Slug tests: Experimental study of hydraulic shock tests on the Oise structures (application to the Hydrogeological Experimental Site of Beauvais)

The Upper Cretaceous chalk aquifer is a vital water resource for industrial and agricultural activities in the Oise department (Hauts-de-France). To obtain the hydrodynamic characterization of the aquifer, field tests were implemented. This study aims to determine the hydraulic properties of the Hydrogeological Experimental Site of Beauvais (HESB, UniLasalle) with series of slug tests, which is a common field test method preferred for reasons such as cost-effectiveness, fast implementation, and quick response. Results obtained from the hydraulic investigations will be used while creating the hydrogeological model and developing the numerical code to identify the spatial distribution of the HESB transmissivity values which is useful to determine the groundwater circulation and potential mitigation of groundwater pollution. It will also provide information about the parameters required to define hydrogeological wells that are favorable for installing the pump system. Numerous experiments were carried out in eighteen wells in the study area. For understanding the behavior of groundwater, the applied tests need to be analyzed. Experimental results were analyzed with the Bouwer & Rice method, which is applicable for unconfined aquifers. Analytical solutions were performed by using an aquifer test analysis software called AQTESOLV. Experienced hydraulic conductivity value of site varies between 4.43e-8 and 7.56e-6 m/s. Concurrently, the groundwater recharge was estimated with episodic event-based approaches of the water table fluctuations (WTF) method. Another approach used in this study is the steady-state and transient-state modeling. These models resulted in hydraulic conductivity distribution maps and transmissivity values.