Investigating the effect of seasonal variations, expressed by moisture and temperature changes, on soil surface stability using proximal remote sensing

I. Ymeti

Research output: ThesisPhD Thesis - Research UT, graduation UT

36 Downloads (Pure)

Abstract

Soil is the outmost layer of earth that supports plant growth and many living creatures depending on it. It provides a suitable environment for forest growth, crop production, securing human food supplies, filtering and storing water and a carbon reservoir. However, the soil is subject to degradation as a result of natural and human factors. Soil degradation weakens an ecosystem’s capacity to function appropriately, affects the climate by changing the water and energy balances, and disrupts the carbon, nitrogen or sulphur cycles. Soil stability is defined as the aggregates’ ability to maintain their bonds under stresses that might trigger their disintegration. While we may understand the factors dominating soil stability, the spatial and temporal variations of these factors controlling the soil stability dynamics are still missing. There is limited knowledge of the soil mineralogical behaviour at varying temperatures and soil moisture contents occurring in a short period at the microscale. Therefore, the research’s objective is to investigate the seasonal effect on soil surface stability using proximal remote sensing. The effect of soil surface mineralogy alterations due to moisture variations under laboratory conditions using imagine spectroscopy is one of this study’s objectives. Similarly, freeze-thaw cycles might encourage migration and alter the soil matrix’s chemical constituents exposed to different moisture conditions.
The Spectral Information Divergence was applied to quantify the soil image occupied by Mg-clinochlore, goethite, quartz coated 50% by goethite, hematite dimorphous with maghemite. The results showed that the minerals’ percentage changed over time, depending on soil type and moisture conditions. Mineralogical alterations of soils with organic matter occur at field capacity. Likewise, these minerals behaved differently under freeze-thaw cycles, depending on the soil type and soil condition. Also, the amount and the type of organic matter are vital in soil experiencing freeze-thaw cycles.
Monitoring soil aggregate breakdown was analysed using the shadow ratio showing a gradual change over time, with no details about weather conditions. Both the entropy and the Huang thresholding technique show variations of soil aggregate breakdown responding to weather conditions. Using data obtained with a regular camera, the results show that freeze-thaw cycles cause soil aggregate breakdown.
Original languageEnglish
QualificationDoctor of Philosophy
Awarding Institution
  • Faculty of Geo-Information Science and Earth Observation
  • University of Twente
Supervisors/Advisors
  • van der Meer, Freek, Supervisor
  • Shrestha, Dhruba, Co-Supervisor
Award date27 May 2021
Place of PublicationEnschede
Publisher
Print ISBNs978-90-365-5173-1
DOIs
Publication statusPublished - 27 May 2021

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