Abstract

The small spatial and temporal scales at which flash floods occur make predicting events challenging, particularly in data-poor environments where high-resolution weather models may not be available. Additionally, the uptake of warnings may be hampered by difficulties in translating the scientific information to the local context and experiences. Here we use social science methods to characterise local knowledge of flash flooding among vulnerable communities along the flat Lake Malawi shoreline in the district of Karonga, northern Malawi. This is then used to guide a scientific analysis of the factors that contribute to flash floods in the area using contemporary global datasets; including geomorphology, soil and land-use characteristics, and hydro- meteorological conditions. Our results show that communities interviewed have detailed knowledge of the impacts and drivers of flash floods (deforestation, sedimentation), early warning signs (changes in clouds, wind direction and rainfall patterns), and distinct hydro-meteorological processes that lead to flash flood events at the beginning and end of the wet season. Our analysis shows that the scientific data corroborates this knowledge, and that combining local and scientific knowledge provides improved understanding of flash flood processes within the local context. We highlight the potential in linking large-scale global datasets with local knowledge to improve the usability of flash flood warnings.

Highlights

  • 25 Weather related hazards are responsible for 78% of the economic losses and 38 % of the fatalities related to disasters worldwide, with a drastic increase in the number of events in the last 35 years attributed to global climate change

  • Local knowledge on flash flooding in Karonga district has been compiled from the thematic analysis of the local knowledge, and integrated and corroborated with the flash flood 220 occurrence and impact analysis from the secondary data

  • We explore the predictability of the binary occurrence of the observed flash flood events with these simple indicators at three spatial scales; i) at the scale of predicting the flash flood events in each catchment; ii) at the scale of predicting a flash occurring in the North and or in the South of Karonga district; and iii) at the scale of predicting the occurrence of flash flood events in the district as a whole

Read more

Summary

Introduction

25 Weather related hazards are responsible for 78% of the economic losses and 38 % of the fatalities related to disasters worldwide, with a drastic increase in the number of events in the last 35 years attributed to global climate change. Seen significant progress in developing warning systems in flash flood prone catchments (Hapuarachchi, 2011; Braud, 2018), though these rely extensively on the availability of high-resolution quantitative precipitation estimates and forecasts, in particular helped by the availability of radar-based precipitation estimates and nowcasts (Creutin and Borga, 2003; Werner and Cranston, 2009; Javelle et al, 2010). Such weather radars are practically non-existent in developing countries. Medium to high-resolution numerical weather prediction (NWP) models may, be available and are applied in selected cases, such as in the Flash Flood Guidance System for Southern

Objectives
Results
Discussion
Conclusion
Full Text
Paper version not known

Talk to us

Join us for a 30 min session where you can share your feedback and ask us any queries you have

Schedule a call