CHANGES OF GROUNDWATER LEVE AND SELF-POTENTIAL RESPONSE CHARACTERISTICS DURING PUMPING

This paper designed and processed flume model test,carried out pumping tests of single-hole complete wells with constant flow,combined with real-time dynamic monitoring of self-potentia(SP),and studied the groundwater level changes and SP response characteristics during the pumping process of phreatic aquifers. The results show that when pumping,both the groundwater level and SP decrease rapidly and gradually stabilize,but it takes a short time for the groundwater level to decrease to stability,and it takes a longer time for the SP to decrease to stability,with hysteresis. The greater the pumping flow,the greater the drop in groundwater level and SP; the farther away from the pumping well wall,the longer it takes for SP to stabilize. The self-potential difference(ΔSP) and the groundwater level drop depth(s_w) satisfy the linear function relationship,and the ΔSP and the radial distance r both satisfy the exponential function relationship. According to the fitting formula,the groundwater level drop values at different positions in the model are calculated and compored with the observation values. The comparison of groundwater level and precipitation shows that the error between the calculated and observed values is relatively small,which indicate that this formula can be used to calculate and predict the groundwater level during pumping.