Response of Phosphorus Near Reservoirs in South Branch of the Yangtze Estuary to the Upstream Runoff and Sediment Load Variations

Xian Zhu, Xian Zhu, Zhenshan Xu, Zhenshan Xu, Ao Chu, Ao Chu, Hongwei Ding, Min Gan, Min Gan, Yongping Chen, Yongping Chen

2021

Abstract

The water quality of reservoirs in the south branch of the Yangtze estuary is strongly influenced by the phosphorus loadings. The variations of runoff and sediment loads from upstream cause the temporal variations of phosphorus loadings here, which poses potential risks to the reservoirs. The changes of runoff and sediment loads from upstream in the future are uncertain because of human activities and global climate change. An integrated water quality model was established to study the possible changes of phosphorus loadings in the south branch of the Yangtze estuary in the future in response to variations of runoff and sediment loads from upstream. The model contains hydrodynamic, sediment dynamics, and some biochemical processes. The model is well-calibrated and verified based on the related data in 2018. Different sets of runoff and sediment loads from upstream were then applied in this model to learn the changes of concentration of total phosphorus (TP), phosphate (PO43-), and particle phosphorus (PP). Results show that the TP concentration has no significant change with different conditions of input of runoff and sediment loads. However, the PO43- and PP concentrations are significantly influenced by both the changes of runoff and sediment loads. The annual mean value of PO43- concentration would increase by 10-25% if the input of runoff increases by 20% or the sediment loads decrease by 20%. It would decrease by 8-20% if the input of runoff decreases by 20% or the sediment loads increase by 20%. The annual mean value of PP concentration would increase by 12-35% if the input of runoff decreases by 20% or the sediment loads increase by 20%. It would decrease by around 15-30% if the input of runoff increases by 20% or the sediment loads decrease by 20%. The changes of the PO43- and PP are caused by the convection and diffusion of the flow, and the adsorption and desorption of sediments. Notwithstanding, these changes would reconstitute the component of TP of reservoirs in the south branch of the Yangtze estuary. Although the PP still takes the main proportion, the proportion of PO43- would increase significantly and the growth of plankton would be promoted which may cause a high risk of eutrophication.

Paper Citation

in Harvard Style

Zhu X., Xu Z., Chu A., Ding H., Gan M. and Chen Y. (2021). Response of Phosphorus Near Reservoirs in South Branch of the Yangtze Estuary to the Upstream Runoff and Sediment Load Variations. In Proceedings of the 7th International Conference on Water Resource and Environment - Volume 1: WRE, ISBN 978-989-758-560-9, pages 179-188

in Bibtex Style

@conference{wre21,
author={Xian Zhu and Zhenshan Xu and Ao Chu and Hongwei Ding and Min Gan and Yongping Chen},
title={Response of Phosphorus Near Reservoirs in South Branch of the Yangtze Estuary to the Upstream Runoff and Sediment Load Variations},
booktitle={Proceedings of the 7th International Conference on Water Resource and Environment - Volume 1: WRE,},
year={2021},
pages={179-188},
publisher={SciTePress},
organization={INSTICC},
doi={},
isbn={978-989-758-560-9},
}

in EndNote Style

TY - CONF

JO - Proceedings of the 7th International Conference on Water Resource and Environment - Volume 1: WRE,
TI - Response of Phosphorus Near Reservoirs in South Branch of the Yangtze Estuary to the Upstream Runoff and Sediment Load Variations
SN - 978-989-758-560-9
AU - Zhu X.
AU - Xu Z.
AU - Chu A.
AU - Ding H.
AU - Gan M.
AU - Chen Y.
PY - 2021
SP - 179
EP - 188
DO -