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Estuary breaching and mouth state prediction in South Africa
Thesis (MEng)--Stellenbosch University, 2022.
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| Format: | Thesis |
| Language: | en_ZA |
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Stellenbosch : Stellenbosch University
2022
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| _version_ | 1867613882922565632 |
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| access_status_str | Open Access |
| author | Le Roux, Jana Hendrina |
| author2 | Theron, Andre Karl |
| author_browse | Le Roux, Jana Hendrina Theron, Andre Karl |
| author_facet | Theron, Andre Karl Le Roux, Jana Hendrina |
| author_sort | Le Roux, Jana Hendrina |
| collection | Thesis |
| dc_rights_str_mv | Stellenbosch University |
| description | Thesis (MEng)--Stellenbosch University, 2022. |
| format | Thesis |
| id | oai:scholar.sun.ac.za:10019.1/125007 |
| institution | Stellenbosch University (South Africa) |
| language | en_ZA |
| last_indexed | 2026-06-10T12:43:12.690Z |
| license_str | Other — see source repository |
| provenance_str_mv | Harvested via OAI-PMH from SUNScholar — Stellenbosch University Repository |
| publishDate | 2022 |
| publishDateRange | 2022 |
| publishDateSort | 2022 |
| publisher | Stellenbosch : Stellenbosch University |
| publisherStr | Stellenbosch : Stellenbosch University |
| record_format | dspace |
| source_str | SUNScholar — Stellenbosch University Repository |
| spelling | oai:scholar.sun.ac.za:10019.1/125007 Estuary breaching and mouth state prediction in South Africa Le Roux, Jana Hendrina Theron, Andre Karl Stellenbosch University. Faculty of Engineering. Dept. of Civil Engineering. Estuary breaching UCTD Estuarine health Discriminant analysis Forms, Quadratic Thesis (MEng)--Stellenbosch University, 2022. ENGLISH ABSTRACT: Estuaries are the most important link between terrestrial and marine environments and must therefore be maintained to ensure they remain in an optimal state. Humans have interfered with the natural functioning of estuaries to such an extent that to restore them to their natural state, they must be managed. Various management authorities have the responsibility to ensure that the natural functioning of estuaries is achieved or restored. The current lack of published information regarding the hydro- and morpho-dynamics of South African temporarily open or closed estuaries however reduces the ability of management authorities to ensure the health of these estuarine systems. This thesis aims to provide a better understanding of estuaries, and in specific, South African temporarily open or closed estuaries. This thesis also serves as an initial study into the development of an estuarine mouth state predictor, where the mouth state describes the connection (or lack thereof) between the ocean and estuary. The first step in achieving these goals was to investigate the various factors influencing the mouth states of temporarily open or closed estuaries. These factors included river inflow, precipitation, evaporation, wave height, wave period, and tidal levels. Various combinations of these physical factors were tested during the development of the prediction model. The resulting model was developed using Python and predicts the daily mouth states and water levels by combining various logical tests and calculations. The mouth state predictions are based on the combined results of a Quadratic Discriminant Analysis model (employing various wave, tide, and river inflow parameters), a berm height predictor based on wave runup modelling, and the calculated estuarine water levels. The estuarine water levels during a closed mouth state are calculated by means of a water balance model, whereas during an open mouth state the estuarine water levels are related to the adjacent sea tidal levels. The Mngazi and Groot Brak Estuaries were chosen to test the various prediction models. These estuaries were chosen based on their classification (i.e., they are temporarily open or closed estuaries), the availability of input data, and because they are located in different coastal regions. The results were then compared to the measured estuarine water levels as well as the mouth states observed during the same period. The accuracy with which the mouth state could be predicted was between 65% and 81% for both estuaries. The percentage of predicted estuarine water levels that were within one standard deviation of the actual values was between 56% to 76% for both estuaries. The results obtained were deemed to be satisfactory. The results can however be improved in future studies through various specific actions. These actions include the use of more complete data sets, longer data sets, more accurate measurement methods, and various others. It should also be noted that this prediction model was developed for South African temporarily open or closed estuaries and may need