## 7 Conclusions  
This paper aimed to describe a pilot flood decision support system (FDSS) for the Vaisigano River, Samoa, which is comprised of a suite of integrated rainfall/river observations and forecast tools that are linked with precomputed hazard exposure scenarios to enable real-time flood-impacts warnings forecasting for the Vaisigano catchment.  
A number of challenges face the development of such systems in data sparse areas. In particular, the availability of sufficient and consistent historic rainfall and flow data is required to design, calibrate and validate even parsimonious runoff models such as those used in the developed system. Despite such challenges, this study illustrates that it is possible to develop an early warning system by identifying specific thresholds of hazard (flood) occurrence and then targeting prediction capability on those thresholds. Although, the absence of soil and vegetation data as well as the need for model parsimony were pivotal in the decision to use the unit hydrograph approach for peak flow prediction.  
The effectiveness of the developed FDSS was demonstrated in the lead up to the 18 th December 2020 extreme rainfall and flooding, whereby residents in affected floodplains were successfully warned and evacuated several hours prior to river channel overtopping. This was achieved through the use of a multi-layered warning system that provided 1-h resolution rainfall and river level forecasts (30-h into the future); 10-min resolution prediction of rainfall and river level (24-h into the future); and real-time rainfall and river level monitoring.  
While this pilot provides a benchmark for future work and extension to other catchments in the Samoa region, the findings offer a conceptual framework for developing similar impacts-based flood decision support systems in comparable Pacific Islands and SIDS contexts.  
Conceptualization, S.W., J.G., B.M. and M.I.; methodology, S.W., B.M., J.G., M.O., E.R., R.P., M.L. and G.E.; software, B.M., J.G., S.W., G.E., M.O. and R.P.; validation, J.G., B.M., M.O., E.R. and R.P.; formal analysis, E.R., M.L., M.I, S.M. and J.C.T.; investigation, B.M., J.G., S.W., M.O., R.P., E.R., M.L., S.M. and J.C.T.; resources, G.E., S.W., M.I., E.R., M.L., S.M. and J.C.T.; data curation, B.M., E.R., J.C.T., M.O. and S.W.; writing--original draft preparation, S.W. and J.G.; writing--review and editing, B.M., R.P., E.R., M.L. and M.I.; visualization, B.M., J.G. and S.W.; supervision, M.I., G.E. and S.W.; project administration, S.W. and M.L.; funding acquisition, M.I., G.E. and S.W. All authors have read and agreed to the published version of the manuscript.  
This pilot project was enabled through the Government of Samoa's Green Climate Fund, Vaisigano Catchment Project No: MNRE-2019/001 implemented by the Samoa Ministry of Natural Resources and Environment (E.R.; M.L.; M.I.; S.M. and J.C.T.), and NIWA Tailboro Nukurangi Project No: MNR20901 and CARH2206 (S.W.; J.G.; B.M.; M.O.; R.P. and G.E.). The APC was funded by NIWA Taihoro Nukurangi, Project No:MNR20901.  
Not applicable.  
**Data Availability Statement:** Hydrometeorological and climate data used in this study are available via formal request to the Samoa Ministry of Natural Resources and Environment, and were sourced from the MNRE-NEON, BOM CliDE and MNRE-NIWA Tideda databases.  
**Acknowledgments:** The authors would like to thank [PERSON], [PERSON], [PERSON], [PERSON] and [PERSON] for the helpful advice provided throughout this research. The Australian Bureau of Meteorology, Tides Unit through the Pacific Sea Level & Geodetic Monitoring project as part of the Climate and Oceans Support Program in the Pacific (COSPPac), is thanked for facilitating the integration of the Apia tide gauge data. BMT Ltd. are thanked for providing the flood inundation layers via the Samoa Ministry of Natural Resources and Environment. Three anonymous reviewers are thanked for their helpful comments which improved the paper.  
**Conflicts of Interest:** The authors declare no conflict of interest.