Effect of underground urban structures on eutrophic coastal environment

Tadanobu Nakayama, Masataka Watanabe, Kazunori Tanji, Tohru Morioka

Research output: Contribution to journalArticlepeer-review

41 Citations (Scopus)

Abstract

The NIES Integrated Catchment-based Eco-hydrology (NICE) model was expanded to include the density current and solute-transport process of groundwater in the Kanto Plain and to incorporate the effects of water table and tidal fluctuations around the eutrophic Tokyo Bay, Japan (NICE-SEA). The simulation reproduced excellently the observed values of river discharge and groundwater level in the catchment. The simulated groundwater level shows a minus value (below the sea level) around the Tokyo metropolitan area because of excessive withdrawal around the urban area in the past. The model shows that the underground urban structures, sewage pipes, seashore concrete dikes, and embankments have changed the hydrologic cycle in the catchment and the nutrient supply to Tokyo Bay. In particular, the groundwater flow is interrupted and the phase is delayed, resulting in an increase in the groundwater level, and a decrease of groundwater seepage into Tokyo Bay. Furthermore, we propose four types of political scenario for provisioning human ecosystem service (ES) sites to promote infiltration. The simulated result forecasts that the groundwater level increases predominantly at a maximum value exceeding 40 cm in a scenario for farmland and productive green areas and that the level recovers in some parts of the urban area. This phenomenon is related to the cut-off of groundwater flow by underground urban structures and the sewer leakage into the aquifer, which also influences the decrease of submarine groundwater discharge around the western side of Tokyo Bay.

Original languageEnglish
Pages (from-to)270-288
Number of pages19
JournalScience of the Total Environment
Volume373
Issue number1
DOIs
Publication statusPublished - 2007 Feb 1

Keywords

  • Groundwater
  • NICE-SEA
  • Political scenario
  • Underground urban structures

ASJC Scopus subject areas

  • Environmental Engineering
  • Environmental Chemistry
  • Waste Management and Disposal
  • Pollution

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