The Analysis Of Rainfall Runoff Pollution On Typical Underlying Surfaces In The Industrial Park Of Haihe River Middle Reaches Area

In recent years, the non-point source pollution has become the focus of attention. More and more researchers began to explore the influence factors of nonpoint source pollution and its control method, aiming to control the pollution effectively. This article selected three kinds of underlying surface, including bituminous street, impervious tile and grass, in the middle reaches area of Haihe River, to represent the water proof and water permeable underlying surface. Using self-made device to moderate different raining conditions, for example, uniform rainfall intensity of 0.6mm/min, 1.0mm/min, 1.4mm/min and two unimodal type rainfall. After collecting the runoff of underlaying surface, the output rule and characteristics of pollutants were measured.Firstly, an automatic non-point source runoff pollution monitoring experiment device was made and rainfall intensity, homogeneity, raindrop diameter size and terminal velocity were measured. Results show that the rainfall intensity of this device was 0.3~2.0mm/min, and in this range rainfall uniformity coefficients were all over 85%. The raindrop median diameter was 1.09~2.25 mm. In addition, as the nozzles and rainfall diameter range both met the requirements, this device can be used to simulate the real rainfall exactly.Secondly, the pollutants output characteristics of different underlying surface were explored. Results show that at the beginning of the runoff, each pollutant concentration was higher, dropped rapidly, and than it became slow, at last gradually stabilized. In the rainfall of unimodal type, runoff-yielding time was later in the back peak type rainfall. In each rainfall, the EMC values of different underlaying surface contaminants were obviously different. The overwhelming majority of nitrogen and phosphorus were dissolved nitrogen and particulate phosphorus.In addition, the flush effects of different underlying surface were analyzed. Under the condition of uniform rainfall intensity of rainfall, each pollutant showed different degrees of first flush effect except PN. The first flush effect of back peak type rainfall was weaker than the front peak type rainfall. The appearance time of the max rainfall tensity was the key factor influencing the first flush effect. The relationship of first flush effect on different underlying surface was bituminous street > impervious tile > grass.At last, correlation of different pollutants was analyzed. Results shows that the correlation of SS-TN, SS-TP and SS-COD were good under the uniform rainfall intensity. SS-TN conformed to the linear relationship on bituminous street and impervious tile, but conformed to power function relationship on the grass. SS-TP and SS-COD conformed to the linear relationship on all the three underlying surfaces. Under the condition of unimodal type rainfall, fitting degree of the four regression equation were not good. Overall, the relationships of SS-TN, SS-TP and SS-COD were stronger in the front peak type rainfall than the back one.