REVIEW OF RESEARCHES ON INFLUENCE MECHANISM OF RAINFALL，TOPOGRAPHY ON THE PRODUCTION AND TRANSPORTATION OF NON-POINT SOURCE POLLUTION

With the control of point source pollution，non-point source ( NPS) pollution has become the dominant source which affects water quality due to its multi-source，wide distribution，controlling difficulties and so on． Production and transportation mechanism of NPS pollution is the basis of quantitative study，model simulation and pollution control． Moreover，it is also an important and difficult issue in the field of NPS pollution research． According to the previous researches，rainfall is the driving force of NPS pollution，and topography is the main influencing factor of NPS pollution． As for the two important factors，a lot of researches concerning their influence on the production and transportation of NPS pollution have been carried out at home and abroad nowadays． In this article，such researches were reviewed so as to provide a reference for related studies．