Under The Action Of Water Physical And Chemical Mechanism Of Change The Coefficient Of Permeability Of Weihe River Is Studied

Streambed vertical hydraulic conductivity is of great importance in the exchange of water discharge and water quality between stream water and groundwater. The Weihe River, one of the mother river of the Guanzhong area in Shaanxi Province, has35groundwater water sources along its riversides.When contaminated river water seep into the groundwater, it is possible to enter and pollute the pumping system. Therefore, it is necessary toillustrate the variation of the streambed vertical hydraulic conductivity of the Weihe River. Water pollution is serious and water quality composition is relatively complex in the Weihe River.Physical and chemical effects between infiltrating river water and sediment will affect the riverbed permeability.Therefore, it is necessary to conduct in-depth study of physical and chemical effects on the influence of the Wei River bed permeability coefficient. After field investigation, the study area is selected in the Lower Wei River of Xianyang, Lintong, Huaxian, Meixian, Caotan. An in-situ permeameter test using the falling head method had been done in the study area.The river water and sediment samples in measuring tube had been collected, which used for laboratory analysis. The result of in-situ permeameter test showed that the permeability coefficient displayed variability in time and space.Feature size d60which obtained from particle size analysis and vertical permeability coefficient Kv related formula: Kv=9×10-6×d608.9343.Through the sudy of permeability coefficient of each measuring tube,it is concluded that the coefficient of permeability is not only influenced by the particle size, but also influenced by the riverbed sediment structure and texture.Using permeability coefficient and the physical and chemical parameters (except feature size) of river water and riverbed sediment for relevant analysis, it showed that permeability coefficient is significantly correlated with total phosphorus, alkalinity and is significant correlation with the river flow, CODMn in river water.lt is also significantly negative correlated with the riverbed effective phosphorus、Cu element、organic matter and is significant negative correlation with K element in sediments. The permeability tests conducted in the laboratory that each tube in the condition of clean water and river water show that Ktw value obtained from the condition of clean water is greater than Krw value that under the condition of river water.lt is because that permeability coefficient affected by leachate viscosity, and it is also affected by the river suspended matter, which will settlement accumulation and jam gap between sediment particles. Carbonate buffer have side effect on sediment permeability, making permeability decrease with the increase of the concentration of carbonate buffer. Although the side effect is bigger as the increase of the concentration of carbonate buffer, the degree which affects is relatively lower. Under the action of nutrient solution, the vertical hydraulic conductivity of measuring pipe increased with time firstly, and then decreased. Infiltration experiments that tube in tap water and acid solution show that acid solution can enhance the permeability of sediment, but the influence is different.to different sediment structure or composition. Through fitting permeability coefficient getted from Xianyang and second Caotan field experiment and organic content, fitting curve equations can be getted,respectively is:y=-0.065+0.138x-0.0139x2, y=0.232-0.044x+0.0028x2, and the influence mechanism that sediment organic matter affect penetration performance had been analyzed.