Parametric sensitivity analysis of tracer and groundwater contaminant transport models

The parametric sensitivity of three one-dimensional convection-dispersion models has been investigated for both design and interpretation of field experiments. Two of the models describe the transport in a unidirectional flow system such as tracer and/or contaminant transport in a fracture(s) located in an infi-nite/finite matrix. The third model describes the transport in fractures during a recirculating tracer test. In this work the model parameters are specified as the characteristic times of convective and dispersive transport along the flow direction and fracture matrix interaction. Regardless of the employed model, the instantaneous injection solutions are found to have higher sensitivity to parameters than do the continuous injection solutions. For a homogeneous system model our conclusions on sensitivities to convection and dispersion parameters agree with those of earlier studies. For a fracture matrix system, the model sensitivity decreases significantly to convection and dispersion characteristics times when compared with those of a homogeneous system. In recirculating tracer test models, recirculations contribute only insignificantly to reduce the uncertainty in the estimates. In case of a supporting injection well, the model is practically insensitive to the transport parameters of the path connecting the supporting well to the production well