legion: 30 cm pan-sharpened optical imagery, up to 15 revisits per day over a target in mid-latitudes. Used for building-level damage grading and population exposure refinement where cloud permits. Maxar participates in Charter activations as a contributing entity; tasking priority is governed by the activation order.
How an activation actually starts
The Charter operates on an Authorised User model. Only designated national civil protection agencies, space agencies, and a small set of UN bodies can formally trigger an activation. An Authorised User contacts the Charter's 24/7 on-call operator, provides a brief disaster description and geographic scope, and the activation is logged. From that moment, a Project Manager drawn from the duty member agency takes responsibility for coordinating data acquisition.
The roster of member agencies includes ESA, JAXA, NASA, CNES, CSA, ISRO, CONAE and roughly a dozen others. Each member commits to making its satellite assets available for tasking within the activation window. The Project Manager issues tasking requests to whichever members hold relevant satellites in useful orbital geometry over the affected area. There is no single automated system doing this: it is a human-coordinated process, which is both its strength (flexibility) and its vulnerability (latency depends on who answers the phone).
From tasking request to first map: the honest timeline
Charter documentation and published activation records indicate that a first satellite pass over the affected area typically occurs within 24 to 48 hours of activation, assuming a member satellite is in an appropriate orbital slot. First derived products, meaning georeferenced flood extents or preliminary damage-grade polygons, generally reach the requesting authority within 24 to 72 hours of activation. That range is not a failure of ambition; it reflects genuine orbital mechanics, processing queues and the time required for human analysts to quality-check outputs before they are sent to field commanders.
Sentinel-1's 6-day repeat cycle at the equator means the Charter cannot simply conjure a fresh pass on demand. What it can do is combine ascending and descending passes from both Sentinel-1A and 1B, request ALOS-2 or RADARSAT-2 tasking to fill the gap, and pull archive imagery for pre-event baselines. The pre-event baseline is not optional: change detection requires it, and an analyst who skips it will misclassify permanent water bodies as new flood extent.
What the derived products actually contain
Charter-standard products fall into three broad classes. Reference maps show the pre-event situation: administrative boundaries, road networks, settlement footprints drawn from existing geodatabases. Delineation maps show the event extent: flood boundaries, landslide scarps, fire perimeters. Grading maps add an assessment layer: building damage classified by the COPERNICUS/EMS grading scheme into Destroyed, Major Damage, Minor Damage and No Damage, typically derived from very-high-resolution optical imagery at 30-50 cm where cloud allows, or from SAR coherence loss where it does not.
Population exposure estimates are computed by intersecting event-extent polygons with gridded population datasets such as WorldPop or the Global Human Settlement Layer. These figures carry significant uncertainty: a flooded polygon does not mean all residents are displaced, and building-damage grades from space do not distinguish between an occupied structure and an abandoned one. Responsible product notes acknowledge this. The Charter's own quality assurance process requires analysts to flag confidence levels, though field verification remains the only way to resolve ambiguity.
Copernicus EMS: parallel mechanism, different governance
The Copernicus Emergency Management Service runs a rapid-mapping component that overlaps substantially with Charter activations but operates under different governance. CEMS can be triggered by EU member states, EU institutions, and certain partner countries without going through the Charter's Authorised User list. It draws primarily on Sentinel data and Copernicus Contributing Missions, and its products are publicly released, typically within 24-48 hours of activation, under an open licence.
The practical difference matters to non-EU governments. A Pacific island state affected by a cyclone can trigger a Charter activation through its national disaster agency if that agency holds Authorised User status, but it cannot directly trigger CEMS. The two systems are increasingly coordinated: ESA sits in both, and a Charter activation often runs in parallel with a CEMS activation for the same event, producing complementary products. For a civil protection authority trying to decide which mechanism to call first, the answer is usually both, because the data sources and analyst pools are partially distinct.
The access problem non-member states rarely discuss openly
Charter products are delivered to the requesting Authorised User, not published openly by default. A national disaster management office that lacks Authorised User status cannot initiate an activation and will not automatically receive products even if a neighbouring country triggers one for a cross-border event. CEMS products are publicly released, which partially compensates, but CEMS coverage is not universal.
