Karst Spring Flow Simulation Considering Effects Of Unsaturated Zone And Pipe Flow

The carbonate rock is widespread in Southwest China with abundant karst water resources.In this area,the karst water is always the main water resource for life and production.Due to the dissolvability of carbonate rocks,conduits often exists in the karst aquifer besides small fractures.Generally,the karst aquifer can be divided into fissure system with high storage capacity and conduit system,which acts as the main drain passage.The groundwater in the aquifer is drained by the conduit network in springs.Karstic springs,as the karst surface and groundwater drainage channel,are often used as sources of drinking water.Their dynamic changes are the integrated responses of the regional hydrological characteristics.Therefore,it is of great theoretical and practical significance to deeply study its response mechanism to environmental factors,establish a hydrological application model and explore its hydrological processes.The Jiji test site is located in the eastern suburbs of Guilin City.It is a typical karst peak-cluster depression landform.The entire test field can be roughly divided into 4 sub-spring fields.The S31 spring field is the largest sub-spring field in the Jiji test field,mainly subject to No.1 Relief of No.3 and No.4 depressions.In this study,the S31 spring field of Guilin Yuji Test Site was used as an example.UAV remote sensing technology,climatic and hydrological observation,tracer and infiltration tests were used to obtain the research area and rainfall.The hydrological parameters corresponding to the measured flow rate of the actual spring,combined with sinkholes and tracer data to divide the basin,determine the groundwater flow direction and the general location of the karst pipeline,and generalize the model and establish the three-dimensional spring field of the S31 No.Groundwater numerical simulation model,using the three-dimensional finite difference groundwater flow model(MODFLOW-2005)UZF(Unsaturated-Zone Flow)unsaturated zone flow module and CFP(Conduit Flow Process)karst pipeline flow module to simulate the karst spring flow,successively identified model Parameter calibration,calibration and validation are used to determine the reliability of the model.Finally,the comparison and analysis of the unsaturated zone and the pipeline in the karst Hydrological processes Cluster Depression and its role.The results show that the different modules can be implemented by adding different modules or two modules at the same time.The UZF module can better simulate the regulation and storage of the unsaturated zone.The CFP pipeline module can simulate the pipelines in the karst area.The flow Errors for various simulation scenarios are expressed in terms of correlation coefficients.The closer the correlation coefficient is to 1,the higher the degree of fit,and the correlation coefficient when two modules are added at the same time is 0.975.When only adding CFP module correlation coefficient is 0.971.When only UZF was added,the correlation coefficient was 0.612.When neither module added is 0.517.It shows that adding UZF and CFP modules at the same time has the best effect.Using both of them can simulate the spring flow in the karst area more accurately.