Analysis of critical river discharge for saltwater intrusion control in the upper South Branch of the Yangtze River Estuary

Zhaohua SUN; Jiewei FAN; Xin YAN; Cuisong XIE

doi:10.1007/s11442-020-1757-0

Journals >Journal of Geographical Sciences >Volume 30 >Issue 5 >Page 823 > Article

Journal of Geographical Sciences
Vol. 30, Issue 5, 823 (2020)

Analysis of critical river discharge for saltwater intrusion control in the upper South Branch of the Yangtze River Estuary

Zhaohua SUN^1、*, Jiewei FAN¹, Xin YAN¹, and Cuisong XIE²

Author Affiliations

¹State Key Laboratory of Water Resources and Hydropower Engineering Science, Wuhan University, Wuhan 430072, China

²Shanghai Water Affairs Bureau, Shanghai 200050, China

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DOI: 10.1007/s11442-020-1757-0 Cite this Article

Zhaohua SUN, Jiewei FAN, Xin YAN, Cuisong XIE. Analysis of critical river discharge for saltwater intrusion control in the upper South Branch of the Yangtze River Estuary[J]. Journal of Geographical Sciences, 2020, 30(5): 823 Copy Citation Text

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Fig. 1. Sketch of the Yangtze River Estuary displaying the location of measuring stations

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Fig. 2. Correlation between the daily mean tidal ranges of Xuliujing and Qinglonggang stations

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Fig. 3. Chlorinity of Dongfengxisha observation point, discharge at Datong station and tidal ranges at Xuliujing station in the dry seasons of 2009-2014

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Fig. 4. Relationship between the discharge at Datong station and the tidal range at Xuliujing station (Red line across the data points represents the trend line between the two variables.)

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Fig. 5. Relationship between lunar calendar date and daily mean tidal range at (a) Xuliujing station and (b) Qinglonggang station (Curves of different colors represent different tidal range estimation modes.)

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Fig. 6. Characteristics of river discharge at Datong station in dry seasons of three different periods: (a) multi-year average monthly discharge; (b) the maximum and the minimum discharge in every month (Total height represents the maximum value of each month. Colored fill portion represents the minimum value of each month. Red represents the period of 1950-2002, brown represents the period of 2003-2007, blue represents the period of 2008-2017)

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Fig. 7. Characteristics of saltwater intrusion under different river discharges: (a) relationship between daily discharge at Datong station and daily chlorinity at the Dongfengxisha observation point, (b) probability of chlorinity exceeding the drinking water standard in each discharge interval, and (c) the discharge at Datong station vs the cumulative probability of excessive chlorinity

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Fig. 8. Tidal range of Xuliujing station vs chlorinity of Dongfengxisha observation point: (a) data of all discharges, and (b) data corresponding to the river discharge of approximately 11,000 m³/s

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Fig. 9. Accumulative frequency of the tidal range of Xuliujing station

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Fig. 10. Comparison of the measured and calculated salinity values using different empirical models

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Fig. 11. Calculated chlorinity processes of the Dongfengxisha observation point under different river discharges (t denotes the duration when chlorinity exceeds the required drinking water standard)

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Data type	Station	Period	Source
Daily discharge	Datong	1950-2017	Yangtze River Hydrographic Yearbook
Daily mean tidal range	Xuliujing	2009, 2011-2014	Yangtze River Hydrographic Yearbook
Daily mean tidal range	Qinglonggang	Certain months in 2005, 2009, 2011, 2014 and 2017	Jiangsu Provincial Hydrology and Water Resources Bureau, Zheng et al. (2014)
Daily mean chlorinity	Dongfengxisha	2009-2014	Shanghai Water Affairs Bureau

Table 1.

Data sources

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Source	Relationship	Variable explanation
Mao et al.(1993)	S~exp(ΔH^α/Q^β)	S is the salinity of Baogang; ∆H is the tidal range of Qinglonggang; Q is the discharge at Datong station.
Zheng et al.(2014)	S=ae^b^Δ^H+ ae^b^Δ^H(c₁Q³+ c₂Q²+c₃Q+c₄)	S is the salinity of Qinglonggang station; ∆H is the tidal range of Qinglonggang station; Q is the discharge at Datong station.
Chen et al.(2013b)	S=(4.16×10^‒⁹Q²‒2.745Q+4.317)×0.02404×e^0.009085Δ^H	S is the salinity of Chenhang; ∆H is the tidal range of Qinglonggang station; Q is the discharge at Datong station.
Sun et al.(2017)	C=Aexp(aΔH₀‒bQ)	ΔH₀ is the tidal range of Xuliujing station; Q is the discharge at Datong station; C is the chlorinity of Dongfengxisha.

Table 2.

Selected empirical models for salinity prediction in the upper South Branch of the Yangtze River Estuary

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Measured time	Cumulative frequency of less than a certain value of discharge (%)
Measured time	< 25000 m³/s	< 15000 m³/s	< 12000 m³/s	< 10000 m³/s
1950-2002	45.71	25.71	16.9	10.06
2003-2007	55.83	24.85	14.29	2.74
2008-2017	50.33	21.59	7.73	0.1

Table 3.

Frequency of daily discharge at Datong station in different periods

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Measured time	Observation point	Salinity excessive days (d)	Average discharge at Datong station during the salinity excessive periods (m³/s)	Data source
Winter of 1978-Spring of 1979	Wusong	64	7256	Shen et al.(2002)
February-March 1987	Chenhang	13	8467	Gu et al.(2003), Chen et al.(2011), Xu and Yuan(1994)
February-March 1999		25	9487	Shen et al.(2002), Gu et al.(2003)
February 2004		9.8	9479	He et al.(2006)
October 2006		9	14,300	Zhu et al.(2010)
February 2014		19	10,900	Wang (2016)
November 3-12, 2009	Dongfengxisha	10	14,030	Shanghai Water Affairs Bureau
November 15-24, 2013		10	12,240
December 3-11, 2013		9	12,500
December 17-25, 2013		9	11,365
January 2-10, 2014		9	12,144
January 30-February 22, 2014		24	11,138

Table 4.

Statistical features of certain saltwater intrusion events in the upper South Branch of the Yangtze River Estuary in recent decades

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Chlorinity of Dongfengxisha observation point (mg/L)	Discharge at Datong station Q_c (m³/s)	Daily tidal range of Xuliujing station ∆H_c (m)
250	11,000	2.05
250	12,000	2.24
250	13,000	2.42
250	15,000	2.61

Table 5.

Corresponding tidal ranges of Xuliujing station (∆H_c) and discharges of Datong station (Q_c) to maintain the drinking water standard

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Empirical salinity prediction model	Tidal range estimation mode	Determination coefficient R²	Tidal range estimation mode	Determination coefficient R²
Mao et al. (1993)	Qinglonggang station, curve B	0.45	Qinglonggang station, curve C	0.51
Zheng et al. (2014)	Qinglonggang station, curve B	0.85	Qinglonggangstation, curve C	0.88
Chen et al. (2013b)	Qinglonggang station, curve B	0.7	Qinglonggang station, curve C	0.74
Sun et al. (2017)	Xuliujing station, curve B	0.8	Xuliujing station, curve C	0.81

Table 6.

Determination coefficient between measured and calculated salinity using different tidal range estimation modes and different empirical salinity prediction models

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