Integrated Analysis of Water and Heat Balances in Tokyo Metropolis with a Distributed Model.

Abstract

Integrated analysis of water and heat balances in Tokyo metropolis is conducted by applying a distributed model. The subgrid heterogeneity of land covers is considered by using a nesting method. Evapotranspiration is computed by the Penman-Monteith equation and sensible heat flux by the aerodynamic method. Surface temperature is solved by the Force-Restore method. Infiltration excess during heavy rains is simulated by a generalized Green-Ampt model which considers soil stratification and rain unsteadiness. Saturation excess during the left periods is obtained by balance analysis in unsaturated soil layers. Two dimensional groundwater flow is simulated to consider the inter-actions between grid cells and the impact of groundwater table on surface runoff generation and heat flux partition. The simulated water and heat balances are dually verified both in the whole study area and in a catchment inside it. It is shown that both urbanization and weather variation have big impacts on water and heat balances in Tokyo me-tropolis.