| Contaminated groundwater sites requiring remediation treatment exist all over the world. However, many of these sites have inadequate hydraulic information leading to inefficient cleanup strategies. Thus, many studies investigate the best way to obtain accurate hydraulic information (i.e., hydraulic conductivity or permeability) of the subsurface from secondary measurements such as hydraulic head and tracer/contaminant concentrations. Due to the limited amount of information and their associated uncertainty, these problems are often ill posed and non-unique. To minimize these shortcomings, different methods have been applied. An increasingly popular method to determine hydraulic conductivities in a given site is the pilot point method (PPM). The physical meaning of pilot points is that they are not direct measurement points; rather these selected points are added to the parameter search procedure to reduce the ill-posedness.;Two different evolutionary search based PPM approaches are developed in thesis as follows: (1) D-optimality sensitivity based method (SBM) that uses D-optimality criterion to search for pilot points and then a subsequent search for hydraulic conductivity values at these points, (2) A simultaneous search-based method (SSBM), where pilot points and hydraulic conductivities are searched simultaneously. These methods are first tested with hydraulic head measurements and then with both hydraulic head and concentration measurements using several synthetic problem scenarios.;Results show that the selected pilot points using SBM lead to a more accurate hydraulic conductivity characterization than a random set of pilot points and a sequential PPM developed previously. SSBM provide comparable hydraulic conductivity distributions to those from SBM, however it has more variance in searching hydraulic conductivities when performed over several trials. When tracer concentration measurements are added to the head measurements, both methods result in improved hydraulic conductivity characterization. |
