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Modeling of water table profile for a subirrigation system and evaluation of reliability of drainmod for the Lower Fraser Valley

University of British Columbia

Subsurface drainage and sub irrigation were simulated in the Lower Fraser Valley of British Columbia under different water regimes with DRAINMOD and the results were compared with data obtained from conventional subsurface drainage and subirrigation field experiment at Boundary Bay in the Lower Fraser Valley. Predicted and measured water table depth were compared for 4 years (1985, 1986, 1987 and 1988), where 1986 was a normal year from the total rainfall standpoint. Model simulations of water table depth were closer to the actual value of wet season. The model overestimated water storage capacity of the soil profile. For the drier than normal year, 1985, water table depth was over predicted as evapotranspiration was over predicted by the model. When rooting depth for the dry year was increased, soil water withdrawal by ET increased and predictions for water table depth were significantly improved. Laboratory experiment was performed to evaluate the shape of the water table under subirrigation and the time required for the profile to attain a stable state from a steady recharge. A slow transition from semi elliptical water table at the initiation of irrigation to a nearly flat water table profile at a stable state was observed. A linear relationship between capillary rise and water table elevation was observed.

Thesis/Dissertation

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2008-09-15

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http://hdl.handle.net/2429/1968

Chemical and Bio-Resource Engineering

University of British Columbia

UBCV

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