Abstract
The authors have analized comprehensively the mechanism of the groundwater flow in large scale landslide areas based on the results obtained from groundwater quality analyses in two large scale landslide areas in Tertiary system in Tohoku region. A comprehensive analysis of groundwater flow is effective and credible by executing comparisons of the results of groundwater quality analyses, groundwater level observation, and groundwater tracing in addition to analyses of surveying of geological structure.
In Takisaka landslide the flowing behavior of groundwater was comprehended by the analyses combined with groundwater quality and groundwater tracing with due consideration of variations of groundwater levels in each geological formation and sliding block. Furthermore it is suggested by the analysis of the distribution of Cl- ion concentration in groundwater that the deep groundwater through granite rock mass has a certain influence for raise up of groundwater level during snow melting period.
In Hirane landslide the flowing behavior of groundwater was comprehended by the interpretation of mixing of groundwater from Tertiary system and groundwater from deep zone. The flowing behavior of the groundwater estimated by the groundwater quality analyses is coincident with the results of groundwater tracing.
As a result a holistic method to analyze behavior of groundwater flow in large scale landslide areas is newly proposed. It is appropriate and effective to carry out the following steps, namely groundwater quality analysis, comparison with groundwater tracing, identification of groundwater level variation, estimation of groundwater flow pass and lastly holistic analysis of characteristics groundwater flow in whole landslide area.
