3.1 DPSIR framework
DPSIR is a widely recognized analytical framework, which specifically addresses a sequence of steps for analyzing environmental disturbances: Driver (D), Pressure (P), State (S), Impact (I), and Response (R) (Apostolaki S, Koundouri P, Pittis N 2019; Vannevel R 2018). The DPSIR framework was developed from the pressure-state-response (PSR) model that was initially used by the Organization of Economic Cooperation and Development in 1993 (OECD 1993). Then further improved by the European Environmental Agency (European Environment Agency 1999) and scientists to construct an integrated framework that was primarily used to assess causes, impacts, outcomes, and responses. This framework has been demonstrated to be effective in addressing environmental issues at global and sectoral scales (Ramos-Quintana F, Ortíz-Hernández ML, Sánchez-Salinas E, Úrsula-Vázquez E, Guerrero JA, Zamorano M 2018), and has been used widely in researches about water resources (Zare F, Elsawah S, Bagheri A, Nabavi E, Jakeman AJ 2019; Liu WX, Sun CZ, Zhao MJ, Wu YJ 2019), water quality (Gari SR, Ortiz Guerrero CE, A-Uribe B, Icely JD, Newton A 2018), water pollution (Apostolaki S, Koundouri P, Pittis N 2019) and water accidents (Yang Y, Lei X, Long Y, Tian Y, Zhang Y, Yao Y, Hou X, Shi M, Wang P, Zhang C, Wang H, Quan J 2020). Therefore, DPSIR framework is used here to evaluate the performance of water pollution management (WPM) in Tianjin, and the final results could truly reflect the effects of social, economic, public management and other components on water pollution management. With the coordination of society, economy and water, important foundation can be laid for sustainable development (Luo Z, Zuo Q 2019). Furthermore, clarifying Driver, Pressure, State, Impact and Response is crucial to identify shortcomings in water pollution prevention and control of Tianjin. Thus, policy implications with important value can be put forward. The details of the five components in the framework are as follows.
3.1.1. Driver
Drivers are high level factors that compel changes in the quality and availability of water in profound and fundamental ways (Liu WX, Sun CZ, Zhao MJ, Wu YJ 2019). They usually include factors relating to the productivity of the economy and the activities of society. Population growth and demand increases are the most fundamental drivers in this regard.
3.1.2. Pressure
Pressures are influences which can be exerted on water pollution and water environment management from numerous different types of human activities. These pressures usually exist in the form of consequences produced in the industrial production and household consumption process, and can be divided into water use pressure and water environment pressure.
3.1.3. State
States describe the physical attributes of the water environment at different levels of ecosystem, mainly including hydrological characteristics, water resources sustainability, water quality and other water environment factors.
3.1.4. Impact
Impacts include qualitative and quantitative indices that promote changes in water, production, life, and environment after the water environment state has played its role. Generally, socio-economic impact, ecological and environmental impact and public impact are significant factors under the framework.
3.1.5. Response
Responses are defined as management and control measures enacted to deal with multiple factors of water environment, including the driver component, pressure component, state component and impact component. It contains the most descriptive indices of governance behavior, and can be considered from the aspects of environment response and management response (Posthuma L, Backhaus T, Hollender J, Bunke D, Brack W, Müller C, Gils J, Hollert H, Munthe J, Wezel A 2019).
There is complex interaction between the five elements of DPSIR model, and the specific influence mechanism of various components and the contents of components can be seen in Fig. 4. It is because of this correlation mechanism between the five modules that we hope to use this model framework to understand and assess regional water pollution management more comprehensively and systematically, and then to identify the shortcomings of water pollution management and the room for improvement by comparing the scores of different modules, thus providing a valuable reference basis for the next water pollution management policy formulation.
3.2 Development of the index system based on the DPSIR framework
In order to construct a scientific, representative, and comprehensive evaluation index system, “Water Pollution Prevention and Control Regulations of Tianjin” (Tianjin Municipal People's Congress 2016) was selected as the policy basis. The proposed index system fully took seven chapters of the regional policy into consideration, and representative indices were chosen according to the specific requirements of the regulations, so as to fully feedback the actual situation and facilitate more reasonable evaluation of the regulations.
