Full Text Available
Note: Clicking the button above will open the full text document at the original institutional repository in a new window.
A comparative assessment of water quality of two reservoirs in an ephemeral river in the desert climate of Namibia: Measures to control, and factors affecting growth of toxic cyanobacteria
Thesis (PhD)--Stellenbosch University, 2022.
Saved in:
| Main Author: | |
|---|---|
| Other Authors: | |
| Format: | Thesis |
| Language: | en_ZA |
| Published: |
Stellenbosch : Stellenbosch University
2022
|
| Subjects: | |
| Tags: |
No Tags, Be the first to tag this record!
|
| _version_ | 1867614058635591680 |
|---|---|
| access_status_str | Open Access |
| author | Sirunda, Jaime Johannes |
| author2 | Wolfaardt, Gideon M. |
| author_browse | Sirunda, Jaime Johannes Wolfaardt, Gideon M. |
| author_facet | Wolfaardt, Gideon M. Sirunda, Jaime Johannes |
| author_sort | Sirunda, Jaime Johannes |
| collection | Thesis |
| dc_rights_str_mv | Stellenbosch University |
| description | Thesis (PhD)--Stellenbosch University, 2022. |
| format | Thesis |
| id | oai:scholar.sun.ac.za:10019.1/126112 |
| institution | Stellenbosch University (South Africa) |
| language | en_ZA |
| last_indexed | 2026-06-10T12:45:58.010Z |
| 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:10019.1/126112 A comparative assessment of water quality of two reservoirs in an ephemeral river in the desert climate of Namibia: Measures to control, and factors affecting growth of toxic cyanobacteria Sirunda, Jaime Johannes Wolfaardt, Gideon M. Oberholster, Paul Stellenbosch University. Faculty of Science. Dept. of Microbiology. Water quality -- Swakop River (Namibia) Climatic changes-- Effect of global warming on Cyanobacteria -- Effect of temperature on Water salinization - Namibia Ephemeral streams -- Environmental aspects UCTD Thesis (PhD)--Stellenbosch University, 2022. ENGLISH SUMMARY: Globally, there is an increasing demand for freshwater of suitable quality. Satisfying the water requirement for ecosystem services and anthropogenic activities is challenging and may prove difficult in the context of climate change, growing population, and an increase in pollution from land use activities. With the rapid increase in human population in catchment areas, sustaining the associated human needs will often result in the generation of waste which will end up in water sources downstream causing eutrophication resulting in the proliferation of toxin-producing phytoplankton. The overall aim of the research was to carry out a comparative assessment of the water quality deterioration of ephemeral river connected dams with desert climate conditions, found in the Omaruru-Swakop catchment associated with a mixture of land use activities. The Swakoppoort (SWP) and Von Bach (VB) dams as the major dams in the Omaruru-Swakop catchment found on the Swakop River were selected and assessed seasonally for a number of years. Water samples were analyzed for various constituents, firstly to assess the water quality status of the two dams receiving a mixture of pollutants over space and time using the combination Water Quality Index (WQI). Secondly, to describe the vertical and temporal dynamics of phytoplankton communities in the two dams. Thirdly to investigate the effect of prolonged drought on phytoplankton biomass measured as Chlorophyll a (Chl a) and cyanobacteria. Lastly, a case study to compare the effectiveness of two phytoplankton control measures employed in the SWP Dam was conducted. The two dams were found to be impacted by nutrient, salinity, and particulate matter pollution. The WQIs showed poor water quality conditions in both dams for 17 years. Given the poor water quality of the two dams, Microcystis dominated the vertical and temporal dynamics, followed by Dolichospermum. In the dry seasons, higher cyanobacteria cell numbers were observed in comparison to the rainy season in both dams. In the SWP Dam, the preferable depth ranges for toxic cyanobacteria species were 5 to 10 m while in the VB Dam at 0 to 5 m range. Higher frequencies of prolonged drought years were recorded in the VB Dam in comparison to SWP Dam. The influence of a decrease in vol % on the phytoplankton biomass was observed in the SWP Dam but not in the VB Dam. However, the pattern and magnitude of the statistically significant responses (t-test, p < 0.05) varied among the drought and rainy years. Furthermore, the results showed that, the Solar Powered Circulation (SPC) and Phoslock® as the two phytoplankton control measures employed in the SWP Dam had no effect on cyanobacteria cells. It was evident that the two control measures were ineffective in reducing cyanobacterial cells. Incorporation of the current study research outputs in the utility surface water quality assessment and control program, water withdrawal for treatment and transfer plans, wastewater discharge regulations, and the revision of the integrated water resources management plan in Namibia, may ultimately safeguard the scarce water resources to improve resilience to climate change. AFRIKAANS OPSOMMING: Wêreldwyd is daar 'n toenemende vraag na varswater van geskikte gehalte. Die bevrediging van die waterbehoefte vir ekosisteemdienste en antropogeniese aktiwiteite is uitdagend en kan moeilik wees in die konteks van klimaatsverandering, groeiende bevolking en 'n toename in besoedeling deur grondgebruik aktiwiteite. Met die vinnige toename in menslike bevolking in opvanggebiede, sal die instandhouding van die gepaardgaande menslike behoeftes dikwels lei tot die