This report describes various problem solving techniques in mathematical modeling for calculating various parameters of water e.g. temperature, pH, Dissolved oxygen. A mathematical model provides the ability to predict the contaminant concentration levels of a river. Here we are using an advection-diffusion equation as our mathematical model. The numerical solution of equation is calculated using Matlab & Mathematica. Parameter estimation is necessary in water modeling to predict the different parameters of water at different point with minimal errors. So here we use 2D & 3D interpolation technique for parameter estimation.