Ground Water and Spring Water in Terrace Soil properties and water movement in a volcanic deposit (Shirasu) area (IV)

• Published in: Transactions of The Japanese Society of Irrigation, Drainage and Reclamation Engineering Vol. 1981; no. 93; pp. 22 - 30,a1
• Main Authors: AMEMIYA, Yu, NAKANO, Masashi, MUTO, Isao
• Format: Journal Article
• Language: Japanese
• Published: The Japanese Society of Irrigation, Drainage and Rural Engineering 25.06.1981
• ISSN: 0387-2335; 1884-7234
• DOI: 10.11408/jsidre1965.1981.93_22

Movement of ground water and spring water in the Tsukabaru Shirasu terrace in Miyazaki Prefecture into which no influx is considered negligible from the outside the area is investigated in an attempt to understand the water circulation through the terrace. The followings are the summarized results 1. Ground water begins to rise from the shortest distance between the ground surface and water table during the water increasing period, and begins to fall from the thickest and highest part of the aquifer during the depletion period. Changes in the water table are classified into three groups according to depth and precipitation patterns (Figs. 3, 4 and 5, respectively): a) Water table found between ground level and three meters, which quickly responds to dirnal rainfall patterns. b) Found at depths of between 5 and 13 meters in response to monthly rainfall patterns. c) Found at a depth of over 13 meters, which shows some small variations due to seasonal rainfall patterns. 2. Stored water in aquifer shows an insignificant change in quantity of between 1, 150 and 1, 200mm during the observed period (1976 November to 1979 July) due to the large 35% value in the specific yield of the Shirasu layer (Fig. 7). 3. Geographical distribution of springs has a certain principal tendency, but intensive locality appears simultaneously. This is because the ground water flow depending on superficial outline of nonpermeable layer (the Tertiary) submits intensity of spring efflux (Figs. 9 and 11). 4. Changes in spring efflux are subject to those of the water table behind the springs. So, the topographical features of the ground surface, which extend to the interior of the terrace, must be examined in detail, as well as the features of ground water as they stands, in order to establish clearly the movement of the spring water efflux (Figs. 2 and 10).