Shallow Groundwater Pollution Risk Assessment And Prediction In The Plain Area Of Baiyangdian Basin

Groundwater pollution has the characteristics of complexity,concealment and difficulty in treatment and recovery after pollution.Therefore,effective preventive measures are the key to protecting groundwater from pollution.Carrying out groundwater pollution risk assessment and pollution prediction and early warning are important to prevent groundwater pollution and protect groundwater resources.Initiative.Baiyangdian Lake is the largest freshwater lake on the North China Plain in my country and enjoys the reputation of "the kidney of North China".and it is also an important regulator of the ecological environment of the Xiongan New Area.Therefore,it is of great consequence to study the risk of groundwater pollution and early admonition of pollution in the Baiyangdian Lake Basin.Based on the national key research and development project "Xiong’an New Area Groundwater Environmental Risk Prediction,Early Warning,Prevention and Control",this paper uses the Baiyangdian River Basin plain area as a typical research area to identify the source of groundwater pollution through field surveys and sampling and multiple statistical methods;Based on the groundwater environment and hydrogeological conditions,construct a groundwater environmental pollution risk assessment index system,conduct groundwater pollution risk assessment in the study area,use GIS spatial analysis methods to analyze the spatial distribution of groundwater pollution risks in the study area;select the main study area The pollution component "nitrate nitrogen" is used as a pollution simulation factor,and HYDRUS-1D is used to forecast and early warning of nitrate nitrogen pollution in groundwater in the study area,and the following knowledge and results have been obtained:(1)Through systematic field sampling investigation and test analysis,there are10 excessive components in the groundwater in the plain area of Baiyangdian Lake Basin,and the SO42-,TDS,Mn,NO3-and F-components exceed the standard rate by more than 20%;among them,the nitrate exceeds the standard.The highest rate is31.71%.Through multivariate statistical analysis,it is concluded that TDS,SO42-,Mn,and F-exceeding the standard are caused by the poor original geological environment in the exceeding standard area,while the excessive NO3-is mainly caused by agricultural planting activities in human activities.The nitrate exceeding standard area is located in the alluvial-proluvial plain area of the Baiyangdian Lake Basin,and the other exceeding-standard components are mainly distributed in the alluvial lake plain area around the Baiyangdian Lake.(2)Guided by the systematic thinking of pollution risk assessment,using methods such as data collection,field investigation,and pollution roots danger load assessment to identify agricultural pollution roots,industrial pollution roots,and domestic pollution roots as the main groundwater pollution danger roots in the study area;based on groundwater pollution The characteristics of the danger transmission path,select the seven most critical factors such as the lithology of the aeration zone,the depth of the groundwater level,and the net recharge amount,and use the DRASTIC model to carry out the groundwater anti-pollution performance evaluation;select the groundwater volume and groundwater volume according to the characteristics of the groundwater environment system Water quality serves as the basis for the evaluation of groundwater value functions.On this basis,a progressive multi-dimensional index system for groundwater pollution risk evaluation in the study area was constructed,which laid a theoretical foundation for groundwater pollution risk evaluation in the study area.(3)The superposition index method is used to identify and characterize the pollution risk of the study area,and the pollution danger of the study area is divided into three levels;the areas with higher pollution danger are mainly distributed in Baoding,Mancheng and other places,with a total area of 1,747.04 km2,accounting for the study area.15.89% of the total area of the district,agricultural planting has the greatest impact on it,followed by anti-fouling performance.60.32% of the study area is a medium-danger area,with a total area of 6631.94km2,and the factory’s sewage discharge affects it the most.The low-danger areas are mainly distributed in Laishui and Xiong’an New District in the front of the plains of the Baiyangdian River Basin,with a total area of 2,15.62 km2,accounting for 23.79% of the total area of the study area.(4)Nitrate is the pollution component with the highest rate of exceeding the standard in the study area.The main cause of pollution is the application of human agricultural fertilizers.In order to predict the future pollution trend of shallow groundwater in the Baiyangdian Lake Basin,nitrate nitrogen is selected as a numerical simulation factor.On the basis of considering the lithology,fertilization amount and thickness of the unsaturated zone,15 representative points were selected in the study area,and HYDRUS-1D was used to predict groundwater nitrate in the study area for 15 years and 30 years.Pollution risk.The results show that by 2035,the early warning of nitrate nitrogen in shallow groundwater in most areas of the Baiyangdian Basin plain is at level I,and that in some areas of Baoding City is at level II.By 2050,the early warning of nitrate nitrogen in shallow groundwater in alluvial lake areas such as Xiongxian County and Anxin will be at level I;in most areas of the northern Baiyangdian Basin Plain,the early warning of nitrate nitrogen in shallow groundwater will be at level III;In the alluvial plains of the Baiyangdian River Basin in Tangxian County and Quyang County,the groundwater nitrate-nitrogen warning is level IV.(5)Based on the results of groundwater pollution risk assessment and nitrate-nitrogen early warning results in the plains of the Baiyangdian Lake Basin,based on the three elements of risk sources,risk pathways and risk receptors,from the control source — the dangerous path interception — the risk receptor protection and restoration Based on the concept of “Risk Classification and Grading Control and Control ”,the groundwater pollution grading and classification management and control plan has been formulated,which highlights the identification and control of groundwater pollution risks under different hydrogeological conditions.