CONVOLUTION IN TIME-DEPENDENT SYSTEM FROM ARTIFICIAL TRACER TEST RESPONSES - APPLICATION ON A KARST SYSTEM (CAUSSE DE GRAMAT, LOT, FRANCE)

Artificial tracer tests conducted under different hydrodynamic conditi ons on the karst system of Ouysse (Causse de Gramat, France) and chemi cal measurements have permitted the use of the time-dependent tracer t est analysis. For artificial tracer experiments in different hydrologi c periods (water rise and high flow), the relationships between the re sponses to an instantaneous injection are improved in a system defined by two inputs (losses of Themines and Theminettes). They show that th e space occupied by the mass of tracer during its transfer can be cons idered as independent of the discharge according to the range of flow rate in which the tracer experiments have been conducted. Therefore, c onvolutions on chlorides, nitrates and suspended sediments are simulat ed under the hypothesis of a constant-volume and time-dependent system . The computed results are compared with the experimental data at the output (cave of Besaces).