ANALYSIS ON THE CLIMATOLOGICAL EQUILIBRIUM STATE OF SOIL MOISTURE AND GROUNDWATER TABLE ON GLOBAL SCALE

Abstract

 The role of soil moisture and groundwater is important to reveal how land surface water balance is determined by long-term mean climate. The discusstion about how to define equilibrium state of soil moisture and groundwater table in hydrological simulation have been continued to understand terrestrial water balance. The aim of this study is to clarify how equilibrium soil moisture and groundwater table is explained by hydro-climate on global scale by using land surface model with explicit representation of groundwdater table dynamics. The new concept for defineing climatological equilibrium state of soil mositrue and groundwater table under assumpition that a similar climate pattern has been repeated for a long term period is proposed in this study. The analysis showed that around 80[％] of land surface area have climatological equilibrium state though the groundwater table and soil moisture did not reach climatological equilibrium state through a thousand simulation at arid and semi-arid region. It suggested that soil moisture and groundwater table are transient at arid and semi-arid region under current climate.