Sri Lanka Rainfall: Dekadal Subnational Indicators and CHIRPS Forecasts

WFP provides dekadal rainfall indicators for Sri Lanka's subnational administrative units based on CHIRPS satellite imagery and CHIRPS-GEFS forecasts. The data tracks 10-day, 1-month, and 3-month rainfall totals alongside long-term averages and anomalies. It is updated frequently to transition from initial forecasts to final observations.

Use Cases

• Drought monitoring using the 3-month rainfall anomaly (r3q) to identify regions with significant precipitation deficits
• Agricultural planning by comparing current 10-day rainfall (rfh) against the long-term average (rfh_avg) for specific administrative units
• Flood risk assessment by analyzing 1-month rolling aggregations (r1h) in relation to historical norms

Strengths

• Includes long-term averages (rfh_avg, r1h_avg, r3h_avg) for baseline comparison
• Uses standardized WFP Pcodes for easy integration with other humanitarian datasets
• Provides pixel counts (n_pixels) to indicate the spatial data density for each administrative unit

Limitations

• Relies on satellite-derived estimates (CHIRPS) which may differ from ground-based rain gauge measurements
• Data status changes over time (forecast vs. final), requiring users to track the type column for data stability

Provenance

Source

World Food Programme (WFP) using CHIRPS v2 and CHIRPS-GEFS

Collection Method

Aggregation of satellite imagery and station data into administrative units

Freshness

Updated multiple times per month following a 10-day cycle.

Geography

Sri Lanka