Assessing the potential of using microcomputerized tomography to determine the physical properties of different textured soils
| dc.contributor.advisor | Du Plessis, Anton | en_ZA |
| dc.contributor.advisor | Lategan, Eugene | en_ZA |
| dc.contributor.author | Hartnick, Emke Kim | en_ZA |
| dc.contributor.other | Stellenbosch University. Faculty of AgriSciences. Dept. of Soil Science. | en_ZA |
| dc.date.accessioned | 2020-11-23T16:13:15Z | |
| dc.date.accessioned | 2021-01-31T19:40:48Z | |
| dc.date.available | 2020-11-23T16:13:15Z | |
| dc.date.available | 2021-01-31T19:40:48Z | |
| dc.date.issued | 2020-12 | |
| dc.description | Thesis (MScAgric)--Stellenbosch University, 2020. | en_ZA |
| dc.description.abstract | ENGLISH ABSTRACT: The physical properties of soil, particularly the structure, texture, and pore geometry affect hydraulic conductivity in soils. The hydraulic conductivity is an important parameter for understanding the flow of water through different soil types for determining irrigation rates, monitoring of groundwater, and runoff. The hydraulic conductivity is a highly variable soil property and there are several methods for determining the hydraulic conductivity in soils. Each has its advantages and limitations. Traditional methods are time-consuming and the application of X-ray micro-computer tomography (microCT) offers fast and effective analysis and results. The additional use of microCT for this purpose might improve the accuracy of laboratory constant hydraulic head tests if these methods are used in combination. The application of microCT technology can visualize the internal pore geometry of a soil sample without destroying the soil sample. Thus, the microCT technology can examine the porosity and the pore connectivity in soils, which influence the hydraulic conductivity. The purpose of this study was to apply microCT technology to examine the range within it can be used to determine the saturated hydraulic conductivity (Ksat) and porosity of homogeneous and heterogeneous soils. This was done in the context of considering if the advantages of this application (fast and efficient analysis) exceed the disadvantages (cost). The investigation of an effective sampling method for soil samples for X-ray microCT scans and associated image-based analysis were examined. The saturated hydraulic conductivity (Ksat) and porosity of five different soil types (homogeneous and heterogeneous soil) will be obtained through standard laboratory methods (constant hydraulic head test and calculating the porosity from the bulk and particle density) and microCT image-based simulations and analysis. Additional calculation of the Ksat based on grain size theoretical equations such as Hazen and Kozenzy & Carman equation will be used. The results showed that the Ksat of the homogeneous soil very coarse, coarse, and medium sand were underestimated by the microCT simulations. The Ksat of the fine and very fine sand determined through microCT simulations and constant hydraulic head tests compared well. MicroCT simulations underestimated the Ksat of the heterogeneous soil. The porosity values for the homogeneous soil were overestimated by microCT image-based analysis. The porosity values of the heterogeneous soil obtained from microCT image-based analysis for the coarse and pure fine sand were higher than the sandy clay loam, sandy loam and sandy clay soils. The sandy clay loam, sandy loam and sandy clay soils porosity were measured inaccurately by microCT due to resolution limitations. The Ksat of the homogeneous soil analysed by microCT simulation, however, fell within the same order of magnitude as the Ksat obtained from the constant hydraulic head test. Fundamentally, the microCT technology demonstrated great capabilities for analysing both the Ksat and porosity of homogeneous soils. The microCT application is best used for soils with larger particle sizes due to image resolution limits. The 2D visualization of the microCT scans can be useful for investigating structural changes within a soil sample caused by laboratory analysis. Such analysis may include constant hydraulic head tests or the examination of soil samples after sample preparations. | en_ZA |
