Discussion on the Function and Scale of Dasha Regulating and

Storing Reservoir in Zhoushan Continental Diversion Project

Jing Wei, Haibo Ma

, Xiongwei Zheng, Yueqing Chen and Yujie Li

Zhejiang Design Institute of Water Conservancy and Hydroelectric Power, Zhejiang Hangzhou 310002, China

Keywords: Continental Water Diversion, Dasha Regulating and Storing Reservoir, Zhoushan Continental Diversion

Project

Abstract: The construction of Zhoushan Archipelago New Area in Zhejiang Province is strategically important,

however, an insufficient supply of water resources in Zhoushan has become one of the main factors

affecting its economic and socially sustainable development. Zhoushan Continental Diversion Project

provides a reliable guarantee for the construction and development of the Zhoushan islands. Based on the

project water diversion and local water resources conditions, this paper analyzes the necessity of setting up

Regulating and Storing Reservoir and discusses the rationality of the reservoir scale in terms of water

supply guarantee rate, emergency water sources, and development costs.

1 INTRODUCTION

Zhoushan City is located in the East of Zhejiang

Province, on the East China Sea at the South side of

the Yangtze River Estuary and the outer edge of

Hangzhou Bay. It is the junction of China's North-

South coastal routes and the Yangtze River

waterway, and its strategic position is very

important. On June 30th, 2011, Zhoushan became

the first national level new district with the theme of

marine economy in China. With the increasing

demand for water resources in the construction of

new islands and coastal defense, the shortage of

freshwater resources has become a bottleneck that

seriously restricts the sustainable development of

Zhoushan Islands. The total water resources of

Zhoushan Islands are 692 million m

, and the per

capita water resources are 618 m

, which is less than

1/3 of the national per capita level (Wan et al., 2018;

Dou et al., 2018; Wang et al., 2010).

Zhejiang Province put forward the strategic

layout of water diversion from the mainland to

Zhoushan Islands, which named Zhoushan

Continental Diversion Project (ZCDP). The water

intake is located in Yao River, with a planned water

diversion flow of 5.0 m

/s and an annual water

diversion of 107 million m

. The project was

implemented in three phases. The first phase of the

project was completed in 2003, with a water

diversion scale of 1.0 m

/s and an annual average

water diversion volume of 21.6 million m

. In 2015,

the second phase of the project achieved trial water

supply, with a water diversion scale of 2.8 m

/s and

an annual average water diversion capacity of 60

million m

, and the Huangjinwan Regulating and

Storing Reservoir (HRSR) was built. The water

diversion scale of the third phase water diversion

project in Zhoushan City under construction is 1.2

/s, with an average annual water diversion volume

of 25.9 million m

. At the same time, it is planned to

build Dasha Regulating and Storing Reservoir

(DRSR) in 2017 (Gu et al., 2019; Zhang et al.,

2020).

To give full play to the benefits of the project,

cope with the unevenness of water sources for water

transfer across river basins, and increase the

guaranteed rate of water supply, long distance water

transfer projects need to build Regulating and Storing

Reservoir (RSR) (Han et al., 2013; Liu et al., 2011).

At the same time, RSR also serves as an emergency

water source and improves the utilization of local

water resources. Therefore, as an important part of

the ZCDP Project, RSR is a key guarantee for the

scientific deployment of water diversion from the

mainland and local water intake. This paper takes the

2030 level year as the future working condition,

considers the scheduling principles and

compensation mechanism of water diversion from

the mainland and local water intake, and

Wei, J., Ma, H., Zheng, X., Chen, Y. and Li, Y.

Discussion on the Function and Scale of Dasha Regulating and Storing Reservoir in Zhoushan Continental Diversion Project.

In Proceedings of the 7th International Conference on Water Resource and Environment (WRE 2021), pages 99-102

ISBN: 978-989-758-560-9; ISSN: 1755-1315

demonstrates the necessity and rationality of

constructing DRSR.

2 METHODOLOGY

2.1 Reservoir Operation Principle

Continental Water Diversion (CWD) directly enters

HRSR and DRSR, meanwhile, carries out joint

water supply dispatching with Local Networked

Reservoir (LNR). The dispatching principles are as

follows.

(1) Water diversion conditions: According to the

comprehensive consideration of the actual water

level of the Yao River, the surrounding water intake

requirements and navigation requirements,

Zhoushan City and Ningbo City have signed a water

intake agreement. The minimum water intake level

determined by the agreement is 0.73 m, that is, the

water level of the Yao River. When it is lower than

0.73 m, water of the Yao River must be stopped

from withdrawing.

(2) Peak shaving compensation: In the dry

season (October to May of the following year), when

the storage capacity of LNR is less than 90% of the

RSR, CWD is used priority, otherwise LNR is used

priority; in the wet season (June to September),

when the LNR storage capacity is lower than 40% of

the RSR, the CWD is used priority, otherwise the

LNR is used priority.

(3) System maintenance: Considering that the

ZCDP has a longer distance and a longer cross-sea

section of pipelines, in order to ensure the safety of

water supply, consider a one-month maintenance

period for each water pipe every year. According to

the habits of water work and the water level of the

Yao River, try to choose months with less impact

from water cuts.

2.2 Basic Parameters of Joint

Operation

(1) Calculation sequence: A total of 49 years from

1961 to 2009 was selected as the calculation

sequence, and the calculation step was daily.

