Hydrogen and oxygen isotope measurements on river waters collected from the Kurobegawa, Joganjigawa and Shogawa Fans, and their surrounding areas in Toyama Pref., Japan, have been made to examine their utility as an index of the source of groundwaters in aquifers beneath the fan.
Water samples were monthly collected from 7 major and 5 minor rivers at the fixed sampling point on or by the fan for the period from 6 to 39 monthes. Although the river waters show a tendency of slightly decreasing their δD and δ¹⁸O values during the summer, the range of variations in their δD and δ¹⁸O values are found to be small at each sampling point throughout the year (1σ : ±2-5‰ δD, ±0.2-0.3‰ ¹⁸O).
The average δD and ¹⁸O values of river waters are inversely correlative to the average altitude(h, m) of their catchment area;
δD=-(0.0193±0.017)h-(48.4±2.3)
δ¹⁸O=-(0.00236±0.00016)h-(8.68±0.22)
By using these relationships, the δD and δ¹⁸O values of river waters from the catchment area with an average altitude of 0 to 100m are estimated to be -48 to -50‰ and -8.7 to -8.9‰, respectively. These estimates agree well, respectively, withthe δD and ¹⁸O values of the groundwater (spring water) of local precipitation origin, collected at the foot of the hill with an altitude lower than 100m in Toyama Prefecture.

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Although hysteretic phenomena which appear during the infiltration of water or nonaqueous phase liquids (NAPLs) into soil play an important role on various field problems, only few fundamental studies have been done so far on the expression of soil water characteristics and unsaturated hydraulic conductivity with hysteresis. In this paper a new method is proposed to express the phenomena associated with soil water characteristics in a mathematical way which imposes two conditions obtained from experimental results. And the theoretical results compared quite favorably with experimental results. This method enables one to evaluate hystretic relationships of θ (h) by providing the parameters for main dry curve and main wet curve together with some informations on scanning curves. A new method for evaluating hysteretic relationships of unsaturated hydraulic conductivity is also proposed and the calculated results agreed well with all the conditions based on qualitative characteristics obtained from various experimental data.

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Pumping tests are usually performed under the multilayered aquifer system. The exact determination of hydraulic properties of each aquifer is very important for the correct groundwater flow prediction. It is, however, difficult to analyze the data obtained from the pumping test under these conditions “analytically”.
In this paper, a new approach to parameter determination methodology is presented which estimates the soil hydraulic properties from pumping test data with the aid of Genetic algorithms (GA). GA belong to a family of increasingly popular global optimization methods that are designed to overcome the multimodality of the objective function without incurring the enormous expense of exhaustive search. GA are based on the mechanics of natural selection and natural genetics, which combine an artificial survival of the fittest with genetic operators abstracted from nature. The advantages of the proposed method are in the possibility of identifying the optimal hydraulic properties of aquifers. Pumping test data which are simulated under the multilayered conditions are used to evaluate availability of our proposed method.

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