Additionally, relevant literatures were investigated (Lu W, Xu C, Wu J, Cheng S 2019; Sun C, Wu Y, Zou W, Zhao L, Liu W 2018; Vannevel R 2018; Zare F, Elsawah S, Bagheri A, Nabavi E, Jakeman AJ 2019). Based on the literature review for water management indices (Apostolaki S, Koundouri P, Pittis N 2019; Liu X, Liu H, Chen J, Liu T, Deng Z 2018; Xiao Z, Gao J, Su Y 2019; Yang W, Xu K, Lian J, Bin L, Ma C 2018) and the peculiar situation of Tianjin's water pollution management, the final index system was determined through on-the-spot investigation and demonstration by many experts in the field, which comprised four layers (target layer, component layer, factor layer, index layer) and thirty indices (Table 1).
Table 1
Index system for evaluating implementation effect of Water Pollution Management in Tianjin
Target layer
|
Component layer
|
Factor layer
|
Index layer
|
Unit
|
Corresponding to the Regulation
|
Performance of Water Pollution Management (WPM) in Tianjin
|
Driver (\({\text{C}}_{1})\)
|
Economy (\({\text{F}}_{1})\)
|
Annual GDP growth rate (\({\text{I}}_{1})\)
|
%
|
Article 14: “…… Economic and social development……”
|
Society (\({\text{F}}_{2})\)
|
Natural population growth rate (\({\text{I}}_{2})\)
|
‰
|
Growth rate of water resources per capita (\({\text{I}}_{3})\)
|
%
|
Article 18: “…… Improve the carrying capacity of environmental resources in river basins……”
|
Pressure (\({\text{C}}_{2})\)
|
Water use (\({\text{F}}_{3})\)
|
Total water consumption (\({\text{I}}_{4})\)
|
\({10}^{9}\)m³
|
Article 40: “…… Save water……”
|
Water consumption for industrial output value of 10,000 yuan (\({\text{I}}_{5})\)
|
m³
|
Effective utilization coefficient of farmland irrigation water (\({\text{I}}_{6})\)
|
-
|
Article 58: “…… Encourage water-saving irrigation……”
|
Water environment (\({\text{F}}_{4})\)
|
Discharge of domestic waste water from urban residents (\({\text{I}}_{7})\)
|
\({10}^{9}\)t
|
Article 13: “…… Control water pollutant discharge concentration and total discharge of key water pollutants……”
|
Discharge of waste water from Industry and Construction Industry (\({\text{I}}_{8})\)
|
\({10}^{9}\)t
|
Discharge of Chemical Oxygen Demand (COD) in wastewater (\({\text{I}}_{9})\)
|
\({10}^{4}\)t
|
Discharge of Ammonia Nitrogen (\({\text{N}\text{H}}_{3}\)-N) in wastewater (\({\text{I}}_{10})\)
|
\({10}^{4}\)t
|
State (\({\text{C}}_{3})\)
|
Water state (\({\text{F}}_{5})\)
|
Proportion of Class I-III water quality sections in National Examination Sections (\({\text{I}}_{11})\)
|
%
|
Article 4: “…… Protect and improve water environment quality……”
|
Penetration rate of urban water (\({\text{I}}_{12})\)
|
%
|
Articles 46 to 55: “…… Prevent and control urban water pollution……”
|
Growth rate of total water storage of large and medium-sized reservoirs at the end of the year (\({\text{I}}_{13})\)
|
%
|
Article 18: “…… Improve the carrying capacity of environmental resources in river basins……”
|
Compliance rate of water functional zone evaluation based on full indicators (\({\text{I}}_{14})\)
|
%
|
Article 4: “…… Protect and improve water environment quality……”
|
Average utilization rate of water resources (\({\text{I}}_{15})\)
|
%
|
Article 34: “…… Increase water reuse rate……”
|
Impact (\({\text{C}}_{4})\)
|
Socio-economic impact (\({\text{F}}_{6})\)
|
GDP per cubic meter of water (\({\text{I}}_{16})\)
|
yuan/m³
|
Article 40: “…… Save water……”
|
Ecology and environment impact (\({\text{F}}_{7})\)
|
Green coverage rate of built-up areas (\({\text{I}}_{17})\)
|
%
|
Article 18: “…… Ecological environment governance and protection project……”
|
Water supplement to ecology and environment (\({\text{I}}_{18})\)
|
\({10}^{9}\)m³
|
Article 18: “…… Carrying capacity of river basin environmental resources……”
|
Public impact (\({\text{F}}_{8})\)
|
Public satisfaction with water environment management (\({\text{I}}_{19})\)
|
%
|
Article 10: “…… Public participation……”
|
