Study On Leakage And Pollution Of Groundwater In Urban Drainage Network Based On GMS

With the rapid expansion of urbanization process and the rapid increase of population,the amount of municipal sewage discharge has increased greatly.Due to insufficient investment,lagging construction of municipal pipeline network,poor quality of construction and late maintenance,the pipeline network has been damaged,resulting in sewage leakage,thus polluting groundwater and soil.Based on the collection of meteorological,hydrological and geological data,the groundwater environment in the study area is investigated and analyzed through hydrogeological surveying and mapping,hydrogeological drilling,water quality analysis,pumping test,leaching test,seepage test,dispersion test and water level measurement.The groundwater in the study area contains high or high iron,manganese and aluminium,among which iron,manganese and aluminium are mostly of type IV and V of quality,which are related to regional stratigraphic structure.The ammonia nitrogen ion index is mainly of type III,IV and V,indicating that groundwater has been affected.The study area has formed a landing funnel centered on two construction sites.The central water level of the landing funnel is buried between 9.13 and 10.72 meters.Compared with the regional data,the central water level of the funnel falls about 6 meters,and the groundwater flow field changes from southeast to northwest in the natural state to flow around the new town.Based on the analysis of the hydrogeological conditions and the present situation of groundwater development and utilization in this area,a hydrogeological conceptual model is established,and the study area is divided into Liaohe alluvial plain area;according to the characteristics of aquifer and water-rich characteristics,it is divided into two aquifers:porous phreatic aquifer of loose rock type and porous micro-confined aquifer of loose rock type;according to the hydrogeological test and hydrodynamic conditions,the boundary conditions and water of the model are The hydrogeological parameters and source-sink terms are calculated and generalized to homogeneous and isotropic two-dimensional unsteady flow.On this basis,the finite difference method is chosen to solve the problem.The MODFLOW(water flow)module and MT3D(solute)module in GMS software are used to establish the corresponding mathematical models of groundwater flow and water quality.The model is identified and validated by the measured water level data in the observation period.Finally,the simulation results are obtained through the parameters,and the water balance calculation and analysis are carried out.On the basis of water flow model,solute transport model was established.Ammonia nitrogen and chemical oxygen consumption were selected as predicting factors?Under the condition of leakage at 32 points,the range of pollution plume was predicted for 100 days,1000 days,3650 days and 7300 days under artificial disturbance and natural flow field,respectively.Finally,some suggestions are put forward for the prevention and control of sewage exosmosis.