Full Text Available
Note: Clicking the button above will open the full text document at the original institutional repository in a new window.
Exploring managed aquifer recharge as a nature-based solution to water diversification in the Goukou River catchment
Thesis (PhDConsEcol)--Stellenbosch University, 2025.
Saved in:
| Main Author: | |
|---|---|
| Other Authors: | |
| Format: | Thesis |
| Published: |
Stellenbosch : Stellenbosch University
2025
|
| Subjects: | |
| Tags: |
No Tags, Be the first to tag this record!
|
| _version_ | 1867613886193074176 |
|---|---|
| access_status_str | Open Access |
| author | De Witt, Marlene |
| author2 | Roets, Francois |
| author_browse | De Witt, Marlene Roets, Francois |
| author_facet | Roets, Francois De Witt, Marlene |
| author_sort | De Witt, Marlene |
| collection | Thesis |
| dc_rights_str_mv | Stellenbosch University |
| description | Thesis (PhDConsEcol)--Stellenbosch University, 2025. |
| format | Thesis |
| id | oai:scholar.sun.ac.za:10019.1/132138 |
| institution | Stellenbosch University (South Africa) |
| last_indexed | 2026-06-10T12:43:15.981Z |
| 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:10019.1/132138 Exploring managed aquifer recharge as a nature-based solution to water diversification in the Goukou River catchment De Witt, Marlene Roets, Francois Watson, Andrew Stellenbosch University. Faculty of AgriSciences. Dept. of Conservation Ecology and Entomology. Aquifer recharge -- South Africa -- Goukou River Hydrologic cycle -- Climatic factors Water-supply -- South Africa -- Management -- Data processing Groundwater recharge -- Management Water quality management Water resources development -- Environmental aspects -- South Africa -- Goukou River Groundwater -- Management Climatic changes UCTD Thesis (PhDConsEcol)--Stellenbosch University, 2025. de Witt, M. 2025. Exploring managed aquifer recharge as a nature-based solution to water diversification in the Goukou River catchment. Unpublished doctoral dissertation. Stellenbosch: Stellenbosch University [online]. Available: https://scholar.sun.ac.za/items/56348975-c6af-4e3b-8a32-10d4bc80c01d ENGLISH ABSTRACT: This study aimed to assess the potential of diverting flood peaks for Managed Aquifer Recharge in a data-deficient catchment. An interdisciplinary approach was employed to evaluate if this could overcome some of the hydrological modelling challenges caused by limited hydroclimatic input data. The data-deficient Goukou River catchment of South Africa was used as a case study, where water managers face a complex task of ensuring water security for residents, industry, farmers and the environment, against the backdrop of climate change and anthropogenic impacts, as well as a ten-fold increase in population numbers over peak tourist seasons. Two overarching methods were employed in the effort to overcome challenges related to deficient hydroclimatic data: 1) Exploring the parameter space through four different optimization solutions to constrain groundwater flow to realistic proportions; and 2) Using stable isotopes and stakeholder inputs to validate model results and provide clarity on catchment hydrology. These methods were implemented in the fully-distributed conceptual rainfall-off model J2000 to generate natural recharge and percolation maps of the catchment to inform where MAR efforts should be focused to maximize impact. In addition, the model was used to investigate flood peaks and to assess inflow to the estuary against the published ecological flow requirements, to determine if and where flood water can be diverted for MAR. Stakeholder input was used to assess MAR potential in terms of public acceptance. The efforts to constrain groundwater flow proved useful, and the DiffeRential Evolution Adaptive Metropolis (DREAM) optimization solution performed best to find parameter sets with realistic groundwater flow proportions, while maintaining sufficient Nash-Sutcliffe efficiencies around 0.38. Non-evolutionary optimization methods require high numbers of model runs, even when considering few objectives, and therefore less suitable for timely applications. Evidence was provided that the choice of optimization solution used in data-scarce circumstances does have an impact on the ability of the model to overcome the uncertainty of model parameters. The J2000 simulated annual inflow into the estuary is between 63.7 and 72 million m3/annum, lower than the required inflow in the published ecological reserve determination study for the catchment. This discrepancy is a major barrier to the possibility of using flood peaks for MAR in this catchment. However, the integrated assessment of J2000, isotopes and stakeholder results helped clarify hydrological processes and provided insights into MAR site selection across the catchment, showing potential for two MAR schemes in the lower part of the catchment. The results from this interdisciplinary and holistic approach to MAR potential assessment provides a more objective decision-making process on where to invest in detailed, site-specific geohydrological assessments and cost-benefit analyses. The approach also proved useful in identifying various potential barriers to uptake upfront, which could now be addressed concurrently with the more in-depth technical investigations. Partnerships with residents and local associations, who expressed interest in collaboration through this study’s stakeholder engagement efforts, may be central to make MAR more implementable. AFRIKAANSE OPSOMMING: Hierdie studie het ten doel gehad om die potensiaal van die verlegging van vloedpieke vir bestuurde waterdraeraanvulling in 'n data-tekorte opvanggebied te bepaal. 