【作者】 荣琨；

【导师】 陈兴伟；

【作者基本信息】 福建师范大学 ， 环境工程， 2009， 硕士

【摘要】 非点源污染是指由于降雨产流过程中的冲刷、侵蚀或者灌溉等,使得大面积上的污染物进入水体造成的污染,已经成为我国水环境恶化的重要诱因。晋江西溪流域主要位于东南沿海的泉州市境内,是福建省内水土流失最严重的区域,随着近年来工业污水等点源污染得到有效控制,非点源污染的影响日益显著,研究晋江西溪流域的非点源污染具有重要意义。运用GIS软件建立了由DEM、土地利用、土壤、降雨等数字化资料构成的SWAT模型数据库,将流域划分为21个亚流域与309个水文响应单元,利用1973～1979年氨氮与矿物磷各年的输出总量实测资料对氨氮与矿物磷的模拟结果进行率定,氨氮年模拟效率系数(Ens)为0.69,相关系数(R~2)为0.95,7年平均相对误差(RE)为-18.6%;同期矿物磷年模拟Ens为0.79,R~2为0.85,平均RE为-1.5%。模型计算结果的分析表明,1973～1979年,西溪流域各年非点源污染物的输出量较为均衡,年内总氮、总磷负荷随季节呈不规则的“M”形态变化;流域非点源污染负荷与土地利用方式有密切关系,水田与旱地两者相加产生了研究区非点源总氮、总磷污染总量的66%、83%;西溪流域非点源污染的空间分布不平衡,蓝溪流域更严重;SWAT模型能较好的模拟预测东南沿海植被恢复后流域产流、产沙、非点源污染的年变化与月变化;植被恢复对产沙与非点源污染的影响远大于产流;西溪流域由于土地利用变化所造成的非点源污染由20世纪70年代的年均1530 t N(6.3kg N/ha)与266 t P(1.1 kg P/ha)上升到2001年的2641 t N(10.8 kg N/ha)与542 t P(2.2kg P/ha),非点源总氮、总磷污染分别增长了72%、104%;对水系分维的初步研究表明,通常水系分维值越大,非点源污染负荷越大。更多还原

【Abstract】 Non-point source (NPS) pollution is one of the most important factors for water environmental deterioration in Xixi watershed of the Jinjiang basin. So it’s significant to study the NPS pollution in the area.SWAT model is a continuous and distributed model which is used to estimate the NPS pollution. At first DEM, land use, soil, weather data are collected for model applying, then they must be projected and transformed to meet the need of the model by GIS software. Topographic characteristics of the stream network and 21 subbasins were derived from the DEM of Xixi watershed. 309 hydrological response units were defined by overlaying the land use map and soil map. The model was calibrated by comparing the observed ammonia-nitrogen and mineral phosphorous with the simulated results, and it was found that the Ens of ammonia-nitrogen and mineral phosphorous reached 0.69 and 0.79 with the minimum relative error 5.3% and 1.4%, respectively.The simulated results showed that the annual TN pollution from non-point source was 1 530t, or 6.3 kg/hm~2 and the annual TP pollution from non-point source was 270t, or 1.1 kg/hm~2 during 1973 and 1979 in the watershed. Farmlands in the study area were major source of non-point source pollution. The spatial distribution of the pollution is uneven in the sub-watersheds, particularly the situation in Lanxi sub-watershed was more serious. The effect of land use/cover change on non-point source (NPS) pollution loadings in the watershed was also simulated with the mode, and the results showed that the TN and TP load increased from 1 530 tons and 266 tons in 1970s’ to 2 641 tons and 542 tons in 2001, because of the land use change. Due to the reduction of the area of farm and the increase of orchard, the most important land use catalog for the production of NPS pollution was the orchard in 2001 instead of the farm in 1970s’.SWAT model can be successfully used to model the effect of vegetation restiration on NPS pollution. The impact of vegetation restoration on sediment yield and NPS pollution is much bigger than that on runoff. According to the SWAT model simulation results, analyzed the relationship between the non-point source pollution and the river fractal dimension of the five subbasins. The results show that, the higher the watershed fractal dimension, the higher the farmland area ratio is, and more serious the soil erosion is, so more serious the non-point source pollution is.更多还原