Towards impact-based flood forecasting and warning in Bangladesh: a case study at the local level in Sirajganj district

Abstract. Impact-based forecasting and warning services aim to bridge the gap between producers and users of warning information by connecting and increasing synergies between the components of effective early warning systems. We tested qualitatively whether a warning message based on colour codes is understandable and useful to trigger risk mitigation actions at the local level in the flood-exposed communities of Rajapur and Ghorjan unions in Sirajganj district, Bangladesh. With a community-based approach for different groups of users (i.e. sectors), flood-impact scenarios were determined from past events and related to colour codes. These were developed into impact-based forecasting and warnings that can connect water levels, through the colour code, to localised guidance information tailored to sectors’ needs on how to respond to the expected flood. This approach was tested through a limited number of focus group discussions and interviews at the community level. Overall, the colour coded impact-based warnings were found to be an easy and understandable way to link water level forecasts to the necessary risk mitigation actions, however, further investigation is needed to validate these findings under real-time conditions. IBFW has huge potential in Bangladesh but its integration requires significant institutional changes, such as an inter-facing agency (long term) or team (short term), adjusted policy frameworks (standing orders on disasters), and new resource allocations for skills development and technological innovation from national to local levels. Overall, this paper aims to offer a first insight into impact-based forecasting and warning services in Bangladesh to trigger further research and project developments.