海河流域面源污染风险格局识别与模拟优化

面源污染是海河流域面临的主要水生态环境问题,如何通过流域景观格局优化实现对面源污染的控制一直是研究的热点问题。通过最小累积阻力模型,以海河流域为研究对象,将流域景观要素及影响流域景观过程的外部因子相结合,对海河流域面源污染风险格局进行了识别,并将阻力格局与海河流域实测水环境指标进行相关性分析及验证,在此基础上对流域污染风险进行识别与优化模拟。结果表明海河流域有40%以上(130380 km2)区域面临高污染风险,集中分布在中南部平原地区以及山区河谷地带;对此设置河流植被缓冲带进行格局优化模拟分析,通过比较不同措施格局优化阻力值变化趋势表明,对于二级河流水系,加强河流两岸600—1600 m范围的人类活动管控,可以有效降低污染物输出,显著降低流域面源污染发生的风险。在面源污染风险等级较高的平原地区,设置300—400 m植被缓冲带,可将风险等级降低50%,设置700—800 m岸边植被缓冲带即可达到最佳效果;而在山区地区因风险较低,设置400—500 m的植被缓冲带即可达到最佳效果,能够将污染风险在现有基础上降低30%—40%。这一研究结果对海河流域景观格局优化和面源污染风险控制提供科学参考。

Identification and optimized simulation of non-point source pollution risk patterns in the Haihe River Basin

Non-point source pollution is a major water ecological environment problem that influences the water environment in the Haihe River Basin. Mechanisms for controlling non-point pollution by optimizing landscape patterns at the watershed scale has been a popular issue. In this study, the risk patterns of non-point source pollution was established using minimum cumulative resistance model, which combines landscape elements and external factors that influence landscape processes. Risk pattern verification was performed by correlation analysis between resistance values and measured pollutant data in the Haihe River Basin. Watershed non-point pollution risk was identified and simulation of landscape patterns were optimized based on the verified non-point source pollution risk patterns. The results showed that in the Haihe River Basin, more than 40% of the areas are at extremely high or high risk level, and are mostly concentrated in the southern plain area and mountain valleys along the river. The landscape pattern was optimized by setting the vegetation buffer zone along the riverside. The simulation analysis results indicatedthat in different sub-basins, strengtheningcontrols onhuman activities to reduce the pollutant output in theareas within 600-1600 meters on both sides of the river can significantly reduce the risk of non-point source pollution. In plain areas of the Haihe River Basin, the high risk levels of non-point source pollutioncan be reduced by 50% by setting the vegetation buffer zone to 300-400 meters and a 700-800 meter vegetation buffer zone can achieve the best effect. In mountainous areas with relatively low risk level, a 400-500 metervegetation buffer zone can reduce non-point source pollution risk most effectively. The results of this study provide a scientific reference for optimizing landscape patterns to control non-point source pollution risk in the Haihe River Basin.