| dc.description.abstract | AFRIKAANSE OPSOMMING: Die fisiese eienskappe van grond, spesifiek die struktuur, tekstuur en poriegeometrie het 'n invloed op die hidrouliese geleidingsvermoë in gronde. Die hidrouliese geleidingsvermoë is 'n belangrike parameter om die vloei van water deur verskillende grondsoorte te verstaan vir die bepaling van besproeiingstempo, monitering van grondwater en dreinering van afloop water. Die hidrouliese geleidingsvermoë is 'n baie veranderlike grondeienskap en daar is baie verskillende metodes om die hidrouliese geleidingsvermoë in gronde te bepaal, elk met sy eie voordele en beperkings. Tradisionele metodes is tydrowend en die toepassing van X-straal-mikro-rekenaartomografie (mikroCT) bied vinnige, effektiewe analise en resultate. Die bykomende gebruik van mikroCT vir hierdie doel kan die akkuraatheid van konstante hidrouliese toetse in laboratorium verbeter, indien hierdie metodes in kombinasie gebruik word. MikroCT-tegnologie kan die interne poriegeometrie van 'n grondmonster visualiseer sonder om die grondmonster te vernietig. Die mikroCT-tegnologie kan dus die porositeit en porieverbinding in gronde ondersoek wat die hidrouliese geleidingsvermoë beïnvloed. Die doel van hierdie studie was om die toepassing van mikroCT-tegnologie te gebruik om die reikwydte te ondersoek, wat gebruik kan word om die versadigde hidrouliese geleidingsvermoë (Ksat) en porositeit van homogene en heterogene gronde te bepaal. Dit word gedoen in die konteks van die oorweging of die voordele van hierdie toepassing (vinnige en doeltreffende ontleding) die nadele (koste) oorskry. Die assessering na n effektiewe steekproefmetode vir grond monsters vir X-straal mikroCT-skanderings en gepaardgaande beeldgebaseerde analise was ondersoek. Die versadigde hidrouliese geleidingsvermoë (Ksat) en porositeit van vyf verskillende grondtipes (homogene en heterogene grond) sal gemeet word deur standaard laboratoriummetodes (konstante hidrouliese drukhoogte en digtheidsmetode) en op mikroCT beeldgebaseerde simulasies en analise. Bykomende berekening van die Ksat gebaseer op teoretiese vergelykings met korrelgrootte, soos Hazen en Kozenzy & Carman, sal gebruik word. Vir die homogene grond is die Ksat van baie growwe, growwe en medium sand deur die mikroCT-simulasies onderskat. Die Ksat van die fyn en baie fyn sand bepaal deur mikroCT-simulasies en konstante hidrouliese drukhoogte vergelyk goed. MikroCT-simulasies het die Ksat van die heterogene grond onderskat. Die porositeit waardes van die homogene grond, gemeet deur mikro-gebaseerde beeldanalise, was oorskat. Die porositeit van die growwe en suiwer fyn sand heterogene grond was hoër gewees as die sandkleileem, sandleem en sandklei wat geanaliseer was deur mikroCT. Die porositeit van die sandkleileem, sandleem en sandklei, wat geanaliseer was deur mikroCT, was foutief as gevolg van die resolusie limitasie. Die Ksat van die homogene grond wat deur mikroCT-simulasie geanaliseer was, het egter binne dieselfde groottevlak as die Ksat wat verkry is uit die konstante hidrouliese drukhoogte geval. Fundamenteel het die mikroCT-tegnologie groot moontlikhede getoon om sowel die Ksat as die porositeit van homogene grond te ontleed. Die mikroCT-toepassing word die beste gebruik vir gronde met groter deeltjiegroottes soos growwe sand as gevolg van die beperking van die beeld resolusie. Die 2D-visualisering van die mikroCT-skanderings kan nuttig wees om strukturele veranderinge binne 'n grondmonster te ondersoek. Dit sluit in veranderinge wat veroorsaak word deur die analise wat in die laboratorium uitgevoer is, soos die konstante hidrouliese drukhoogte of die ondersoek van grondmonsters na monstervoorbereidings. | af_ZA |
| dc.description.version | Masters | |
| dc.format.extent | ix, 70 pages : illustrations (some color) | en_ZA |
| dc.identifier.uri | http://hdl.handle.net/10019.1/109239 | |
| dc.language.iso | en_ZA | en_ZA |
| dc.publisher | Stellenbosch : Stellenbosch University | en_ZA |
| dc.rights.holder | Stellenbosch University | en_ZA |
| dc.subject | Bulk Density | en_ZA |
| dc.subject | Soil porosity | en_ZA |
| dc.subject | MicroCT | en_ZA |
| dc.subject | Soil hydrology | en_ZA |
| dc.subject | Saturated hydraulic conductivity | en_ZA |
| dc.subject | Soils -- Analysis | en_ZA |
| dc.subject | Hydraulic conductivity of soils | en_ZA |
| dc.subject | Soils -- Classification | en_ZA |
| dc.subject | Soil permeability -- Computer simulation | en_ZA |
| dc.subject | UCTD | en_ZA |
| dc.title | Assessing the potential of using microcomputerized tomography to determine the physical properties of different textured soils | en_ZA |
| dc.type | Thesis | en_ZA |