Hydraulic Pipe

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Front. Environ. Sci. Engin. China 2008, 2(1): 57–62DOI 10.1007/s11783-008-0013-0

RESEARCH ARTICLE

Hydraulic model for multi-sources reclaimed water pipe

network based on EPANET and its applicationsin Beijing, China

Haifeng JIA ()1, Wei WEI1, Kunlun XIN2

1 Department of Environmental Science and Engineering, Tsinghua University, Beijing 100084, China2 College of Environmental Science and Engineering, Tongji University, Shanghai 200092, China

© Higher Education Press and Springer-Verlag 2008

Abstract Water shortage is one of the major water related

problems for many cities in the world. The planning for

utilization of reclaimed water has been or would be drafted in

these cities. For using the reclaimed water soundly, Beijing

planned to build a large scale reclaimed water pipe networks

with multi-sources. In order to support the plan, the integrated

hydraulic model of planning pipe network was developed

based on EPANET supported by geographic information

system (GIS). The complicated pipe network was divided into

four weak conjunction subzones according to the distribution

of reclaimed water plants and the elevation. It could provide

a better solution for the problem of overhigh pressure inseveral regions of the network. Through the scenarios analy-

sis in different subzones, some of the initial diameter of pipes

in the network was adjusted. At last the pipe network planning

scheme of reclaimed water was proposed. The proposed

planning scheme could reach the balances between reclaimed

water requirements and reclaimed water supplies, and

provided a scientific basis for the reclaimed water utilization

in Beijing. Now the scheme had been adopted by Beijing

municipal government.

Keywords hydraulic model, multi-sources reclaimed water

pipe network, EPANET, GIS, Beijing

1 Introduction

As a metropolis of China, Beijing is facing a serious water

shortage. The water resources per capita are less than 300 m3.

In order to abate the shortage of water resources in Beijing,

the full utilization of reclaimed water is one of the most viable

ways.

In “the Olympic Game 2008 Application Report”, Beijing

had also promised that 90% wastewater would be treated

and 50% of it would be reused in 2008. Both for fulfillingthe promise to the world and implementing the sustainable

development in Beijing, the reclaimed water utilization

planning was drafted [1]. In the plan, in order to layout the

reclaimed water pipe network, the hydraulic calculation in

the planning was necessary. On the analysis of hydraulic

calculation, the node pressure, pipe diameter, pipe velocity,

and hydraulic gradient could be adjusted for reducing the risk

of leak or break in pipe network, and cutting the cost.

However, the reclaimed water planning pipe network inthe urban areas of Beijing was a complicated structure of

large scale network with multi-sources. Most of the hydraulic

models which base on looped equation were designed to

calculate the looped network, not the large scale network with

hybrid structure. And being limited by the calculation ability,the network usually needs to be simplified before the set-up

model. Despite the predigestion could make the calculation

converge and easy, it brought the difference between the

Received July 9, 2007; accepted September 13, 2007

E-mail: [email protected]

Table 1 Data demand of the network integrated hydraulic model

node pipe

data items ID ID

elevation pipe start and end points

node flow diameter

node coordinates length

Table 2 Network node topological structure datasheet

ID elevation

/m

X coordinates

/m

Y coordinates

/m

flow

/m3 · d−1

1 33.0 20,451,890.75 4,403,995.86 0

2 39.5 20,446,198.06 4,406,185.69 5,751.172

… … … … …

25 39.9 20,445,114.62 4,410,814.11 0

… … … … …



58 Haifeng JIA, et al.

network model and real network [2–6]. In this paper, the

above problems were solved by the integrated hydraulic

model which was built up using EPANET supported by GIS,

where EPANET could be used for hydraulic simulation of

the large scale network with hybrid structure, and GIS can

support more reasonable predigestion [7].

2 Methods and data

The network of Beijing reclaimed water planning pipelinesconsisted of multiple reclaimed water sources and was a large

scale network with mix structure. It covered the whole urban

area of Beijing which is about 1,085 km2. Thus, this requested

the model could solve the problem of large scale network

Fig. 1 Development of the reclaimed water network integrated hydraulic model

Table 3 Network pipe topological structure datasheet

ID Quantity Start point ID End point ID Diameter /mm Length /m

1 2 96 103 600 356.05

2 2 140 141 400 1,439.27

3 2 111 112 600 1,419.79

… … … … … …

Fig. 2 Reclaimed water plants and its network of Beijing



Hydraulic model for multi-sources reclaimed water pipe network and its applications 59

with multiple sources [8,9]. In this paper, EPANET was

chosen to build up the network integrated hydraulic model

with the support of GIS. EPANET was developed by National

Risk Management Research Laboratory of the Water Supply

and Water Resources Division of the U.S. Environmental

Protection Agency [5]. In EPANET, the method to solve the

flow continuity and head loss equations that characterize

the hydraulic state of the pipe network at a given point in time

can be termed a hybrid node-loop approach. EPANET could

directly use the real network to build up the model without

Fig. 3 Hydraulic simulation result of whole network

Fig. 4 Subzones of the reclaimed water pipe network




any change and select Hazen-Williams, Chezy-Manning, and

Darcy-Weisbach as the head loss formula [10,11].

The technical route for development of Beijing reclaimed

water planning network hydraulic model is shown in Fig. 1.