Sentinel-1 and Sentinel-2 data are freely available through Copernicus Dataspace regardless of Charter membership, so a government with its own processing capability can run its own flood-extent analysis in parallel. The Charter's value is not the raw data; it is the coordinated tasking of commercial and non-Copernicus assets, the analyst labour, and the quality-assured product delivery chain. Governments that want reliable access to that chain need to pursue Authorised User designation before the next disaster, not after it. Satellize works with governments at that preparedness stage, building the technical capacity and institutional connections that make Charter and CEMS products actionable when they arrive.
Where the workflow breaks down, and what compensates
Three failure modes recur in publicly documented activations. First, persistent cloud cover over tropical disasters can prevent any optical acquisition for days, leaving SAR as the only source and limiting damage grading to coherence-based proxies rather than direct visual inspection. Second, very rapid-onset events, flash floods, dam breaks, tsunami inundation, can be largely over before the first tasked pass arrives, making the Charter more useful for damage assessment than for real-time response. Third, communication infrastructure failures in the affected area mean that even a perfectly produced map may not reach the field teams who need it.
None of these is a reason to avoid the Charter. They are reasons to pair it with pre-positioned analysis pipelines, pre-downloaded baseline data, and offline-capable delivery formats. The Charter itself has evolved: its Value Added Resellers programme and the integration with CEMS have expanded the analyst pool, and the addition of very-high-resolution commercial members has improved damage-grading fidelity. The workflow is genuinely useful. It is also genuinely dependent on preparation that most governments do not complete until after their first bad activation.
Typical figures
| Sentinel-1 IW spatial resolution | 5 x 20 m (ground range x azimuth), 250 km swath |
| Sentinel-1 revisit (dual-satellite) | 6 days at equator; 1-3 days at mid-latitudes with combined ascending/descending passes |
| ALOS-2 PALSAR-2 resolution range | 1-3 m (Spotlight) to 10 m (Stripmap); 70 km standard swath |
| WorldView Legion pan-sharpened resolution | ~30 cm; up to 15 revisits per day over priority targets |
| Typical activation-to-first-product latency | 24-72 hours (Charter documented range; orbital geometry and cloud cover are the primary variables) |
| Damage grading classes (CEMS standard) | Destroyed / Major Damage / Minor Damage / No Damage (4-class scheme) |
| Population exposure input datasets | WorldPop (100 m grid) or Global Human Settlement Layer (GHS-POP, 100 m) |
| Charter archive depth | Activation records publicly available from 2000 (first activation) to present |
| CEMS rapid-mapping product licence | Open, publicly released; accessible without Authorised User status |
| Standard delivery formats | GeoTIFF, shapefile, KMZ; PDF situation reports; WMS feeds for some activations |
Analytics Satellize can run
| Flood extent polygon with confidence tier | Sentinel-1 IW backscatter thresholding against pre-event baseline; water pixels classified by sigma-naught reduction below empirically derived threshold (typically -15 to -18 dB over open water) | GeoJSON polygon layer with per-polygon confidence flag (high / medium / low); updated per new SAR pass |
| Building damage grade map | Change detection on very-high-resolution optical imagery (pre/post pair); pixel-level and object-level classification aligned to CEMS 4-class grading scheme | Shapefile of building footprints with damage grade attribute; summary statistics by administrative unit |
| Population exposure estimate | Spatial intersection of event-extent polygon with WorldPop or GHS-POP gridded population raster; uncertainty range reported from input dataset confidence intervals | Tabular report by district with exposed population range; GIS layer for field coordination |
| SAR coherence-loss damage proxy | Interferometric coherence computed from pre/post Sentinel-1 or ALOS-2 image pairs; coherence loss below 0.3 used as proxy for structural change where optical imagery is cloud-obscured | Raster layer of coherence difference with damage-probability overlay; flagged as proxy product pending optical verification |
| Activation readiness gap assessment | Review of national Authorised User status, baseline geodata holdings, and SAR processing capability against Charter and CEMS access requirements | Written gap report with prioritised steps to Authorised User designation and pre-positioned baseline data strategy |
| Multi-source product reconciliation | Comparison of Charter-delivered products against independently processed Sentinel-1 and CEMS outputs for the same event; discrepancy flagging and confidence weighting | Reconciled GIS layer with source attribution; briefing note for civil protection authority |
Who does the work
We can get this done for you. Satellize runs its own analyst desk and a strong science team. You do not buy a data feed and work out what it means; our people source the imagery, run the analysis described on this page, and hand you the answer with its confidence limits stated. Discuss this requirement.