Reconstruction project of groundwater balance experiment site of Zhengzhou: general ideas and application prospect

The reconstruction project of groundwater balance experiment site of Zhengzhou was hosted by geo-environmental monitoring institute of Henan Province, belongs to one of the national groundwater monitoring projects, which is performed by Institute of China Geo-Environment Monitoring. This paper discusses in detail the general ideas, the specific practices of each implementation link, operation and its application prospects of the reconstruction project. In the reconstruction, the representative of test medium to Henan Province should be fully noticed, the test column should have better mechanical and thermal properties, the data collection should be fully automated, and the monitoring area should be properly broadened. Under the general idea, a test tube constructed of FRP material was designed, and the test media collected by five typical geomorphic units in Henan Province were selected to construct a total of 25 test columns of 1, 2, 3, 5, 7 meters for simulating multi-layer geological structure of vadose zone. A total of 25 automatic water supplying instrument were designed to simulate and control the depth of water level around the test column，and 140 negative pressure sensors and 140 moisture sensors (including temperature) were set to detect the moisture movement information in the test column. Data collection adopts a step-by-step integration approach that greatly simplifies the cable line, based on this, a data acquisition box is designed to obtain the environmental information of the experimental process in time. In the experiment site, a small (3 m main pole) weather station capable of measuring air temperature, air humidity, air pressure, wind direction, wind speed, precipitation, and evaporation was set up; one set of solar radiation, solar radiation and direct sunlight is installed; a comparative observation facility for evaporation (including precipitation) of 0.3 m2 and 1 m2calibres was also set up. Finally, the paper points out that attention should be paid to the study of vadose zone parameters in the field in order to truly solve the practical application of test results.