[Phosphorus output characteristics under different rainfall-runoffs in Gaolan River].

Through capturing the dynamics of water quantity and quality during varied intensities of rainfall, the variation characteristics of different forms of phosphorus and flux during the producing of runoff were studied systematically in Gaolan River watershed (a secondary tributary of Three Gorges Reservoir). Meanwhile, the phosphoric loadings from point and non-point sour,-were identified, respectively. The results show that: the variation of rainfall-runoff under " squat" rain was relatively slow, while un,c "pointed thin" rain it presented quickly both during rising and recession. Total phosphorus concentration increased quickly because soil carried particulate phosphorus into water under the heavy rainfall, while the relative variations of dissolved total phosphorus and orthophosphate concentration were slightly elevated. Compared with "squat" rain, the maximum value of total phosphorus concentration and flux were both higher in "pointed thin" rain, which led to the more heavily soil erosion. The dynamics of flux and concentratiorn of phosphorus were generally consistent with that of the flow rate between the two different types of rain. Phosphorus from non-point source accounts for 90% during the whole heavy rain. Because of the long lasted time during " squat" rain, the contribution of the "squat" rain outweighs the "pointed thin" rain.