Batticaloa Flood Early Warning System

What is BFEWS?

The Batticaloa Flood Early Warning System (BFEWS) is an operational, physically-based flood forecasting system covering the basins that drain into the Batticaloa lagoon on Sri Lanka's east coast. It combines real-time rain and water-level observations with ECMWF rainfall forecasts and a chained HEC-HMS / HEC-ResSim / HEC-RAS model suite to produce 9-day streamflow forecasts, floodplain inundation maps and threshold-based flood alerts.

Basins draining into the Batticaloa lagoon

Four major river basins feed the Batticaloa floodplain. Each is modelled end-to-end — from upstream rainfall–runoff, through reservoir operations, to 2-D floodplain hydraulics around the lagoon.

Terrain DEM of the Batticaloa catchment with the four basins and major reservoirs.

Basins covered

• Maduru OyaLargest basin in the system. Maduru Oya reservoir operations routed through HEC-ResSim.
• Mundeni AruUpstream rainfall–runoff routed to the lagoon; alert-monitored at Sink_Mundeni.
• Magilawattuwan (Mahawelliganga downstream)Routed to Wadamunei — a primary alert-monitored junction.
• Andella OyaDrains directly to the lagoon; routed to Manduur for alerting.

Real-time observation network

A dedicated network of telemetered rain and river gauges feeds the system every few minutes. Live data is hosted at rivernet.lk and ingested into BFEWS through the obs-collector service.

Network composition

10

River gauges

10

Rain gauges

• Telemetered & 2-minute polledobs-collector service polls the RiverNet API every 2 minutes.
• ECMWF IFS forecast feedGridded numerical weather prediction refreshed every 6 hours, 9-day horizon.
• Validated against satelliteInundation outputs verified against UNOSAT 10 m flood maps.

Rain gauges, river gauges and reservoirs across the Batticaloa basins.

Field installations

Gauges are deployed on bridges and tank bunds across the four basins, with solar-powered telemetry feeding real-time data into the central database. Stations are accessible publicly at rivernet.lk.

Rain gauge on a bridge crossing

Water-level gauge at a reservoir

A chained HEC modelling suite

BFEWS chains three USACE Hydrologic Engineering Center models — HEC-HMS, HEC-ResSim and HEC-RAS — each handling one stage of the rainfall-to-flood pathway. Models run on a dedicated server while only the observations and live outputs are exposed through the cloud.Sri Lanka's Irrigation Department set up these models and continuously refines them based on field measurements and observations.

Alert thresholds

Each basin has explicit trigger thresholds combining reservoir water-level and accumulated rainfall. When any trigger fires for a forecast cycle, the Distributor service generates a bulletin and pushes it to subscribed operators by email and FTP.

Open the operational dashboards

Four web tools sit on top of the live database — accessible to operators, partners and decision-makers.

Clients & implementing team