Development of Flood Monitoring Index for daily flood risk evaluation: case studies in Fiji

Moishin, Mohammed and Deo, Ravinesh C. ORCID: and Prasad, Ramendra and Raj, Nawin and Abdulla, Shahab ORCID: (2020) Development of Flood Monitoring Index for daily flood risk evaluation: case studies in Fiji. Stochastic Environmental Research and Risk Assessment. pp. 1-16. ISSN 1436-3240

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Both fluvial and pluvial floods are a common occurrence in Fiji with fluvial floods causing significant economic consequences for island nations. To investigate flood risk and provide a mitigation tool on daily basis, the Flood Index (IF) is developed based on the rationale that the onset and severity of an event is based on current and antecedent day’s precipitation. This mathematical methodology considers the notion that the impact of daily cumulative precipitation on a particular flood event arising from a previous day’s precipitation, decreasing gradually over time due to the interaction of hydrological factors (e.g., evaporation, percolation, seepage, surface run-off, drainage, etc.,). These are accounted for, mathematically, by a time-reduction weighted precipitation influencing the magnitude of IF. Considering the duration, severity and intensity of all identified events, the applicability of IF is tested at 9 study sites in Fiji using 30-year precipitation datasets (1990–2019) obtained from Fiji Meteorological Services. Newly developed IF is adopted at flood prone sites, with results demonstrating that flood events were common throughout the country, mostly notable between November to April (or the wet season). Upon examining the variations in daily IF, the flood properties were determined, showing that the most severe events generally started in January. Flood events with the highest severity were recorded in Lautoka [IaccF (flood severity) ≈149.14, ImaxF (peak danger) ≈3.39, DF (duration of flood) ≈151days, tonset (onset date) =23rdJanuary2012], followed by Savusavu (IaccF≈141.65,ImaxF≈1.75,DF≈195days,tonset=27thNovember1999) and Ba (IaccF≈131.57,ImaxF≈3.13,DF≈113days,tonset=9thJanuary2009). The results clearly illustrate the practicality of daily IF in determining the duration, severity, and intensity of flood situation, as well as its potential application to small island nations. The use of daily IF to quantify flood events can therefore enable a cost-effective and innovative solution to study historical floods in both developing and first world countries. Our methodology is particularly useful to governments, private organizations, non-governmental organizations and communities to help develop community-amicable policy and strategic plans to prepare for flood impacts and undertake the necessary risk mitigation measures.

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Item Type: Article (Commonwealth Reporting Category C)
Refereed: Yes
Item Status: Live Archive
Faculty/School / Institute/Centre: Current - USQ College (8 Jun 2020 -)
Faculty/School / Institute/Centre: Current - Faculty of Health, Engineering and Sciences - School of Sciences (6 Sep 2019 -)
Date Deposited: 21 Oct 2020 06:28
Last Modified: 22 Oct 2020 01:25
Uncontrolled Keywords: Flood monitoring; Flood Index ; Risk mitigation
Fields of Research (2008): 12 Built Environment and Design > 1299 Other Built Environment and Design > 129999 Built Environment and Design not elsewhere classified
Socio-Economic Objectives (2008): D Environment > 96 Environment > 9603 Climate and Climate Change > 960399 Climate and Climate Change not elsewhere classified
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