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Extreme rainfall events over the Pongola-Mtamvuna Water Management Area of South Africa
Subtropical southern Africa experiences substantial rainfall variability both spatially and temporally, due to regional orography, geographic position, and local sea-surface temperatures. Extreme weather conditions such as droughts and floods are not uncommon and can result in both positive and nega...
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| Format: | Thesis |
| Language: | English |
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Department of Oceanography
2023
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| _version_ | 1867613285992366080 |
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| access_status_str | Open Access |
| author | Mpungose, Nomvula Bongekile |
| author2 | Reason, Christopher |
| author_browse | Mpungose, Nomvula Bongekile Reason, Christopher |
| author_facet | Reason, Christopher Mpungose, Nomvula Bongekile |
| author_sort | Mpungose, Nomvula Bongekile |
| collection | Thesis |
| description | Subtropical southern Africa experiences substantial rainfall variability both spatially and temporally, due to regional orography, geographic position, and local sea-surface temperatures. Extreme weather conditions such as droughts and floods are not uncommon and can result in both positive and negative socio-economic impacts. The Pongola-Mtamvuna Water Management Area (PM) located over north-eastern South Africa consists of communities that depend on rain-fed agriculture, as well as an inter-linked ecosystem and fresh water bodies that are dependent on rainfall. Extreme rainfall events and the systems that produce them are still not well understood, therefore, a detailed analysis of such events can contribute to an improved understanding and management of their associated risks. Here, the main focus is on the summer rainy season (October – March), rainfall variability is examined using CHIRPS daily rainfall data covering a period of thirty-seven years from 1981 – 2018. Extreme rainfall events are identified and classified for the PM area. The analysis points to the highest rainfall amounts typically occurring over low-lying coastal areas and near mountainous regions. About 60% of the extreme rainfall events were associated with tropical lows (40%) and MCS (20%). Cut-off lows (18%), cloud bands (16%), and tropical cyclones (6%) contributed to the remaining proportion. The highest frequency of events occurred during late summer months (January – March) when tropical lows and occasionally, tropical cyclones are more common. Rainfall over the PM has a statistically significant relationship with ENSO, most of the seasons with below-average rainfall and extreme events coincided with El Niño conditions. Odd cases where this was the opposite were more influenced by regional circulation anomalies which acted to enhance or reduce moisture over the land-mass thereby increasing conditions favourable/unfavourable for rainfall over the region. |
| format | Thesis |
| id | oai:open.uct.ac.za:11427/37429 |
| institution | University of Cape Town (South Africa) |
| language | eng |
| last_indexed | 2026-06-10T12:33:43.673Z |
| license_str | Not specified — see source repository |
| provenance_str_mv | Harvested via OAI-PMH from UCTD — University of Cape Town Open Access Repository |
| publishDate | 2023 |
| publishDateRange | 2023 |
| publishDateSort | 2023 |
| publisher | Department of Oceanography |
| publisherStr | Department of Oceanography |
| record_format | dspace |
| source_str | UCTD — University of Cape Town Open Access Repository |
| spelling | oai:open.uct.ac.za:11427/37429 Extreme rainfall events over the Pongola-Mtamvuna Water Management Area of South Africa Mpungose, Nomvula Bongekile Reason, Christopher Blamey, Ross Ocean and Atmosphere Science Subtropical southern Africa experiences substantial rainfall variability both spatially and temporally, due to regional orography, geographic position, and local sea-surface temperatures. Extreme weather conditions such as droughts and floods are not uncommon and can result in both positive and negative socio-economic impacts. The Pongola-Mtamvuna Water Management Area (PM) located over north-eastern South Africa consists of communities that depend on rain-fed agriculture, as well as an inter-linked ecosystem and fresh water bodies that are dependent on rainfall. Extreme rainfall events and the systems that produce them are still not well understood, therefore, a detailed analysis of such events can contribute to an improved understanding and management of their associated risks. Here, the main focus is on the summer rainy season (October – March), rainfall variability is examined using CHIRPS daily rainfall data covering a period of thirty-seven years from 1981 – 2018. Extreme rainfall events are identified and classified for the PM area. The analysis points to the highest rainfall amounts typically occurring over low-lying coastal areas and near mountainous regions. About 60% of the extreme rainfall events were associated with tropical lows (40%) and MCS (20%). Cut-off lows (18%), cloud bands (16%), and tropical cyclones (6%) contributed to the remaining proportion. The highest frequency of events occurred during late summer months (January – March) when tropical lows and occasionally, tropical cyclones are more common. Rainfall over the PM has a statistically significant relationship with ENSO, most of the seasons with below-average rainfall and extreme events coincided with El Niño conditions. Odd cases where this was the opposite were more influenced by regional circulation anomalies which acted to enhance or reduce moisture over the land-mass thereby increasing conditions favourable/unfavourable for rainfall over the region. 2023-03-14T10:22:55Z 2023-03-14T10:22:55Z 2022 2023-03-14T10:21:47Z Master Thesis Masters MSc http://hdl.handle.net/11427/37429 eng application/pdf Department of Oceanography Faculty of Science |
| spellingShingle | Ocean and Atmosphere Science Mpungose, Nomvula Bongekile Extreme rainfall events over the Pongola-Mtamvuna Water Management Area of South Africa |
| thesis_degree_str | Master's |
| title | Extreme rainfall events over the Pongola-Mtamvuna Water Management Area of South Africa |
| title_full | Extreme rainfall events over the Pongola-Mtamvuna Water Management Area of South Africa |
| title_fullStr | Extreme rainfall events over the Pongola-Mtamvuna Water Management Area of South Africa |
| title_full_unstemmed | Extreme rainfall events over the Pongola-Mtamvuna Water Management Area of South Africa |
| title_short | Extreme rainfall events over the Pongola-Mtamvuna Water Management Area of South Africa |
| title_sort | extreme rainfall events over the pongola mtamvuna water management area of south africa |
| topic | Ocean and Atmosphere Science |
| url | http://hdl.handle.net/11427/37429 |
| work_keys_str_mv | AT mpungosenomvulabongekile extremerainfalleventsoverthepongolamtamvunawatermanagementareaofsouthafrica |