A series of type curves is presented for evaluating vertical groundwater fluxes under the condition of a linear increase in surface temperature. The depths of minimum groundwater temperature in the temperature-depth profiles indicate the magnitude of the downward groundwater flux. The type curve method has been applied to the subsurface thermal regime observed in Tokyo metropolitan area, Japan, to estimate the vertical groundwater fluxes under the condition of surface warming caused by global warming and urbanization. The groundwater fluxes obtained from the type curves and the depths of minimum groundwater temperature agree well with the values obtained from the other studies in the Tokyo metropolitan area. The inversion due to the surface warming could be a good tracer to detect the groundwater flow system. ¿ 1999 American Geophysical Union