| Abstract: | Chalk crops out from a wide belt around the Paris basin, France, covering an area of about 70 000 km2. In this region, the chalk presents the most important unconfined aquifer because of its extent and the size of its resources ((11–12) × 109 m3 year?1). The assessment of underground outflow depends on the vertical feeding, the infiltration and the hydrometry. This paper analyses the regional structural map, interprets the groundwater reaction under rainfall, explains the water circulation in such media where the reservoir geometry plays an essential role on aquifer response, and determines different aquifer physical parameters. Attempts are made to identify the rapid transfer of groundwater at the level of faults and their important fissures. Based on a quantitative study of the seasonal and interannual piezometry fluctuations, it is noted that the mode and the piezometric chronology events are controlled by major parameters of geological and hydrogeologic contexts, aquifer hydraulic characteristics, the position of upstream and downstream basin limits, groundwater depth and replenishment time. This paper ends with determination of groundwater physical parameters of the diffusivity (T/S, T and S) values by examination of the groundwater replenishments periods. Copyright © 2005 John Wiley & Sons, Ltd. |
