Study Of Groundwater Typical Pollutant Spatiotemporal Distribution And Water Quality Evaluation

Groundwater is an important component of the water resources system.Recently,due to the combined effects of human factors and natural factors,problems such as deterioration of groundwater environment and reduction of available water volume have emerged.If this is the case,the long-term development of society will be restricted to a certain extent.Linyi Economic and Technological Development Area is located in the southeastern part of Linyi.As a new urban area with a large agricultural development background,the groundwater quality has been affected by long-term and large-scale agricultural production.At the same time,with the acceleration of urbanization construction,the industrial industry in the development area has developed rapidly,and the groundwater is affected to some extent by the risk of industrial pollution.Therefore,as the agricultural irrigation water and auxiliary water for development in the development area,the quality of the groundwater is the key to the sustainable development of the development area.Taking Linyi Economic and Technological Development Area as the research object,the dissertation focuses on the application of GIS to reveal the spatial-temporal distribution and causes of typical groundwater pollutants in the study area,and analyzes the overall water quality status and changes by means of annotation scoring method and fuzzy comprehensive evaluation method.The study provides a basis for the long-term and effective implementation of scientific planning and sustainable use of groundwater in the study area.The main contents and results of the study are as follows:(1)The typical pollutants affecting the shallow groundwater quality in the dry season of 2012 and 2017 in the study area using the priority control pollutions screening method based on pollution assessment were nitrite,anionic surfactant,ammonia nitrogen,fluoride,sodium,nitrate,permanganate index,sulfate,chloride,total hardness,total dissolved solids.The typical groundwater pollutants in 2012 and 2017 are the same in the types of indicators,and the difference is that the order of each indicator is different.(2)GIS and inverse distance weighted interpolation were used to analyze typical groundwater pollutants in the study area in 2012 and 2017,and a series of results were obtained to realize spatial visualization of pollutants,and then the spatial-temporal distribution and formation reasons of each typical pollutant were analyzed in detail.Among them,nitrate and total hardness concentration have positive correlation,which is the most significant impact indicator of water quality in the study area.It is mainly related to large-scale agricultural fertilization activities and its own stratum lithology in the study area.(3)The annotated scoring method and the fuzzy comprehensive evaluation method were used to evaluate the shallow groundwater quality in the dry seasons of the study area in 2012 and 2017.The results show,the quality of groundwater in the study area was poor in 2012 and 2017,but the water quality in 2017 has obviously improved compared with 2012;The water quality evaluation results obtained by the fuzzy comprehensive evaluation method are generally better than the annotated scoring method,and the degree of compliance with the actual water quality is better.The study area belongs to the large area category,and the fuzzy theory is more suitable for the groundwater quality evaluation in this study area.(4)Based on the comprehensive analysis of the pollutant characteristics and water quality evaluation results in the study area,it is concluded that the main reason for the poor groundwater quality in the study area are the high primary total hardness content under hydrogeological conditions,large-scale agricultural fertilization activities and slight industrial pollution.