Using Mixed Quantitative and Qualitative Methods to Reconstruct Floods in Tropical Coastal Catchments in Data-Limited Regions

Keywords: coastal flooding, data-limited regions, Nicaragua, hydrology, Latin America
Session Type: Virtual Paper Abstract
Day: Friday
Session Start / End Time: 2/25/2022 03:40 PM (Eastern Time (US & Canada)) - 2/25/2022 05:00 PM (Eastern Time (US & Canada))
Room: Virtual 53

Abstract

Extreme floods are becoming more frequent and severe, particularly along coasts. They often cause significant economic damage and loss of life, creating great need to estimate extreme flood risk. However, quantifying the magnitude, timing, and duration of these events is challenging, particularly in data-limited regions. In the tropics, flood data and hydrometeorological monitoring networks are often insufficient and can lead to high uncertainty in flood modeling and mapping. Yet hydrologic modelling is a main tool used for water resource management and policy decisions. This study uses quantitative paleohydrology and qualitative survey methods to reconstruct the timing, duration, and magnitude of an extreme flood event from Tropical Storm Nate within an ungauged tropical coastal catchment in Ostional, Nicaragua. Debris lines were measured to estimate peak flood stage and the competent depth method was used to estimate minimum critical discharge. The timing and duration of rainfall and flood discharge were estimated from 32 structured household interviews in three villages within the Ostional catchment. Results show peak flood stage is commensurate for both qualitative responses and paleoproxy estimates. Furthermore, data show spatial variability of flooding between the upper, middle, and lower reaches of the catchment. Interestingly, 91% of the respondents never experienced a similar or worse flood. Future work includes modelling the flow and linking upstream fluvial information to mangrove sediment records to assess the recurrence interval of extreme floods in this region. This work demonstrates these indirect data and methods can reconstruct flood events to improve knowledge of flooding in data-limited regions.