Surface water - groundwater interactions: development of methodologies suitable for South African conditions

Abstract

English: Winter (1999) succinctly, made a profound statement to the effect that understanding the basic principles of the interaction between surface water and groundwater is needed for effective management of water resources. Hence, the research investigation was aimed at identifying appropriate methodologies for assessment of surface water - groundwater interaction, thus enhancing the understanding thereof. The methodology used entailed a review of national and international literature on related previous and current models, systems and methods used in assessment and quantification of water exchange between groundwater and surface water. This was then followed by relevant case study analyses where distinct areas where chosen based on availability of relevant data and information by previous investigators. The findings were that various methods and classification systems are widely available but the applicability thereof under the South African conditions depends on the conceptual understanding of the area or system under investigation, availability of data and the basic assumptions associated with the particular model or method. The surface water - groundwater interaction cannot easily be quantified with confidence without requisite data available. The other finding is that use of multiple techniques to reduce uncertainties and to confirm or verify the existence or non-existence of the interaction is essential. Preferably, at least one method should be utilised to trace flow or qualitatively establish the water exchange while the alternative method is used for quantitative estimation of the interaction between surface water and groundwater. Some of the products emerging from this research investigation include decision tables for choosing applicable analytical method, applicable numerical method and the framework for guiding the selection of appropriate methodologies for assessing or quantifying the interaction between surface water and groundwater. Knowledge generated is applicable to water resource management, resource protection, water allocation and monitoring.

Afrikaans: Winter (1999) het In diepgaande verklaring gemaak tot die effek dat die begrip van die basiese beginsels van die interaksie tussen oppervlak-en grondwater is wat nodig is vir die doeltreffende bestuur van waterhulpbronne. Dus, is die navorsingsondersoek gemik op die identifisering van toepaslike metodologieë vir die assessering van oppervlak water grondwater interaksie, en om die begrip daarvan te verbeter. Die metodologie wat gebruik word behels 'n oorsig van die nasionale en internasionale literatuur oor verwante vorige en huidige modelle, stelsels en metodes wat gebruik word in die bepaling en kwantifisering van water uitruil tussen grondwater en oppervlakwater. Dan was die regte gevallestudie ontleding gemaak,en duidelike gebiede gekies, en op die beskikbaarheid van data en inligting deur vorige navorsers gebaseer. Die bevindinge was dat verskeie metodes en klassifikasie stelsels is wyd beskikbaar, maar die toepaslikheid daarvan onder die Suid- Afrikaanse toestande hang af van die konseptueie begrip van die gebied of stelsel wat ondersoek word, beskikbaarheid van data en die basiese aannames wat verband hou met die spesifieke model of metode. Die oppervlak water grondwater interaksie kan nie met selfvertroue gekwantifiseer word sonder die nodige data. Die ander bevinding is dat die gebruik van verskeie tegnieke om onsekerhede te verminder en om te bevestig of te verifieer die bestaan of nie-bestaan van die interaksie, is noodsaaklik. Moet verkieslik ten minste een metode gebruik word op te spoor vloei of kwalitatief die water ruil vestig terwyl die alternatiewe metode word gebruik vir kwantitatiewe skatting van die interaksie tussen oppervlak-en grondwater. Die produkte wat na vore kom uit hierdie navorsingsondersoek sluit besluit tafels vir die keuse van toepaslike analitiese metode, toepaslike numeriese metode, en die raamwerk vir die begeleiding van die seleksie van toepaslike metodologieë vir die beoordeling of die kwantifisering van die interaksie tussen oppervlak-en grondwater. Kennis wat deur hierdie navorsing gegenereer is op waterhulpbronbestuur, beskerming van die hulpbronne, water toekenning en monitering van toepassing.