|Budget Amount *help
¥1,500,000 (Direct Cost : ¥1,500,000)
Fiscal Year 1992 : ¥500,000 (Direct Cost : ¥500,000)
Fiscal Year 1991 : ¥1,000,000 (Direct Cost : ¥1,000,000)
Yoshioka who is a investigator of this project examined the relationship among the calculated dissolved carbon dioxide gas, bicarbonate contents and pH in the ground water sampled from various area. He reported the following results ; (1)The mode value of partial pressure distribution of carbon dioxide gas was found at 10^<-2.3> atmosphere in landslide areas, but at 10^<-3.1> atmosphere in granite areas, (2)A possibility of distinction between stream and ground water from water quality was found by using a pH-HCO_3^--PCO_2 diagram, etc.
The object of the research is to examine the view. The test field is placed on a mountain slope composed of granite and is 0.3 ha in area. In the field, the head investigator of this project was reported elsewhere that a translatory flow was recognized at the beginning of runoff. Observations and sampling of water were started from October, 1992, made in every week, and is continued over one year.
Waters are sampled at various points ; (1) horizontal bore
holes which were drilled to drain water contained in a base rock(point name as 1,2 and 4), (2) vertical bore holes which were drilled to collect water in a surface soil layer(point name as A-E), (3) a seepage out point in the test field(point name as 10G), (4) runoff water from the test field(point name as 10).
From the apparent sampling sites, ground water is seemed to be those from horizontal and vertical bore holes and from a seepage out point. Stream water is supposed to be runoff water. But the result shows that the water sampled at a seepage point is classfied as stream water, and the runoff water, as ground water. The water sampled from a seepage out point is that of a drop of water which fall down along roots of plants. A sampling bottle is placed below the roots during one week. The water, therefore, is supposed as ground water. The data of this seepage out water, sometimes, scattered on the diagram in comparison to other data. This scattering is found to be caused by the total amount of rainfall in a week. Then, it concluded that the origin of seepage out water is rainwater. The pH-HCO_3^--PCO_2 diagram, therefore, shows that the seepage out water is stream one.
The sampling point of runoff water is placed at a head hollow on a mountain slope. The runoff water, therefore, is considered to be classified as ground water. Thus, we can distinguish stream water from ground water by the pH-HCO_3^--PCO_2 diagram.
The result of runoff water shows that data which was sampled at two hours later after the stop of a heavy rainfall is plotted near to the area of stream water on the diagram. The result suggests that a possibility of distinction between stream water and ground water is made by quality of water sampled during a heavy rainfall. Less