ABSTRACT
As urbanisation continues to accelerate in China, the contradiction between rapid economic development and water scarcity in semi-arid cities is becoming increasingly evident. Consequently, the study of the relationship between water resources use and economic growth is of particular importance. Lanzhou City was selected as the study area, an evaluation index system was established to comprehensively evaluate the status of water resources utilisation, meanwhile, the water footprint method and Tapio decoupling model were adopted to measure the decoupling status between water utilisation and economic development from 2002 to 2021. The result showed that the total water footprint and per capita water footprint followed an increasing and then decreasing trend. The water footprint varied significantly by industrial sector, with agriculture accounting for 72.87% of total water use. The self-sufficiency rate of water resources was above 96.5%. The economic value increased substantially from 22.25 CNY/m3 in 2002 to 183.99 CNY/m3 in 2021. The water scarcity index and the pressure index were high, with annual mean values of 0.96 and 1, respectively. Water consumption and economic growth are generally decoupled weakly and strongly, with the number of strong decoupling occurrences increasing significantly from 2011 to 2021.
HIGHLIGHTS
In the semi-arid regions of Lanzhou City, agricultural water use was the largest flow of water resources.
To relieve stress on water resources and promote stable socio-economic development, this study combined the Tapio decoupling model to analyze the water resources.
Paths of realising sustainable water consumption while developing economy are discussed.
INTRODUCTION
Water is the source of life and the indispensable material for human survival and development (Wang & Li 2018). In recent years, economic growth and population expansion have led to a global shortage of water around the world, a problem that is particularly acute in rapidly developing countries (Süme et al. 2024). Despite China's 7% share of the world's freshwater resources, it must supply water to approximately 20% of the world's population, this makes water scarcity a threat to the sustainable development of some cities (Sun et al. 2021). Consequently, scientific analyses of the sustainable use of urban water resources and studies of the relationship between urban water consumption and economic development can assist in the achievement of sustainable economic development and the resolution of water resource issues.
A substantial body of research has been conducted on the utilisation of water resources. The principal methods employed for the evaluation of water resource utilisation are the system dynamics model (Li et al. 2023), the analytic hierarchy process (Lu et al. 2017) and fuzzy comprehensive evaluation methods (Wang et al. 2021a; Abbaszadeh et al. 2024), etc. For example, Li et al. (2023) constructed an integrated water resources assessment system and a system dynamics model to assess and predict the water resources carrying capacity of Xiongan from 2010 to 2035, they found that scenarios combining the three models of primary development, environmental protection and efficient water conservation not only meets the balance of water resources supply and demand but also has the best-carrying index. Lu et al. (2017) used the hierarchical analysis method (Analytical Hierarchy Process (AHP)) to study the carrying capacity of Huai'an water environment from 2005 to 2014, they found that water environment carrying capacity appeared an upward tendency. The application of these evaluation models and methods can obtain better results; however, these major methods have certain limitations. They are based on statistics of water consumption in various industries and fail to encompass water resources and their dynamics within products and services. Meanwhile, the above methods are difficult to use to explore the relationship between changes in water use and economic development. Therefore, the water footprint theory has been introduced to the evaluation of water utilisation.
The water footprint theory was first proposed by Hoekstra in 2002, this footprint was defined as the virtual water amount of all products (or services) consumed by the population in a certain area during their normal life in a certain period (Hoekstra 2003). Scholars have primarily focused on calculating the water footprint of different industries, the evaluation and analysis of national water resources (Hossain et al. 2021), and the study of the water footprint of specific product consumption (Agnusdei et al. 2022; Xiao et al. 2022). Most of their research concentrated in pivotal regions such as river basins (Fu et al. 2022; Lu et al. 2022a), and provinces (Jiang et al. 2022; Wen et al. 2023). For example, Fu et al. (2022) analyzed the grey water footprint in the Yangtze River Basin, they found the average grey water footprint in the central regions was higher than eastern region and western region. Despite the considerable research on footprint theory, but there are still some shortcomings, previous studies have concentrated on larger regions, with comparatively little research having been conducted on the differences between smaller regions. However, in the context of China's development planning, the city levels are more conducive to the implementation of policies. Moreover, many studies in the literature do not study the decoupling of water use and economic growth in the context of analysing the water scarcity situation in semi-arid regions. This is an obstacle to the achievement of sustainable water resources development in semi-arid regions of Northwest China. Consequently, the relationship between water resources utilisation and economic development at the smaller spatial unit level requires further study, which will facilitate the formulation of specific and critical zoning management strategies.
