澎溪河流域土地利用对非点源污染时空分布影响

基于流域DEM、土地利用和土壤数据构建澎溪河流域非点源污染SWAT模型,采用2009~2014年逐日实测资料进行模型的率定验证,模型率定期和验证期的决定系数R2和Nash-Sutcliffe效率系数ENS均在0.7以上,模拟结果可靠。利用所建模型分析了澎溪河流域不同土地利用类型的非点源污染负荷的时空分布。结果表明,流域非点源污染负荷年际分布不均,2010~2014年中2011年TN和TP负荷最大,分别为2 655.17 t和167.14 t;不同土地利用类型的氮磷负荷均集中在流域南部及沿河地势低洼区;在流域坡度和土壤类型相同的情况下,耕地的负荷最大,TN和TP的年均负荷分别为1 631.47 t和146.34 t。

Impact of different land use on temporal and spatial distribution of non-point source pollution in Pengxi River Basin

Based on Digital Elevation Model (DEM), land use and soil data, the Soil and Water Assessment Tool (SWAT) model for non-point source pollution in Pengxi River Basin was established. The monitoring data series of hydrology and water quality from 2009 to 2014 in sub-basins were used to calibrate the parameters and validate the model. The results show that the correlation coefficient R2 and the Nash-Sutcliffe coefficient （ENS）in calibration and validation periods are greater than 0.7 for runoff , so reliability of the model is verified. The calibrated model was used to reveal the spatial distribution of non-point source pollution characteristics for different land use in Pengxi River Basin. The results indicate that the non-point source pollution interannual distribution is uneven；the total nitrogen and total phosphorus pollution loads in 2011 were the highest from 2011 to 2014, which were 2655.17 t and 167.14 t; in general, the non-point source pollution of different land use were concentrated in the south of the basin and the low-lying area along the river; for the same watershed slope and soil type, the total nitrogen and total phosphorus pollution loads of the arable lands were the highest ,which were 1631.47 t and 146.34 t; the grasslands was the second highest contributor, and the pollution load of the woodlands was the smallest.