A study of groundwater management (development utilization conservation) in the Rokugo Alluvial Fan, Akita Prefectre

六乡冲积扇位于日本北方北纬39 25'，东经140 34'。它占地面积近14平方公里。扇头（海拔90米）和外缘（海拔45米）之间的距离约为4公里。位于边缘的六乡镇中心有7,000名居民。他们私自打浅威尔斯井，抽取无压地下水供家庭使用。地下水主要用于水稻种植，在5月至8月的融雪季节和灌溉活动期间，地下水位很高。1985/86年和1986/87年冬季，为了防止地下水位下降，进行了稻田回灌试验。选址在扇形中部的一片稻田中：1985/86年为12，493平方米，1986/87年为15，588平方米。通过实地观察，这个地方被认为是边缘地带地下水最有效的补给区之一。从灌溉渠中抽取一定量的水，以大约1000立方米的速度供应。从1985年11月7日到1986年3月31日，每分钟1,600升，从1986年10月24日到1987年3月31日，每分钟3,000升。可以发现，补给试验对地下水位的上升有影响。摘要中省略了对水质的提及。

The Rokugo alluvial fan lies 39 25' north latitude and 140 34' east longitude in northern Japan. It covers an area of nearly 14 square kilometers. The distance between the head (90 meters above sea level) and outer fringe (45 meters above sea level) of the fan is about four kilometers. The center of Rokugo town which is situated on the fringe numbers 7,000 inhabitants. they privately bore shallow wells and pump unconfined ground water for domestic uses. Ground water is recharged in the fan's area, which is utilized mainly for rice cultivation.Ground water levels are high during the season of melting snow and the period of irrigation activities from May to August. The highest level appears at the end of the melting of the snow and the beginning of irrigation, and the lowest one occurs around the time when snow cover reaches a maximum, which is usually about 130 centimeters in depth.Gound water recharge via paddy fields was tested during the winters of 1985/86 and 1986/87 in order to protect declining water levels. The site was selected fron an area of paddy fields in the middle of the fan : 12,493 square meters in 1985/86 and 15,588 square meters in 1986/87. This place was known through field observations to be one of the most effective recharge areas for the ground water in the fringe. A volume of water, which was withdrawn from an irrigation canal, was supplied at the rate of ca. 1,600 liters per minute from Nov. 7, 1985 to March 31, 1986 and of ca. 3,000 liters per minute from Oct. 24, 1986 to March 31, 1987.It could be found that the recharge tests had an effect as regards the rise of ground water levels. A reference to water quality is omitted in the abstract.