MATERIALS AND METHODS
Study area
Geographical location map: (a) map of the study area and (b) geographical location map of Lanzhou City.
Geographical location map: (a) map of the study area and (b) geographical location map of Lanzhou City.
Lanzhou City has a temperate continental climate, with an average annual temperature of 11.2 °C. Precipitation falls predominantly from June to September, with an average annual precipitation of about 327 mm (Hu et al. 2017). There are few self-produced water resources in Lanzhou City, and the per capita water resources stand at only one-quarter of the national per capita level (Zhang et al. 2020). The security of the water supply is primarily contingent upon the Yellow River surface water. Under the restrictions of the Yellow River water allocation scheme, the available water resources are very limited. Problems concerning water resources such as unequal distribution of water resources and imbalance between supply and demand have directly hindered the efficient and sustainable development of Lanzhou City.
In 2021, the total population of Lanzhou City was 4,384,300, the urban population totalled 3,663,500, and the rural population was 720,800. Meanwhile, the urbanisation rate was 83.56%, and the natural population growth rate stood at 1.77‰. The city's gross regional product was CNY 323,129 million, representing a 6.1% increase over the previous year. The value added by the primary, secondary, and tertiary industries was CNY 6,252 million, CNY 111,391 million, and CNY 205,486 million, respectively, and the ratio of the industrial structure was 1.94:34.47:63.59. Based on the permanent population, the per capita GDP was CNY 73,807 (https://tjj.lanzhou.gov.cn/).
Data sources
The data for this study were sourced from the Gansu Water Resources Bulletin, the Gansu Provincial Statistical Yearbook, the Lanzhou Municipal Statistical Yearbook, and previous research results. The data employed in this study were categorised into two distinct groups: socio-economic data and water resource data. The initial category encompasses data pertaining to the primary agricultural and livestock products, the population of Lanzhou City at the end of the year, its gross domestic product (GDP), and its import and export trade values. The data presented here were obtained from the Statistical Yearbooks of Gansu Province and the Statistical Yearbooks of Lanzhou City, covering the period from 2002 to 2021. (https://tjj.gansu.gov.cn/, https://tjj.lanzhou.gov.cn/). The second category included domestic water consumption, industrial water consumption, and ecological water consumption. These data were from 2002 to 2021 Gansu Water Resources Bulletin (https://slt.gansu.gov.cn/slt/c106726/c106732/c106773/zcfg.shtml). The available water resources in Lanzhou City from 2002 to 2012 were based on the findings of Feng's research (Feng 2012).
The agricultural water footprint included two components: water demand for crop products, and water demand for animal products. The main crop products were wheat, corn, potatoes, oil, vegetable, and fruit. Livestock products mainly include pork, beef, mutton, milk, poultry eggs, and aquatic product. The virtual water content per unit of product was based on the previous research results (Wang et al. 2021b; Lu et al. 2022b; Liu et al. 2022a) (Table 1).
Virtual water contents of main agricultural and livestock products
Product category . | Product name . | Virtual water content per unit of product . |
---|---|---|
Agricultural products | Wheat | 0.69 |
Corn | 0.80 | |
Potato | 0.28 | |
Oil | 2.20 | |
Vegetable | 0.22 | |
Fruits | 0.82 | |
Livestock products | Pork | 2.20 |
Beef | 12.56 | |
Mutton | 5.20 | |
Milk | 1.03 | |
Poultry eggs | 3.55 | |
Aquatic products | 5.00 |
Product category . | Product name . | Virtual water content per unit of product . |
---|---|---|
Agricultural products | Wheat | 0.69 |
Corn | 0.80 | |
Potato | 0.28 | |
Oil | 2.20 | |
Vegetable | 0.22 | |
Fruits | 0.82 | |
Livestock products | Pork | 2.20 |
Beef | 12.56 | |
Mutton | 5.20 | |
Milk | 1.03 | |
Poultry eggs | 3.55 | |
Aquatic products | 5.00 |
Unit: m3/kg.
