A long term simulation test on salt-water dynamics in unsaturated soils with different groundwater depths and soil texture profiles under stable evaporation condition was conducted.Salinity sensors and tensiometers we...A long term simulation test on salt-water dynamics in unsaturated soils with different groundwater depths and soil texture profiles under stable evaporation condition was conducted.Salinity sensors and tensiometers were used to monitor salt and water variation in soils.The experiment revealed that in the process of fresh groundwater moving upwards by capillary rise in the column,the salts in subsoil were brought upwards and accumulated in the surface soil,and consequently the salinization of surface soil took place.The rate of salt accumulation is determined mainly by the volume of capillary water flow and the conditions of salts contained in the soil profile.Water flux in soils decreased obviously when groundwater depths fell below 1.5m.When there was an interbedded clay layer 30cm in thickness in the silty loam soil profile or a clay layer 100cm in thickness at the top layer,the water flux was 3-5 times less than in the soil profile of homogeneous silty loam soil.Therefore,the rate of salt accumulation was decreased and the effect of variation of groundwater depth on the water flux in soils was weakened comparatively.If there was precipitation or irrigation supplying water to the soil,the groundwater could rarely take a direct part in the process of salt accumulation in surface soil,especially,in soil profiles with an interbedded stratum or a clayey surface soil layer.展开更多
文摘A long term simulation test on salt-water dynamics in unsaturated soils with different groundwater depths and soil texture profiles under stable evaporation condition was conducted.Salinity sensors and tensiometers were used to monitor salt and water variation in soils.The experiment revealed that in the process of fresh groundwater moving upwards by capillary rise in the column,the salts in subsoil were brought upwards and accumulated in the surface soil,and consequently the salinization of surface soil took place.The rate of salt accumulation is determined mainly by the volume of capillary water flow and the conditions of salts contained in the soil profile.Water flux in soils decreased obviously when groundwater depths fell below 1.5m.When there was an interbedded clay layer 30cm in thickness in the silty loam soil profile or a clay layer 100cm in thickness at the top layer,the water flux was 3-5 times less than in the soil profile of homogeneous silty loam soil.Therefore,the rate of salt accumulation was decreased and the effect of variation of groundwater depth on the water flux in soils was weakened comparatively.If there was precipitation or irrigation supplying water to the soil,the groundwater could rarely take a direct part in the process of salt accumulation in surface soil,especially,in soil profiles with an interbedded stratum or a clayey surface soil layer.
