Abstract
Most flood early warning systems have predom-
inantly focused on forecasting floods with lead times of
hours or days. However, physical processes during longer
timescales can also contribute to flood generation. In this
study, we follow a pragmatic approach to analyse the hydro-
meteorological pre-conditions of 501 historical damaging
floods from 1980 to 2010 in sub-Saharan Africa. These
are separated into (a) weather timescale (0–6 days) and
(b) seasonal timescale conditions (up to 6 months) be-
fore the event. The 7-day precipitation preceding a flood
event (PRE7) and the standardized precipitation evapotran-
spiration index (SPEI) are analysed for the two timescale
domains, respectively. Results indicate that high PRE7 does
not always generate floods by itself. Seasonal SPEIs, which
are not directly correlated with PRE7, exhibit positive (wet)
values prior to most flood events across different averaging
times, indicating a relationship with flooding. This paper pro-
vides evidence that bringing together weather and seasonal
conditions can lead to improved flood risk preparedness
inantly focused on forecasting floods with lead times of
hours or days. However, physical processes during longer
timescales can also contribute to flood generation. In this
study, we follow a pragmatic approach to analyse the hydro-
meteorological pre-conditions of 501 historical damaging
floods from 1980 to 2010 in sub-Saharan Africa. These
are separated into (a) weather timescale (0–6 days) and
(b) seasonal timescale conditions (up to 6 months) be-
fore the event. The 7-day precipitation preceding a flood
event (PRE7) and the standardized precipitation evapotran-
spiration index (SPEI) are analysed for the two timescale
domains, respectively. Results indicate that high PRE7 does
not always generate floods by itself. Seasonal SPEIs, which
are not directly correlated with PRE7, exhibit positive (wet)
values prior to most flood events across different averaging
times, indicating a relationship with flooding. This paper pro-
vides evidence that bringing together weather and seasonal
conditions can lead to improved flood risk preparedness
| Original language | English |
|---|---|
| Pages (from-to) | 271-285 |
| Number of pages | 15 |
| Journal | Natural Hazards and Earth System Sciences |
| Volume | 18 |
| Issue number | 1 |
| DOIs | |
| Publication status | Published - 19 Jan 2018 |
Funding
Acknowledgements. We thank Munich Re for providing reported flood data from the NatCatSERVICE database for the IMPREX project. This project was funded by NWO VICI grant no. 016.140.067, by NWO grant no. 869-15 001, by FP7 project Earth2Observe grant no. 603608 and by UK Natural Environment Research Council (NE/P000525/1).
| Funders | Funder number |
|---|---|
| Seventh Framework Programme | 603608 |
| Natural Environment Research Council | NE/P000525/1 |
| Nederlandse Organisatie voor Wetenschappelijk Onderzoek | 869-15 001, 016.140.067 |
| Seventh Framework Programme |
