Country intelligence page
Sri Lanka LKA
Operation Tropical Cyclone Ditwah at Admin 1. Every comparison below is confined to this operation, because operations differ in geographic scope, cadence and method and are not additive.
Comparability flags on this comparison
- Assessed-unit count changed between rounds
What changed?MOSAIC-derived
Comparing round 4 (31 Dec 2025) with round 3 (24 Dec 2025) inside the Tropical Cyclone Ditwah operation. Thresholds are MOSAIC monitoring settings, not IOM categories.
Areas at or above +5 per cent momentum
| Area | Latest | Baseline | Change | Momentum | Comparability | Analysis |
|---|---|---|---|---|---|---|
| Southern | 8,165 | 28 | +8,137 | +29060.7% |
|
Methodology and provenance
- Source
- International Organization for Migration (IOM), Displacement Tracking Matrix (DTM). Public API v3.
- Endpoint
- /v3/displacement/admin1
- Geographic level
- Admin 1
- Operation
- Tropical Cyclone Ditwah
- Reporting period
- 24 Dec 2025 to 31 Dec 2025
- Assessment round
- Round 4 compared with round 3
- Retrieved
- 2026-09-04T01:36:27.040Z
- Calculation
- Rows are summed to a present-IDP figure per area and round, then the latest round is compared with the preceding round of the same operation. Areas present in only one of the two rounds are reported as such and are never treated as zero.
Known limitations
- An area that disappears between rounds may have ceased to be assessed rather than ceased to host displacement.
- A newly reported area may be newly affected or newly assessed. The API does not distinguish between these.
- Threshold bands are MOSAIC monitoring settings and are not calibrated to this country's assessment cadence.
MOSAIC-derived indicator. Not an IOM classification.
National displacement timeline
Present IDPs by assessment round within the Tropical Cyclone Ditwah operation. Breaks in the line mark non-consecutive round numbers, where an intervening round exists that this series does not include.
Methodology and provenance
- Source
- International Organization for Migration (IOM), Displacement Tracking Matrix (DTM). Public API v3.
- Endpoint
- /v3/displacement/admin1
- Geographic level
- Admin 1
- Operation
- Tropical Cyclone Ditwah
- Reporting period
- 2025-12-07 to 2025-12-31
- Assessment round
- Round 4
- Retrieved
- 2026-09-04 01:36 UTC
- Calculation
- Present IDP figures are summed across all disaggregated source rows for each area, then across areas, for every round of the selected operation.
Known limitations
- Figures may be estimates derived from key informants and secondary sources rather than exact enumeration.
- Assessment coverage and cadence vary by country and operation, so cross-country comparison of change rates is not supported.
- A change in a recorded figure may reflect population movement, altered assessment coverage, changed access, or enumeration method, and the API does not distinguish between these.
- The public API exposes aggregated non-sensitive figures only, and does not carry the full detail of the underlying DTM datasets.
Admin 1 ranking, latest round
Areas ranked by present IDPs reported in the latest round. Bar length is proportional to the largest area.
- -14.6%Central118,550
- -35.3%Sabaragamuwa39,411
- -10.9%Uva38,257
- +29060.7%Southern8,165
- -97.3%Western664
- -87.4%Northern69
- -88.3%Eastern62
- -98.3%North Western60
Methodology and provenance
- Source
- International Organization for Migration (IOM), Displacement Tracking Matrix (DTM). Public API v3.
- Endpoint
- /v3/displacement/admin1
- Geographic level
- Admin 1
- Operation
- Tropical Cyclone Ditwah
- Reporting period
- 31 Dec 2025
- Assessment round
- Round 4
- Retrieved
- 2026-09-04 01:36 UTC
- Calculation
- Areas assessed in the latest round of this operation, ranked by summed present IDP individuals. Momentum shown alongside is the change from the preceding round.
Known limitations
- Only areas assessed in the latest round appear. An unassessed area is absent, not zero.
- Bar length encodes the reported figure only. It carries no information about area size, population or need.
MOSAIC-derived indicator. Not an IOM classification.
Anomaly signalsMOSAIC-derived
Areas whose latest figure moved unusually relative to their own recent history in this operation. Each signal names the rule that fired and the evidence behind it. A signal is a cue for collection, not a finding.
- SabaragamuwaAbrupt decrease
- Latest
- 39,411
- Baseline
- 60,893
- Magnitude
- -0.35
- Basis
- 4 obs, moderate
Latest round-to-round change is at or below -25 per cent and the absolute decrease is at least 1,000 individuals. Between three and five observations. Treat the historical comparison as indicative only.
- SouthernSudden surge
- Latest
- 8,165
- Baseline
- 28
- Magnitude
- 290.61
- Basis
- 4 obs, moderate
Latest round-to-round change is at or above +30 per cent and the absolute increase is at least 1,000 individuals. Between three and five observations. Treat the historical comparison as indicative only.
- SouthernSustained multi-round increase
- Latest
- 8,165
- Baseline
- 28
- Magnitude
- 407.25
- Basis
- 4 obs, moderate
Three or more consecutive rounds of positive change, with cumulative growth of at least +25 per cent. Between three and five observations. Treat the historical comparison as indicative only.
- North CentralAbrupt decrease
- Latest
- 1,099
- Baseline
- 30,631
- Magnitude
- -0.96
- Basis
- 3 obs, moderate
Latest round-to-round change is at or below -25 per cent and the absolute decrease is at least 1,000 individuals. Between three and five observations. Treat the historical comparison as indicative only.
