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 －Uchinuki Distribution |
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■Kamogawa River
The Kamogawa River has approximately a 33 km-extended flow channel and 200 km2 of drainage basin area, partly because it is rich in abundant forest resources that cultivate the riverbed. Surface water is easily permeable because the riverbed is higher than the neighboring plain at the alluvial fan around the base of the mountain. The rapid flow through the sediments in the riverbed, which are constituted of a gravel layer including many coarse fragments, also contributes to this easy permeability. The surface water permeates the riverbed from Bujo Park to upstream of Furukawa Bridge to form a broad abundant ground-water zone. Therefore, the stream rarely reaches the estuaries except for the wet season and flooding.
■Groundwater Basin
The groundwater basin refers to a reservoir to store the groundwater. The groundwater basin of the Kamogawa River system is divided into two areas at the inferred fault. One area is interbedded between the Okamura fault and the inferred fault. The other area is on the lower part of the river on the other side of the inferred fault. In the internal structure of the groundwater basin, the aquifer made from extremely permeable coarse fragments is divided into two parts, which are the upper and lower parts, and the groundwater in the aquifer interbedded with semi-permeable layers is the confined groundwater.
■Spring Waters
Many spring waters are found in an arc around the edge of the alluvial fan of the Kamogawa River. Kannon Sui (Kannon Water), Sangenya Izumi (Sangenya Spring), Tennoh Izumi (Tennoh Spring), Matsunoki Izumi (Matsunoki Spring) and other springs on the right bank of the Kamogawa River are at the headwaters of the Honjingawa, Mifunegawa, and Sarasaragawa Rivers. Tatehara Izumi (Tatehara Spring), Nakanishi no Shimizu, Bankyoji Izumi (Bankyoji Spring), and other springs are on the left bank.
■Flow area
The flow area is located in the groundwater basin containing confined groundwater on the side downstream of the Kamogawa alluvial fan. Approximately 2,000 uchinuki are scattered around the 800 ha-area, about 5,600m above the groundwater basin in the east and west, and about 400 to 2,200m above the groundwater basin in the north and south across the both sides of Kamogawa River in the city. In addition, flowing caused by the tidal range is seen in some coastal areas. |
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