Spatiotemporal variability in salinity and hydraulic relationship with salt intrusion in the tidal reaches of the Minjiang River, Fujian Province, China.
Salinity is one of the most important factors for tidal-affected water bodies including estuaries and tidal river reaches. However, due to the limitations of simultaneous manual monitoring in long-distance areas, studies of estuaries are preferred to tidal reaches. Hence, in this study, we investigated the tidal reach of the Minjiang River and five sets of field observations were used to determine the influence of saltwater intrusion in different seasons. During the dry and wet season with low discharge, the longitudinal salinity profiles showed that a station located about 45 km from the river mouth still suffered from saltwater intrusion especially when the upstream discharge was under 754 m3s-1, where the periodical fluctuation in the salinity remained the same with the water level, but there was a time lag of approximately 4 h compared with the discharge process. However, during the wet season in April and May 2016, the monitored salinity was approximately at the detectable limit of 0.02-0.04 ppt at the station close to the river mouth, which indicated that there was no saltwater exchange into the river, although dual flow directions were observed in the survey periods. The major differences among five survey periods were mainly related to upstream discharge rather than the seasons, the tidal range, and tidal excursion. The conclusions of this study have strategic importance for protecting water sources by guiding the government to assess the optimal freshwater release time and discharge rate to prevent saltwater entering the important tidal-affected river reaches.
College of Environmental Science and Engineering, Fujian Normal University, 8 Shangsan Rd, Fuzhou, 350007, China.
Rongrong
R
Xie
College of Environment, Hohai University, Nanjing, 210098, China.|Key Laboratory of Integrated Regulation and Resource Development on Shallow Lakes of Ministry of Education, Hohai University, Nanjing, 210098, China.
Yong
Y
Pang
Hydrology and Water Resources Survey Bureau of Fujian Province, Fuzhou, 350001, China.
Bingrong
B
Luo
College of Environmental Science and Engineering, Fujian Normal University, 8 Shangsan Rd, Fuzhou, 350007, China.
Jiabing
J
Li
College of Environmental Science and Engineering, Fujian Normal University, 8 Shangsan Rd, Fuzhou, 350007, China.
Chunshan
C
Wu
College of Environmental Science and Engineering, Fujian Normal University, 8 Shangsan Rd, Fuzhou, 350007, China.
Yuyi
Y
Zheng
College of Environmental Science and Engineering, Fujian Normal University, 8 Shangsan Rd, Fuzhou, 350007, China.
Qiyuan
Q
Sun
College of Environment, Hohai University, Nanjing, 210098, China.
Peng
P
Zhang
College of Environmental Science and Engineering, Fujian Normal University, 8 Shangsan Rd, Fuzhou, 350007, China. wffeng@126.com.
Feifeng
http://orcid.org/0000-0002-9702-1988
F
Wang
D002681:China; D004784:Environmental Monitoring; D063366:Estuaries; D045483:Rivers; D054712:Salinity; D062211:Spatio-Temporal Analysis; D014872:Water Movements
Dry season; Minjiang river; Monitoring; Salt intrusion; Wet season