Chikasui Gakkai-Shi, 61(4), P. 346, 2019/11
no abstracts in English
Mochizuki, Akihito; Sasamoto, Hiroshi; Mezawa, Tetsuya*; Miyakawa, Kazuya
Chikasui Gakkai-Shi, 61(1), p.3 - 20, 2019/02
Redox potential of deep groundwater in the Horonobe area, Hokkaido, was measured, and uncertainty of the measurement and thermodynamic interpretation was evaluated. The redox potential of groundwater obtained using monitoring units in the Underground Research Laboratory ranged between -250 and -100 mV, and the effect of the excavation of drifts on the redox potential is considered to be small in spite of its temporal variation. The redox potential is controlled by the reaction of chemical pairs of SO/FeS, SO/HS and CO(aq)/CH(aq). The comparison between the equilibrium potential for these reactions and the measured redox potentials suggests that 50 mV of uncertainty for the measurement of the redox potential is appropriate.
Murakami, Hiroaki; Tanaka, Kazuhiro*
Chikasui Gakkai-Shi, 57(4), p.415 - 433, 2015/11
This study examined the geochemical properties and the distribution of mineral spring water, river water and bubbling gas in the Tsuwano Town, Shimane Prefecture, Western Japan. In Tsuwano, high Na-Cl concentration groundwater is discharged with bubbling gas mainly composed of CO. The geochemical properties of mineral spring water, gas, hydrogen-oxygen isotopes and rare gas isotopes suggest that mineral spring water at Tsuwano possibly contains deep-seated fluid. In addition, the largest flux of the deep-seated fluid is found along active fault, suggesting that active fault acts as a path way for fluid upwelling. Furthermore, In Tsuwano, deep-seated fluid discharges along the Lake Ohara-West Yauneyama fault system and surface fracture.
Amano, Yuki; Nanjo, Isao; Murakami, Hiroaki; Yabuuchi, Satoshi; Yokota, Hideharu; Sasaki, Yoshito; Iwatsuki, Teruki
Chikasui Gakkai-Shi, 54(4), p.207 - 228, 2012/11
We verified the surface-based hydrochemical investigation for deep underground at Horonobe Underground Research Laboratory (URL) at Horonobe, Hokkaido, Japan, and identified the hydrochemical changes during the URL construction. The evaluation of the relationship between the number of borehole and understanding of water chemistry suggests that three basic borehole investigations and additional borehole for high permeable geological structure (fault and fractured zone) are required to illustrate cross-sectional hydrochemical distribution including the uncertainty in kilometers scale survey line. The observation and numerical analysis of hydrochemical variation (salinity, pH, ORP) around URL indicate that the groundwater pressure and the salinity in the vicinity of high permeable geological zone are varying due to groundwater inflow into the drift. The variation was consistent with the prediction reported previously. These results are considered to be referred to the management during surface-based investigation and construction of underground facility at the other sedimentary rock area.
Yokota, Hideharu; Yamamoto, Yoichi; Maekawa, Keisuke
Chikasui Gakkai-Shi, 53(2), p.193 - 206, 2011/05
It is important for assessing the safety of geological disposal of high-level radioactive waste to understand shallow to deep groundwater flow as the driving force of mass transport. JAEA has been carrying out the surface hydrological investigation in the Horonobe area, Hokkaido. Results of groundwater-level observations, and relationship between distributions of groundwater-level and geological structures suggest that constructions of underground facilities have no effect on shallow groundwater-level fluctuations, and that water infiltrate from ground surface into shallow underground in the snow covered season, and that water infiltrate into deeper underground along faults. In the future, it is necessary to quantitatively assess the water infiltration and recharge based on directly and/or indirectly observed data of evapotranspiration and soil moisture content by weighing lysimeter and ADR method soil moisture meter, and tensiometer.
