Abstract:Irrigation zones located in the lower reaches of Yellow River is a vital food security base in China. Currently, this area is facing the problem of rapid decline of groundwater level due to serious water shortage and insufficient water resources allocation. Therefore, there are many unknown and uncertain impacts on the future agriculture and ecological environment, and it is the current hotspot of agroecosystem research. However, under the dynamic scenarios, for innovatively carrying out the studies on large groundwater table from surface, and conducting the critical process researches such as sectional structure of farmland soil, crop root growth dynamics, interaction between surface water and groundwater, groundwater-soil-plant-atmosphere continuum response, dynamic variation and influence mechanism of water-salt-nutrient of agroecosystem, it is urgently needed to build a comprehensive experiment simulation infrastructure. Funded by the "Key Scientific and Technological Infrastructure Construction Project for the Field Station Network of Chinese Academy of Sciences (CAS)", Yucheng Comprehensive Experiment Station of Chinese Academy of Sciences (Shandong Yucheng Agro-ecosystem National Observation and Research Station) completed the platform construction of GroundwaterAgroecosystem Experimental Simulator (Yucheng GAS), an infrastructure with three floors (10 m underground) constituted by 16 bottom sealed sample plots with controllable groundwater levels after five-year strenuous efforts (from 2016 to 2020). Yucheng GAS integrates nine subsystems including the large scale bottom sealed sample plots system, underground water level automatic controlling; soil temperature, water content, and salinity monitoring; soil water sampling; root growth monitoring; groundwater quantity and quality monitoring; critical zone observation of agroecosystem; water-carbon-nitrogen nexus in agroecosystem; and multispectral crop condition monitoring by unmanned aerial vehicle (UAV). Yucheng GAS, a comprehensive monitoring methodology with multiple methods of stereo-position monitoring, multi-factors chromatograph, and multi-scales three-dimensional observation, is expected to support the basic experimental research and international frontier explore in water-carbon-nitrogen cycles in agroecosystem, food security, ecological security, and environmental security under the scenario of dynamically changed groundwater in future.