基于SWAT模型的浑太河流域农业面源污染物产生量估算

结合浑太河流域的下垫面、水文气象、污染源的物理特征,基于实际监测数据,率定验证模型,建立降雨径流、土地利用方式对应下的SWAT模型,对农业面源污染物的迁移-转化过程进行模拟计算,系统解析流域面源污染物排放量、分布特征。划定浑河、太子河、大辽河干流左右岸河流两侧l km、水库周围5 km为缓冲区,改变现有的土地利用方式,恢复天然生态。以常规发展模式为基础,计算在区域生态保护占优模式下污染物产生量。在常规发展模式下,浑太河流域年平均土壤侵蚀模数为400 kg/hm~2,总氮、总磷输出强度为19、7 kg/hm~2;从单位面积上看,总氮、总磷负荷强度最大值分别为317、260 kg/hm~2。总氮、总磷负荷强度空间差异较大,通过面积加权计算,平均负荷强度为29和10 kg/hm~2。在生态保护占优模式下,耕地的氮、磷损失量有所减少,总氮、总磷单位面积年减少量为9.5、0.9 t/hm~2;从农业面源污染物化学需氧量(chemical oxygen demand,COD)、氨氮来源层面分析,单位面积土地退耕后化学需氧量、氨氮污染物减少量为14、5 kg/hm~2。经比较,在生态保护占优发展模式下面源污染物产生量相对常规发展模式下减少9%,化学需氧量、氨氮、总磷、总氮分别减少5.12%、31.67%、10.40%、25.95%,农业面源污染减排效果明显。研究为实现浑太河流域污染物排放总量不超标、水体水质达标,并确保农业基础地位不动摇,充分挖掘区域农业减排增收潜力提供策略依据。

Yield calculation of agricultural non-point source pollutants in Huntai River Basin based on SWAT model

Abstract: The establishment of non-point source pollutants output load model under the mode of rainfall-runoff and land use, analog calculation of agricultural non-point source pollutants in the process of migration and transformation, and systematic analysis of non-point source pollutants discharge quantity, distribution and composition characteristics are based on actual monitoring data, calibration and validation model, in consideration of underlying surface, hydrology and meteorology, and physical features of Huntai River Basin. 1 km distance from each side of master stream Huntai river, Taizihe river and Daliaohe river should be left respectively, and 5 km distance surrounding reservoir should be defined as buffer zone, so as to transform the mode of land use and restore natural ecosystem. Under the pattern of conventional development, average annual soil erosion modulus of Huntai river basin is 400 kg/hm2, and total phosphorous and nitrogen output intensity are 6.8 kg/hm2 and 19.5 kg/hm2, respectively. From the aspect of unit area, maximum load intensity for total nitrogen and phosphorous are 317 and 260 kg/hm2, respectively. Owing to spatial variation in load intensity for total nitrogen and phosphorous, through the calculation of area weighting, average load intensity for total nitrogen and phosphorous are 29 kg/hm2 and 10 kg/hm2, respectively. Under prevailing pattern of ecological protection, loss amount of nitrogen and phosphorous are decreased. Annual reduction in unit area of total nitrogen and phosphorous are 9500 kg/hm2 and 900 kg/hm2, respectively; Through the analysis of agricultural non-point source pollution COD and ammonia nitrogen source, ammonia nitrogen pollutants of arable land converted to forestry per unit area decreased to 14 and 5 kg/hm2, respectively. Through the comparison, the amount of pollutants generated under prevailing pattern of ecological protection is 9% less than that under the pattern of conventional development, and reduction in COD, ammonia nitrogen, total nitrogen and total phosphorous are 5.12%, 31.67%, 10.40% and 25.95%, respectively.