Methods
Water footprint calculation model
The construction of a water resources evaluation indicator system
To evaluate water resource utilisation in Lanzhou, this study referred to the evaluation index system constructed by Qi et al. (2011) and Liu et al. (2022b). Six indicators were selected with which to evaluate the water resources of Lanzhou City based on three aspects: the water footprint structure, water footprint benefit, and water footprint security.
Construction of the Tapio decoupling model
Decoupling refers to the situation in which energy consumption does not increase with economic growth in the process of economic development but decreases with economic growth (Schandl et al. 2016). The use of decoupling models has been employed to assess the relationship between water resources and economic development in various regions. The decoupling models used by scholars usually encompass the Tapio decoupling model, the IGT decoupling model and the OECD decoupling model. However, the IGT decoupling model and the OECD model are not comprehensive enough in evaluating the specific types of decoupling, including undecoupling, relative decoupling, and absolute decoupling. The Tapio decoupling model is advantageous in terms of accuracy, comprehensiveness, scientific rigour, and thus this paper employed the Tapio decoupling model (Du et al. 2021; Pan et al. 2022).
Decoupling state classification criteria
Classify . | Decoupling type . | ΔWFP . | ΔGDP . | E . |
---|---|---|---|---|
Decoupling | Strong decoupling | − | + | (−∞, 0) |
Weak decoupling | + | + | (0, 0.8) | |
Recessive decoupling | − | − | (1.2, +∞) | |
Coupling | Expensive coupling | + | + | (0.8, 1.2) |
Recessive coupling | − | − | (0.8, 1.2) | |
Negative decoupling | strong negative decoupling | + | − | (−∞, 0) |
Weak negative decoupling | − | − | (0, 0.8) | |
Expensive negative decoupling | + | + | (1.2, +∞) |
Classify . | Decoupling type . | ΔWFP . | ΔGDP . | E . |
---|---|---|---|---|
Decoupling | Strong decoupling | − | + | (−∞, 0) |
Weak decoupling | + | + | (0, 0.8) | |
Recessive decoupling | − | − | (1.2, +∞) | |
Coupling | Expensive coupling | + | + | (0.8, 1.2) |
Recessive coupling | − | − | (0.8, 1.2) | |
Negative decoupling | strong negative decoupling | + | − | (−∞, 0) |
Weak negative decoupling | − | − | (0, 0.8) | |
Expensive negative decoupling | + | + | (1.2, +∞) |
RESULT
Composition of water footprint
Water footprint composition of Lanzhou City from 2012 to 2021
Year . | AWU . | IWU . | EWU . | DWU . | VWI . | VWU . | Total WFP . | WFP per Capita . |
---|---|---|---|---|---|---|---|---|
2002 | 7.59 | 8.38 | 0.03 | 1.86 | 0.58 | 1.28 | 17.38 | 577.50 |
2003 | 7.94 | 7.98 | 0.05 | 1.69 | 0.47 | 1.88 | 16.25 | 533.96 |
