Linking Variations of Soil Moisture and Groundwater Levels to Dynamics of Evapotranspiration and Rainfall Infiltration

Evapotranspiration (ET) and rainfall infiltration are important water exchangesbetween land and atmosphere. Climate changes and human induced land use changesfurther complicate the dynamics and predictions of such water exchanges. Variationsof both fluxes are controlled by micrometeorology, surface condition, andhydrogeology. Groundwater is the most important water resources in addition tosurface water. Except human pumping, although groundwater budget is conceptuallydominated by ET and infiltration by root uptaking and downward moving of soilwater, respectively, there is a critical hydrological knowledge gap on how thesenear-surface fluxes facilitate variations of groundwater levels. Interestingly, how fastor delayed responses of groundwater levels to these fluxes during event or seasonalscales and their interconnected mechanisms are furthermore complicated. This studyproposed the first phase of 2 years studies to integrate hydrometeorologyexperimental measurements and variable saturated groundwater simulations. Thisproposal is the send year of our first phase studies. On the experimental setup,capacity of subsurface hydrological measurement will be deployed to integratedcurrent micrometeorology instruments at the National Central University site. On themodeling aspect, variable saturated groundwater simulations will be employed toexam the linkage in variations of soil moisture and groundwater levels to dynamics ofevapotranspiration and rainfall infiltration. The research will provide contributions tounderstand dynamic nexus of ET, infiltration, soil moisture and groundwater fromevent to seasonal scales. Novel scientific knowledge and solution tools of handlinginteractions among atmospheric water, surface water, soil water, and groundwater willbe delivered to facilitate simulations of land surface process and watershed hydrology.