UBC Theses and Dissertations
Hydrologic behaviour of some structurally organic soils Bonsu, Mensah
This thesis describes the hydrologic behaviour of some organic soils of the Serpentine-Nicomekl area in the Lower Fraser Valley near Cloverdale in British Columbia, in relation to their structural degradation. An index was developed to characterize the structural stability of the organic soils based on relative hydraulic conductivity approach following dispersion. The study showed that the structural stability of the organic soils decreased with increasing ash content. It was suggested that structural stability ratings in organic soils could be established from a knowledge of their ash content. High bulk density and penetration resistance, low satiated hydraulic conductivity and field profile investigations confirmed the presence of a cultivation pan within the depth of cultivation. Ponding of water on these organic soils was attributed to the cultivation pan. On flooding eroded organic and mineral soil particles settled to form a surface seal of low infiltrability. The presence of trash disrupted a continuous formation of the surface seal. Structural degradation of the organic top soil due to cultivating the soil when it was not adequately trafficable or workable was responsible for the limited capacity of the organic top soil to release water. This effect was shown by relatively flat partial water retention curves. Recommendations are given as to how organic soils found in cold, wet climates could be managed in order to maintain good structural characteristics.
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