著者

山中 勤 田中 正 浅沼 順 濱田 洋平 YAMANAKA Tsutomu TANAKA Tadashi ASANUMA Jun HAMADA Yohei

出版者

Terrestrial Environment Research Center, the University of Tsukuba

雑誌

筑波大学陸域環境研究センター報告 = Bulletin of the Terrestrial Environment Research Center,the University of Tsukuba (ISSN:13463381)

巻号頁・発行日

vol.4, pp.51-59, 2003-10

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Water levels were measured for 34 wells in the Nasu Fan, Tochigi prefecture, in the end of October, 2002. Water quality of groundwater (34 samples), river water (6 samples) and spring water (3 samples) were also analyzed. Local relief of groundwater table is considerably low, and the typical value of its gradient is approximately 1/100. At an elevation between 220m and 250m, groundwater table approaches to the ground surface. Revival of interrupted stream of the Sabi River and the Houki River can recharge groundwater. These facts indicate that there is active interaction between groundwater and surface streams. Groundwater level fell over most part of the fan in recent 10 years. The maximum reduction of the groundwater level exceeds 3m. Increase in electric conductivity of groundwater was detected in some areas including urban areas.

著者

Liu Yaping Zhou Xun Fang Bin Zhou Haiyan Yamanaka Tsutomu

出版者

Springer

雑誌

Environmental earth sciences (ISSN:18666280)

巻号頁・発行日

vol.66, no.7, pp.1887-1896, 2012-08

被引用文献数

18 6

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The Jifei hot spring emerges in the form of a spring group in the Tibet–Yunnan geothermal zone, southwest of Yunnan Province, China. The temperatures of spring waters range from 35 to 81°C and are mainly of HCO3–Na·Ca type. The total discharge of the hot spring is about 10 L/s. The spring is characterized by its huge travertine terrace with an area of about 4,000 m2 and as many as 18 travertine cones of different sizes. The tallest travertine cone is as high as 7.1 m. The travertine formation and evolution can be divided into three periods: travertine terrace deposition period, travertine cone formation period and death period. The hydrochemical characteristics of the Jifei hot spring was analyzed and compared with a local non-travertine hot spring and six other famous travertine springs. The results indicate that the necessary hydrochemical conditions of travertine and travertine cones deposition in the Jifei area are (1) high concentration of HCO3 − and CO2; (2) about 52.9% deep source CO2 with significantly high PCO2 value; (3) very high milliequivalent percentage of HCO3 − (97.4%) with not very high milliequivalent percentage of Ca2+ (24.4%); and (4) a large saturation index of calcite and aragonite of the hot water.

著者

Sato Tomonori Tsujimura Maki Yamanaka Tsutomu Iwasaki Hiroyuki Sugimoto Atsuko Sugita Michiaki Kimura Fujio Davaa Gombo Oyunbaatar Dambaravjaa

出版者

American Geophysical Union

雑誌

Journal of geophysical research: Atmospheres (ISSN:2169897X)

巻号頁・発行日

vol.112, no.D17, pp.D17112, 2007-09

被引用文献数

48

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Origin of water vapor, which falls as precipitation over arid/semiarid area in northeast Asia, is investigated by modeling and observational approaches. The regional climate model evaluates the spatiotemporal variations of precipitation and water vapor budget, which are used to drive the single-layer isotope circulation model. Intraseasonal variations of δ 18O in precipitation are well simulated during June-July-August of 2003. The δ 18O in water vapor experiences rapid decreases according to the passage of synoptic-scale disturbances. The rapid decreases of δ 18O are attributed to two processes. (1) The δ 18O in air mass locally decreases over the western mountains associated with the mountain precipitation; the light vapor is advected to eastern Mongolia by the prevailing westerly wind. (2) Convective systems pass by in the vicinity of the observation site, which persistently keep the lower δ 18O in the air mass. Origin of the water vapor during June-July-August in 2003 is evaluated by the colored moisture analysis in which the tracers are assigned depending on the region where the water vapor finally evaporated. Seasonal mean result indicates that the regions contributing to precipitation in Mongolia are not low-latitude regions but central Asia and western Siberia located to the northwest of Mongolia. Observed multilevel isotopic composition supports the model estimation. The moisture transport along the southwesterly wind of the Asian summer monsoon has difficulty reaching Mongolia as a monthly/seasonal mean perspective. However, eastern Mongolia and northeast China are situated on the border area between westerly wind moisture transport (by midlatitude synoptic cyclones) and southerly wind moisture transport (by Asian summer monsoon).

著者

Liu Yaping Yamanaka Tsutomu

出版者

Elsevier B.V.

雑誌

Journal of hydrology (ISSN:00221694)

巻号頁・発行日

vol.464–465, pp.116-126, 2012-09

被引用文献数

99 4

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Mountain–plain transitional landscapes are especially important as groundwater recharge zones. In this study, the oxygen and hydrogen stable isotopic composition (δ18O and δD) of water and hydrochemical information were employed to quantify contribution ratios of different sources of groundwater recharge in the Ashikaga area of central Japan. The study area is situated between the Ashio Mountains and the Kanto Plain, and the Watarase River flows into the region parallel to the mountain–plain boundary. There was an obvious isotopic altitude effect in and around the study area (−0.25‰ per 100 m for δ18O and −1.7‰ per 100 m for δD), and the isotopic signatures of water from the Watarase River and local precipitation could be clearly distinguished. In addition, it was possible to identify the occurrence of mountain block recharge using hydrochemistry, specifically the chloride ion. End-member mixing analysis using δ values and Cl− concentration revealed spatial variation in the contribution ratios of the river water, mountain block groundwater and local precipitation. Seepage from the Watarase River contributed a significant amount of water to aquifers along its channel. The river-recharged water reached 5 km from the channel in the south (i.e., plain) side and 1.6 km or less in the north (i.e., mountain) side. Remarkable mountain block recharge was observed in the foothills near the axis of the syncline, which has layers of chert and sandstone that likely hinder river channel seepage into the mountain-side aquifers. Major factors controlling the river-water contribution ratio include the distance from the river channel, topography, and hydrogeological settings. The results presented here should facilitate integrated management of groundwater and surface water resources.