Along with the elevation data, the reclaimed water demand

data, the node and pipe information were needed by the

hydraulic model. The data shown in Table 1 would be pre-processed by GIS. And then, the spatial data would be

developed and stored in spatial database through format

conversion, spatial analysis, and topological analysis.

All these data would be stored in attributed database, and

then the model could be established using the database.

The structure of network layer in database is shown in

Tables 2 and 3. In the tables, the node and pipe’s ID was

AutoNumber. The ID of the pipe’s start and end points

were the node’s ID which attached to this pipe. The initial

Beijing reclaimed water planning network is shown in

Fig. 2, which consisted of 19 reclaimed water plants, 277

nodes and 435 pipes. The total amount of reclaimed water isabout 2x106 m3/d. In the research areas, the user of the

reclaimed water include industry, scenes water, road cleaning,

grass irrigation and toilet flushing.

3 Results and discussion

3.1 Calculation and analysis of the whole network

In the beginning, the integrated hydraulic model was used to

simulate the hydraulic states in the whole network. In Beijing

City, the most major reclaimed water users are located in the

west part of the whole network. And the major reclaimed

water sources are located in the east part of the whole

network. After the hydraulic calculation in the whole network,

as shown in Fig. 3, when it met the 15 m pressure requirement

in most demanding area, the whole pipe network’ pressure

was between 50 and 100 m, the nodes’ pressure was over

100 m at the east part of the network. This pressure was too

high. In this situation, the risk of the pipe network would be

large, and the operational cost would be high.

The main reasons of this result were analysed. First, the

terrain in Beijing City is that the elevation in the west areas is

about 75 m higher than that in the east areas. So, the pressurein east is higher than that in west. Second, the sources of

the reclaimed water supply distribution system are from the

wastewater treatment plants (WWTPs). Because wastewater

Fig. 5 Hydraulic calculation result of subzone III network (before adjustment)



Hydraulic model for multi-sources reclaimed water pipe network and its applications 61

is collected by gravitational pipeline, the wastewater treat-

ment plants are usually standing in lower places. So, the water

supply capability of the plants in east is larger than the ones

in west. In order to meet the water supply demand of the

distribution system, the pressure of the pipelines in the east

should be heightened.

3.2 Subzones dividing

According to the distribution of reclaimed water plants and its

reclaimed water supply quantity, water demand quantity, and

the terrain of Beijing, the pipe network was divided into four

weak conjunction subzones (I–IV), as shown in Fig. 4. In

general, the four subzones would be separated; however, they

could link via valve when needed in extreme situations.

The subzone I consisted of Shougang WWTP, Wujiacun

WWTP, Tiancunlu WWTP, Wulituo WWTP, Mentoucun

WWTP, and Wanquanzhuang WWTP; the subzone II consi-

sted of Lugouqiao WWTP, Zhengwangfen WWTP, Xiao-hongmen WWTP, and Fangzhuang WWTP; the subzone III

consisted of the sixth WTP, Gaobeidian WWTP, Dongba

WWTP, and Jiuxianqiao WWTP; the subzone IV consisted

of Beixiaohe WWTP, Beiyuan WWTP, Qinghe WWTP I,

Qinghe WWTP II, and Xiaojiahe WWPT. The four subzones

were conjunct weakly, and would be respectively calculated.

3.3 Calculation and analysis of the subzone network

The networks of the four subzones were analysed andthen adjusted respectively using the integrated model. Take

the subzone III for instance, the calculation result is shown in

Fig. 5, the node pressure could be divided in three regions,

the pressure was between 20 and 50 m, 50 and 75 m, and 75

and 80 m in west, middle part, and east, respectively. The

pressure was over 80 m around Jiuxianqiao WWTP. The

velocity of flow was between 1.1 and 2.0 m/s, already

exceeded the economic velocity of flow.

After the analysis of calculation results, the reasons why

the pressure and flow velocity were over the normal level

were that the diameter of the pipes connecting east and west

network was too small, as well as the four sources were alllocated in east. Thus, when the water was transported from

east to west, there was excessive head loss. Therefore, the

diameter of pipes should be adjusted.

Fig. 6 Hydraulic calculation result of subzone III network (after adjustment)




The calculation result after adjustment is shown in Fig. 6.

The node pressure was between 20 and 55 m. The velocity

of flow was below 1.44 m/s. The result was reasonable and

accorded with the economic velocity of flow. Other subzones

were also analysed and then adjusted after hydraulic simulation

to make the network reasonable which were not described

here.

4 Conclusions

Aiming at Beijing reclaimed water utilization planning, the

multi-sources reclaimed water network integrated hydraulic

model was developed based on EPANET and GIS. With the

higher efficiency, the model provided strong support to the

reclaimed water network planning and management. In case

of the large reclaimed water utilization area, it is better to use

the reclaimed water in some topographical subzones for it

would keep the proper pressure of the network.According to the calculation and analysis of Beijing

reclaimed water planning network, the adjustment for the

planning network was completed. The adjusted network could

meet the water demand, and provided the scientific basis for

the built of Beijing reclaimed water pipe network.

Acknowledgements This work was supported by the Beijing MunicipalPlanning Committee. The authors thank Mr. Wang Jun and Mr. Liu Jing for their helps.

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