Tempo-spatial analysis of water quality in tributary bays of the Three Gorges Reservoir region (China)

As a giant newly built man-made canyon-shaped reservoir, the Three Gorges Reservoir (TGR) receives much attention around China and other parts of the world. Bays were deemed to be the most critical zone for water management of TGR; thus, a 3.5-year temporal and spatial investigation was performed to disclose water quality variation in TGR bays and to elucidate the potential affecting factors based on an integrated hydrographical analysis. The results showed that TGR bays had been moderately polluted with averaged nitrogen (N) concentration over 2 mg L-1 and phosphorus (P) concentration less than 0.1 mg L-1 in dry season and while high P over 0.2 mg L-1 and low N of 1.54 mg L-1 in average in flooding season. The interaction of dam regulation and flooding events influenced the temporal pattern of water quality in the TGR bays, in which particulate nutrients dynamic played an important role. Urban effluents and agricultural catchment area also influenced water quality in the bays, showing local spatial distribution characteristics via diffusion mechanism. Backwater ends might be the most critical areas of water quality degradation. Alleviation measures had been proposed for sustainable development of TGR region.