| Budget Amount *help |
¥1,600,000 (Direct Cost: ¥1,600,000)
Fiscal Year 1986: ¥400,000 (Direct Cost: ¥400,000)
Fiscal Year 1985: ¥1,200,000 (Direct Cost: ¥1,200,000)
|
|---|
| Research Abstract |
The capillary fringe between soil-water and groundwater zones might play an important roles in solute transport, especially under fluctuations of grounwater level.
This research dealt with this subject through laboratory experiments and field observations in Dejima area of Ibaraki Prefecture, where groudwater levels change largely due to irrigation.
In the laboratory experiments, relationships among water and solute transports, water content, and solute concentrations in small columns were analyzed.
In the field observations, groundwater level, soil moisture, hydraulic head, rainfall, and water quality were measured. Fluctuations of groundwater were also induced artificially by pump-up and water and solute behaviors were observed.
Some of observed results are as follows:
Behaviors of water and solute vary after the manner of water table fluctuation. That is quick falldown seems to induce different behaviors from those of slow falldown of water table. Falldown and rising of water table could cause different behaviors of water and solute.
Hysteresis of solution behaviors as wells as water is recognized, which seems to come from the hysteresis of pF-water content relationship.
With positions and range of groundwater level, discontinuity (or non-homogeneity) of geology, especially silt or clay in layered soils affects behaviors of water and solute, and depth profiles of solute concentration.
Simulation study will be done after field observations of two more years.
|