2004 | 8.34 | 7.56 | 0.05 | 1.76 | 0.37 | 1.44 | 16.64 | 539.97 |
2005 | 8.56 | 7.74 | 0.23 | 1.82 | 0.51 | 1.17 | 17.69 | 567.50 |
2006 | 9.20 | 8.23 | 0.23 | 1.91 | 0.41 | 1.22 | 18.76 | 573.65 |
2007 | 9.57 | 7.10 | 0.97 | 1.91 | 0.25 | 0.95 | 18.85 | 572.24 |
2008 | 9.15 | 7.21 | 0.98 | 1.98 | 0.17 | 0.79 | 18.71 | 565.25 |
2009 | 9.77 | 6.62 | 0.99 | 1.98 | 0.21 | 0.36 | 19.21 | 578.37 |
2010 | 10.28 | 6.69 | 1.00 | 2.12 | 0.19 | 0.84 | 19.44 | 537.20 |
2011 | 10.81 | 6.53 | 0.99 | 2.11 | 0.51 | 0.96 | 19.98 | 551.77 |
2012 | 11.47 | 5.16 | 0.99 | 2.16 | 0.41 | 1.58 | 18.61 | 512.70 |
2013 | 12.27 | 3.96 | 0.40 | 1.90 | 0.20 | 1.55 | 17.18 | 471.74 |
2014 | 12.90 | 3.77 | 0.40 | 1.92 | 0.20 | 1.48 | 17.71 | 483.27 |
2015 | 13.33 | 3.92 | 0.71 | 1.98 | 0.22 | 1.87 | 18.30 | 495.39 |
2016 | 13.75 | 3.94 | 0.71 | 1.99 | 0.32 | 1.23 | 19.47 | 525.52 |
2017 | 9.52 | 4.27 | 0.71 | 2.04 | 0.26 | 0.36 | 16.44 | 440.75 |
2018 | 9.47 | 3.31 | 0.84 | 2.14 | 0.26 | 0.34 | 15.68 | 417.85 |
2019 | 10.02 | 3.56 | 1.15 | 2.34 | 0.19 | 0.29 | 16.97 | 447.65 |
2020 | 10.50 | 1.53 | 1.54 | 1.99 | 0.24 | 0.11 | 15.69 | 358.79 |
2021 | 11.14 | 1.62 | 2.33 | 2.25 | 0.35 | 0.12 | 17.56 | 400.56 |
Year . | AWU . | IWU . | EWU . | DWU . | VWI . | VWU . | Total WFP . | WFP per Capita . |
---|---|---|---|---|---|---|---|---|
2002 | 7.59 | 8.38 | 0.03 | 1.86 | 0.58 | 1.28 | 17.38 | 577.50 |
2003 | 7.94 | 7.98 | 0.05 | 1.69 | 0.47 | 1.88 | 16.25 | 533.96 |
2004 | 8.34 | 7.56 | 0.05 | 1.76 | 0.37 | 1.44 | 16.64 | 539.97 |
2005 | 8.56 | 7.74 | 0.23 | 1.82 | 0.51 | 1.17 | 17.69 | 567.50 |
2006 | 9.20 | 8.23 | 0.23 | 1.91 | 0.41 | 1.22 | 18.76 | 573.65 |
2007 | 9.57 | 7.10 | 0.97 | 1.91 | 0.25 | 0.95 | 18.85 | 572.24 |
2008 | 9.15 | 7.21 | 0.98 | 1.98 | 0.17 | 0.79 | 18.71 | 565.25 |
2009 | 9.77 | 6.62 | 0.99 | 1.98 | 0.21 | 0.36 | 19.21 | 578.37 |
2010 | 10.28 | 6.69 | 1.00 | 2.12 | 0.19 | 0.84 | 19.44 | 537.20 |
2011 | 10.81 | 6.53 | 0.99 | 2.11 | 0.51 | 0.96 | 19.98 | 551.77 |
2012 | 11.47 | 5.16 | 0.99 | 2.16 | 0.41 | 1.58 | 18.61 | 512.70 |
2013 | 12.27 | 3.96 | 0.40 | 1.90 | 0.20 | 1.55 | 17.18 | 471.74 |
2014 | 12.90 | 3.77 | 0.40 | 1.92 | 0.20 | 1.48 | 17.71 | 483.27 |
2015 | 13.33 | 3.92 | 0.71 | 1.98 | 0.22 | 1.87 | 18.30 | 495.39 |
2016 | 13.75 | 3.94 | 0.71 | 1.99 | 0.32 | 1.23 | 19.47 | 525.52 |
2017 | 9.52 | 4.27 | 0.71 | 2.04 | 0.26 | 0.36 | 16.44 | 440.75 |
2018 | 9.47 | 3.31 | 0.84 | 2.14 | 0.26 | 0.34 | 15.68 | 417.85 |
2019 | 10.02 | 3.56 | 1.15 | 2.34 | 0.19 | 0.29 | 16.97 | 447.65 |
2020 | 10.50 | 1.53 | 1.54 | 1.99 | 0.24 | 0.11 | 15.69 | 358.79 |
2021 | 11.14 | 1.62 | 2.33 | 2.25 | 0.35 | 0.12 | 17.56 | 400.56 |
Note: Unit of AWU, IWU, EWU, DWU, VWI, VWU, and total WFP is 100 million m3. Unit of WFP per capita is m3.