'n Interdissiplinêre benadering is aangewend om te evalueer of dit sommige van die hidrologiese modelleringsuitdagings wat veroorsaak word deur beperkte hidroklimatiese insetdata kan oorkom. Die data-tekorte Goukourivier-opvanggebied van Suid- Afrika is gebruik as 'n gevallestudie, waar waterbestuurders voor 'n komplekse taak staan om watersekuriteit vir inwoners, nywerhede, boere en die omgewing te verseker, teen die agtergrond van klimaatsverandering en antropogeniese impakte, sowel as 'n tienvoudige toename in bevolkingsgetalle oor piektoeristeseisoene. Twee oorkoepelende metodes is aangewend in ‘n poging om uitdagings wat verband hou met gebrekkige hidroklimaatdata te oorkom: 1) Verkenning van die parameterruimte deur vier verskillende optimaliseringsoplossings om grondwatervloei tot realistiese proporsies te beperk; en 2) Die gebruik van stabiele isotope en insette van belanghebbendes om modelresultate te valideer en duidelikheid te verskaf oor opvanggebiedhidrologie. Hierdie metodes is in die volledig-verspreide konseptuele reënvalmodel J2000 geïmplementeer om natuurlike herlaai- en perkolasiekaarte van die opvanggebied te genereer om in te lig waar MAR-pogings gefokus moet word om impak te maksimeer. Daarbenewens was die model gebruik om vloedpieke te ondersoek en om invloei na die riviermond te evalueer teen die gepubliseerde ekologiese vloeivereistes, om te bepaal of en waarheen vloedwater vir MAR herlei kan word. Insette van belanghebbendes is gebruik om MAR-potensiaal in terme van openbare aanvaarding te assesseer. Die pogings om grondwatervloei te beperk was nuttig, en die Differential Evolution Adaptive Metropolis (DREAM) optimeringsoplossing het die beste gevaar om parameterstelle met realistiese grondwatervloeiverhoudings te vind, terwyl voldoende Nash-Sutcliffe-doeltreffendheid rondom 0.38 gehandhaaf is. Nie-evolusionêre optimaliseringsmetodes vereis hoë getalle modellopies, selfs wanneer min doelwitte oorweeg word, en dus minder geskik vir tydige toepassings. Bewyse is gelewer dat die keuse van optimeringsoplossing wat in data- skaars omstandighede gebruik word, wel 'n impak het op die vermoë van die model om die onsekerheid van modelparameters te oorkom. Die J2000 gesimuleerde jaarlikse invloei in die riviermond is tussen 63,7 en 72 miljoen m3/jaar, laer as die vereiste invloei in die gepubliseerde ekologiese reserwebepalingstudie vir die opvanggebied. Hierdie teenstrydigheid is 'n groot hindernis vir die moontlikheid om vloedpieke vir MAR in hierdie opvanggebied te gebruik. Die geïntegreerde assessering van J2000, isotope en resultate van belanghebbendes het egter gehelp om hidrologiese prosesse op te klaar en insigte verskaf in MAR- terreinkeuse regoor die opvanggebied, wat potensiaal toon vir twee MAR-skemas in die onderste deel van die opvanggebied. Die resultate van hierdie interdissiplinêre en holistiese benadering tot MAR potensiële assessering verskaf 'n meer objektiewe besluitnemingsproses oor waar om te belê in gedetailleerde, terreinspesifieke geohidrologiese assesserings en koste-voordeel-ontledings. Die benadering was ook nuttig in die identifisering van verskeie potensiële hindernisse vir opname vooraf, wat nou saam met die meer in- diepte tegniese ondersoeke aangespreek kan word. Vennootskappe met inwoners en plaaslike verenigings, wat belangstelling in samewerking uitgespreek het deur middel van hierdie studie se belanghebbende- betrokkenheidspogings, kan sentraal wees om MAR meer implementeerbaar te maak. Doctoral 2025-05-27T11:54:24Z 2025-05-27T11:54:24Z 2025-03 Thesis https://scholar.sun.ac.za/handle/10019.1/132138 Stellenbosch University x, 138, 9 unnumbered pages : illustrations, maps application/pdf Stellenbosch : Stellenbosch University |
| spellingShingle | Aquifer recharge -- South Africa -- Goukou River Hydrologic cycle -- Climatic factors Water-supply -- South Africa -- Management -- Data processing Groundwater recharge -- Management Water quality management Water resources development -- Environmental aspects -- South Africa -- Goukou River Groundwater -- Management Climatic changes UCTD De Witt, Marlene Exploring managed aquifer recharge as a nature-based solution to water diversification in the Goukou River catchment |
| title | Exploring managed aquifer recharge as a nature-based solution to water diversification in the Goukou River catchment |
| title_full | Exploring managed aquifer recharge as a nature-based solution to water diversification in the Goukou River catchment |
| title_fullStr | Exploring managed aquifer recharge as a nature-based solution to water diversification in the Goukou River catchment |
| title_full_unstemmed | Exploring managed aquifer recharge as a nature-based solution to water diversification in the Goukou River catchment |
| title_short | Exploring managed aquifer recharge as a nature-based solution to water diversification in the Goukou River catchment |
| title_sort | exploring managed aquifer recharge as a nature based solution to water diversification in the goukou river catchment |
| topic | Aquifer recharge -- South Africa -- Goukou River Hydrologic cycle -- Climatic factors Water-supply -- South Africa -- Management -- Data processing Groundwater recharge -- Management Water quality management Water resources development -- Environmental aspects -- South Africa -- Goukou River Groundwater -- Management Climatic changes UCTD |
| url | https://scholar.sun.ac.za/handle/10019.1/132138 |
| work_keys_str_mv | AT dewittmarlene exploringmanagedaquiferrechargeasanaturebasedsolutiontowaterdiversificationinthegoukourivercatchment |