- WesternAbrupt decrease
- Latest
- 664
- Baseline
- 24,199
- Magnitude
- -0.97
- Basis
- 4 obs, moderate
Latest round-to-round change is at or below -25 per cent and the absolute decrease is at least 1,000 individuals. Between three and five observations. Treat the historical comparison as indicative only.
- North WesternAbrupt decrease
- Latest
- 60
- Baseline
- 3,498
- Magnitude
- -0.98
- Basis
- 4 obs, moderate
Latest round-to-round change is at or below -25 per cent and the absolute decrease is at least 1,000 individuals. Between three and five observations. Treat the historical comparison as indicative only.
Methodology and provenance
- Source
- International Organization for Migration (IOM), Displacement Tracking Matrix (DTM). Public API v3.
- Endpoint
- /v3/displacement/admin1
- Geographic level
- Admin 1
- Operation
- Tropical Cyclone Ditwah
- Reporting period
- 2025-12-07 to 2025-12-31
- Assessment round
- Round 4
- Retrieved
- 2026-09-04 01:36 UTC
- Calculation
- Transparent statistical rules applied to each area's own trailing series within the operation. No model is fitted and no learned parameters are used.
Known limitations
- An anomaly can be produced by a change in assessment coverage or method rather than by population movement.
- Areas with short histories are flagged as low quality because normal variation cannot be characterised.
- The public API supplies no adjacency graph, so no claim of spatial contiguity is made.
MOSAIC-derived indicator. Not an IOM classification.
Geographic concentrationMOSAIC-derived
Displacement is moderately concentrated across 8 assessed units, with 95.6 per cent in the largest 3.
| Area | Present IDPs | Share |
|---|---|---|
| Central | 118,550 | 57.8% |
| Sabaragamuwa | 39,411 | 19.2% |
| Uva | 38,257 | 18.6% |
Normalised concentration index: 0.322 on a zero-to-one scale across 8 assessed areas.
Methodology and provenance
- Source
- International Organization for Migration (IOM), Displacement Tracking Matrix (DTM). Public API v3.
- Endpoint
- /v3/displacement/admin1
- Geographic level
- Admin 1
- Operation
- Tropical Cyclone Ditwah
- Reporting period
- 31 Dec 2025
- Assessment round
- Round 4
- Retrieved
- 2026-09-04 01:36 UTC
- Calculation
- Concentration is computed over the administrative units reported in the selected round of the selected DTM operation. It uses the Herfindahl-Hirschman Index of unit shares, normalised so that zero is an even distribution across assessed units and one is total concentration in a single unit. Units not assessed in the round are absent from the calculation, so a narrowing of assessment coverage will raise measured concentration without any population movement.
Known limitations
- Concentration rises mechanically when assessment coverage narrows, with no population movement required.
MOSAIC-derived indicator. Not an IOM classification.
Coverage and confidenceMOSAIC-derived
What the observation process supports, stated separately from what the figures say.
- Assessed areas, latest
- 8
- Assessed areas, baseline
- 9
- Rounds in operation
- 4
- Median round interval
- 7 days
- 1 administrative unit reported in the previous round is absent from the latest round. Absence may reflect access, assessment scope or a genuine end of reporting, and MOSAIC does not distinguish between these.
Confidence derivation
The change is usable but qualified. At least one comparability or recency condition is not met.
- −10: Assessed-unit count changed between the two rounds
- −12: Latest assessment is between six months and a year old
- −8: Between three and five observations of this unit in the operation
Methodology and provenance
- Source
- International Organization for Migration (IOM), Displacement Tracking Matrix (DTM). Public API v3.
- Endpoint
- /v3/displacement/admin1
- Geographic level
- Admin 1
- Operation
- Tropical Cyclone Ditwah
- Reporting period
- 2025-12-07 to 2025-12-31
- Assessment round
- Round 4
- Retrieved
- 2026-09-04 01:36 UTC
- Calculation
- MOSAIC confidence describes how well a change is grounded in comparable DTM observations. It begins at 100 and applies fixed deductions for missing baselines, non-consecutive rounds, coverage changes, short unit histories and assessment age. It is a statement about data comparability and recency only. It carries no claim about the cause of a change.
Known limitations
- Confidence describes data comparability and recency only. It carries no claim about the cause of a change.
MOSAIC-derived indicator. Not an IOM classification.
Recorded displacement reason, latest round
Taken directly from the DTM records. This is a source field, not a MOSAIC classification.
| Reason | Present IDPs | Share |
|---|---|---|
| Natural disaster | 205,238 | 100.0% |
Methodology and provenance
- Source
- International Organization for Migration (IOM), Displacement Tracking Matrix (DTM). Public API v3.
- Endpoint
- /v3/displacement/admin1
- Geographic level
- Admin 1
- Operation
- Tropical Cyclone Ditwah
- Reporting period
- 31 Dec 2025
- Assessment round
- Round 4
- Retrieved
- 2026-09-04 01:36 UTC
- Calculation
- The displacementReason field on each source row, summed over the latest round of the selected operation.
Known limitations
- Reason is recorded at assessment. It reflects the reason as reported, and may not capture compound or sequential causes.
Generate analyst brief
A deterministic, template-generated brief covering situation snapshot, key changes, trend, concentration, anomalies, analytic questions, information gaps, collection priorities and methodological caveats. No generative model is in the path, so the same data always produces the same brief.