Abstract

Water scarcity has been the main restraint factor for the development of oasis cities around the world. Urumqi, a typical oasis city in arid northwestern China, is facing an increasing water shortage with rapid development over the past decades. In this paper, we use a system dynamics method and multi-scenario simulation to predict the water-resource demand and the supporting capacity of water resources for the urban development of Urumqi under different scenarios. The results show that existing water resources can hardly meet the needs of urban development. Even if water transfer and saving projects are adopted, in the medium and high-speed development scenarios, there will still be a large water deficit in Urumqi in 2030. Also, to relieve the constraint of water resources on urban development, both water-use structure and industrial structure should be optimized. It is suggested that the demands of ecological water and domestic water are given a primary guarantee; that the proportion of industrial water should significantly increase while drastically decreasing the proportion of agricultural water; that the development of secondary industry should be strengthened while reducing the proportion of primary industry; and, finally, restriction placed on high-water-consuming industry while encouraging low- and medium-water-consuming industries.

Introduction

Water scarcity has received worldwide attention in the past decades. In the more arid regions of the world, water scarcity has become the single greatest threat to food security, human health and natural ecosystems (Seckler et al., 1999). This problem is particularly prominent in developing countries, such as China (Wu & Tan, 2012), India (Srinivasan et al., 2013) and Kenya (Thuo, 2013), resulting from fast economic development, urbanization and population growth. With increasing water scarcity and decreasing supply augmentation options, water managers and policy makers worldwide are turning to water-demand-management solutions (Saleth & Dinar, 2000). As a result, an increasing number of cities, especially those oasis cities in arid areas, are facing the rising challenge of sustainable development under water constraints. Oasis cites are usually the economic and cultural centre of arid areas; therefore, analysis of the supporting capacity of water resources and exploration of effective solutions for water scarcity in oasis cities are of great significance for the development of arid areas.

Considerable researches have been conducted on water scarcity, such as the assessment of water scarcity (Zeng et al., 2013), water scarcity and climate change (Iglesias et al., 2007), and water scarcity and irrigation (Pereira et al., 2009) among others. There is also a large volume of literature on water issues of urban development (Taylor, 2000; Praskievicz & Chang, 2011); some are on the development of oasis cities (Hong-wei, 2007). Countermeasures have been discussed by some researchers, most of which focus on increasing water supply or improving water-saving technology, such as establishing water-saving society systems and water markets, and forming technology systems, management systems, and evaluation systems (Chang et al., 2008).

However, relatively few studies (Zhang et al., 2015) combined the two systems – water-use system and urban-development system – and analysed the supporting capacity of water resources for urban development. Moreover, few studies mention countermeasures under a relatively stable water supply and water-saving technology.

Providing that surface water and groundwater are not likely to increase in the near future, water scarcity problems should be solved not only by providing extra water supply, which is very limited as well as costly, nor simply by water-saving utilization programmes, but also by improving the optimization of water structure. Therefore, based on the historical data of Urumqi in 1995–2010, this paper used a system dynamics (SD) method and multi-scenario simulation to predict water resource demand and the supporting capacity of water resources in Urumqi in 2010–2030 under different water-supply projects, different water-utilization programmes and under different urban-development scenarios, and discussed the optimization of water-use structure and industrial structure under the control of total water use.

The main goals of this paper include: (1) To figure out the water resources' supporting capacity of an oasis city based on the simulation of water-resource demand as well as the relationship between water-resource demand and urban development; (2) To optimize the water-resource allocation through the adjustment of water-use structure and industrial structure; (3) To provide optimization programmes and decision-making reference of water resources supporting the sustainable development of oasis cities around the world.

Methods

Study area

China has been facing increasingly severe water scarcity, especially in the arid northern part of the country. While rapid economic development, combined with population growth and urbanization, triggers a potential conflict between water supply and demand, poor water-resource management increases China's vulnerability and further intensifies the problem (Jiang, 2009). Urumqi is the largest oasis city in the arid area of northwestern China. Its development is greatly limited by water shortage and a vulnerable ecological environment. With the growth of population, urbanization and socio-economic development, especially the continuous expansion of irrigation agriculture as well as the fast development of industries, the gap between water supply and demand has become increasingly prominent. There is a serious mismatch between water-use structure and economic structure (Tang et al., 2013). Therefore, this paper chooses Urumqi as the research area to analyse the supporting capacity of water resources and optimization of water-use structure with the expectation that it can shed light on the sustainable development of other oasis cities around the world.

Establishment of system dynamics simulation model

System dynamics (SD) model is a suitable method to reveal the complex and dynamic behaviour of integrated sustainable-management systems. A great number of researchers have employed SD model in their analyses. Meadows (1972) discussed the WORLD3 model in the book, The Limits to Growth, based on SD thinking. The model analyses possible relationships between population, pollution, natural resources, and economic growth on planet Earth. SD models assess sustainable development on global and national scales, and are well suited for local-scale sustainable management. Fletcher (1998) employed SD as a decision-support tool to manage water resource shortage. SD model is also widely used in the prediction of water-resource demand (Du et al., 2011; Campana et al., 2013) and has been proved to be effective. Therefore, we choose SD model in predicting the water-resource demand of 2010–2030 in Urumqi city.

