Research On Formation Mechanism And Evolution Rule Of Groundwater Funnel In Northern Weifang

With the development of social economy and the increase of the demand for water resources,the groundwater level in northern Weifang is declining.The landing funnel was formed in Shouguang,Hanting,Changyi and other places since 1983.With the overexploitation of groundwater,landing funnel in northern Weifang continued to develop,and caused a series of problems such as salt water intrusion,groundwater pollution and land subsidence.The contradiction between economic development and environmental resources has become increasingly prominent.It is of great significance to study the formation and evolution mechanism of the landing funnel in northern Weifang,to restore and protect the groundwater level,to guide the reasonable exploitation and utilization of the groundwater and to achieve healthy development of ecological environment.In this paper,the coniferous funnel formed in Changyi city,Shouguang city and Hanting district in northern Weifang are taken as the research object.The following studies are mainly carried out:(1)The dynamic characteristics of groundwater level and water chemistry in northern Weifang were analyzed.(2)The evolution of the falling funnel in northern Weifang was analyzed,and the development stage of funnel was defined.The developing trend of funnel and the developing characteristics of funnel were studied.(3)The correlation analysis was used to quantitatively study the relationship between groundwater level and groundwater exploitation,rainfall infiltration,river infiltration recharge and agricultural irrigation infiltration in northern Weifang,and the influence degree of various factors on the groundwater descent funnel were analyzed.(4)Determined the main cause of groundwater funnel in northern Weifang by principal component analysis,and explored its mechanism.(5)Put forward the governance measures of Weifang funnel area.The main results are as follows:(1)The groundwater level in northern Weifang is affected by the exploitation of groundwater.With the increase of groundwater exploitation,the groundwater level declines.The change of groundwater level during the year is affected by agricultural irrigation water and precipitation.(2)From 2000 to 2015,the content of chemical ions and types of groundwater in northern Weifang were changed.While the over-exploitation of groundwater changed the flow field of groundwater,infiltration and recharge increased,calcium and magnesium minerals which areoxidized and dissolved into the water,combined with increased groundwater pollution,resulting in the increase of hardness and TDS concentrations.(3)Using Surfer to visualize the funnel of northern Weifang,the contour map and threedimensional surface map of groundwater level in northern Weifang were drawn.The development of groundwater level descent funnel was presented from horizontal and vertical image,and the evolution of funnel,analyzed and summarized the characteristics of the funnel in northern Weifang,including regional,inheritance,inconsistent development,center mobility and so on.(4)The development stage of funnel in northern Weifang is divided.Changyi funnel:from 1984 to 2007 for the straight-line development stage,2008 to 2012 for the stable development stage,2013 to 2015 for the rapid expansion stage,the future for the gradual recovery stage.Shouguang funnel: from 1983 to 2005 for the straight-line development stage,from 2006 to 2009 for the stable development stage,2010 ~ 2015 for the rapid expansion phase,the future for the gradual recovery stage.Hanting funnel: 1983 to 2003 for the straight line development stage,2004 to 2007 for the stable development stage,2008 to 2015 for the rapid expansion stage,the future for the gradual recovery stage.(5)According to the correlation coefficient obtained by the Pearson correlation coefficient,the groundwater level was correlated with several influencing factors,such as groundwater exploitation,rainfall infiltration,river leakage,irrigation infiltration and so on.And we can see that there is a strong correlation between the groundwater level and the groundwater exploitation of northern Weifang,and the negative correlation shows that the groundwater level continues to decrease with the increase of exploitation volume.There is a significant positive correlation between groundwater level and rainfall infiltration.Rainfall infiltration plays a leading role in the formation of the falling funnel in northern Weifang.In addition,the groundwater level is also correlated with the channel leakage recharge and agricultural irrigation infiltration.The rapid socio-economic development,population growth and the establishment of water storage projects indirectly affect the development of the landing funnel by influencing the recharge and excretion of groundwater.(6)The main cause of the funnel in northern Weifang is analyzed by using principal component analysis(PCA).The analysis can be divided into nature factors and man-made factors,and then determine its impact mechanism.The man-made factor is that in the process of regional economic development,the over-exploitation of groundwater continuously,population growth and urbanization development reduces the groundwater level,which leads to the formation of the falling funnel.Nature factors are manifested in climate change,reduce of precipitation and runoff leading to the recharge of groundwater which cause the development of a landing funnel.Among them,precipitation and groundwater exploitation are the greatest impacts,which can be the main driving force of the funnel.