HR: 1400h
AN: H53E-03    [Abstracts]
TI: A nested modeling scheme to integrate regional groundwater flow and local groundwater flow/land subsidence processes; an application to the Tokyo metropolitan area, Japan
AU: * Aichi, M
EM: aichi@geoenv.k.u-tokyo.ac.jp
AF: Department of Geosystem Engineering, School of Engineering, University of Tokyo, 7-3-1, Hongo, Bunkyo-ku, 113-8656, Japan
AU: Tokunaga, T
EM: tokunaga@k.u-tokyo.ac.jp
AF: Department of Environment Systems, School of Frontier Science, University of Tokyo, 5-1-5, Kashiwanoha, Kashiwa-shi, 277-8561, Japan
AU: Hayashi, T
EM: t.hayashi@k.u-tokyo.ac.jp
AF: Department of Environment Systems, School of Frontier Science, University of Tokyo, 5-1-5, Kashiwanoha, Kashiwa-shi, 277-8561, Japan
AB: Many mega cities have experienced huge land subsidence due to significant groundwater extraction, and hence, enacted strict regulation of groundwater use. In Tokyo metropolitan area, the groundwater potential has recovered relatively rapidly after the cessation of groundwater extraction, however, it has caused damages to the underground infrastructures. Now, some researchers state that it is better to re-start using appropriate amount of groundwater to reduce the costs necessary for maintain underground infrastructures. To incarnate this, it is desirable to quantitatively estimate what amount of ground re-subsidence might occur by groundwater extraction. In the fields where both significant drawdown/land subsidence and the recovery of groundwater potential have been experienced, past maximum effective stress inside clayey layers is critical for estimating subsidence behavior. To trace the effective stress profiles in the clayey layers by numerical simulation, spatially high- resolution modeling is necessary. On the other hand, groundwater flow regime is rather large in space, and hence, it is difficult to set the boundary condition for the area of interest. Thus, combining both regional flow model with high resolution groundwater flow/land deformation model is desirable. We developed a new scheme to integrate regional groundwater flow and local groundwater flow/land subsidence coupled models to reduce computer load without large errors and applied it to the Tokyo metropolitan area, Japan. This modeling scheme could represent temporal changes of the stress profile in clayey layers, land subsidence in the drawdown period and land expansion in the groundwater recovery period in the Tokyo lowland quite well, and we believe that this scheme works out for predicting future groundwater potentials and land deformation in urban areas.
DE: 1822 Geomechanics
DE: 1829 Groundwater hydrology
DE: 1847 Modeling
SC: Hydrology [H]
MN: 2007 Joint Assembly