Response (\({\text{C}}_{5})\)
|
Environment response (\({\text{F}}_{9})\)
|
Centralized treatment rate of sewage (\({\text{I}}_{20})\)
|
%
|
Article 46: “…… Increase the treatment rate of urban sewage……”
|
Water quality compliance rate of discharged sewage (\({\text{I}}_{21})\)
|
%
|
Article 50: “…… Ensure that the effluent water quality meets relevant emission standards……”
|
Compliance rate of discharged industrial wastewater (\({\text{I}}_{22})\)
|
%
|
Article 43: “…… Construct centralized sewage treatment facilities and install automatic online monitoring facilities……”
|
Sewage reuse rate (\({\text{I}}_{23})\)
|
%
|
Article 9: “…… Encourage reuse of water……”
|
Water quality compliance rate of urban drinking water sources (\({\text{I}}_{24})\)
|
%
|
Articles 35 to 39: “…… Protect drinking water sources……”
|
Management response (\({\text{F}}_{10})\)
|
Growth rate of Pollution Discharge Permit issued by Environmental Protection Department to enterprises (\({\text{I}}_{25})\)
|
%
|
Article 16: “…… Pollution discharge permit management system……”
|
Growth rate of urban sewage network (\({\text{I}}_{26})\)
|
%
|
Article 46: “…… Strengthen the planning and construction of urban sewage centralized treatment facilities and pipe networks……”
|
The soundness of laws and standards related to water pollution prevention and control (\({\text{I}}_{27})\)
|
-
|
Article 11: “…… Formulate environmental management measures, implementation plans and local standards……”
|
Improvement rate of water pollution prevention and control management system (\({\text{I}}_{28})\)
|
-
|
Article 8: “…… Water Environmental Protection Target Responsibility System and Assessment System……”
|
Proportion of investment in water resources (\({\text{I}}_{29})\)
|
%
|
Article 5: “…… Irreplaceable financial investment……”
|
Regional water environment management and ecological compensation (\({\text{I}}_{30})\)
|
-
|
Article 65: “…… A coordinated watershed environment management mechanism……”
Article 68: “…… Ecological protection mechanism for permanent protection of ecological regions……”
|
3.3 Quantitative evaluation steps of index system
After establishing the index system, a series of assessment tasks were undertaken according to the following stepwise procedure.
3.3.1 Step 1 - Data procurement
In order to reflect the actual effects of the “Water Pollution Prevention and Control Regulations of Tianjin” more accurately, which were implemented in March 2016, researchers evaluated the performance of water pollution management (WPM) in Tianjin on the basis of the regional policy during the period of 2014-2018. Annual data were obtained mainly from the website of China National Bureau of Statistics, the Statistical Yearbook of Tianjin, the Water Resources Bulletin of Tianjin and so on. The exact sources of index data are enumerated in Table 2.
Additionally, researchers visited the major reservoirs, rivers and lake basins in Tianjin, interviewed the staff of Tianjin Water Bureau and Ecology and Environment Bureau in April 2019, successfully obtained internal data and their thoughts.
For the policy implementation survey, researchers focused not only on the tangible effects but also assessments of public satisfaction and opinion (Fu J, Geng Y 2019; Li L, Xia XH, Chen B, Sun L 2018). To this end, we developed a public opinion survey which asked questions about the levels of public satisfaction with water pollution management in Tianjin. 345 valid submissions were collected and the complete questionnaire is provided in Appendix A.
3.3.2 Step 2 - Calculation of indicator score
Because of the distinctive indicator measuring units, it’s necessary to transfer and calculate original data for subsequent assessments. Owing to the differences between the properties of different indicators, we divided the thirty indicators into three types, with the indicator score of each type being generated according to separate methods.
