Influence Of Incoming Water From South-to-North Water Transfer Project On Soil Characteristics Of The Reservoir Area Of Miyun Reservoir

As an important source of domestic water consumption in Beijing,Miyun Reservoir provides about two-thirds of the domestic water consumption in Beijing.At the same time,Miyun Reservoir also plays an important role in flood control of rivers such as Chaohe and Baihe.The South-to-North Water Transfer Project is a basic project to optimize water resources allocation and promote regional coordinated development.It is the most strategic project with the largest investment and the widest coverage since the founding of New China.In the South-to-North Water Diversion Project,Beijing belongs to the middle line project of the South-to-North Water Diversion Project.According to the project plan,Beijing receives an annual water transfer of about 1.05 billion m3,and Miyun Reservoir undertakes the main task of accepting water transfer.With the influx of a large amount of fresh water resources,the water level of the Miyun Reservoir will also rise,with a rise of about 10m.The rise of the water level will inevitably affect the soil in the Kubin belt and the water level variation area,resulting in changes in its physical and chemical properties.Therefore,it is necessary to study the soil in the reservoir area of the Miyun Reservoir and the water level variation area after water transfer,to find out the soil status of the Miyun Reservoir after water transfer,and to explore the impact of the water from the South-to-North Water Transfer Project on this part of the soil.In this study,the soil physical properties and heavy metal pollution,nitrogen and phosphorus organic matter content,etc.Background data,a comparative analysis of the impact of the South-to-North Water Transfer Project on the soil properties of the Miyun Reservoir reservoir belt and water level variation zone.After research,the main conclusions are as follows:(1)In terms of soil physical properties,the soil density in the study area after water intake is between 1.10 and 1.44 g/cm3,the total porosity is between 39.97 and 68.40%,and the capillary porosity is between 22.81-46.89%.Between 11.75 and 31.62%.After the water coming into the study,the soil density in the study area decreased by 7.5%on average,the capillary porosity increased by 3.1%on average,the total porosity increased by 6.2%,and the field water holding capacity increased by 1.3%.In terms of soil texture,the soil particle size in the study area after the incoming water is 0.02-2mm,about 66%of the soil is sandy loam,and the rest of the soil is silty loam.According to the gravel,57.2%of the soil is medium gravel soil.After the incoming water,the average sand content decreased by 28%,the average grain content increased by 1.6 times,and the clay content decreased by 85%on average.The soil was mainly gravel before coming to the water,and the water was converted to medium gravel.Mainly,the gravel content decreased by an average of 24%.(2)In terms of soil heavy metal content,about 77%of the soil in the study area had a heavy metal pollution level of one level,which was 26%higher than before the water.After the water is coming,the soil heavy metal pollution level decreases.From the average value,the chromium content decreases by 37.84%,the nickel content decreases by 34.92%,the arsenic content decreases by 36.82%,the lead content decreases by 68.65%,and the cadmium content decreases by 92.86%.The copper content decreased by 16.5%,the mercury content increased by 9.6%,and the zinc element change was relatively insignificant,only increasing by 0.1%.(3)In terms of soil nutrient content,the total nitrogen content in the study area was higher,the total phosphorus and available phosphorus content were lower,the organic matter content was not evenly distributed as a whole,and the extremely low to very high water level existed in the study area.Compared with pre-water,the contents of total phosphorus,organic matter,available phosphorus and ammonium nitrogen increased,and the contents of total nitrogen and nitrate nitrogen decreased in various samples in the study area.In general,the total phosphorus content increased by an average of 73%,the ammonium nitrogen content increased by an average of 2.3 times,the effective phosphorus content increased by an average of 91%,the organic matter content decreased by an average of 16.6%,the total nitrogen content decreased by an average of 25%,and the nitrate nitrogen content.The average reduction is 7%.