Application of Systematic Management in Ecological Environment

Restoration of “Plant - Net - River and Lake”: A Case Study of the

Shiwuli River Basin

Xuekai Chen

, Xiaobo Liu

1,*

, Zhanpo Mao

, Wenqi Peng

, Fei Dong

, Qiuyue Lian

, Aiping Huang

and Weijie Wang

Department of Water Ecology and Environment, China Institute of Water Resource and Hydropower Research, Beijing

100038, P. R. China

POWERCHINA ECO-ENVIRONMENTAL GROUP CO., LTD, Guangzhou 518102, P. R. China

Keywords: Shiwuli river, Systematic management, Urban water ecological environment, Problem analysis, Engineering

measure

Abstract: The current basin water ecological environment management technology is inefficient due to the complexity

and diversity of the cities. In pursuit of targeting the problems faced by the primary basin water ecological

environment, the Basin of Shiwuli River, the first tributary of Chaohu Lake, was taken as the research object.

Using the existing basin water ecological environment control engineering measures, and the concept of

systematic management and principle of simultaneous development of project and research, the research

objectives and contents of the water ecological environment systematic management of the Shiwuli river basin

were proposed in this paper. Our work establishes a technical platform for ensuring the stability and long-

term maintenance of qualified water in the basin.

1 INTRODUCTION

The Shiwuli river rises from the southeastern foot of

the Dashu mountain, and is a primary tributary of the

Chaohu Lake. This river is located in the southwest

of Hefei City and flows through High-tech, Shushan,

Jingkai, Baohe, and Binhu New regions of Hefei. It is

not only the main channel of regional drainage, but

also an important landscape river channel and

ecological economic belt of the city. Meanwhile, the

Shiwuli river basin is also an important section of the

comprehensive National Science Center, made-in-

China 2025 pilot demonstration city, international

metropolitan area, Chaohu Lake ecological

civilization pioneering demonstration area, and new

highland of the inland development. In 2017, the

fourth environmental protection supervision group of

the Central Committee pointed out that "the water

environmental protection situation of Chaohu Lake

basin is severe, and the pollution load of runoffs

flowing into the lake is large. The water quality of

Shiwuli, Nanfei, and Pai rivers is at class V for a long

time, and the pollution load of these three rivers is

huge." The Shiwuli river undertakes the important

task of urban flood drainage (Lu, 2019) and thereby

plays an important role in the social and economic

development of Hefei. Also, it plays the role of the

urban sewage receiving water body of Hefei (Tian et

al., 2019). This river is an important source of water

pollution load of the Chaohu Lake. As a result, the

treatment of water ecological environment in the

Shiwuli river basin is particularly important.

For the realization of the long-term, stable, and

qualified water ecological environment management

objectives of the Shiwuli river basin, the present study

was envisaged to identify comprehensively analyze

the current water ecological environment problems of

the Shiwuli river, and systematically categorize the

basin water ecological environment management

measures. By employing the basin systematic

management concepts of overall basin research,

comprehensive management, entire process control,

and all-round connection (Peng, 2019), and following

the principle of simultaneous development of project

and research, the present study proposed the research

objectives and contents of water ecological

environment management of the Shiwuli river basin.

488

Chen, X., Liu, X., Mao, Z., Peng, W., Dong, F., Lian, Q., Huang, A. and Wang, W.

Application of Systematic Management in Ecological Environment Restoration of “Plant - Net - River and Lake”- A Case Study of the Shiwuli River Basin.

In Proceedings of the 7th International Conference on Water Resource and Environment (WRE 2021), pages 488-493

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

2 SURVEY OF THE STUDY AREA

The trunk stream of the Shiwuli river from the Swan

lake dam to the entry point of Chaohu Lake is 22.9

km long, with a basin area of 106.6 km

, including

26.6 km

of economic development zone in the

upstream part of the Tangxi river. The geographical

location is shown in Figure 1. Swan lake and Kuang

river are located in the upstream section of Shiwuli

river. The primary tributaries, including Xuxiao,

Weixi, Xingfuqu, and Wangniangou rivers, are

located on the left bank of the middle and lower

reaches of the basin. In addition, five overflow dams

have been currently built on the trunk stream to

regulate the river level, and a wetland project is built

near the entry point of the Chaohu Lake to degrade

the water pollutants.

Figure 1: Geographical location of the Shiwuli river basin.

