Study On The Aquifer Clogging Along With The Groundwater Recharge By The Yellow River Water In The Strong Leakage Area Of The Yufu River

In order to ensure the water supply and the spring spewing in the urban area,a series of Managed Aquifer Recharge(MAR)projects had been carried out in the Western and Southern of the Jinan city,where was the main recharge area of the spring water.However,no matter what kind of groundwater recharge will face the problem of aquifer clogging due to the poor recharge water quality.Aiming at the aquifer clogging problem during the groundwater recharge by the Yellow River water,the strong leakage area of the Yufu River which was located in the southwest of Ji'nan city was chosen to be the study area.Combining field monitoring and sampling tests with the laboratory sand column experiment,the aquifer clogging forms,clogging factors,the sources and micro motion of the particles were studied and the effects of the groundwater recharge was verified.The conclusions of this research are as below.(1)The main aquifer clogging risk along with the groundwater recharge in Yufu River strong leakage area by the Yellow River water was the physical clogging,others,such as chemical clogging,biological clogging and mechanical clogging were not the main problem along with the groundwater recharge.The main influencing factors of the aquifer physical clogging in the study area were the height of the water head and the content of the particles including the internal and external particles.(2)The clogging of the sand column showed that although the concentration of the external particles cannot affect the stable permeability coefficient of the sand column,but the higher concentration of the external particles,the faster and more dense of the sand column clogging,the increase of the external particle concentration will promote the downward movement and accumulation of internal particles to a certain extent;in general,a higher recharge water head causes a greater degree of sand column clogging,the low recharge water head can promote the clogging caused by the internal particles and the high recharge water head is easy to take the particles into the deep layer of the sand column causing the deep clogging of the sand column.The effluent water quality of the sand column showed that the higher concentration of the external particles,the greater the effluent water turbidity;the presence of internal particles is crucial for the control of the turbidity during the recharge process;the recharge water head shows no connection with the stable effluent water turbidity of the sand column.(3)The weighting of the particles after the sand column experiments show that the weight of the particles in the upper layer of the sand column is 1.4 times to the original sand particles,the particles in the upper layer in the middle layer is nearly the same with that of the original sand and the lower layer is 1.2 times to the original sand.The weight differences of the particles showed that the external particles mainly accumulated in the upper layer,and internal particles mainly accumulated in the lower layer,the distribution of the fine particles in sand column shows a " More on both sides,less in the middle" phenomenon,more attention should be paid to the shallow aquifer clogging as well as the deep one.From the microscopic point of view,the particles whose diameter is in 1?m~10?m and 50?m~74?m show weak mobility and tend to accumulate in the sand column,the 10?m~50?m diameter particles show strong mobility and tend to flow out of the sand column with the recharge water.The mobility and accumulation of the external particles in all diameter ranges showed a relatively uniform tendency.(4)The groundwater levels in the monitoring wells rises with the increase of water supply in Yufu River according to the field monitoring results,which indicated that the groundwater recharge through the Yufu River increased the groundwater amount effectively.The sampling tests results showed that the groundwater quality have been greatly improved through the filtration of the aquifer.At the same time,the results of the laboratory sand column experiment have been proved by the field monitoring and the sampling tests,which shows that the laboratory results can be applied to the field.(5)The fine particle content in the sand collected in the field is about 5%,and the maximum fine particle content causing clogging is about 7.2%.Considering the capacity to accommodate the particles in the aquifer as well as the clogging of the Yufu River strong leakage area,the operation of the MAR project in Yufu River is good and the Yufu River strong leakage area will have a long life for recharge.The results of this study may not only have a certain guiding significance on the project location,recharge water amount,recharge duration,recharge safety and sustainability as well as the impact on the groundwater environment and water quality,but also have a certain reference value to the area which have the similar hydrogeological conditions with the Yufu River.