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流域营养物质输入是湖泊富营养化的重要营养物质来源.应用分布式水文模型SWAT,以长江中游洪湖流域为研究对象,对流域营养物质输移变化的时间序列进行数值模拟.根据不同阶段流域营养物质输移驱动因子分析,设计了3个阶段的模拟试验,以反映变化环境条件下流域营养物质输移演变的特征.研究界定出流域营养物质输移演变3个阶段中,营养物质输移通量的变化幅度、变化速率.由自然状态,经建国初期,至20世纪80年代以来,流域营养物质的输出浓度与总量分别经历了以下变化,总氮(TN):0.12→0.31→1.15mg/L,420→1650→6522t/a,总磷(TP):0.018→0.057→0.117mg/L,78→303→665t/a.流域营养物质输移演变经历了1840到1950年间的缓慢增长,20世纪80年代初年平均增长率1.4%的渐增,再到90年代初2.4%的年增长率,直至90年代后期的15%,富营养化趋势明显增强,反映了流域人类活动影响程度不断增强,逐渐取代气候因子,成为流域营养物质输移的主导驱动因子.
Watershed nutrient input is an important nutrient source of lake eutrophication.Using the distributed hydrological model SWAT, taking the Honghu basin in the middle reaches of the Yangtze River as the research object, the numerical simulation of the time series of nutrient transport and transport changes in the basin is carried out.According to the different stages of watershed nutrition In order to reflect the evolvement characteristics of nutrient transport in watershed under changing environmental conditions, three driving tests were designed to simulate the transport of nutrients, From the natural state, from the early days of the founding of New China to the 1980s, the output concentration and the total amount of nutrients in the watershed underwent the following changes respectively: total nitrogen (TN): 0.12 → 0.31 → 1.15 mg / L, 420 → 1650 → 6522 t / a, total phosphorus (TP): 0.018 → 0.057 → 0.117 mg / L, 78 → 303 → 665 t / a. The evolution of nutrient transport in the watershed experienced a slow growth from 1840 to 1950, The average annual growth rate of 1.4% in the early 1980s increased from 2.4% to the annual growth rate of 2.4% in the early 1990s and increased to 15% in the late 1990s. The trend toward eutrophication was significantly enhanced, reflecting the continuous influence of human activities in the basin increase Gradually replace climatic factors, nutrients become the dominant drivers of transport basin.