Graded scoring method means set four grades (Grade I/ II/ III/ IV) for potential performance of indicators. The boundary values for four grades are decided according to relevant laws, regulations and regional targets, together with literature views(Yang W, Xu K, Lian J, Bin L, Ma C 2018). We then compare index data with four boundary values, ensure grade of each index, then calculate exact score as follows:
$${\mathbf{S}}_{\mathbf{i}}=\frac{{\mathbf{X}}^{\mathbf{i}}-{\mathbf{X}}_{\mathbf{m}\mathbf{i}\mathbf{n}}^{\mathbf{i}\mathbf{b}}}{{\mathbf{X}}_{\mathbf{m}\mathbf{a}\mathbf{x}}^{\mathbf{i}\mathbf{b}}-{\mathbf{X}}_{\mathbf{m}\mathbf{i}\mathbf{n}}^{\mathbf{i}\mathbf{b}}}\cdot {\mathbf{P}}_{\mathbf{i}\mathbf{b}}+{\mathbf{S}}_{\mathbf{m}\mathbf{i}\mathbf{n}}^{\mathbf{i}\mathbf{b}}$$
1
where \({\text{S}}_{\text{i}}\) is the score of ith index (\({\text{I}}_{\text{i}}\)); \({\text{X}}^{\text{i}}\) is the actual data of \({\text{I}}_{\text{i}}\); b is the grade number ranks 1 to 4, and the value of \({\text{X}}^{\text{i}}\) belongs to grade b; \({\text{X}}_{\text{m}\text{i}\text{n}}^{\text{i}\text{b}}\) is the minimum value of grade b of \({\text{I}}_{\text{i}}\); \({\text{X}}_{\text{m}\text{a}\text{x}}^{\text{i}\text{b}}\) is the maximum value of grade b of \({\text{I}}_{\text{i}}\); \({\text{P}}_{\text{i}\text{b}}\) is the score interval of grade b; \({\text{S}}_{\text{m}\text{i}\text{n}}^{\text{i}\text{b}}\) is the minimum score of grade b.
Twenty of the thirty indicators used in the index system were calculated according to this method.
Median-based standardized calculation method means calculating the score according to the median between five years. This method applied to six of thirty indicators in the index system. Due to the differences in natural resources endowment, population, economic development level and other factors, these values cannot be directly compared with the national and global average level. Therefore, it was deemed more judicious to reflect the growth or decline of the data obtained for Tianjin across a sample of multiple different years. The specific calculation method is therefore as follows:
\({\mathbf{S}}_{\mathbf{i}}={\mathbf{S}}_{0}\cdot (1\pm \frac{{\mathbf{X}}^{\mathbf{i}}-{\mathbf{X}}_{\mathbf{m}\mathbf{e}\mathbf{d}\mathbf{i}\mathbf{a}\mathbf{n}}^{\mathbf{i}}}{{\mathbf{X}}_{\mathbf{m}\mathbf{e}\mathbf{d}\mathbf{i}\mathbf{a}\mathbf{n}}^{\mathbf{i}}}\) ) (2)
where \({\text{X}}_{\text{m}\text{e}\text{d}\text{i}\text{a}\text{n}}^{\text{i}}\) is the median of (\({\text{I}}_{\text{i}})\) during 2014 – 2018; make \({\text{S}}_{0}\)=80; when the index is positive, use “+” of “\(\pm\)”, and when the index is negative, use “-” of “\(\pm\)”; when the value of \({\text{S}}_{\text{i}}\) > 100, make \({\text{S}}_{\text{i}}\)=100.
In addition to the above two calculation methods, there are four indicators related to the perfection of water pollution management system and public satisfaction in the proposed index system, which need to be assigned quantitatively. According to the expert scoring method, indicator values are decided by numerous experts in water management field based on extensive and in-depth investigation and the collection of relevant supporting materials.
3.3.3 Step 3 - Calculation of indicator weight
The relative weighting of different indicators is an important concern which can have a significant impact on the overall index ranking of the study area and subsequent policy decisions. This is because relative indicator weights may significantly differ depending on the chosen weighting procedure (Mikulic J, Kožic I, Krešić D 2015). According to the results of most studies, common weighting methods can be segregated into two categories: subjective weighting and objective weighting. In order to address the presence of extreme values for several indicators in various years without unduly skewing the overall results, we chose analytic hierarchy process (AHP) to calculate each indicator’s weight.