From the perspective of landform, the Shiwuli

river basin is at high altitude in the northwest and at

low altitude in the southeast (Figure 2 (a)), with

geographical elevations of -25 to 75 m. Low

mountains and hills as well as low-lying plain with

rivers and lakes are the dominant two landforms.

According to the land use types in the basin in 2018

(Figure 2 (b)), the urban land is the principal land use

type in the basin, and accounts to 72%. From the

perspective of hydrometeorology, the Shiwuli river

basin has a subtropical humid monsoon climate, with

an average temperature of 16.5°C (from 1990 to

2019) and an average annual evaporation capacity of

835 mm. The daily precipitation data provided by the

Hefei Station (Figure 3) shows that the average

annual precipitation is 1018.8 mm, and the

precipitation is concentrated in April to August, of

which the precipitation accounts for 62.18% of the

annual value.

Figure 2: Geographical elevation and spatial distribution of

the land use types in the Shiwuli river basin.

3 CURRENT PRIMARY WATER

ECOLOGICAL ENVIRONMENT

PROBLEMS

Shiwuli river is the primary tributary of the Chaohu

Lake. Under the influence of the rapid development

of urban society and economy and the construction of

upstream lakes and reservoirs, the water quality of the

Shiwuli river was at the class-V level before 2017. It

has gradually evolved into an urban sewage receiving

water body with an extreme lack of ecological base

flow. This change not only affected the production

and living conditions of the residents along the river,

but also led to a great impact on the water

environment quality of Chaohu Lake (Tian, 2018). In

view of this adverse situation, since 2018, the Hefei

municipal government constructed a series of

treatment projects, and the pollution load into the

river and lake was reduced. The water quality

monitoring data of each section showed that the water

quality of the Shiwuli river was improved (Wu et al.,

2015). However, the current engineering measures

Application of Systematic Management in Ecological Environment Restoration of “Plant - Net - River and Lake”- A Case Study of the

Shiwuli River Basin

489

cannot ensure the long-term, stable qualified water

quality in each control section. The primary water

ecological environment issues include the follows.

Figure 3: Annual and monthly precipitation in the Shiwuli

river basin from 1990 to 2019.

3.1 Lack of Initial-Stage Rainwater

Pollution Treatment Capacity

Besides agricultural non-point source pollution, the

urban surface runoff pollution has become the second

largest non-point source pollution, and 80% of the

pollutants in a single precipitation event get entrained

in the rainwater at the initial stage (Shen et al., 2020).

In order to reduce the pollution load from Tangxi

river in the Chaohu Lake, the rainwater at the initial

stage from the upstream economic development zone

of Tangxi river was discharged into the middle part of

Shiwuli river. It has been reported that the instant

contents of COD, NH

-N, and total phosphorus (TP)

in the initial-stage rainwater transferred from the

upstream section of Tangxi river reached 452, 5.8,

and 4.8 mg/L, respectively, and the average contents

reached to 85.52, 2.15, and 0.59 mg/L, respectively,

far higher than the levels specified in the class-V

water standard (Zhou et al., 2017). The existing

project treatment measures, including the urban land

use, roads, residential areas, and other facilities

constructed in the Shiwuli river basin, did not

completely take the urban non-point source pollution

control measures into account, and these facilities

insufficiently retain the rainwater in the initial stage.

In addition, the Shiwuli sewage plant with a total

capacity of 200000 m

/d has been operated in the

basin. Also, the Hudaying sewage plant with a

capacity of 100000 m

/d is under construction.

Considering the sewage transferred from the west to

the east to the Wangxiaoying sewage plant, the

capacity can only meet the regional sewage treatment

requirement. The space accommodating the initial-

stage rainwater is insufficient, and the initial-stage

rainwater treatment capacity is low.

3.2 Potential Risk of Pollutants

Released from the River Sediment

The sediment pollution of the Shiwuli river is

relatively severe (Li et al., 2019), and a gush of black

lump from the sediment of some river sections was

observed in summer due to anaerobic fermentation. It

has been reported that the contents of total organic

matter, total nitrogen, and total phosphorus in the

sediment of the Shiwuli river trunk stream reached

5.32%, 2352.04 mg/kg, and 982.83 mg/kg,

respectively (Wang, 2016). According to the

standards of the “Investigation and Evaluation of

Sediment Pollution Situations of National Rivers,

Lakes and Reservoirs”, the levels of total organic

matter and total nitrogen in the sediment of Shiwuli

river should not exceed class IV, and level of total

phosphorus should be in class II. Overall, the results

indicate that the sediment pollution was severe in the

Shiwuli river.

