Abstract
Groundwater discharge into under ground gallery and rain fall have been automatically recorded during about 14 years at Inuyama Crustal-Movement Observatory of Nagoya University. The whole discharge can be devided into two parts from the view point of the seepage pass, and one is the discharge through fracture zone developing near cut-face of the gallery and another is through weathered zone below the ground surface. These discharges have been recorded individually.
The response of former discharge to rain fall as an aid to understanding the flow behavior in fracture zone was also examined.
At the same time, we simulated numerically the steady condition of the groundwater flow around the gallery assuming constant infiltration rate into the groundwater table. The transient behavior of the flow caused by depletion of infiltration rate after stopping of rain fall was also simulated. The depletion curve of infiltration rate which was used in the simulation was assumed from the record of decreasing discharge through weathered zone after rain fall.
Results obtained are as follows;
1) Discharge through fracture zone has not so good response to rain fall, and this nature is mainly caused by the nearly constant water flow in the saturated zone below the groundwater table.
2) The transient discharge change calculated from the simulation of transient groundwater flow shows good accordance with observed records.
3) The proper modeling of hydro-geological structure of the area is very important to simulate the groundwater flow in rock basement.
