Stochastic Analysis Of Response Functions Of Nitrogen In Stream Water

Abstract

In the present study, a stochastic model of nitrogen in streams is created using a new mathematical technique, Probability Density Function/Moment technique (PDF/M). The model is based on a set of four highly non-linear second order equations for nitrogen species in streams (NH$\sb3,$ NO$\sb2,$ NO$\sb3,$ and organic-N). The purpose of the PDF/M technique is to include occurrence of natural variability. The first step is to separate the stochastic terms from the non-stochastic terms and solve the resulting set of equations simultaneously. The moments of the output variables then are obtained using expectation mathematics. The moments are used in a solution of the Fokker-Planck equation to produce an analytical solution for the probability density functions of the dependent variables. Comparison of the present study to the results of the Monte Carlo method showed the application of PDF/M technique to nitrogen cycle simulation valid. <p>