地下ダムを用水源とする畑地灌漑地帯における地下水分布の推定と貯水機能の評価

抄録

  This study aims to evaluate groundwater distribution in irrigated upland farming areas with a subsurface dam and clarify its effects on storage ability. A field investigation was conducted in Kikai Island, in southwest Japan, to clarify the topography and groundwater levels. The geological stratum spatial conditions were visualized using Geographic Information System data from existing bore-well surveys, and a numerical model for groundwater analysis in a non-irrigated area with an existing subsurface dam was developed. Model parameters for groundwater analysis, including hydraulic conductivity and effective porosity, were estimated using measured groundwater level data. Using simulated groundwater flow data in relation to the existing subsurface dam, the groundwater storage effects of the dam were clarified and the possibility of enhancing groundwater usage for irrigation was identified. This method for estimating the parameters of groundwater analysis from groundwater level observations could be effective for groundwater development in cases where the stratum characteristic data are insufficient.