Study On Groundwater Hydraulic Connection In Different Aquifers Under Mass Pumped Conditions In Typical Area North China Plain

The purpose of present work is to revealed hydraulic connection among five different depth aquifers in test field of The ministry of Land and Resources P.R.C. in Hengshui in east North China Plain. The main work mean was pumping test. The present work studied stratum constructuction feafure, groundwater level dynamic during one year and pumping test pierod, geohydrochemistry, isotopes, trace elements, groundwater age and numerical simulation and gave the study result and provied scientific data for rational exploitation and utilization groundwater resources and scientific management.Taken the system theory as guide and the chemical, trace elements and isotopic component as information of hydraulic connection, the present work carried out the research by using hydrogeology, geohydrochemistry, isotope hydrology and relevant mathematics methods, groundwater dynamics theory. Firstly, based on understanding of the research achievements in research area, physical frame of groundwater system and constituted detailed pumping test project which observed water level dynamic by using advanced observation devices were analyzed. Secondly, groundwarer recharge and discharge character of different aquifers using chemistry, trace elements and isotopes in groundwater was identified. Finally, the hydraulic connection among different aquifers using numerical simulation was investigated and ascertained in the present work.The following results were obtained from present research.1. Undering large sclae exploitation conditions, they take on each hydrological dynamic character in shallow groundwater system and deep confined groundwater system. Pricipitation directly recharged shallow groundwater and oxy hydrogen isotope contents are higher than deep confind groundwater. The isotope age indicated that shallow groundwater actively participated in hydrological cycle present period. The recharge sorces are areaal groundwater flow and leaky flow from other aquifers in deep confined groundwater.2. Two subsystems were separated from deep confined groundwater system in research area. Up groundwater subsystem was named by the 2nd and 3rd aquifers, and down groundwater subsystem by the 4th and 5th aquifers. There are idiographic hydrogeochemical type and isotopical character in two subsystems. Groundwater was admixing water by present water and fossil water in up groundwater subsystem and fossil water in down groundwater subsystem based on Tritium isotope.3. Deep groundwater was recharged by shollow groundwater as leakage. 21.4% of exploitation quantity come from shollow groundwater by leakage in 2nd aquifer. Exploitation quantity was mainly storage in deep groundwater but the groundwater composition was diversitible in different aquifers. The exploitation quantity was made up storage and leakage in 2nd aquifer and storage and level influs in 3rd, 4th and 5th aquifers.4. There is pumped effect in groundwater system. Pumped effect was defined a kind of phenomenon when water level was fall in unpumped aquifer with fall in pumped aquifer. The fall in unpumped aquifer was brought by formation pressure change when pumping in pumped aquifer. Pumped effect was not water exchange. A lot of test data indicated that have leaky effcet as well as pumped effect among five aquifers in research area undering large sclae exploitation conditions. The two effects were simultaneously existence.5. Based on the analysis result, rational exploitation and utilization groundwater resources project were put forward in the present work. The 3rd aquifer was prefered to exploit, the 2nd aquifer was rationally exploit, the 4th aquifer was restrictically exploited and the 5th aquifer was forbad exploitation.