Influences of land use on water quality in a reticular river network area: A case study in Shanghai, China

The land use in the reticular river network areas (RRNAs) in China has changed during the past decades. Because of the special hydrological conditions, there are challenges in discussing how the land uses affect the water quality in such a high-density stream network area. The primary purpose of this paper is to reveal the relationship between land use and water quality and the scale effect in a typical RRNA, Shanghai. A clear distribution of water quality along an urban-to-rural gradient was identified in this metropolitan area using correspondence analysis. The industrial land use showed negative effect on water quality only at smaller scales. In contrast, the impact of urban turned to be more obvious as scales enlarged. At each scale, land use and hydrological variables could explain more than 50% of the variation in water quality, of which urban and industrial accounted for more than 70%. The effect of land use and hydrological condition on water quality became more diversified as the spatial scale increased.