Modeling of the groundwater flow system in excavated areas of an abandoned mine

The Komesu underground dam is the first full-scale underground dam constructed to prevent saltwater intrusion in Japan. Although the cutoff wall of the dam effectively reduces the movement of saltwater into the reservoir area, saltwater masses remained behind the dam at the time of its completion, and saltwater can intrude beneath and diffuse through the wall, particularly when the reservoir level is below the sea level because of high pumping levels during the drought years. Therefore, it is necessary to estimate in advance whether the saltwater concentration in the pumped water is likely to exceed or not the permissible salinity level because of an increase in the residual saltwater mass as a result of saltwater intrusion and to take necessary measures to suitably manage the saltwater level behind the dam. To analyze saltwater intrusion, we first selected the optimal program suitable for the analysis of saltwater intrusion. Second, we examined the longitudinal dispersivity and the effect of the cone of depression around the pumping wells. Then we analyzed saltwater intrusion into the reservoir area in detail by using a two-dimensional convective–dispersive analysis. The results of the analysis make it possible to improve management of saltwater in the reservoir area behind the underground dam.

The analysis of saltwater intrusion through Komesu underground dam and water quality management for salinity

The chemistry and flow of water in the abandoned Tomitaka mine of Miyazaki, western Japan were investigated. This mine is located in a non-ferrous metal deposit and acid mine drainage issues from it. The study was undertaken to estimate the quantities of mine drainage that needs to be treated in order to avoid acidification of local rivers, taking into account seasonal variations in rainfall. Numerical models aimed to reproduce observed water levels and fluxes and chemical variations of groundwater and mine drainage. Rock-water interactions that may explain the observed variations in water chemistry are proposed. The results show that: (1) rain water infiltrates into the deeper bedrock through a highly permeable zone formed largely by stopes that are partially filled with spoil from excavations (ore minerals and host rocks); (2) the water becomes acidic (pH from 3 to 4) as dissolved oxygen oxidizes pyrite; (3) along the flow path through the rocks, the redox potential of the water becomes reducing, such that pyrite becomes stable and pH of the mine drainage becomes neutral; and (4) upon leaving the mine, the drainage becomes acidic again due to oxidation of pyrite in the rocks. The present numerical model with considering of the geochemical characteristics can simulate the main variations in groundwater flow and water levels in and around the Tomitaka mine, and apply to the future treatment of the mine drainage.

Flow and geochemical modeling of drainage from Tomitaka mine, Miyazaki, Japan

A new method for determination of heavy metal adsorption parameters in compacted clay by batch tests.

独立行政法人日本原子力研究開発機構は，北海道幌延町において地層処分研究の一環として幌延深地層研究計画を進めている．本論文では，地上からの調査研究段階のうち，地下水流動に関する主な調査研究の成果を体系的に説明した．水文調査では，涵養量が河川流域によって異なり，これが植生や地形に依存する可能性を示した．ボーリング調査では，原位置試験規模の透水係数にはばらつきや深度依存性があること，室内試験規模の透水係数は過去に受けた応力状態の影響も反映していることがわかった．調査を踏まえた地下水流動解析からは，地下水が河川流域を跨いで流動していることや，深部に高い全水頭が保持されていることがわかった．

Hydrogeological investigations of surface-based investigation phase of horonobe url project

オイラリアンーラグラジアン法は地下水物質輸送解析手法として非常に有用な手法である. 本研究では, オイラリアンーラグラジアン法を密度依存を考慮した不飽和領域の2次元移流分散問題に拡張した. 本手法による解析結果と理論解および実験結果との比較を行い, 本手法の妥当性を検証した. また, 本手法を用いることで, メッシュサイズに依存せず精度良くシミュレートできることを示した.

The numerical method for saturated-unsaturated fluiddensity-dependent groundwater flow with mass transport

本研究では, オイラリアン・ラグランジアン法を密度依存を考慮した不飽和領域の3次元移流分散問題に拡張した. 本手法による解析結果と実験結果および既存の解析コードによる解析結果との比較を行い, 本手法の妥当性を検証した. また, 従来の移流項の演算手法の代わりにブロック探査手法を提案し, 演算時間を大幅に短縮した.

The three dimensional numerical analysis method for density dependent groundwater flow with mass transport

In this paper the author will be describe phenomena of advection dispersion in subsurface flow by using Eulerian Lagrangian Finite Element Method Where Finite Element Method with Galerkin formulation and weigthed residual method is used to solve seepage and advection dispersion equation The problem of one dimensional and two dimensional rectangular wave are analyzed in this paper And the result of numerical analyses will be compared with analytical solutions The numerical results showed the very good agreement with the analytical solutions

/pdf/advection-dispersion-by-eulerian-lagrangian-finite-element-2n4coaam6s.pdf

Advection Dispersion by Eulerian Lagrangian Finite Element Method

In this paper, method of Eulerian Lagrangian numerical analysis is used to described Advection-Dispersion phenomena. The influence of concentration to the density of fluid is considered. A laboratory model of a two dimensional confined aquifer containing an isotropic, homogeneous porous medium (Hosokawa et.al 1989) was used to validate the applicability of Advection-Dispersion of numerical analysis with steady and unsteady state condition [1].

/pdf/numerical-analysis-of-salt-intrusion-into-aquifer-by-12t2pfaotb.pdf

Tomoyuki Hishiya

Papers

The numerical method for saturated-unsaturated fluiddensity-dependent groundwater flow with mass transport

The three dimensional numerical analysis method for density dependent groundwater flow with mass transport

Advection Dispersion by Eulerian Lagrangian Finite Element Method

Numerical Analysis of Salt Intrusion into Aquifer by Eulerian Lagrangian Finite Element Method

論文孔内3次元流向・流速測定における計測区間内の地下水流動状況評価について

Tomoyuki Hishiya

Papers

The numerical method for saturated-unsaturated fluiddensity-dependent groundwater flow with mass transport

The three dimensional numerical analysis method for density dependent groundwater flow with mass transport

Advection Dispersion by Eulerian Lagrangian Finite Element Method

Numerical Analysis of Salt Intrusion into Aquifer by Eulerian Lagrangian Finite Element Method

論文 孔内3次元流向・流速測定における計測区間内の地下水流動状況評価について

論文孔内3次元流向・流速測定における計測区間内の地下水流動状況評価について