Water levels of 39 wells and water qualities of samples from the wells have been measured to determine the groundwater movement in the Wani river delta, on the western shore of Lake Biwa. In the littoral zone around the delta, direct seepage measurements and sampling of seepage water and porewater have been carried out to clarify the seepage process of groundwater flow into Lake Biwa.
Shallow groundwater is strongly recharged by effluent water from the Wani river an d moves into the lake in the direction perpendicular to the shore line. Slopes of water table near the shore range from 0.005∼0.01 at Wani beach and about 0.005 at Imajyuku beach throughout the year.
Both seepage flux and electrical- conductivity of seepage water change spatially along the shore line. Areas along the transect perpendicular to the shore line show high values of seepage flux and electrical conductivity while near the shore, these values decrease abruptly with increasing distance from the shore. These patterns along the transect perpendicular to the shore line, however, do not show any significant spatial and seasonal changes throughout the study period. There are similar correlation between the quality of seepage waterwithin about 20m from the shore and that of well water near the shore. The distribution of chloride concentrations of groundwater in the vicinity of the lake indicates that the shallow groundwater (3∼5m depth below water table) in the aquifer discharges almost vertically into the lake within 20∼30m from the shore; the deeper water discharges into the lake at a distance of over 30m offshore.
These results indicate that it is important to measure groundwater seepage at many sites near and along the shore line in order to estimate seepage amount into a lake and also suggest that the direct method employed is available to investigate shallow groundwater flow system near shore.

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We propose a new method to determine the three-dimensional hydraulic parameters of fissured rock mass. More than three boreholes are required for a conventional cross-hole method and many water injection experiments have to be repeated during the test. However, our method make the estimation of hydraulic parameters possible through the use of only two boreholes along with information on fissure orientation. A constant volume of water is injected into one borehole, and the head increase with time in a packed-off interval in the other borehole is monitored. Data of fissure orientation are sampled from boreholes or nearby outcrops. When a rock mass is regarded as an equivalent porous media, the hydraulic conductivity, hydraulically and geostatistically obtained by using in situ information of fissures from the crack tensor theory, will be expressed by a second-rank, symmetric, positivedifinite tensor. Principal directions of the hydraulic conductivity tensor obtained are reliable because orientation and distribution density of the fissures are reliable. Whereas, absolute values of the tensor are not reliable because of low reliability of aperture data. Thus, our proposing method can be applicable for the case of the rock mass that is regarded as an equivalent porous media. The method uses a non-linear least squares iteration to determine the three-dimensional hydraulic conductivity tensor and specific storage, which give the same variation curve of the theoretically calculated water head by using the already known data of orientation and density of fissures as the observed one during crosshole test. The theoretical fitting curve of water head used for this purpose was calculated by Hsieh's three-dimensional theory of transient seepage flow in a homogeneously and anisotropically porous media which has the estimated hydraulic parameters.
Finite element analyses of three-dimensio n al seepage for getting the cross-hole test data were applied to two kinds of rock mass models to check the reliability of our method. The observed change of water head with time obtained from a three-dimensional finite element analysis and given the fissure orientation are analysed by our method. The calculated values of hydraulic conductivity tensor and specific storage are sufficiently accurate for practical application.

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