Linkages Beyond the Surface–Subsurface and Land–Ocean Boundaries for Better Environmental Management in Asia

Abstract

Coastal cities in Asia were established and developed with little thought of their significance to surrounding subsurface and water environments. The Research Institute for Humanity and Nature (RIHN) project “Human impacts on subsurface environment” has shown important surface–subsurface and land–ocean linkages in the Tokyo, Osaka, Bangkok, Jakarta, Manila, Seoul, and Taipei basins. The relationships between city development stage and various subsurface environments in Asia were evaluated beyond the boundary between surface and subsurface environments. To partition earth surface water, thermal energy and materials into above- and below-surface components, land use/cover changes at three periods (the 1930s, 1970s and 2000s) in seven Asian cities were analyzed using GIS with a 0.5 km grid resolution. Urbanization reduced water transfer between the surface and subsurface environments and the land and ocean environments through decreasing groundwater recharge into aquifers and groundwater discharge into the ocean. Saltwater intrusion due to excessive pumping and thermal transport into the subsurface due to heat island effect increased after urbanization. Documenting the linkages of water, heat and materials between the surface–subsurface and land–ocean environments improves understanding of the full dynamism of the biogeophysical and geochemical flows that sustain the biosphere, and can improve urban planning, particularly in relation to critical groundwater and coastal resources.