Abstract: The output characteristics of pollutants in farmland runoff under different artificial rainfall intensity was researched at typical farmland in Changshu suburban area. The contribution of runoff pollution to the river pollution was also discussed. Result revealed that 1) the maximum concentration of pollutant appeared at the beginning of the rainfall under small intensity, while emerged later under big rainfall intensity; 2) the summation of TN and COD_Mn outputs were far larger than the output of TP and ammonia nitrogen, also the summation of pollutant increased with the increase of rainfall intensity but the change was nonlinear; 3) TN and TP had a greater contribution to the river contamination.

Key words: farmland, runoff, pollution, artificial rainfall, output characteristic