The AHP is a methodology created by Saaty TL (2004), where an importance level is selected according to a comparison between parameters (Sun S, Wang Y, Liu J, Cai H, Wu P, Geng Q, Xu L 2016). The AHP provides a framework to handle decisions without making assumptions about the independence of higher-level elements from lower-level elements or about the independence of the elements within a level (Do HT, Lo S, Thi LAP 2013; Saaty TL 2002).
In this paper we conducted AHP twice among Component layer and Index layer in the same Component layer. The importance levels were chosen by water management experts according to the requirements in water pollution prevention and control. The main calculation processes are as follow:
First, construct an evaluation matrix. An n-criteria evaluation matrix A in which every element \({\text{a}}_{\text{i}\text{j}}\)(i, j = 1, 2, …, n) is the quotient/ratio of the preference values attached to the criteria as shown in the following matrix (Gao L, Hailu A 2013):
$$\mathbf{A}=\left(\begin{array}{ccc}1& \cdots & {\mathbf{a}}_{1\mathbf{n}}\\ ⋮& \ddots & ⋮\\ {\mathbf{a}}_{\mathbf{n}1}& \cdots & 1\end{array}\right)={{(\mathbf{a}}_{\mathbf{i}\mathbf{j}})}_{\mathbf{n}\mathbf{*}\mathbf{n}}$$
3
where \({\text{a}}_{\text{i}\text{j}}\)>0; \({\text{a}}_{\text{i}\text{j}}\)=1/\({\text{a}}_{\text{j}\text{i}}\); \({\text{a}}_{\text{i}\text{i}}\)=1.
Next, derive criteria weight. The consistency index (CI) is used to determine whether and to what extent decisions violate the transitivity rule, the equation provides optimal results when CI < 0.1 (Feng L, Zhu X, Sun X 2014; Saaty TL 2006):
CI = (λmax-n)/(n-1) (4)
where \({{\lambda }}_{\text{m}\text{a}\text{x}}\) is the largest eigenvalue of matrix a, n is the order of matrix A, and \({{\lambda }}_{\text{m}\text{a}\text{x}}\) is calculated as follows (Feng et al., 2014; Sun S, Wang Y, Liu J, Cai H, Wu P, Geng Q, Xu L 2016):

(5)
The weight of an index was calculated using the importance scales in the second and fourth layers. For this process, the square-root method was used as follows (Feng L, Zhu X, Sun X 2014; Saaty TL 2006; Sun S, Wang Y, Liu J, Cai H, Wu P, Geng Q, Xu L 2016):
m
i =
=1 a
ij, i = 1,2, ..., n (6)

, i =1, 2, ..., n (7)

(8)
The calculation result of indicator weight can be checked in Table 2. The above results have passed the consistency test.
Table 2
Index weights and calculation method
Index layer
|
Weight (relative to the component layer)
|
Weight (relative to the target layer)
|
Positive or negative
|
Grading standard
|
Data source
|
Grade IV (<60 points)
|
Grade III (60-80 points)
|
Grade II (80-100 points)
|
Grade I (=100 points)
|
\({I}_{1}\)
|
0.2857
|
0.0244
|
P
|
<0
|
0~5
|
5~10
|
≥10
|
C
|
\({I}_{2}\)
|
0.2857
|
0.0244
|
P
|
<0
|
0~0.5
|
0.5~1
|
≥1
|
C
|
\({I}_{3}\)
|
0.4286
|
0.0366
|
P
|
<-40
|
-40~0
|
0~40
|
≥40
|
C
|
\({I}_{4}\)
|
0.1208
|
0.0190
|
N
|
Median-based standardized calculation method
|
D
|
\({I}_{5}\)
|
0.1453
|
0.0228
|
N
|
>20
|
20~10
|
10~5
|
≤5
|
D
|
\({I}_{6}\)
|
0.0996
|
0.0156
|
P
|
<0.64
|
0.64~0.68
|
0.68~0.72
|
≥0.72
|
F
