Full Text Available
Note: Clicking the button above will open the full text document at the original institutional repository in a new window.
The El Nino Southern Oscillation, rainfall and wheat yields in South Africa
This thesis assesses the relationships between the El Nino-Southern Oscillation (ENSO), rainfall and South African commercial winter wheat yields from 1974 - 2000. The analysis is through a combination of the Pearson's product moment correlation coefficient and an assessment of the magnitude and con...
Saved in:
| Main Author: | |
|---|---|
| Format: | Thesis |
| Language: | English English |
| Published: |
Department of Oceanography
2026
|
| Subjects: | |
| Tags: |
No Tags, Be the first to tag this record!
|
| _version_ | 1867613493902966784 |
|---|---|
| access_status_str | Open Access |
| author | Begley, Paul |
| author_browse | Begley, Paul |
| author_facet | Begley, Paul |
| author_sort | Begley, Paul |
| collection | Thesis |
| description | This thesis assesses the relationships between the El Nino-Southern Oscillation (ENSO), rainfall and South African commercial winter wheat yields from 1974 - 2000. The analysis is through a combination of the Pearson's product moment correlation coefficient and an assessment of the magnitude and consistency of rainfall and wheat anomalies in the year of, and the year following warm (El Nino) and cold (La Nina) ENSO events. The ENSO - rainfall relationship is analysed on timescales from 1 - 24 months and this study finds that there are more unusually dry and unusually wet months during El Nino events than during La Nina episodes (where dry and wet months are <75% and over 25% more than the 1921 - 2000 mean, respectively) and these conditions are consistently found in some rainfall areas during each El Nino or La Nina event; there is marked inter - El Nino and inter La Nina variation in late summer and annual rainfall; and that there has been a significant shift in the timings of maximum rainfall anomalies during El Nino episodes from an earlier investigation. The effects of rainfall on the wheat yield vary spatially, but are most apparent in the Free State where severe droughts have resulted in reduced yields. In the Northern Cape and Western Cape anomalously wet conditions, especially in late summer, coincide with reduced wheat yields. The ENSO - wheat yield relationship is not a simple linear one, and despite yields in the Northern Cape and Western Cape tracking Pacific sea surface temperatures by nearly a year, El Nino and La Nina years are not synonymous with increased or decreased yields in any province. ln fact, maximum and minimum yields in the Free State and Northern Cape are found in the year of, or year following a La Nina event, and consequently the present predictability of wheat yields by ENSO is limited. The relationships between ENSO, rainfall and wheat yield in South Africa is not readily apparent, which may be due to the short (<30 years) data set or mediating factors outside this study such as farm management strategies or hemispheric variation in the evolution of El Nino and La Nina events. |
| format | Thesis |
| id | oai:open.uct.ac.za:11427/43213 |
| institution | University of Cape Town (South Africa) |
| language | English eng |
| last_indexed | 2026-06-10T12:37:02.109Z |
| license_str | Not specified — see source repository |
| provenance_str_mv | Harvested via OAI-PMH from UCTD — University of Cape Town Open Access Repository |
| publishDate | 2026 |
| publishDateRange | 2026 |
| publishDateSort | 2026 |
| 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:11427/43213 The El Nino Southern Oscillation, rainfall and wheat yields in South Africa Begley, Paul Applied Marine Science rainfall South Africa This thesis assesses the relationships between the El Nino-Southern Oscillation (ENSO), rainfall and South African commercial winter wheat yields from 1974 - 2000. The analysis is through a combination of the Pearson's product moment correlation coefficient and an assessment of the magnitude and consistency of rainfall and wheat anomalies in the year of, and the year following warm (El Nino) and cold (La Nina) ENSO events. The ENSO - rainfall relationship is analysed on timescales from 1 - 24 months and this study finds that there are more unusually dry and unusually wet months during El Nino events than during La Nina episodes (where dry and wet months are <75% and over 25% more than the 1921 - 2000 mean, respectively) and these conditions are consistently found in some rainfall areas during each El Nino or La Nina event; there is marked inter - El Nino and inter La Nina variation in late summer and annual rainfall; and that there has been a significant shift in the timings of maximum rainfall anomalies during El Nino episodes from an earlier investigation. The effects of rainfall on the wheat yield vary spatially, but are most apparent in the Free State where severe droughts have resulted in reduced yields. In the Northern Cape and Western Cape anomalously wet conditions, especially in late summer, coincide with reduced wheat yields. The ENSO - wheat yield relationship is not a simple linear one, and despite yields in the Northern Cape and Western Cape tracking Pacific sea surface temperatures by nearly a year, El Nino and La Nina years are not synonymous with increased or decreased yields in any province. ln fact, maximum and minimum yields in the Free State and Northern Cape are found in the year of, or year following a La Nina event, and consequently the present predictability of wheat yields by ENSO is limited. The relationships between ENSO, rainfall and wheat yield in South Africa is not readily apparent, which may be due to the short (<30 years) data set or mediating factors outside this study such as farm management strategies or hemispheric variation in the evolution of El Nino and La Nina events. 2026-05-08T13:38:34Z 2026-05-08T13:38:34Z 2005 2026-05-06T09:14:42Z Thesis / Dissertation Masters MSc http://hdl.handle.net/11427/43213 en eng application/pdf Department of Oceanography Faculty of Science University of Cape Town |
| spellingShingle | Applied Marine Science rainfall South Africa Begley, Paul The El Nino Southern Oscillation, rainfall and wheat yields in South Africa |
| thesis_degree_str | Master's |
| title | The El Nino Southern Oscillation, rainfall and wheat yields in South Africa |
| title_full | The El Nino Southern Oscillation, rainfall and wheat yields in South Africa |
| title_fullStr | The El Nino Southern Oscillation, rainfall and wheat yields in South Africa |
| title_full_unstemmed | The El Nino Southern Oscillation, rainfall and wheat yields in South Africa |
| title_short | The El Nino Southern Oscillation, rainfall and wheat yields in South Africa |
| title_sort | el nino southern oscillation rainfall and wheat yields in south africa |
| topic | Applied Marine Science rainfall South Africa |
| url | http://hdl.handle.net/11427/43213 |
| work_keys_str_mv | AT begleypaul theelninosouthernoscillationrainfallandwheatyieldsinsouthafrica AT begleypaul elninosouthernoscillationrainfallandwheatyieldsinsouthafrica |