Definitions
সংজ্ঞা
Terms used in FFWC forecasts, bulletins and this website.
- Danger Level (DL)
- The water level above which a flood is likely to cause damage to crops, homesteads and infrastructure in the vicinity of the station.
- Warning level
- Water level within 50 cm below the danger level.
- Flood
- Water level at or above the danger level.
- Severe flood
- Water level more than 1 m above the danger level.
- Recorded Highest Water Level (RHWL)
- The highest water level ever recorded at a station.
- PWD datum
- Public Works Department datum — the reference level (in metres) used for water levels in Bangladesh.
- Water level station
- A gauge where the river water level is observed, typically at 06:00, 09:00, 12:00, 15:00 and 18:00.
- Forecast point
- A station for which FFWC issues water level forecasts.
- Deterministic forecast
- A single best-estimate forecast of water level (FFWC: up to 5 days).
- Mid-range / probabilistic forecast
- A forecast that gives a range of likely water levels based on ensemble rainfall forecasts (FFWC: up to 10 days).
- Lead time
- The time between issuing a forecast and the event being forecast (e.g. +24 h, +48 h).
- Hydrograph
- A graph of water level (or discharge) at a station over time.
- Flash flood
- A rapid rise in water level following intense rainfall, common in the north-eastern haor and south-eastern hill regions.
- Inundation
- Area covered by flood water; inundation maps show the extent and depth.
- Rising / falling trend
- Change in water level over the last 24 hours.
- CAP
- Common Alerting Protocol — an international XML standard for exchanging public warnings.