|
\({I}_{7}\)
|
0.1208
|
0.0190
|
N
|
Median-based standardized calculation method
|
D
|
\({I}_{8}\)
|
0.1577
|
0.0248
|
N
|
Median-based standardized calculation method
|
D
|
\({I}_{9}\)
|
0.1779
|
0.0279
|
N
|
Median-based standardized calculation method
|
A
|
\({I}_{10}\)
|
0.1779
|
0.0279
|
N
|
Median-based standardized calculation method
|
A
|
\({I}_{11}\)
|
0.2230
|
0.0558
|
P
|
<15
|
15~25
|
25~40
|
≥40
|
C
|
\({I}_{12}\)
|
0.1609
|
0.0403
|
P
|
<90
|
90~95
|
95~98
|
100
|
A
|
\({I}_{13}\)
|
0.1982
|
0.0496
|
P
|
<0
|
0~5
|
5~10
|
≥10
|
D
|
\({I}_{14}\)
|
0.2356
|
0.0590
|
P
|
<5
|
5~20
|
20~40
|
≥40
|
D
|
\({I}_{15}\)
|
0.1823
|
0.0456
|
P
|
<90
|
90~95
|
95~100
|
≥100
|
G
|
\({I}_{16}\)
|
0.2128
|
0.0426
|
P
|
<500
|
500~600
|
600~800
|
≥800
|
F
|
\({I}_{17}\)
|
0.2374
|
0.0475
|
P
|
<25
|
25~35
|
35~45
|
≥45
|
A
|
\({I}_{18}\)
|
0.2653
|
0.0531
|
P
|
Median-based standardized calculation method
|
D
|
\({I}_{19}\)
|
0.2844
|
0.0569
|
P
|
Expert scoring evaluation method
|
I
|
\({I}_{20}\)
|
0.0738
|
0.0227
|
P
|
<80
|
80~90
|
90~98
|
≥98
|
C
|
\({I}_{21}\)
|
0.0894
|
0.0275
|
P
|
<80
|
80~90
|
90~98
|
≥98
|
E
|
\({I}_{22}\)
|
0.0983
|
0.0302
|
P
|
<60
|
60~80
|
80~100
|
≥100
|
G
|
\({I}_{23}\)
|
0.0808
|
0.0248
|
P
|
<15
|
15~30
|
30~40
|
≥40
|
D
|
\({I}_{24}\)
|
0.1078
|
0.0331
|
P
|
<90
|
90~95
|
95~100
|
≥100
|
B&C
|
\({I}_{25}\)
|
0.0706
|
0.0217
|
P
|
≤0
|
0~50
|
50~100
|
≥100
|
G
|
\({I}_{26}\)
|
0.0867
|
0.0266
|
P
|
<0.4
|
0.4~1.2
|
1.2~2
|
≥2
|
C
|
\({I}_{27}\)
|
0.1058
|
0.0325
|
P
|
Expert scoring evaluation method
|
H
|
\({I}_{28}\)
|
0.1058
|
0.0325
|
P
|
Expert scoring evaluation method
|
H
|
\({I}_{29}\)
|
0.0855
|
0.0263
|
P
|
<1
|
1~1.5
|
1.5~3
|
≥3
|
C
|
\({I}_{30}\)
|
0.0957
|
0.0294
|
P
|
Expert scoring evaluation method
|
H
|
*Data source:
A. Website of China National Bureau of Statistics
B. Website of Tianjin Eco-Environment Bureau
C. Statistical Yearbook of Tianjin (2013-2018)
D. Water Resources Bulletin of Tianjin (2013-2018)
E. Environmental Status Bulletin of Tianjin (2013-2018)
F. Calculated from statistical yearbook data
G. Obtained from relevant government departments
H. Scored by experts
I. Scored according to Public Satisfaction Questionnaire Survey
3.3.4 Step 4 - Calculation of annual scores of WPM in Tianjin
After indicator weights have been computed according to the AHP method, comes the calculation of annual scores of WPM in Tianjin. It’s inevitable for missing values to occur within the underlying data supporting such an index system, and there were still three vacancies out of 150 pieces of data. Consequently we calculated the scoring rate as a reasonable approach to avoid unbalance due to blank in specific years and indicators. Finally, we regard the rate calculated as annual scores of regulations implementation.
*100%, i=1, 2, …, n, when Ii isn’t missing value (9)
where \({\text{W}}_{\text{i}\text{c}}\) is the weight of the ith index relative to component layer; \({\text{W}}_{\text{c}\text{t}}\) is the weight of the cth component relative to target layer; and n is the number of indicators.