Water footprint and per capita water footprint of Lanzhou City from 2002 to 2021.
Water footprint and per capita water footprint of Lanzhou City from 2002 to 2021.
Composition of the water footprint of Lanzhou City from 2002 to 2021.
Water resources evaluation indicator system
Lanzhou City water footprint evaluation index system
Year . | Water footprint structural indicators . | Water footprint benefit indicators . | Water footprint security indicators . | |||
---|---|---|---|---|---|---|
WD . | WSS . | WFEB . | WFNTV . | WS . | WP . | |
2002 | 3.36 | 96.64 | 22.25 | 0.69 | 0.94 | 0.97 |
2003 | 2.89 | 97.11 | 27.08 | 1.41 | 0.87 | 0.95 |
2004 | 2.25 | 97.75 | 30.33 | 1.07 | 0.89 | 0.95 |
2005 | 2.86 | 97.14 | 32.05 | 0.66 | 0.95 | 0.99 |
2006 | 2.18 | 97.82 | 34.04 | 0.81 | 1.01 | 1.05 |
2007 | 1.32 | 98.68 | 38.87 | 0.70 | 1.01 | 1.05 |
2008 | 0.93 | 99.07 | 45.23 | 0.62 | 1.01 | 1.04 |
2009 | 1.11 | 98.89 | 48.20 | 0.15 | 1.03 | 1.04 |
2010 | 0.98 | 99.02 | 56.60 | 0.65 | 1.05 | 1.08 |
2011 | 2.53 | 97.47 | 68.07 | 0.45 | 1.07 | 1.10 |
2012 | 2.22 | 97.78 | 84.05 | 1.17 | 1.00 | 1.06 |
2013 | 1.18 | 98.82 | 106.47 | 1.35 | 0.92 | 1.00 |
2014 | 1.15 | 98.85 | 112.94 | 1.28 | 0.95 | 1.02 |
2015 | 1.22 | 98.78 | 114.56 | 1.64 | 0.98 | 1.07 |
2016 | 1.63 | 98.37 | 116.27 | 0.91 | 1.05 | 1.10 |
2017 | 1.59 | 98.41 | 152.14 | 0.10 | 0.88 | 0.89 |
2018 | 1.67 | 98.33 | 174.24 | 0.08 | 0.84 | 0.85 |
2019 | 1.12 | 98.88 | 167.20 | 0.10 | 0.91 | 0.92 |
2020 | 1.54 | 98.46 | 184.04 | −0.13 | 0.84 | 0.84 |
2021 | 1.98 | 98.02 | 183.99 | −0.23 | 0.94 | 0.93 |
Average | 1.79 | 98.21 | 89.93 | 0.67 | 0.96 | 1.00 |
Year . | Water footprint structural indicators . | Water footprint benefit indicators . | Water footprint security indicators . | |||
---|---|---|---|---|---|---|
WD . | WSS . | WFEB . | WFNTV . | WS . | WP . | |
2002 | 3.36 | 96.64 | 22.25 | 0.69 | 0.94 | 0.97 |
2003 | 2.89 | 97.11 | 27.08 | 1.41 | 0.87 | 0.95 |
2004 | 2.25 | 97.75 | 30.33 | 1.07 | 0.89 | 0.95 |
2005 | 2.86 | 97.14 | 32.05 | 0.66 | 0.95 | 0.99 |
2006 | 2.18 | 97.82 | 34.04 | 0.81 | 1.01 | 1.05 |
2007 | 1.32 | 98.68 | 38.87 | 0.70 | 1.01 | 1.05 |
2008 | 0.93 | 99.07 | 45.23 | 0.62 | 1.01 | 1.04 |
2009 | 1.11 | 98.89 | 48.20 | 0.15 | 1.03 | 1.04 |
2010 | 0.98 | 99.02 | 56.60 | 0.65 | 1.05 | 1.08 |
2011 | 2.53 | 97.47 | 68.07 | 0.45 | 1.07 | 1.10 |
2012 | 2.22 | 97.78 | 84.05 | 1.17 | 1.00 | 1.06 |
2013 | 1.18 | 98.82 | 106.47 | 1.35 | 0.92 | 1.00 |
2014 | 1.15 | 98.85 | 112.94 | 1.28 | 0.95 | 1.02 |
2015 | 1.22 | 98.78 | 114.56 | 1.64 | 0.98 | 1.07 |
2016 | 1.63 | 98.37 | 116.27 | 0.91 | 1.05 | 1.10 |
2017 | 1.59 | 98.41 | 152.14 | 0.10 | 0.88 | 0.89 |
2018 | 1.67 | 98.33 | 174.24 | 0.08 | 0.84 | 0.85 |
2019 | 1.12 | 98.88 | 167.20 | 0.10 | 0.91 | 0.92 |
2020 | 1.54 | 98.46 | 184.04 | −0.13 | 0.84 | 0.84 |
2021 | 1.98 | 98.02 | 183.99 | −0.23 | 0.94 | 0.93 |
Average | 1.79 | 98.21 | 89.93 | 0.67 | 0.96 | 1.00 |
Note: Unit of WD and WSS is %. Unit of WFEB is CNY/m3. Unit of WFNTV is 100 million m3.
