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Macro-scale boundary controls on the fluvial geomorphology of floodplain wetlands across South Africa’s hydroclimatic regions
Thesis (MA)--Stellenbosch University, 2024.
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| Language: | English |
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Stellenbosch : Stellenbosch University
2025
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| _version_ | 1867613773674577920 |
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| access_status_str | Open Access |
| author | Chemaly, Hannah Frances |
| author2 | Grenfell, Suzanne |
| author_browse | Chemaly, Hannah Frances Grenfell, Suzanne |
| author_facet | Grenfell, Suzanne Chemaly, Hannah Frances |
| author_sort | Chemaly, Hannah Frances |
| collection | Thesis |
| dc_rights_str_mv | Stellenbosch University |
| description | Thesis (MA)--Stellenbosch University, 2024. |
| format | Thesis |
| id | oai:scholar.sun.ac.za:10019.1/131612 |
| institution | Stellenbosch University (South Africa) |
| language | English |
| last_indexed | 2026-06-10T12:41:28.315Z |
| license_str | Other — see source repository |
| provenance_str_mv | Harvested via OAI-PMH from SUNScholar — Stellenbosch University Repository |
| publishDate | 2025 |
| publishDateRange | 2025 |
| publishDateSort | 2025 |
| publisher | Stellenbosch : Stellenbosch University |
| publisherStr | Stellenbosch : Stellenbosch University |
| record_format | dspace |
| source_str | SUNScholar — Stellenbosch University Repository |
| spelling | oai:scholar.sun.ac.za:10019.1/131612 Macro-scale boundary controls on the fluvial geomorphology of floodplain wetlands across South Africa’s hydroclimatic regions Chemaly, Hannah Frances Grenfell, Suzanne Stellenbosch University. Faculty of Arts and Social Sciences. Dept. of Geography and Environmental Studies. Vegetation classification -- South Africa Floodplains -- South Africa Plant ecology Fluvial geomorphology Hydrometeorology Arid regions -- South Africa Morphotectonics Climatology -- South Africa Wetlands -- South Africa UCTD Thesis (MA)--Stellenbosch University, 2024. ENGLISH ABSTRACT: Floodplains are a unique type of wetland, which owe their formation to a combination of intrinsic and extrinsic controls. Knowing the distribution of floodplain types is important as each floodplain type provides different ecosystem services. The types of floodplains a river has can provide insight into how that river functions. The study aimed to establish the spatial distribution and frequency of floodplain types in South Africa and to establish whether there were any broad-scale continuums related to the macro-scale geomorphic context and/or the aridity gradient. Objectives included mapping and classifying floodplains in six selected sub-catchments across South Africa such that the climatic continuum and various lithologies and biomes were represented. Thereafter floodplains and their catchments were mapped, and a range of different variables and data were collected for each floodplain and its catchment area. Last, it was established whether any broad-scale continuums might be used to describe the spatial occurrence of different floodplain types to macro-scale geomorphic context and/or the aridity gradient. The methods consisted of data collection via a desktop analysis. Floodplain delineation was done with the use of the Height Above Nearest Drainage (HAND) methodology followed by floodplain classification according to the Genetic Geomorphic Classification System for Southern African Palustrine Wetlands (Grenfell et al., 2019). After that data collection included collecting quantitative data on floodplains and their catchment areas through the gathering of primary data and clipping and refining of secondary data. Data analysis, using the data collected, made use of descriptive and investigative statistics as well as multinomial logistic regressions to see trends within the data and to ascertain which variables affected floodplain-type formation in each chosen catchment. It was found that the arid Olifants River, with its higher aridity leading to variable flow regimes, and the semi-arid Goukou River, with its ‘boom-and-bust’ hydrological regime, had mixed bedrock-alluvial anabranching river floodplains as their predominant floodplain type. The semi-arid Nuwejaars River, positioned within a coastal macro-scale setting, and the dry sub-humid Tugela River, an inland lithologically controlled river, had meandering river floodplains as their predominant river type. The semi-arid Great Fish River, with its highly resistant dolerite sills, and the humid Mzimvubu River, with characteristics typical of a humid river system, had straight river floodplains as their predominant floodplain type. It was concluded that geology and tectonic setting are the broad-scale continuums affecting the spatial distribution and frequency of floodplain types in South Africa. Whilst climate and aridity do play a role, it is not to the extent that climate plays a role in the development of floodplain types in Australia as demonstrated in the paper by Larkin et al. (2017). South Africa is unique in that it is super-elevated compared to other tectonically stable regions of the world and it has a westward-sloping plateau. This has resulted in the macro-scale geomorphic context having a greater impact on floodplain-type formation across the country as indicated by the study’s catchments. AFRIKAANSE OPSOMMING: