Agricultural water pollution accounting and exceedance risk analysis of the Yellow River Basin based on grey water footprint and triangular fuzzy numbers
The Yellow River Basin serves as a crucial agricultural production region in China; however, water pollution caused by agricultural activities in this area has posed a severe threat to the water resources security. It is urgent to implement targeted emission reduction measures on the basis of comprehensive accounting for agricultural water pollution and assessing of its risk of exceeding the permitted standards. To overcome the impact of differences in water quality standards among provinces and regions on assessment results, we combined grey water footprint with triangular fuzzy numbers to quantitatively analyze the status of agricultural water pollution in the Yellow River Basin from 2012 to 2022, and further explored the spatiotemporal variation characteristics and exceedance risk of different industries and major pollutants. The results show that the agricultural grey water footprint across the Yellow River Basin exhibited a general decline of 13.01%, but its exceedance risk remained at a high level. There were significant differences in the degree of agricultural water pollution among provinces and regions in the basin. Shandong, Henan, and Inner Mongolia had relatively high agricultural grey water footprints and faced a high risk of exceeding standards. Although Shaanxi, Shanxi, Ningxia, and Gansu had relatively low agricultural grey water footprints, the exceedance risk in these regions was still assessed as high, due to the limited local water resources. In addition, water pollution from animal husbandry in the Yellow River Basin was significantly higher than that from crop cultivation. While the grey water footprint of animal husbandry displayed a fluctuating “increase-decrease-increase” trend, that of crop cultivation showed an overall decline of 33.04%. Notably, the problem of agricultural nitrogen pollution was particularly prominent in all provinces and regions of the Yellow River Basin, and the risk of exceeding standards for the agricultural total nitrogen grey water footprint was widespread and rather high. The research establishes a comprehensive analytical framework for water pollution assessment, providing a crucial decision-making support for the differentiated assessment of water pollution and the formulation of relevant regulatory policies in the basin.