Analysing the changes in bathymetry of Saldanha Bay between the years 1977 and 2021

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dc.contributor.advisorHenrico, Ivanen_ZA
dc.contributor.advisorMtshawu, Babalwaen_ZA
dc.contributor.authorDu Toit, Louisen_ZA
dc.contributor.otherStellenbosch University. Faculty of Military Sciences. School for Geospatial Studies and Information Systems.en_ZA
dc.date.accessioned2022-03-11T03:55:05Z
dc.date.accessioned2022-04-29T12:53:01Z
dc.date.available2022-12-22T03:00:15Z
dc.date.issued2022-04
dc.descriptionThesis (MMil)--Stellenbosch University, 2022.en_ZA
dc.descriptionThe article for this Masters degree is available at https://scholar.sun.ac.za/handle/10019.1/129271
dc.description.abstractENGLISH ABSTRACT: Possessing one of the finest natural harbours on the South African coast, along with its ideal location on a major international trading route, the Saldanha Bay Municipality has been identified as a key development zone in the blue economy, earmarked to lead major developments in the region. Saldanha Bay is strategically positioned to serve the envisaged oil-and-gas sector on the west coast of the African continent and is a critical area for development for South Africa’s ‘blue economy’. Studies like Henrico & Bezuidenhout (2020) have proven that the changes made during the construction of the Port of Saldanha (PoS) have altered the shape and slope profile of Saldanha Bay (herein called the Bay, which refers to both Inner and Outer Bay, described in section 1.2) significantly, thus changing the hydrodynamics of the Bay. The aim of this study is to compare and analyse the changes in bathymetry of Saldanha Bay between 1977 and 2021. The general tendency of gradual increase in depth from the coastline towards the mouth of the Bay, with sharp increases in depth off Elandspunt and Salamanderpunt, is the same for both 1977 and 2021. The Ordinary Kriging (OK) interpolation method, employed by means of a Geographic Information System (GIS), was selected for creating surface models of the bathymetry of Saldanha Bay, and for conducting the comparison between the two datasets. Said comparison will determine the change in bathymetry over the 44-year period. A slope analysis was also performed to determine the stability of the ocean floor of the Bay. The results of this study indicate a general increase in depth since 1977, with most of the pixels in the graphical representation of the Bay (68.2%) indicating a depth increase between 0.395 - 3.203 m, and an average increase in depth within Big Bay of 1.799 m between 1977 - 2021. There were also two areas identified which experienced changes beyond the standard deviation and showed significant increases or decreases in depth. The general slope trend of Big Bay in 2021 remained fairly like that of 1977, with most of the Bay having a relatively low slope, between 0 - 1.3 degrees. However, in 2021 it can be seen that there is a slight increase in overall slope of Big Bay since 1977, with and average slope of 0.51 recorded in 2021, 0.2 degrees more than in 1977. Furthermore, in 2021 the majority of Big Bay had a slope of 1.3 degrees or less, 0.4 degrees more than in1977. Finally, in 2021 Big Bay also showed an increase in the maximum slope recorded in the Bay, with a maximum slope of 14.8 degrees, more than twice the maximum slope recorded in 1977. The findings of this study support the statements made by Flemming (1977) and Henrico & Bezuidenhout (2020) that the construction of the PoS changed the sedimentation processes within Saldanha Bay to some extent. However, the findings of this study are only relevant for a portion of Saldanha Bay, the inclusion zone in Big Bay as indicated in section 4.3. In this area however, there has been a total loss of 49 364 560.0 m3 in volume. The exact nature and driving forces behind this loss in volume still requires further investigation to be fully understood.en_ZA
