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dc.contributor.advisorVan Tonder, G. J.
dc.contributor.authorNel, Gert Pieter
dc.date.accessioned2018-01-12T08:57:03Z
dc.date.available2018-01-12T08:57:03Z
dc.date.issued2007-11
dc.identifier.urihttp://hdl.handle.net/11660/7589
dc.description.abstractEnglish: The study focused on the three major geological units, namely the Natal Group Sandstone (NGS or also called Msikaba Sandstone), the Dwyka Formation and the Ecca Group and was aimed at investigation the geohydrological properties of these units and their potential to produce sustainable groundwater supply. The methodology included Landsat lineament mapping, aerial photography mapping, geological mapping, geophysical exploration, drilling and testing. The investigation can be considered successful as various high yielding boreholes were drilled, some of which constituted new records for the Eastern Cape. Although the entire approach can be commented, it was the geophysical exploration that proofed conclusive in the Msikaba Sandstone where the high yields were obtained. Especially the EM-34 produced excellent anomalies where dolerite dykes were targeted and the fracturing on the sides of the dykes were very well defined. Recharge was calculated using the GIS / GRID based approach where a percentage recharge based on lithological properties was used. The percentage recharge seemed high when compared to the Chloride method where the two scenarios, coastal and inland, were considered. When the coastal scenario was used, the percentage recharge was in the same order of magnitude (10 - 12% of rainfall), but if the inland scenario was used the percentage recharge was much lower (<5%). If the pumping test results are considered, it seems that recharge mostly occurs along the fractured zone associated with the dykes on which the boreholes were drilled and not from the host rock in the case of the Msikaba Sandstone. No monitoring boreholes were available to test this theory in the Dwyka and Ecca, but it should be same in the case of the Dwyka. The Ecca produced low yields and poor water quality and hence it is possible that the overlying dolerite sheets have a negative influence on the recharge from rainfall. The fact that dolerite sheets were intersected at shallow depth (30m) without yielding groundwater, substantiate this. The water quality was acceptable in both the Msikaba and Dwyka, but mostly poor to unacceptable in the Ecca. In terms of ranking the three geological units according to their envisaged groundwater potential, they would rank as follows: o Msikaba Sandstone Ranked first o Dwyka Ranked second o Ecca Ranked third Main targets for drilling would include: o Regional dolerite dykes o Faults and larger lineaments o Geological contactsen_ZA
dc.description.abstractAfrikaans: Die studie het gefokus op die drie hoof geologiese eenhede, naamlik die Natal Group Sandstone (ook genoem NGS of Msikaba Sandstone), die Dwyka Formasie en die Ecca Group. Die vermoë van die drie eenhede om standhoudende water te gee, is ondersoek. Die metodiek wat gevolg is sluit in Landsat lineament kartering, lugfoto interpretasie, geologiese kartering, geofisika en booren toetswerk. Die study kan as suksesvol beskou word omrede verskeie hoë lewering boorgate geboor is, waarvan sommige rekords was vir die Oos Kaap. Alhoewel die hele benadering as korrek beskou kan word, is dit die geofisiese ondersoek wat veral uitstekende resultate gelewer het, veral in die Msikaba sandstene waar dit die gefraktuurde sones langs die doleriet gange duidelik uitgewys het (EM-34). Grondwater aanvulling is geskat vanaf hoofsaaklik twee benaderings, naamlik die karterings metode waar benaderde waardes gebasseer op die litologiese eienskappe van die gesteente geneem is en tweedens die Chloried metode. In laasgenoemde is twee verdere onderverdelings gebruik, naamlik kuslangs en binnelands. Indien die kus waardes gebruik word is die persentasie aanvulling naastenby dieselfde as die litologiese metode (10 - 15%), maar indien die Chloried waardes van binnelanse reenval gebruik word, is die aanvulling minder as 5%. Indien die pomptoets inligting gebruik word waar wel observasiegate beskikbaar was, het dit geblyk dat aanvulling slegs saam met die gefraktuurde sone (langs die strekking van die gange) plaasvind en min of geen aanvulling geskied vanaf die wandgesteentes (veral in die Msikaba). Dieselfde behoort te geld vir die Dwyka, maar die swakker lewerings en ook swakker water gehalte in die Ecca kan moontlik as gevolg wees van die oorliggende doleriet plate. Die feit dat doleriet plate geboor en getref is op vlak diepte (30m) en geen water gelewer het nie, alhoewel geleë in 'n goeie dreinering, is verdere bewys daarvan. Daar is gevind dat die water gehalte goed is in die Msikaba en Dwyka, maar swakker is in die Ecca. Indien die drie eenhede in prioriteit geplaas word vanaf hoë grondwater potensiaal to lae grondwater potensiaal, lyk dit soos volg: o Msikaba eerste o Dwyka tweede o Ecca derde Die hoof grondwater teikens sal wees: o Doleriet gange (regionaal en waar in verskuiwings ingedring) o Regionale verskuiwings en lineamente o Geologiese kontakteaf
dc.language.isoenen_ZA
dc.publisherUniversity of the Free Stateen_ZA
dc.subjectHydrogeology -- South Africa -- Lusikisikien_ZA
dc.subjectGroundwater -- South Africa -- Lusikisikien_ZA
dc.subjectDissertation (M.Sc. (Geohydrology))--University of the Free State, 2007en_ZA
dc.titleGeohydrological characteristics of the Msikaba, Dwyka and Ecca groups in the Lisikisiki area, Eastern Capeen_ZA
dc.typeDissertationen_ZA
dc.rights.holderUniversity of the Free Stateen_ZA


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