22. Green Element Solutions of the Source Identification and Concentration in Groundwater Transport Problems

The inverse problem of source identification in groundwater contaminant transport poses challenges of non-uniqueness and instability of the numerical solutions. In this work, a methodology based on the Green element method (GEM), is presented for simultaneous recovery of the release history of pollution sources and concentration plume from available concentration measurements. The ill-conditioned, overdetermined system of equations that arises from the Green element discretization is solved by the least square method with Tikhonov regularization and aided by the singular value decomposition technique. The performance of the methodology is illustrated using two cases. The influence of the number of pollutant sources and their magnitudes are also examined. It is found that GEM is capable of correctly predicting the source strengths of pollutants instantaneously introduced into the aquifer and as well the concentration plume arising therefrom.