to be adjusted if used outside of South Africa. The knowledge captured in this document will provide future researchers with background on South African temporarily open or closed estuaries and aid in the improvement of future mouth state prediction methods AFRIKAANSE OPSOMMING: Strandmere (soms ook bekend as getyriviere) vorm die belangrikste skakel tussen land en mariene omgewings en moet dus bestuur word om te verseker dat hulle in ‘n optimale toestand gehandhaaf word. Die mens het die natuurlike funksionering van strandmere nadelig beïnvloed tot by die punt waar hulle bestuur moet word om terug te keer na hulle natuurlik funksionerende toestand. Dit is verskeie bestuursowerhede se verantwoordelikheid om te verseker dat die natuurlike funksionering van strandmere bereik of herstel word. Die huidige gebrek aan gepubliseerde informasie aangaande die hidro- en morfodinamika van Suid Afrikaanse tydelike oop- of toe strandmere verminder die vermoë van bestuursowerhede om die gesondheid van hierdie sisteme te verseker. Hierdie tesis wil die begrip rondom strandmere, spesifiek Suid Afrikaanse tydelike oop- of toe strandmere, verbeter. Die tesis dien ook as ‘n aanvanklike studie om die moontlike mondtoestand van ‘n strandmeer by wyse van sekere toestande te kan voorspel, waar die mondtoestand die verbinding (of gebrek daaraan) tussen die see en strandmeer beskryf. Die eerste stap in die behaling van die studie-mikpunte was om navorsing te doen oor die verskeie faktore (naamlik die rivier invloei, neerslag, verdamping, golfhoogte, golfperiode, en getyvlakke) wat die mondtoestand van tydelike oop- of toe strandmere beïnvloed. Verskeie kombinasies van die fisiese faktore is getoets tydens die ontwikkeling van die voorspellingsmodel. Die model is ontwikkel deur gebruik te maak van Python wat daagliks die mondtoestande en watervlakke voorspel deur verskeie logiese toetse en bewerkings te kombineer. Die voorspellings van die mondtoestand, word gebaseer op die gekombineerde resultate van ‘n Kwadratiese Diskriminant Analise model (wat gebruik maak van verskeie golf-, gety-, en rivier invloei waardes), ‘n berm hoogtevoorspeller gebaseer op golf oploop modelering en die berekende watervlakke in die strandmeer. Die strandmeer se watervlakke tydens ‘n toe mondtoestand, word bereken deur gebruik te maak van ‘n waterbalansmodel. Die watervlakke tydens ‘n oop mondtoestand, is aan die aangrensende getyvlakke gekoppel. Die Mngazi en Groot Brak strandmere is gekies om die voorspellings metodes te toets. Hierdie strandmere is gekies na aanleiding van hulle klassifikasie (naamlik tydelike oop- of toe strandmere), die beskikbaarheid van insetdata en die feit dat hulle aan verskillende kusstreke geleë is. Die resultate is vergelyk met die gemete strandmeer watervlakke, sowel as die mondtoestande waargeneem tydens dieselfde periode. Die akkuraatheid waarmee die mondtoestande voorspel is, is tussen 65% en 81% vir albei strandmere. Die persentasie van voorspelde watervlakke in die strandmeer wat binne een standaard afwyking van die gemete waardes val, is tussen 56% en 76% vir albei strandmere. Daar is bevind dat die akkuraatheid van die waargenome resultate voldoende is. Die resultate kan na verwagting wel verbeter word in toekomstige studies, deur verskeie veranderinge aan te bring, soos om gebruik te maak van meer volledige datastelle, langer datastelle, meer akkurate metodes, en verskeie ander. Dit is belangrik om in ag te neem dat die model vir Suid Afrikaanse tydelike oop- of toe strandmere ontwikkel is en daar mag dalk aanpassings nodig wees vir die gebruik buite Suid Afrika. Hierdie studie dra by tot belangrikke kennis ten opsigte van Suid Afrikaanse tydelike oop- of toe strandmere vir verdere gebruik deur navorsers, asook tot die verbetering van toekomstige voorspellingsmetodes vir strandmeer monde. Masters 2022-01-18T13:46:02Z 2022-04-29T09:46:14Z 2022-01-18T13:46:02Z 2022-04-29T09:46:14Z 2022-03 Thesis http://hdl.handle.net/10019.1/125007 en_ZA Stellenbosch University 147 pages application/pdf Stellenbosch : Stellenbosch University |
| spellingShingle | Estuary breaching UCTD Estuarine health Discriminant analysis Forms, Quadratic Le Roux, Jana Hendrina Estuary breaching and mouth state prediction in South Africa |
| title | Estuary breaching and mouth state prediction in South Africa |
| title_full | Estuary breaching and mouth state prediction in South Africa |
| title_fullStr | Estuary breaching and mouth state prediction in South Africa |
| title_full_unstemmed | Estuary breaching and mouth state prediction in South Africa |
| title_short | Estuary breaching and mouth state prediction in South Africa |
| title_sort | estuary breaching and mouth state prediction in south africa |
| topic | Estuary breaching UCTD Estuarine health Discriminant analysis Forms, Quadratic |
| url | http://hdl.handle.net/10019.1/125007 |
| work_keys_str_mv | AT lerouxjanahendrina estuarybreachingandmouthstatepredictioninsouthafrica |