dc.description.abstractAFRIKAANSE OPSOMMING: Saldanhabaai Munisipaliteit, wat een van die beste natuurlike hawens aan die Suid-Afrikaanse kus huisves, en wat ideaal geleë is op ‘n internasionale handelsroete, is as ‘n sleutel-ontwikkelingssone in die Blou Ekonomie van Afrika, Suider Afrika en Suid-Afrika in besonder geïdentifiseer. Die betrokke munisipale area is geoormerk om toonaangewend te wees in grootskaalse ontwikkelings in die streek. Saldanhabaai is strategies uitstekend geposisioneer om die beoogde olie- en gassektore aan die weskus van Afrika as ‘n kritieke komponent van Suid-Afrika se Blou Ekonomie te bedien. Studies soos die van Henrico & Bezuidenhout (2020) het bewys dat veranderinge aangebring tydens die oprigting van die Saldanhabaai Hawe die vorm en hellingprofiel van Saldanhabaai aansienlik verander het end us die hidrodinamieke (Die Baai wat verwys na beide Binne- en Buitebaai, beskryf in afdeling 1.2). Die hoofdoel van hierdie studie was om die veranderinge in die diepte profiel van Saldanhabaai soos in 1977 bepaal met dié van 2021 te vergelyk en te analiseer. Die algemene tendens van geleidelike dieptetoename vanaf die kuslyn na die mond van die Baai, en skerp dieptetoename teenaan Elandspunt en Salamanderpunt, is onveranderd tussen 1977 en 2021. Die Gewone Kriging (GK) interpolasiemetode, toegepas deur middel van ‘n Geografiese Inligtingstelsel (GIS), is gekies om oppervlakmodelle van die diepte profiel van Saldanhabaai te skep, en om genoemde twee stelle data te vergelyk. Sodanige vergelyking sal die verandering in die diepte profiel in die Baai oor die 44-jaarperiode illustreer. ‘n Hellingontleding is ook gedoen om die stabiliteit van die seebodem van die Baai te bepaal. Die resultate van hierdie studie dui op ‘n algemene toename in diepte sedert 1977, met die meeste van die beeldpunte in die grafiese voorstelling van die Baai (68.2%) wat op ‘n dieptetoename van tussen 0.395 en 3.203 m dui, en ‘n gemiddelde dieptetoename in Big Bay (Grootbaai) van 1.799 m vir die periode 1977 tot 2021. Twee sones is ook geïdentifiseer wat die statistiese standaardafwyking verander het. Hul afwykings was tweeledig; enersyds het albei beduidende dieptetoename getoon, andersyds, beduidente diepte-afname. Die algemene hellingtendens vir Big Bay (Grootbaai) in die 2021-meting het feitlik onveranderd van die van 1977 gebly, deurdat die grootste deel daarvan gekenmerk is deur ‘n relatief lae helling, naamlik 0 tot 1.3 grade. Daar was egter in 2021 ‘n geringe toename in die totale helling van Big Bay (Grootbaai) 0.51 wat 0.2 grade meer is as in 1977. Boonop het die meerderheidsdeel van Big Bay teen 2021 ‘n heling van 1.3 grade of minder gehad, 0.4 grade meer as in 1977. Ten slotte, in 2021 het Big Bay (Grootbaai) ook ‘n toename in die maksimumhelling in die Baai getoon, met ‘n maksimumhelling van 14.8 grade, meer as dubbel die maksimumhelling aangeteken in 1977. Die bevindinge van hierdie studie ondersteun die bevindinge van Flemming (1977) en Henrico & Bezuidenhout (2020), naamlik, dat die oprigting van die Saldanhabaai Hawe die sedimentasieprosesse binne Saldanhabaai tot ‘n sekere mate beïnvloed het. Die bevindinge van die huidige studie is direk toepasbaar slegs op ‘n deel van Saldanhabaai - die insluitingsone genaamd Big Bay (Grootbaai). In hierdie area was daar ‘n totale volumeverlies van 49 364 560 m3. Die presiese aard van, en dryfkragte agter hierdie verlies vra vir verdere wetenskaplike ondersoek.af_ZA
dc.description.versionMastersen_ZA
dc.embargo.terms2022-12-01
dc.format.extentxviii, 111 pages : illustrations
dc.identifier.urihttp://hdl.handle.net/10019.1/125078
dc.language.isoen
dc.rights.holderStellenbosch Universityen_ZA
dc.subject.lcshArcGISen_ZA
dc.subject.lcshInterpolationen_ZA
dc.subject.lcshKrigingen_ZA
dc.subject.lcshBathymetric maps -- South Africa -- Saldanha Bay -- 20th centuryen_ZA
dc.subject.lcshGeographic information systemsen_ZA
dc.subject.nameUCTD
dc.titleAnalysing the changes in bathymetry of Saldanha Bay between the years 1977 and 2021en_ZA
dc.typeThesisen_ZA
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