Abstract: In order to explore the runoff and sediment yields and water quality characteristics under varying rainfall types, three types of slope plots (grass slope, fishscale pit slope, and horizontal strip slope) in Yanqing County in Beijing and 112 erosive rainfall events were selected to analyze the losses of runoffsediment, nitrogen and phosphorus, and chemical oxygen demand (COD). The results showed that the precipitation and maximal 30 and 60 minutes rainfall intensities were the critical factors affecting runoff, sediment and water quality. Accordingly, four rainfall types were classified, i.e. Ⅰ (heavy rainfall, high rainfall intensity), Ⅱ (medium rainfall, high rainfall intensity), III (medium rainfall, low rainfall intensity) and IV (small rainfall, low rainfall intensity). Types Ⅰ and Ⅱ were easier to cause water and soil loss, and accounted for 90% of total water and soil loss amounts. Type Ⅱ was easier to cause water pollution, and the resultant contaminants accounted for 45%-50% of the total amount. The water pollution level was similar among types Ⅰ, III and IV. Under type Ⅱ rainfall, the ability of runoffsediment yield of horizontal strip slope was higher than that of the other two slopes, while under types III and IV rainfall, the runoffsediment yield of grass slope was the highest. Compared with the grass slope, N loss increased, P loss decreased, and COD amount was lower on fishscale pit slope and horizontal strip slope.

Key words: seedling accumulation, stable nitrogen isotope, ¹⁵N labeling method, seed dispersal.