Indicators for the evaluation of water resource utilisation. (a) Water footprint structural indicators; (b) water footprint benefit indicators; and (c) water footprint security indicators.
Indicators for the evaluation of water resource utilisation. (a) Water footprint structural indicators; (b) water footprint benefit indicators; and (c) water footprint security indicators.
Over the 20-year period under study, the water scarcity index of Lanzhou City exhibited a pattern of initial increase followed by a decline. The peak value of water resource scarcity was observed in 2011, with a score of 1.07, while the lowest value was recorded in 2020, with a score of 0.84. The annual average value was 0.96 (Figure 5(c)). The change in the water resource stress index was essentially the same as that of the water resource scarcity index. The maximum value of the water resource stress index was 1.10 in 2011, the minimum value was 0.84 in 2020, and the multi-year average was 1.00 (Table 4). From 2006 to 2012, the water stress index and scarcity index of Lanzhou City exceeded 1, indicating that the city is experiencing a shortage of water resources. Its actual consumption of water resources exceeds the available water resources, which greatly limits the sustainable development of the city's economy, society, and ecology. In recent years, the water scarcity index and pressure index of Lanzhou City have decreased. However, the increase in the water pressure index and shortage index still requires control to manage the overall level of water resources utilisation in the city.
Analysis of the decoupling relationship between water resource utilisation and economic growth
The GDP exhibited a consistent upward trend over the course of the study period, while the total water footprint exhibited significant fluctuations. In terms of growth rates, the rate of increase in GDP was considerably faster than that of the water footprint (Table 5). This indicates that the socio-economic development is favourable despite the water resources consume.
Decoupling state of water resource utilisation and economic growth in Lanzhou City in 2002–2021
Year . | Rate of change in water footprint . | Rate of change in GDP . | Decoupling index . | Decoupling state . |
---|---|---|---|---|
2002–2003 | −6.51 | 13.78 | −0.47 | Strong decoupling |
2003–2004 | 2.37 | 14.67 | 0.16 | Weak decoupling |
2004–2005 | 6.34 | 12.36 | 0.51 | Weak decoupling |
2005–2006 | 6.03 | 12.60 | 0.48 | Weak decoupling |
2006–2007 | 0.49 | 14.76 | 0.03 | Weak decoupling |
2007–2008 | −0.75 | 15.50 | −0.05 | Strong decoupling |
2008–2009 | 2.68 | 9.42 | 0.28 | Weak decoupling |
2009–2010 | 1.20 | 18.84 | 0.06 | Weak decoupling |
2010–2011 | 2.76 | 23.60 | 0.12 | Weak decoupling |
2011–2012 | −6.83 | 15.03 | −0.45 | Strong decoupling |
2012–2013 | −7.71 | 16.91 | −0.46 | Strong decoupling |
2013–2014 | 3.10 | 9.37 | 0.33 | Weak decoupling |
2014–2015 | 3.30 | 4.78 | 0.69 | Weak decoupling |
2015–2016 | 6.44 | 8.03 | 0.80 | Expensive coupling |
2016–2017 | −15.59 | 10.45 | −1.49 | Strong decoupling |
2017–2018 | −4.58 | 9.28 | −0.49 | Strong decoupling |
2018–2019 | 8.19 | 3.82 | 2.14 | Expensive negative decoupling |
2019–2020 | −7.57 | 1.74 | −4.35 | Strong decoupling |
2020–2021 | 11.96 | 11.94 | 1.00 | Expensive coupling |
Year . | Rate of change in water footprint . | Rate of change in GDP . | Decoupling index . | Decoupling state . |
---|---|---|---|---|
2002–2003 | −6.51 | 13.78 | −0.47 | Strong decoupling |
2003–2004 | 2.37 | 14.67 | 0.16 | Weak decoupling |