(2) Urban Monthly Unevenness Coefficient

(UMUC): According to the change trend of urban

water supply in Zhoushan over the years, the UMUC

is statistically analyzed and shown in Table 1.

(3) Intake water level process: The 49-year daily

water level process at the Yao River water intake is

used as the statistical sequence. The frequency of

water levels at all levels and Water Supply Guarantee

Rate (WSGR) is shown in Table 2.

Table 1: UMUC of Zhoushan City (1961-2009).

Months Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

UMUC 0.94 0.91 0.96 0.95 0.94 1.01 1.03 1.21 1.20 1.06 0.95 0.84

Table 2: The frequency of water levels in Yao River

(1961-2009).

Water

Level (m)

The number of days above

the water level (days)

WSGR (%)

1.33 95 26.03

0.93 194 53.15

0.73 248 67.95

0.43 284 77.81

0.13 300 82.19

-0.37 352 96.44

-0.87 361 98.90

3 RESULTS AND DISCUSSIONS

According to the forecast of water demand, the total

water demand of Zhoushan in 2030 will be 21.14

million m3, and the different compensation

calculation schemes are shown in Table 3. Firstly,

without the establishment of DRSR, it could be

found that there are 6 hydrological years (April to

March of the following year) of water shortage,

namely 1967-1968, 1968-1969, 1969-1970, 1978-

1979, 1979-1980, 2003-2004. Correspondingly, the

Annual Water Supply Guarantee Rate (AWSGR)

and Monthly Water Supply Guarantee Rate

(MWSGR) are 84% and 93% respectively, which

cannot meet the 95% requirement of MWSGR in the

specification. Secondly, the LNR and CWD joint

dispatch calculations were performed to balance the

supply and demand, and the DRSR calculation

results of 4 sets of different storage capacity

schemes were further obtained, the water shortage as

well as the guarantee rate in each water shortage

period were analyzed.

It is clear that the MWSGRs of Scheme B and C

are 93% and 94% respectively, and less than 95%

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100

cannot meet the requirements. Compared with the

absence of DRSR, Scheme D has a certain degree of

relief for each water shortage period. If the storage

capacity is further increased, the WSGR cannot be

increased accordingly, so Scheme E is also not

recommended.

DRSR is located in the North Line District of

Zhoushan City, which is also the area with the

fastest economic and industrial development.

According to the water demand forecast, the annual

water storage capacity of the North Line District in

2030 is about 90 million m3. DRSR can meet the

water demand for about one month. From the

perspective of emergency and standby water

sources, the storage capacity of Scheme D is

appropriate.

The rainfall collection area of the downstream

river network of DRSR is about 15.18 km2.

Excluding the 2.64 km2 rain collection area of

reservoirs and ponds, there is still 12.54 km2 that

can be used to further tap the potential. This is

extremely precious to Zhoushan City, which is

seriously lacking of water resources. Under the

premise of Scheme D, the design water flow rate can

be 1.6 m3/s, and the annual water supply can reach

4.75 million m3. The unilateral adjustment of

storage capacity investment is about 80 yuan, and

the development cost is acceptable for island areas

with poor water resources.

Table 3: WSGR of different compensation calculation schemes in ZCDP.

Calculation schemes

Water shortage

years

(Hydrological

years)

Number of

water

shortage

months

Water shortage

in 2030 (10000

)

AWSGR

(%)

MWSGR

(%)

Scheme A

(Without DRSR)

1967—1968 8

6 719

84 93

1968—1969 6 4 421

1969—1970 4 1 921

1978—1979 5 2 230

1979—1980 6 2 437

2003—2004 6 2 215

Scheme B

(DRSR with 4 million m

storage capacity)

1967—1968 7

5 941

86 94

1968—1969 6 4 375

1969—1970 4 1 754

1978—1979 4 1 852

1979—1980 6 2 356

2003—2004 5 1 825

Scheme C

(DRSR with 6 million m

storage capacity)

1967—1968 7

5 748

86 94

1968—1969 6 4 379

1969—1970 4 1 760

1978—1979 3 1 626

1979—1980 6 2 364

2003—2004 5 1 627

Scheme D

(DRSR with 8 million m

storage capacity)

1967—1968 7

5 563

88 95

1968—1969 5 4 383

1969—1970 4 1 766

1978—1979 2 1 442

1979—1980 5 2 371

2003—2004 5 1 433

Scheme E

(DRSR with 10 million m

storage capacity)

1967—1968 7

5 379

88 95

1968—1969 5 4 386

1969—1970 4 1 772

1978—1979 2 1 259

1979—1980 5 2 379

2003—2004 5 1 245

Discussion on the Function and Scale of Dasha Regulating and Storing Reservoir in Zhoushan Continental Diversion Project

101

4 CONCLUSIONS

After the implementation of ZCDP, the scientific

deployment of water diversion from the mainland

and local water is the key to Zhoushan's future

water resources protection. Water diversion from

the mainland is affected by the environment of the

submarine pipeline and the changes in the Yao

River, and there are many uncertain factors.

Therefore, the construction of RSR is a

prerequisite for the rational dispatch of water

resources. This paper conducts qualitative and

quantitative analysis on the impact of the storage

capacity on the guarantee rate of water supply, the

role of emergency reserve, and the rational use of

local water resources. It is considered appropriate

that the storage capacity of the DRSR is 8 million

m3. It also has certain reference significance for

other water transfer projects to reasonably

determine the scale of storage projects.

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