Assessment Of Groundwater Pollution And Simulation Forecast Of Nitrate Transport In Laizhou Plain

Groundwater is an important water supply source in Laizhou City,which is of great significance to the local economic and social development.However,due to the excessive application of chemical fertilizer and pesticides in recent years,the problem of nitrogen pollution in groundwater is becoming more and more serious.Therefore,it is of great significance to investigate and evaluate the local groundwater pollution and predict its development trend.On the basis of previous studies,combined with the local hydrogeological survey and agricultural survey data,this paper selects Laizhou plain area as the research object,and carries out sampling detection and pollution evaluation on the groundwater.It is found that the hydrochemical types in the study area are mainly HCO3·Cl-Ca type water,Cl-Na type water and Cl-Ca type water,and the underground water NO3-There was a high positive correlation with total hardness,TDS,NO2-and NH4 +,and there was a significant correlation between pH and NH4+.The results of water quality assessment show that the groundwater quality in the study area is poor,except for a small part of the south of Shiyu village in the southwest,which is class III groundwater,and most of the area is class V groundwater;the overall pollution level in the study area is light and medium pollution,and the north of Houtun village in the northeast is a heavily polluted area;the Dratic index scoring method is used to modify the research by adding the land use type and the allowable exploitation amount of groundwater According to the special vulnerability assessment of groundwater nitrate in the study area,the whole study area is class Ⅱ special vulnerability area,accounting for 77.9%of the total area.The Wanghe River Valley and flood plain area as well as dianwang Caojiabu,goubeiwang Houtun Baowang Qinjia area are class III vulnerability areas,accounting for 18.9%of the total area.The south of Shijiang village and the north edge of Xiaozhu village are class I vulnerability areas,accounting for 18.9%of the total area The proportion is 3.2%,and the risk of nitrate pollution in the study area is above medium.Aiming at the situation of groundwater nitrate pollution in the study area,and aiming at the situation of groundwater nitrate pollution in the study area,using MODFLOW module and mt3ds module of MODFLOW software to establish groundwater seepage model and solute transport model,respectively,to simulate the change trend of NO3--N concentration in groundwater in the study area in the next 20 years.The results showed that according to the current land use and fertilization intensity,the NO3--N concentration in the groundwater in the study area decreased slowly,and the pollution degree decreased slowly.When simulated in different production situa-tions,it was found that adjusting the industrial structure and reducing the amount of chemical fertilizer could reduce the pollution degree of groundwater in the study area.