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Relationship between Elnino Southern Oscillation (ENSO) and the occurrences of floods in the Lower Shire
Elnino cause havoc in the Lower Shire of Malawi
Authors:
L.M. Mtilatila
Publisher:
National Research Council of Malawi, 2007
Malawi is affected by floods each and every year. One of the areas highly affected is the Shire Valley, which has seen extreme conditions including heavy rains that result in floods or prolonged dry spells that lead to drought. It is established that climate variability can also be due to El Nino Southern Oscillation (ENSO).
This paper analyses the relationship between flood occurrences along the Shire Valley of Malawi in relation to ENSO.
The research higlights several aspects of flooding in the Lower Shire. The results show that, strong La Nina years bring increased total DJFM (December, January, February and March) rainfall amounts. Very high increases in rainfall amounts are on the uplands, which are part of the catchment area for the Shire Valley. Therefore there are higher floods occurrences during La Nina due to rains that fall on higher ground. The results also show that strong La Nina year means a flooding year. El Nino and neutral years also have high chances of flood occurrences. ENSO contributes to the performance of DJFM rainfall, so their variations contribute to Malawi's rainfall. That is why during Lanina years there is 100% chance of flood occurrence.
The results indicate that climate change is also affecting Malawi; this is evident by the way the temperature is changing. At all three stations where the research was conducted, an increase in temperature was recorded. So it can be concluded that as much as climate variability contributes to the frequency of flooding, climate change also has contributed a lot by increasing extreme weather and climate events.
The author recommends that:
- there is a need to have a well organised warning system that would benefit the community
- warning procedures have to be put in place with assistance from all stakeholders
- moving people out of flood-prone areas has proved a failure. This is an indication that people benefit from these flood episodes. For example, floods bring fertile alluvial soil that is good for winter cropping. If floods are managed well, they can be more of a benefit than a threat
- flood mitigation and adaptation management call for multidisciplinary approach at all levels.