3.3 Insufficient Ecological Base Flow

Supply

Because the Shiwuli river basin is a relatively small

urban region with a developed pipe network, the

natural runoff supply is not stable in a year, and the

river water is difficult to be self-sufficient. Currently,

thanks to the Swan lake water replenishment project,

Chaohu Lake ecological water replenishment project,

and urban reclaimed water, the situation of

insufficient ecological base flow of Shiwuli river has

been effectively mitigated. However, generally

speaking, the problem of insufficient ecological base

flow of the Shiwuli river has not been addressed

continuously and stably, especially in the upper

reaches of the Shiwuli River, of which the base flow

mainly depends on the irregular discharge from the

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Swan lake overflow dam. And, the slope upstream is

steep, so it is very easy to dry in dry seasons.

3.4 Insufficient Tributary Regulations

The primary tributaries of the Shiwuli river include

the Xingfuqu, Wangniangou, Xuxiaohe and Xuxi

rivers that are located on the left bank of the middle

and lower reaches. They receive the urban and rural

domestic sewage and agricultural irrigation residual

water, and the pollution load is large. The distance

between the intersection of the trunk-stream-tributary

and the entry point of Chaohu Lake was 16.40, 12.36,

9.49, and 4.66 km, respectively. This reflects that the

flow of pollutants in the trunk stream of the Shiwuli

river takes a short time, without complete

degradation. Therefore, it is necessary to promote the

comprehensive treatment of the tributaries in the

middle and lower reaches of the Shiwuli river.

3.5 Poor Linkage of Management

Regime

Currently, the water environment management

regime of the Shiwuli river basin lacks linkage, and

the principle is not systematic enough. The water

environment treatment project can hardly be

developed in accordance with the concepts of source

control, process blocking, and end-of-pipe treatment.

The problems mainly lie in the emergent treatment of

sudden water pollution accidents, optimal dispatch of

river water quantity and quality, and tracing of excess

pollutants in the river.

4 BASIN WATER ECOLOGICAL

ENVIRONMENT CONTROL

PROJECT

Since 2015, many departments of Hefei explored the

transformation of Chaohu Lake treatment from point,

line, to surface. In 2016, the Hefei municipal

government announced the construction of short-term

and long-term projects of the “Scheme of

Requirement Reaching of Shiwuli River Water

Body” to the society. To date, some projects have

been implemented and have played an active role in

restoration and pollution control of the water quality

of the entire Shiwuli river basin (Chen et al., 2018).

However, the existing engineering measures cannot

essentially compensate for the historical damage to

the water ecological environment in the Shiwuli river

basin, and the water ecological environment can be

merely treated in limited zones of the basin and the

end of the river. Both the implementation scopes of

engineering measures as well as the blocking and

control of pollutant transport processes are

insufficient. For the benign cycling of the water

ecological environment of Shiwuli river basin with a

possible self-recovery and stable maintenance, the

Hefei municipal government has carried out the first

Shiwuli river basin management project, and the

construction of some of the projects has begun. The

ongoing and incoming projects and engineering

measures in the Shiwuli river basin are listed as

follows:

The ongoing projects include the bid submission

process in the phase-I project and construction of new

phase-III project of the Shiwuli river sewage plant,

economic development zone, sewage transfer project,

Swan lake upstream water transfer and make-up

project, Shiwuli river estuary wetland project, initial-

stage rainwater regulation and storage project at the

Beijing-Taiwan expressway, community

reconstruction pilot project for sponge city, and

sewage interception project at the Qimen road outlet.

The primary phase-I treatment projects of the

Shiwuli river basin construction include 8 categories

and 16 projects, such as urban point source pollution

treatment, urban non-point source pollution

treatment, endogenous pollution treatment, water

replenishment project, river water quality restoration,

river ecological buffer zone, river ecological

restoration and comprehensive monitoring. The

primary projects include the pipe network tracing,

investigation, reconstruction project, initial-stage

rainwater regulation and storage project at Jinzhai

Road and other six sites, garbage collection and

disposal project, river sediment treatment project,

ecological water replenishment project, ecological

buffer zone project, river ecological restoration

project, water and soil conservation forest project,

oxygenation and aeration project, and the

comprehensive river monitoring project.

