The control of saline groundwater
A study was made of the effect of the watertable, water-conducting properties of the soil, climatic factors and groundwater salinity on the salinization of soils in the Murrumbidgee Irrigation Areas, Australia.Average daily capillary flow rates were calculated from measured salinization (by sampling) for each month between May 1960 and October 1961. Potential gradients were calculated from suction measurements by tensiometers. Field percentages of available water varied from 8 to 14 % for the soils studied. Good agreement was found between values for hydraulic conductivity measured by the augerhole method and capillary conductivity calculated from chloride accumulation (measured monthly sampling).The agreement between field data and the theory of steady-state flow through unsaturated soils was satisfactory when no limit was set on evaporation by the moisture-conducting proporties of the soil. Where potential evaporation exceeded the maximum possible flow, evaporation from the soil was equal to, or less than the predicted maximum flow through the profile. Reduction of evaporation under these conditions was caused either by the establishment of a natural mulch or by the appearance of a salt crust at the surface.It was concluded that 'critical depth' of watertable corresponded to the watertable at which the flow rate through the soil profile was reduced to about 0.1 cm day- 1. Generally the watertable should be kept lower in soils of intermediate texture than in either finely or coarsely textured soils.In the fine-textured soils of the Murrumbidgee Area the salinity hazard was markedly reduced if the watertable was kept at about 120 cm below the surface (bare soil) far below the root zone.
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| Format: | Doctoral thesis biblioteca |
| Language: | English |
| Published: |
Veenman
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| Subjects: | groundwater, irrigation water, minerals, saline water, salinization, sodium, soil, soil chemistry, soil water, bodem, bodemchemie, bodemwater, grondwater, irrigatiewater, mineralen, natrium, verzilting, zout water, |
| Online Access: | https://research.wur.nl/en/publications/the-control-of-saline-groundwater |
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| Summary: | A study was made of the effect of the watertable, water-conducting properties of the soil, climatic factors and groundwater salinity on the salinization of soils in the Murrumbidgee Irrigation Areas, Australia.Average daily capillary flow rates were calculated from measured salinization (by sampling) for each month between May 1960 and October 1961. Potential gradients were calculated from suction measurements by tensiometers. Field percentages of available water varied from 8 to 14 % for the soils studied. Good agreement was found between values for hydraulic conductivity measured by the augerhole method and capillary conductivity calculated from chloride accumulation (measured monthly sampling).The agreement between field data and the theory of steady-state flow through unsaturated soils was satisfactory when no limit was set on evaporation by the moisture-conducting proporties of the soil. Where potential evaporation exceeded the maximum possible flow, evaporation from the soil was equal to, or less than the predicted maximum flow through the profile. Reduction of evaporation under these conditions was caused either by the establishment of a natural mulch or by the appearance of a salt crust at the surface.It was concluded that 'critical depth' of watertable corresponded to the watertable at which the flow rate through the soil profile was reduced to about 0.1 cm day- 1. Generally the watertable should be kept lower in soils of intermediate texture than in either finely or coarsely textured soils.In the fine-textured soils of the Murrumbidgee Area the salinity hazard was markedly reduced if the watertable was kept at about 120 cm below the surface (bare soil) far below the root zone. |
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