Causation of groundwater level descending since October 2009 in Yunnan Yaoan well

Abnormal dynamic change of groundwater could be the precursors of earthquake, but sometimes it was induced by other environmental disturbances, such as rainfall and groundwater exploitation. For distinguishing earthquake precursor, it is important to identify environmental disturbance in time. Water level in Yaoan well consistently declined since October 2009, and the max amplitude was about 3 meters. The influence of rainfall and groundwater pumping was analyzed by using a mathematical physics model in consideration of the characteristics of hydrological geology environment. The result shows that the decline of groundwater level may be related to the increased groundwater pumping owing to the reduced precipitation around Yaoan well since October 2009. The approach of this study may be helpful for future disturbance identification and precursor confirmation.