5 CONCLUSIONS AND

RECOMMENDATIONS

Considering the important geographical location and

the irreplaceable role of the Shiwuli river basin, and

targeting the current water ecological environment

problems in the basin, scientific research should play

a positive guiding role in the treatment of Shiwuli

river water ecological environment by utilizing the

water ecological environment control engineering

Application of Systematic Management in Ecological Environment Restoration of “Plant - Net - River and Lake”- A Case Study of the

Shiwuli River Basin

491

measures in the basin. By following the principles of

simultaneous development of project and research,

research on the project optimization and project

inspection, the aforesaid objectives can be met.

5.1 Research Objective

Aiming at the current primary water ecological

environment problems in the Shiwuli river basin,

according to the overall deployment of the basin

treatment project, the topics of "what to reduce, where

to reduce, how much to reduce, how to reduce, and

how to manage the pollutants in the basin" should be

taken as the core theme. The control of total

maximum daily load (TMDL) of pollutants in the

basin and integrated planning of land and water areas

(point source, non-point source, and endogenous)

should be taken as the basic principles. Subsequently,

the research on the entire basin, all-round treatment

(engineering and non-engineering measures), and

management of all factors should be paid attention.

The comprehensive benefits of various ongoing

engineering and non-engineering measures in the

basin for the improvement of water quality of the

Shiwuli river should be systematically analyzed. With

these solutions, the objectives of stable qualified

water in the basin and its long-term maintenance can

be realized, and a model for the treatment of water

environment in a highly urbanized basin can be

successfully established.

5.2 Research Content

(1) Construction of a water ecological environment

model of Shiwuli river basin by coupling the

hydrology, hydraulics, water quality, and water

conservancy projects

The Shiwuli river is a complex basin, where the

water and pipe networks intersect and the urban and

agricultural land intersect. The transport of water and

pollutants is not only blocked by the initial-stage

rainwater regulation and storage projects in the pipe

network, but also is regulated by the gate and dam

projects in the water network. From the perspective

of systematic management of the basin, a reaction

chain of the entire process of pollutant generation,

pipe network transportation, project regulation, and

water network degradation should be established. In

addition, the current and upcoming treatment

engineering measures should be embedded into the

model to quantitatively evaluate the treatment effects

of the engineering measures. Furthermore, the

quantitative and accurate simulations of the initial-

stage rainwater regulation and storage project in the

pipe-network model and multi-gate-dam dispatching

in the water-network model should be highlighted.

(2) Construction of a technical method for the

distribution of the excessive pollution load in the

cross-section of the Shiwuli river with coupled

natural and social attributes

Based on the successful pollution source

discharge management experience for total maximum

daily loads (TMDLs), through localization,

optimization, and continuous innovation, the

breakthrough of the limitations in thinking of current

pollution load distribution is essential considering the

monotonous factors. There is a need to categorize the

response relationship between the basin pollution

load and water quality change. The

hydrometeorological variation and socio-economic

development factors should be also taken into account

and the dynamic water environment capacity of water

body should be calculate under the influence of multi-

factor disturbance. Additionally, there is a need to

develop a technical method for the distribution of

excessive pollution load in the Shiwuli river basin to

provide a practical goal for the basin water quality

objective management work.

(3) Research and development of a water

ecological environment systematic regulation

platform of the Shiwuli river basin with real-time

monitoring, accurate simulation, and intelligent

mutual feedback

For the informationization, digitization, and

intellectualization of the water ecological

environment management of the Shiwuli river basin,

the basin water ecological environment systematic

regulation platform should be developed. Based on

the multi-source information fusion, with water

ecological environment model as the core and by

using the artificial intelligence modules, this platform

should be developed. This platform should focus on

the issues about the real-time mutual feedback

between the measured data and mathematical models.

Also, the efficient operation of the platform with

multiple objectives needs to be taken into

consideration. In addition, the abilities of emergent

management of sudden water pollution events, early

warning of unqualified water, joint dispatching of the

water quantity and quality, and tracing of pollution

source in the Shiwuli river basin should be improved.

ACKNOWLEDGEMENTS

This work was supported by the Beijing Natural

Science Foundation (No. 8214064), National Key

R&D Program of China (No. 2019YFC0409204),

WRE 2021 - The International Conference on Water Resource and Environment

492

Joint Open Research Fund Program of State key

Laboratory of Hydroscience and Engineering and

Tsinghua–Ningxia Yinchuan Joint Institute of

Internet of Waters on Digital Water Governance (No.

sklhse-2019-Iow07), the Basic Scientific Research

Expense Project of IWHR (No. WE0145B032021,

WR0145B012021).

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