Preliminary establishment of agricultural non-point source pollution model

Loads quantitative research is the basic of control, evaluation and management of agricultural non-point source pollution (AGNSP). Based on the AGNSP characteristic, the AGNSP model was divided into “Sources” module and “Sinks” module. Thereinto, “Sources” Module is further divided into farmland irrigation drainage sub-module and contaminants concentrations in farmland drainage estimating sub-module, in which, irrigation drainage was calculated by DRAINMOD model based on the principle of water balance on farmland. Meanwhile, the synthesis of fertilization and irrigation is used as an impulse input to the farmland, the pollutant concentration change in agricultural drainage is looked as the response process corresponding to the impulse input, the complex migration and transformation process of pollutant in soil is expressed impliedly by Inverse Gaussian Probability Density Function. The one-dimensional transport model of AGNSP pollutants in drainage ditch system was constructed on the basis of the equation of continuity of flow and pollutants migration and transformation. Integrating two modules, the complete AGNSP load model was constructed.