开发建设对敖江水质浊度影响的遥感监测

本文通过2007、2013和2016年3个时相的遥感影像,反演提取水体浊度信息,从较为宏观的角度分析了敖江流域大面积开发建设所引发的水土流失对敖江水质的影响。研究表明,2007年12月,敖江流域尚未有大面积开发,沿岸植被覆盖良好,江水浊度较低,平均约为23 NTU,分布比较均匀;2013年3月,敖江贵安新区处于开发建设期,特别是东雁-海峡段沿岸大片植被为工地裸土所代替,大量沙土流失至江中,使该段江水的浊度比上游高出3倍以上,平均浊度升高37 NTU,最大浊度差可达60 NTU,影响范围可至下游13 km;2016年9月,贵安新区建设基本成型,水土流失大幅减少,敖江整体浊度恢复相对均匀,但东雁-海峡段的平均浊度约39 NTU,仍高出上游5 NTU。其他分散的局部建设,是江水出现高浊度斑块的重要原因。浊度的上升,降低了水体含氧量,导致水质下降。当前中国城市化快速发展,伴随着大量的工程建设,其所致水土流失问题应引起足够重视,并在工程中采取必要控制措施,以降低其对沿江水质的影响。

Remote Sensing of Regional Construction Practice Induced Water Turbidity Changes in the Aojiang River

Three multi-temporal remote sensing images of 2007, 2013 and 2016 were applied to retrieve the turbidity of the Aojiang River in Lianjiang county of Fujian province to investigate water quality change of the river caused by regional construction-induced soil erosion. The remotely sensed data were correlated with in situ measured water monitoring data to generate a statistical model used for retrieving water turbidity of the river. The results showed that the overall turbidity of the river in 2007 was low (23 NTU) and the spatial distribution of the river turbidity was relatively uniform because there was no obvious exploitation in the river area. However, the water turbidity was greatly enhanced in 2013 with a mean of near 40 NTU and the spatial distribution of the river turbidity became diverse. The turbidity in the river sections around the Guian New Area was nearly 3 times higher than that of upstream. The difference can be up to 60 NTU. This high turbidity water can be traced downstream for more than 13 km. The high water turbidity of the river in 2013 was due largely to the exploitation and construction practices near the river. The regional construction-induced soil erosion has brought massive mud and sand particles to the river and thus resulted in a high concentration of suspended particles of the river. The overall turbidity of 2016 was lower down as the construction of the Guian New Area was almost completed and the associated soil erosion has significantly decreased. The spatial distribution of the river turbidity returned to relatively uniform. Nevertheless, the turbidity in the river section close to the core of the Guian New Area was still high (39 NTU), which was about 5 NTU higher than that of upstream. The study also found that high turbidity of the river has reduced the dissolved oxygen content, leading to a poor water quality. With the current rapid urbanization process in China, the soil erosion induced in regional development should be taken into consideration in future construction practices to avoid their considerable impacts on the river's water quality.