The Study On Simulating Of River Pollution To Groundwater During Pumping Near A River

The study of river pollution to groundwater during pumping near a stream has great theoretical and practical significance to development and innovation solute transport theory and research method in aquifer under rivers.Based on the relationship between river and groundwater, the paper studied on water flow and solute transport rule about conservative substance NaCl and non-conservative substance nitrobenzene in river-impendent zone of saturation-zone of aeration-zone of saturation system, combined with indoor physical simulation experiment and numerical simulation. Considering the factor of convection, dispersion and adsorption, a water flow and solute transport coupling model has been built to quantificationally describe the influence of river pollution to groundwater.The following conclusions can be concluded:1,under the condition of no water driving effect, with the increase of time, the solute transport rule shows the gravity differentiation phenomenon. This conclution show that without water driving effect, gravity is an important factor in the process of solute transport.2,Solute transport disciplines in river and groundwater show:the farther from the river, the longer concentration changing time is in horizontal direction; the distribution of solute concentration in the groundwater is changed from the inhomogeneous state in the upper section to the homogeneous state in lower section with the experiment time duration and the increasement of solute transport distance. The speed of solute transport becomes fast with the increase of pumping intensity in saturation zone. As the river and groundwater has unified water level (Plan A-160-130, total time of experiment is 2265min); as the water level is critical disjoined (Plan C-160-90, total time of experiment is 765min); after the water level disconnection (Plan F-160-40, total time of experiment is 890min), solute transport is slightly lower.3,Based on the theory of saturated-unsaturated flow and solute transport, water flow and solute transport about nitrobenzene in the system of river and groundwater is modeled mathematically using FEMWATER module in the GMS.4,Modelling results(1) Once the relationship of river and groundwater stays the same, with the increase of solute concentration, the pollution degree in groundwater increases. (2) The migration of nitrobenzene in groundwater is varying with changing relationship of river and groundwater. When the river level is changeless, the discharge level is critical "disjunction", the speed of solute transport is fastest.