Vloedvlaktes is ʼn unieke soort vleiland en word gevorm deur ʼn kombinasie van intrinsieke en ekstrinsieke kontroles. Dit is belangrik om die distribusie van die soorte vloedvlaktes te ken, aangesien elke soort vloedvlakte verskillende ekostelseldienste lewer. Die soorte vloedvlaktes wat ʼn rivier bevat, kan insig bied in hoe daardie rivier funksioneer. Die studie wou poog om die ruimtelike distribusie en frekwensie van soorte vloedvlaktes in Suid-Afrika te bepaal en ook bepaal of daar enige breedskaalse kontinuums is wat met die makroskaalse geomorfiese konteks en/of die ariditeitsgradiënt verband hou. Die doelwitte het die kartering en klassifisering van vloedvlaktes in ses gekose subopvangsgebiede regoor Suid-Afrika ingesluit, sodanig dat die klimaatskontinuum en verskillende litologieë en biome verteenwoordig is. Daarna is die vloedvlaktes en hulle opvangsgebiede gekarteer en ʼn verskeidenheid veranderlikes en data is vir elke vloedvlakte en sy opvangsgebied ingesamel. Laastens is vasgestel of enige breedskaalse kontinuums gebruik kan word om die ruimtelike voorkoms van verskillende soorte vloedvlaktes aan makroskaalse geomorfiese konteks en/of die ariditeitsgradiënt toe te skryf. Die metode was data-insameling via ʼn lessenaarontleding. Vloedvlakte-afbakening is met behulp van die HAND-metodologie (“Height Above Nearest Drainage” of hoogte bo naaste dreinering) gedoen, gevolg deur vloedvlakteklassifisering volgens die “Genetic Geomorphic Classification System for Southern African Palustrine Wetlands” (genetiese geomorfiese klassifiseringstelsel vir Suider-Afrikaanse moerasvleilande) (Grenfell et al., 2019). Daarna is kwantitatiewe data oor vloedvlaktes en hulle opvangsgebiede deur die insameling van primêre data en die uitdun en verfyning van sekondêre data ingesamel. Dataontleding van die ingesamelde data het gebruik gemaak van beskrywende en ondersoekende statistiek asook polinome logistiese regressies om die tendense in die data raak te sien en om vas te stel watter veranderlikes die vorming van die soorte vloedvlaktes in elke gekose opvangsgebied beïnvloed het. Daar is bevind dat die ariede Olifantsrivier, met sy hoër ariditeit wat veranderlike vloeiregimes tot gevolg het, en die semi-ariede Goukourivier, met sy ‘opbloei-en-ineenstort’- hidrologiese regime, hoofsaaklik gemengde rotsbodem-alluviale gevlegte riviervloedvlaktes het. Die semi-ariede Nuwejaarsrivier, wat binne ʼn makroskaalse kusomgewing geposisioneer is en die droë subhumiede Tugelarivier, ʼn binnelandse litologies beheerde rivier, het hoofsaaklik kronkelende riviervloedvlaktes. Die semi-ariede Groot Visrivier, met sy hoogs weerstandige dolerietbanke, en die humiede Mzimvuburivier, wat kenmerke tiperend van ʼn humiede rivierstelsel het, het hoofsaaklik reguit riviervloedvlaktes. Daar is tot die gevolgtrekking gekom dat geologie en tektoniese omgewing die breedskaalse kontinuums is wat die ruimtelike distribusie en frekwensie van soorte vloedvlaktes in Suid-Afrika beïnvloed. Hoewel klimaat en ariditeit wel ʼn rol speel, is dit nie tot die mate wat klimaat ʼn rol in die ontwikkeling van soorte vloedvlaktes in Australië speel nie, soos blyk uit die referaat van Larkin et al. (2017). Suid-Afrika is uniek daarin dat dit superhooggeleë is vergeleke met ander tektonies stabiele streke van die wêreld en dat dit ʼn plato het wat na die weste afloop. Dit het daartoe gelei dat die makroskaalse geomorfiese konteks ʼn groter impak op die vorming van soorte vloedvlaktes regoor die land het, soos deur die opvanggebiede in die studie aangedui is. Masters 2025-01-29T09:19:41Z 2025-01-29T09:19:41Z 2024-12 Thesis https://scholar.sun.ac.za/handle/10019.1/131612 en Stellenbosch University 271 pages : illustrations application/pdf Stellenbosch : Stellenbosch University |
| spellingShingle | Vegetation classification -- South Africa Floodplains -- South Africa Plant ecology Fluvial geomorphology Hydrometeorology Arid regions -- South Africa Morphotectonics Climatology -- South Africa Wetlands -- South Africa UCTD Chemaly, Hannah Frances Macro-scale boundary controls on the fluvial geomorphology of floodplain wetlands across South Africa’s hydroclimatic regions |
| title | Macro-scale boundary controls on the fluvial geomorphology of floodplain wetlands across South Africa’s hydroclimatic regions |
| title_full | Macro-scale boundary controls on the fluvial geomorphology of floodplain wetlands across South Africa’s hydroclimatic regions |
| title_fullStr | Macro-scale boundary controls on the fluvial geomorphology of floodplain wetlands across South Africa’s hydroclimatic regions |
| title_full_unstemmed | Macro-scale boundary controls on the fluvial geomorphology of floodplain wetlands across South Africa’s hydroclimatic regions |
| title_short | Macro-scale boundary controls on the fluvial geomorphology of floodplain wetlands across South Africa’s hydroclimatic regions |
| title_sort | macro scale boundary controls on the fluvial geomorphology of floodplain wetlands across south africa s hydroclimatic regions |
| topic | Vegetation classification -- South Africa Floodplains -- South Africa Plant ecology Fluvial geomorphology Hydrometeorology Arid regions -- South Africa Morphotectonics Climatology -- South Africa Wetlands -- South Africa UCTD |
| url | https://scholar.sun.ac.za/handle/10019.1/131612 |
| work_keys_str_mv | AT chemalyhannahfrances macroscaleboundarycontrolsonthefluvialgeomorphologyoffloodplainwetlandsacrosssouthafricashydroclimaticregions |