Sakai, Ryutaro; Munakata, Masahiro; Kimura, Hideo
Chikasui Gakkai-Shi, 51(4), p.311 - 329, 2009/11
In order to evaluate the regional groundwater flow system, the author has investigated stream flow of 3 rivers and analyzed flow rates and chemical compositions, isotopic ratios of hydrogen and oxygen of water samples collected from wells, rivers and springs in the feeder streams area in the Yoro river basin, in Chiba Prefecture. As a result of this study, (Na)Ca-HCO type water is evaluated to be recharged from the highly permeable sand-dominant domain (Daifuku Mt.). In addition, it is estimated that the groundwater flow preferentially in direction of strike and discharge at the middle and downstream domain as Ca-HCO type water, and partially pass through fractures of low permeable alteration layer up to the surface area as evolved Na-HCO type water.
Iwatsuki, Teruki; Morikawa, Keita*; Hosoya, Shinichi*; Yoshikawa, Hideki
Chikasui Gakkai-Shi, 51(3), p.205 - 214, 2009/08
Physicochemical parameters of deep groundwater at the depth of 500 m were measured at ground surface and the in-situ sampling depth of borehole to understand the redox condition and dominant redox process. The results show that the redox potential at the depth was approximately -100 mV and was controlled by the reaction of chemical pairs of (Fe, SO)/(FeS) or (SO, FeCO)/(FeS). The pH value at ground surface changed approximately 0.4 from that at the in-situ depth by degassing of dissolved carbon dioxide. The time to reach the stable ORP value in monitoring depends on the shape and surface area of Pt electrode. The columnar-shape Pt electrode is more sensitive for deep groundwater rather than a dot-shape Pt electrode. It is important to correct the pH measured at ground surface for the analysis of in-situ redox reaction process.
Onoe, Hironori; Saegusa, Hiromitsu; Oyama, Takuya; Takeuchi, Shinji
Chikasui Gakkai-Shi, 50(4), p.251 - 274, 2008/11
In order to understand three dimensional groundwater flow condition in deep underground where discrete fracture are distributed, it is essential to construct hydrogeological model and to carried out groundwater flow simulations, which are based on the results of field investigations. In this study, hydrogeological model using hydraulic responses of cross-hole hydraulic tests, which were carried out in the Mizunami Underground Research Laboratory (MIU) project, was calibrated in order to estimate hydrogeological characteristics of the structure having influences on groundwater flow conditions in deep underground. As a result of the study, faults with low permeability and major water-conducting features in and around MIU Construction site were characterized. It could be also confirmed that groundwater flow simulations using data with transient fluctuation is quite useful for hydrogeological characterization in the deep underground.
Mizuno, Takashi; Metcalfe, R.*; Iwatsuki, Teruki; Mie, Hideki*
Chikasui Gakkai-Shi, 49(2), p.139 - 152, 2007/05
Hydrochemical studies are generally conducted based on chemical data of groundwater samples. Various methodologies exist for obtaining samples and for assessing the quality of the collected sample. This study is aimed at establishing a methodology for quality assessment of chemical data obtained from groundwater samples using a method known as Evidence Support Logic. In this study, pH data of groundwater obtained from several boreholes were assessed using this method. The results showed that 23 out of 63 samples satisfied the applied quality criteria. When plotted, the data from the 23 samples show a constant value from top to bottom of investigation area when compared to a plot using data from all samples. These results indicate that the quality assessment method demonstrated by this study is applicable to groundwater studies and that by considering the sample quality it will be possible to develop a clearer interpretation of the deep underground geochemical environment.
Sohail, A. R.*; Watanabe, Kunio*; Takeuchi, Shinji
Chikasui Gakkai-Shi, 48(4), p.233 - 262, 2006/11
Runoff analysis for precise prediction of discharge was carried out by artificial neural network model with real coded genetic algorithm (GAANN), back propagation artificial neural network model (BPANN) and multivariate autoregressive moving average model (MARMA). It was found that for very small catchments seasonal effect on the runoff is dominant. It was also found that estimation by ANN models was better than MARMA model for analyzing the responses to intense rainfalls in summer. The accuracy of the forecasts after several time periods in future was also investigated and found to decrease as time period is increased.
Inaba, Kaoru; Saegusa, Hiromitsu; White, M. J.*; Robinson, P.*
Chikasui Gakkai-Shi, 44(2), p.105 - 123, 2002/00