2004–2005 | 6.34 | 12.36 | 0.51 | Weak decoupling |
2005–2006 | 6.03 | 12.60 | 0.48 | Weak decoupling |
2006–2007 | 0.49 | 14.76 | 0.03 | Weak decoupling |
2007–2008 | −0.75 | 15.50 | −0.05 | Strong decoupling |
2008–2009 | 2.68 | 9.42 | 0.28 | Weak decoupling |
2009–2010 | 1.20 | 18.84 | 0.06 | Weak decoupling |
2010–2011 | 2.76 | 23.60 | 0.12 | Weak decoupling |
2011–2012 | −6.83 | 15.03 | −0.45 | Strong decoupling |
2012–2013 | −7.71 | 16.91 | −0.46 | Strong decoupling |
2013–2014 | 3.10 | 9.37 | 0.33 | Weak decoupling |
2014–2015 | 3.30 | 4.78 | 0.69 | Weak decoupling |
2015–2016 | 6.44 | 8.03 | 0.80 | Expensive coupling |
2016–2017 | −15.59 | 10.45 | −1.49 | Strong decoupling |
2017–2018 | −4.58 | 9.28 | −0.49 | Strong decoupling |
2018–2019 | 8.19 | 3.82 | 2.14 | Expensive negative decoupling |
2019–2020 | −7.57 | 1.74 | −4.35 | Strong decoupling |
2020–2021 | 11.96 | 11.94 | 1.00 | Expensive coupling |
During the study period, the relationship between water resources and economic development in Lanzhou City was observed to assume four states: weak decoupling, strong decoupling, expensive coupling, and expensive negative decoupling. Over the course of the study period, there were 16 years of decoupling, with the level of decoupling increasing over time. This may be attributed to the implementation of a series of water conservation and management measures in Lanzhou in recent years, achieving a notable decoupling of water use from economic development. Lanzhou City achieved a state of coordinated development of water resource utilisation and economic development, in general, and water consumption decreased with economic growth (Table 5). A state of expensive negative decoupling occurred in 2018–2019, during which economic growth did not lead to a reduction in water consumption. Furthermore, in 2015–2016 and 2020–2021, the two variables were in a state of expensive coupling. This was the intermediate state of negative decoupling and decoupling transition. A correlation was observed between the utilisation of water resources and economic growth, although the relationship was not particularly strong.
DISCUSSION
The water footprint of Lanzhou City showed a fluctuating trend, but the magnitude was not significant, thereinto, the agricultural water footprint was the main component of the water footprint, and its proportion was approximately accounted for 72.87% between 2002 and 2021. It is consistent with the composition of the overall water footprint in other regions of China (Kong et al. 2019). The relatively large share of agricultural water consumption may be attributed to the relatively underdeveloped socio-economic context and the prevalence of agricultural mechanisation in Northwest China, as well as the relatively rudimentary mode of agricultural development. This has led to the increasingly prominent issues of agricultural water use efficiency and structural scarcity of water resources. The inefficiency of agricultural water use affected the intensity of agricultural water use (Lu et al. 2021). Meanwhile, as urbanisation progresses and the population increases, the demand for agricultural and livestock products also increases, so the water consumption of the agricultural and livestock industries will also increase accordingly. The ecological water footprint of Lanzhou City has increased by 76.67% since 2002, may be attributed to the 12th Five-Year Plan and 13th Five-Year Plan for Ecological Construction and Development of Lanzhou City, which accelerated the construction of an ecological civilisation.
