Assessment of GIS-interpolation techniques for groundwater evaluation : a case study of the Sandveld, Western Cape, South Africa

Munch, Zahn (2004-12)

Thesis (MSc)--University of Stellenbosch, 2004

Thesis

ENGLISH ABSTRACT: The Sandveld, a potato growing area of the Western Cape is subject to significant groundwater abstraction for both municipal and agriculture purposes. The climate is arid and sensitive and important ecosystems in the area are showing varying degrees of impact. Management measures are needed to ensure ongoing sustainable development of the area. In this study, different interpolation techniques were evaluated to calculate values for unsampled variables rainfall and groundwater elevation. Local deterministic techniques as well as geostatistical techniques were used. It was found that geostatistical techniques, especially with collateral information, such as topography, provided a more accurate result. For environmental studies of this nature, Kriging is recommended as interpolation technique. The underlying data will determine the selection of the particular type of Kriging. Data was extracted from a customized relational database, geoMon, used for data capture, retrieval, processing and reporting. Ease of data extraction facilitated analysis. The interpolated grids were applied in two scenarios: Recharge calculations and quantification as well as a new classification approach according to Resource Directed Measures (RDM). Management classes were defined based on GIS-derived data.

AFRIKAANSE OPSOMMING: Die Sandveld, ‘n aartappelverbouingsgebied in die Wes-Kaap, ondergaan aansienlike grondwateronttrekking vir beide munisipale sowel as landbou doeleindes. Die klimaat is dor en droog en sensitiewe en belangrike ekosisteme in die area ondervind wisselende impakvlakke. Bestuursmaatreëls word benodig om volhoubare ontwikkeling van die area te verseker. In hierdie studie is verskillende interpolasie tegnieke om onbekende waardes vir veranderlikes gebruik in grondwater evaluasie te bereken, evalueer. Lokale deterministiese tegnieke sowel as geostatistiese tegnieke is gebruik. Geostatistiese tegnieke, veral gebruik saam met addisionele inligting soos topografie, bereken meer akkurate resultate. Vir omgewingsstudies van hierdie aard, word Kriging aanbeveel as interpolasie tegniek. Eienskappe van die onderliggende data word gebruik om die tipe Kriging aan te dui. Data is onttrek uit ‘n gebruikersaangepaste databasis, geoMon, wat gebruik is vir datavaslegging, onttrekking, prosessering en verslaggewing. Die gemak waarmee data onttrek kon word het analise vergemaklik. Geïnterpoleerde data is gebruik vir grondwateraanvullingsberekeninge en -kwantifisering sowel as ‘n nuwe benadering tot klassifikasie volgens hulpbron gerigte maatreëls. Bestuursklasse gebaseer op GIS-afgeleide data, is gedefinieer.

Please refer to this item in SUNScholar by using the following persistent URL: http://hdl.handle.net/10019.1/16400
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