Determination Of Groundwater Flow Velocity And Direction Application Of Temoerature Tracer And Study Of Aquifer Hydraulic Tomography

The groundwater velocity and direction are important components of aquifer parameters,whose measurement plays an important role in the utilization of groundwater,environmental pollution prevention,pollutant transport and engineering construction.However,groundwater is buried below the surface.It is very difficult to directly measure the flow velocity and direction of groundwater.The complexity of spatial structure of heterogeneous aquifers in strata will lead to the complexity of groundwater movement.Groundwater flow characteristics can reflect the distribution of aquifer seepage field.By detecting the velocity and direction of groundwater flow,not only the parameters of aquifer seepage can be obtained,but also the characterization of heterogeneous aquifer can be helpful.However,the traditional method of measuring the velocity and direction of groundwater flow in hydrogeology has a long period,and it is difficult to guarantee the accuracy.The artificial isotope tracer method based on point dilution principle uses radioactive isotopes which are harmful to the health of the experimenters and will pollute the groundwater.In this paper,the temperature is used as a tracer to detect the groundwater velocity and direction through temperature variation.This is beneficial to environment,detection.Also,it will not change the material composition of groundwater seepage field.The main research work and results of this paper are as follows:(1)A groundwater flow velocity and temperature tracer detection system was developed.The system includes data acquisition device,the velocity meter system,sand box test system,warm water circulation system,seepage velocity regulating system.It can simulate different horizontal flow velocity under different temperature condition and develop a groundwater temperature probe which can rotate 360 degrees.(2)The detection of velocity and direction of groundwater flow based on temperature tracing was carried out.In the study of groundwater flow velocity,the influence of groundwater temperature,the size of velocity probe and the heat flow velocity in velocity probe on the temperature difference between the inlet and outlet probes is analyzed under different groundwater seepage velocity conditions by using the groundwater flow velocity and temperature tracer detection test system.In the study of groundwater flow direction,the groundwater under different groundwater seepage flow direction conditions is analyzed.The influence of water temperature,seepage velocity of groundwater and heat flow velocity in the probe on the temperature difference between the two ends of the probe is discussed.An empirical formula of flow velocity and direction based on temperature tracing is proposed.(3)A tomographic scanning test system for groundwater aquifer has been developed.The system consists of an aquifer test device,a data acquisition system and a water level regulation system.The pumping test with or without groundwater velocity is carried out by using the system.The influence of groundwater velocity on the characterization of aquifer permeability is analyzed.The results show that under the condition of groundwater,the information of water level change in monitoring wells,K value of fitting curve,regional range of middle and low head in total head,distribution of pressure head and distribution field of permeability characteristics of aquifer obtained by forward modeling are better than those without groundwater flow rate.