This study analyzed three aspects to determine the sustainable utilisation of water resources in Lanzhou. The growing value of the economic benefits of the water footprint in Lanzhou city indicates an improvement in the efficiency of water resources utilisation, which is consistent with the findings of Liang et al. (2023). The results of the analyses of the water stress index and water scarcity index demonstrate that the degree of water shortage has been reduced in recent years, and the contradiction between the supply and demand of water resources has been alleviated. Feng and Zhu's study indicated that water consumption in Gansu Province has been significantly reduced, alleviating the pressure on water resources to a certain extent (Feng & Zhu 2022). The results of this study are further argued by Feng and Zhu's study. This reduction can be attributed to the implementation of a rigorous water resources management system proposed by the Ministry of Water Resources of China in 2011, which provides an important basis for decoupling economic growth from water consumption.
The relationship between water resource utilisation and economic growth in Lanzhou City exhibited a decoupled state overall, weakly so from 2002 to 2011 and then more strongly from 2012 to 2021. This finding is similar to the findings of (Wang & Wang 2020). Their research indicated a pronounced decoupling between water use and economic growth in over 60% of China's 31 provinces from 2011 onwards. This period coincided with the acceleration of the construction of a water-saving society. In recent years, several organisations have indicated that as global water scarcity expands and intensifies, the decoupling of water use from economic growth is critical to sustaining economic growth and human well-being (United Nations Environment Programme 2011). Long et al. (2019) and Zhang et al. (2021) have both reached the clear conclusion that the intensity is the most important driver of the inhibition of the growth of total water use. Furthermore, Richter found that cities could decouple economic growth from water use by adapting to population growth while reducing water consumption (Richter et al. 2020). This study found that agricultural and industrial water use in Lanzhou City constituted a significant proportion of total water use (Bao & Xu 2023). Therefore, it seems that optimising the industrial structure, improving the efficiency of agricultural water use, and increasing the research and development of core water-saving technologies stand as important goals in promoting the decoupling of water resource use from economic development.
CONCLUSIONS
The resolution of the contradiction between economic growth and water resources in semi-arid regions is a key factor in the achievement of regional sustainable development. For this reason, this study took Lanzhou City as the study area. It combined the water footprint model, the Tapio decoupling model and other methods to evaluate the sustainable use of water resources in Lanzhou City. The objective is to identify a feasible way to achieve the synchronisation between the sustainable development of regional water resources and economic growth. This will provide scientific guidance for the achievement of regional sustainable development.
The water footprint of Lanzhou City has exhibited a gradual increase since 2003, followed by a gradual decrease after 2012. Furthermore, the composition of the water footprint of Lanzhou City was highly imbalanced, exhibiting considerable discrepancies in the water footprint values of various categories. During the study period, local water resources were found to be capable of meeting the city's water supply requirements, with a low dependence on outside sources. The efficiency of water use has demonstrably improved, from CNY 22.25/m³ in 2002 to CNY 183.99/m³ in 2021. However, the city continues to confront the challenges of water scarcity and water stress. The relationship between water uses and economic growth exhibited four distinct states: weak decoupling, strong decoupling, expensive coupling, and expensive negative decoupling. The strength of the decoupling gradually increased, accompanied by a corresponding decrease in the dependence of economic growth on water consumption.
In conclusion, it is of paramount importance to accelerate the decoupling of water consumption from economic growth and to achieve sustainable water resources development, which facilitates the formulation of targeted economic development plans. In the agricultural sector, it is imperative to vigorously promote water-saving irrigation, implement refined management of agricultural water use, scientifically determine reasonable irrigation quotas, and optimise and adjust the crop planting structure. In the industrial sector, it is crucial to promote the integration of information technology and industrialisation, increase the research and development of water-saving core technologies, and improve China's water-saving equipment manufacturing innovation capacity.
ACKNOWLEDGEMENTS
This research has been supported by Gansu Province Water Resources Science Experimental Research and Technology Promotion Programme Project (23GSLK082, 24GSLK073), Gansu Provincial Key R&D Projects (22YF7GA107), Gansu Provincial Science and Technology Major Project (23ZDFA009).
DATA AVAILABILITY STATEMENT
All relevant data are included in the paper or its Supplementary Information.
CONFLICT OF INTEREST
The authors declare there is no conflict.