UBC Theses and Dissertations

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UBC Theses and Dissertations

Digital soil mapping to enhance climate change mitigation and adaptation in the Lower Fraser Valley using remote sensing Paul, Siddhartho Shekhar


Globally, the agriculture sector is constantly being challenged by multiple climate change-induced stresses while agricultural activities are responsible for a large portion of global greenhouse gas emissions. At the same time, agroecosystems have a sizable potential to mitigate climate change through the sequestration of atmospheric carbon-dioxide as soil organic carbon (SOC); a key soil quality parameter that can also enhance climate change adaptation. Although the dual benefits of SOC are well established, intensive agricultural production and associated land use/land cover (LULC) changes continue to drive large declines in SOC. Alternatively, sustainable LULC practices can potentially reverse this trend and improve SOC stocks. Digital soil mapping (DSM) using remote sensing can help elucidate SOC dynamics associated with LULC change and agricultural management practices by producing spatially explicit information on SOC at the field- and landscape-scales. In this research, I developed and applied innovative DSM techniques to study the spatiotemporal changes in SOC and related soil properties in the Lower Fraser Valley (LFV), one of the most intensive agriculture regions of British Columbia, Canada. At the field-scale, I evaluated various sampling strategies for DSM using unmanned aerial vehicle imagery, mid-infrared spectroscopy and geostatistical models to identify the most cost-effective approach. At the landscape-scale, using Landsat satellite imagery and machine learning tools, I produced maps of soil workability thresholds (WT) for the agricultural lands in Delta and then, assessed the SOC dynamics across the entire LFV since 1984. My analysis identified that 40% of Delta’s agricultural lands had a WT of <30%, making them extremely vulnerable to the shifting precipitation patterns expected for the region. In addition, 61% of LFV lost SOC, 12% of the region gained SOC, while 27% remained unchanged between 1984 and 2018. Areas that lost the most SOC were those that had experienced changes in LULC; however, I concluded the majority of SOC loss occurred due to agricultural practices. The dissertation contributes to devising cost-effective approaches to quantify and monitor changes in SOC at the field- and landscape-scales that can help in the development of effective agricultural climate change mitigation and adaptation strategies.

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Attribution-NonCommercial-NoDerivatives 4.0 International