genereer van afval wat stroomaf in waterbronne beland, wat eutrofikasie veroorsaak en lei tot die verspreiding van fitoplankton wat toksiese stowwe produseer. Die oorkoepelende doel van die navorsing was om 'n vergelykende assessering uit te voer oor die verswakking van die waterkwaliteit van kortstondige rivierverbonde damme met woestynklimaattoestande, wat gevind word in die Omaruru-Swakop-opvanggebied wat verband hou met 'n kombinasie van grondgebruik aktiwiteite. Die Swakoppoort (SWP) en Von Bach (VB) damme wat geag word as die belangrikste damme in die Omaruru-Swakop- opvanggebied en wat op die Swakoprivier gevind word, is geselekteer en vir 'n aantal jare seisoenaal waargeneem. Watermonsters is vir verskeie komponente ontleed, eerstens om die waterkwaliteitstatus van die twee damme, wat 'n mengsel van besoedelingstowwe oor ruimte en tyd ontvang, te bepaal deur die kombinasie Waterkwaliteit-indeks (WQI) te gebruik. Tweedens, om die vertikale en tydelike dinamika van fitoplankton gemeenskappe in die twee damme te beskryf. Derdens om die effek van langdurige droogte op fitoplankton biomassa, gemeet as Chlorofil a (Chl a), en sianobakterieë te ondersoek. Laastens is 'n gevallestudie uitgevoer om die doeltreffendheid van twee fitoplankton beheermaatreëls wat in die SWP-dam aangewend is, te vergelyk. Daar is gevind dat die twee damme deur nutriënte, soutgehalte en besoedeling van organiese partikels geraak word. Die WQI's het vir 17 jaar swak watergehaltetoestande in beide damme getoon. Gegewe die swak waterkwaliteit van die twee damme, het Microcystis die vertikale en temporele dinamika oorheers, gevolg deur Dolichospermum. In die droë seisoene, is hoër sianobakterie-selgetalle waargeneem in vergelyking met die reënseisoen in beide damme. In die SWP-dam was die voorkeurdieptes vir toksiese sianobakterie-spesies 5 tot 10 m terwyl dit in die VB-dam van 0 tot 5 m was. Hoër frekwensies van langdurige droogtejare is in die VB-dam aangeteken in vergelyking met SWP-dam. Die invloed van 'n afname in vol % op die fitoplankton biomassa is in die SWP Dam waargeneem, maar nie in die VB Dam nie. Die patroon en omvang van die statisties beduidende response (t-toets, p < 0.05) het egter tussen die droogte en reënjare gewissel. Verder het die resultate getoon dat die sonkrag-aangedrewe sirkulasie (SPC) en Phoslock® as die twee fitoplankton beheermaatreëls wat in die SWP-dam aangewend is, geen effek op sianobakterieselle gehad het nie. Dit was duidelik dat die twee beheermaatreëls ondoeltreffend was om sianobakteriese selle te verminder. Inkorporering van die huidige studienavorsingsuitsette deur gebruik te maak van die instrument in oppervlakwater kwaliteit assessering en -beheerprogram, wateronttrekking vir behandeling en oordragplanne, afvalwaterafvoerregulasies, en die hersiening van die geïntegreerde waterhulpbronbestuursplan in Namibië, kan uiteindelik die skaars waterbronne beskerm om weerstand teen klimaatsverandering te verbeter. Doctoral 2022-11-21T15:17:24Z 2023-01-16T12:50:41Z 2022-11-21T15:17:24Z 2023-01-16T12:50:41Z 2022-12 Thesis http://hdl.handle.net/10019.1/126112 en_ZA Stellenbosch University 216 pages : illustrations (some color), maps application/pdf Stellenbosch : Stellenbosch University |
| spellingShingle | Water quality -- Swakop River (Namibia) Climatic changes-- Effect of global warming on Cyanobacteria -- Effect of temperature on Water salinization - Namibia Ephemeral streams -- Environmental aspects UCTD Sirunda, Jaime Johannes A comparative assessment of water quality of two reservoirs in an ephemeral river in the desert climate of Namibia: Measures to control, and factors affecting growth of toxic cyanobacteria |
| title | A comparative assessment of water quality of two reservoirs in an ephemeral river in the desert climate of Namibia: Measures to control, and factors affecting growth of toxic cyanobacteria |
| title_full | A comparative assessment of water quality of two reservoirs in an ephemeral river in the desert climate of Namibia: Measures to control, and factors affecting growth of toxic cyanobacteria |
| title_fullStr | A comparative assessment of water quality of two reservoirs in an ephemeral river in the desert climate of Namibia: Measures to control, and factors affecting growth of toxic cyanobacteria |
| title_full_unstemmed | A comparative assessment of water quality of two reservoirs in an ephemeral river in the desert climate of Namibia: Measures to control, and factors affecting growth of toxic cyanobacteria |
| title_short | A comparative assessment of water quality of two reservoirs in an ephemeral river in the desert climate of Namibia: Measures to control, and factors affecting growth of toxic cyanobacteria |
| title_sort | comparative assessment of water quality of two reservoirs in an ephemeral river in the desert climate of namibia measures to control and factors affecting growth of toxic cyanobacteria |
| topic | Water quality -- Swakop River (Namibia) Climatic changes-- Effect of global warming on Cyanobacteria -- Effect of temperature on Water salinization - Namibia Ephemeral streams -- Environmental aspects UCTD |
| url | http://hdl.handle.net/10019.1/126112 |
| work_keys_str_mv | AT sirundajaimejohannes acomparativeassessmentofwaterqualityoftworeservoirsinanephemeralriverinthedesertclimateofnamibiameasurestocontrolandfactorsaffectinggrowthoftoxiccyanobacteria AT sirundajaimejohannes comparativeassessmentofwaterqualityoftworeservoirsinanephemeralriverinthedesertclimateofnamibiameasurestocontrolandfactorsaffectinggrowthoftoxiccyanobacteria |