Presentation Information
[O12-P65]Visualization of groundwater in Bunkyo City based on the elevation distribution of unconfined groundwater
*Soichiro Wada1 (1. University of Tsukuba Senior High School at Otsuka,Tokyo)
Keywords:
unconfined groundwater,Musashino Upland,Bunkyo City,groundwater level
Abstract
Groundwater levels in the Musashino Upland, including Bunkyo City, Tokyo, have been visualized in previous studies; however, most of these have focused on the Tama–Yoyogi area, where the dip of strata corresponds closely to changes in the elevation of the Tama River. Even when Bunkyo City is included, the groundwater-level maps are generally coarse in resolution. In addition, because no land-subsidence monitoring wells are installed in Bunkyo City, groundwater levels cannot be directly constrained from observational data. This study therefore aimed to conceptually visualize the distribution of unconfined groundwater levels in Bunkyo City.
Based on previous studies, a composite map was produced by superimposing color-coded contour maps of the basal surfaces of the Musashino Upland deposits and the alluvial deposits. To address the limited number of known spring sites and the incomplete spatial coverage of the existing maps, strata of the Shimosa Group that may function as aquifer bases were additionally incorporated. Field surveys were also conducted within Bunkyo Ward to identify spring locations. These field data, together with spring locations listed by the Ministry of the Environment, were overlaid on the geological maps to infer the surfaces functioning as aquifer bases and to construct a final plan-view groundwater-level map.
The resulting map provides a conceptual visualization of unconfined groundwater levels in Bunkyo City using spring elevations as substitute data for observation wells. Although the model is static and depends on simplifying assumptions regarding stratigraphic continuity and aquifer distribution, it offers a first-order overview of groundwater conditions across the ward and may serve as a useful basis for future hydrogeological investigation and groundwater use.
Groundwater levels in the Musashino Upland, including Bunkyo City, Tokyo, have been visualized in previous studies; however, most of these have focused on the Tama–Yoyogi area, where the dip of strata corresponds closely to changes in the elevation of the Tama River. Even when Bunkyo City is included, the groundwater-level maps are generally coarse in resolution. In addition, because no land-subsidence monitoring wells are installed in Bunkyo City, groundwater levels cannot be directly constrained from observational data. This study therefore aimed to conceptually visualize the distribution of unconfined groundwater levels in Bunkyo City.
Based on previous studies, a composite map was produced by superimposing color-coded contour maps of the basal surfaces of the Musashino Upland deposits and the alluvial deposits. To address the limited number of known spring sites and the incomplete spatial coverage of the existing maps, strata of the Shimosa Group that may function as aquifer bases were additionally incorporated. Field surveys were also conducted within Bunkyo Ward to identify spring locations. These field data, together with spring locations listed by the Ministry of the Environment, were overlaid on the geological maps to infer the surfaces functioning as aquifer bases and to construct a final plan-view groundwater-level map.
The resulting map provides a conceptual visualization of unconfined groundwater levels in Bunkyo City using spring elevations as substitute data for observation wells. Although the model is static and depends on simplifying assumptions regarding stratigraphic continuity and aquifer distribution, it offers a first-order overview of groundwater conditions across the ward and may serve as a useful basis for future hydrogeological investigation and groundwater use.