The SD model of this paper is established according to the theory and mechanism of water-resource constraints in the process of urban development. The analysing framework which includes two subsystems (water-resource system and urban-development system) is constructed. The urban-development process and water-resources utilization potential of Urumqi are simulated and predicted. The water-resource system includes two modules of water supply and water demand, while the urban-development system includes four modules of population, economy, society, and space. In order to establish a model that is more scientific and operable, it is necessary to avoid the uncertain factors. So, during the model construction, we assume that the available water resource of the region is certain, the available land resources do not change, the improvement speed of water-saving technology is stable, and the city level follows the pre-set scenario of urban development (Bao & Fang, 2009). The framework of the research is shown in Figure 1 and the SD model of the research is shown in Figure 2.

Fig. 1.

Framework of the research.

Fig. 1.

Framework of the research.

Fig. 2.

System dynamics model.

Fig. 2.

System dynamics model.

Multi-scenario simulation of urban development

For the water demand side in this research, i.e. the urban development, we use multiple scenario analysis to account for various potential future development pathways. Such analysis has been proved to be a sound method for urban development. For example, Crociani, et al. (2016) adapted multi-scale simulation in the crowd management of urban scenario; Prochnow et al. (2008) also conducted multi-scenario simulation in prioritizing management options for an impacted watershed system. Therefore, we use multi-scenario simulation including high-speed, medium-speed, and low-speed scenarios to account for the possibility of different development speeds. According to the regional situation and the future development environment, the high-speed scenario uses the development speed of Urumqi 12th Five-Year Plan; medium-speed scenario uses the average growth rate of 1995–2010; low-speed scenario uses a relatively conservative pace of urban development (Table 1). The water resources' system has set up four programmes. From the water-supply side, a ‘baseline water supply’ programme and an ‘inter-basin water transferring’ programme were included; from the water-utilization side, a ‘baseline water utilization’ programme and a ‘water-saving utilization’ programme were included. The ‘baseline water supply’ programme assumes that the regional surface water and groundwater resources are from 1995 to 2010 mean, the surface water supply rate increases from 62.68% in 2010 to 75% in 2030, the groundwater supply rate remains unchanged at 50%. By 2030, the total water supply capacity is 1.115 × 109 m3. Under the ‘inter-basin water transferring’ programme, the water-transferring capacity gradually increases, the amount of transferring water increases by a uniform rate of 0.02 × 109 m3 per year. And the total amount of available water-resources reaches 1.515 × 109 m3 by 2030. As for water-resource utilization, the ‘baseline water utilization’ programme takes the industrial water reuse rate of the current 70% at 2010 level, and the ‘water-saving utilization’ programme takes the rate of a uniform increase to 85% by 2030, and the agricultural irrigation water quota decreases year by year.

Table 1.

Scenarios of the urban development system in Urumqi (2010–2030).

Development scenario Population growth (‰) GDP growth (%) Growth rate of 1° IOV* (%) Growth rate of 2° IOV* (%) Growth rate of 3° IOV* (%) Industry growth (%) Expansion rate of constructed area (%) 
High 28.0 18.39 5.26 19.00 18.00 19.00 1.18 
Medium 14.0 11.34 5.26 12.39 10.43 12.71 0.88 
Low 7.0 7.04 5.26 8.08 6.04 8.50 0.59 
Development scenario Population growth (‰) GDP growth (%) Growth rate of 1° IOV* (%) Growth rate of 2° IOV* (%) Growth rate of 3° IOV* (%) Industry growth (%) Expansion rate of constructed area (%) 
High 28.0 18.39 5.26 19.00 18.00 19.00 1.18 
Medium 14.0 11.34 5.26 12.39 10.43 12.71 0.88 
Low 7.0 7.04 5.26 8.08 6.04 8.50 0.59 

*1° IOV = Primary industry output value; 2° IOV = secondary industry output value; 3° IOV = tertiary industry output value.

Note that the primary industry output value is much lower than that of the secondary and tertiary industry and makes up an extremely small proportion; thus the growth rate of primary industry output values is set with no difference among the three scenarios.

Based on the different scenarios, the urban-development level and water-resource demand in Urumqi from 2010 to 2030 were simulated. The water-resource deficits under different scenarios were calculated, and the relationship between urban development and water resources' development and utilization was compared and analysed. The supporting capacities of water resources under different scenarios of urban development were predicted.

Optimization of water-use structure and industrial structure

According to the predicted results of water resources' supporting capacity, the water-use structure and industrial structure are optimized. The optimization is conducted to ensure that the water demands can be fully satisfied. Therefore, the water-use structure in this part is actually a water-demand structure.

The optimization and regulation of water-use structure are mainly based on various parameters of water structure and urban industrial-development structure. On the basis of ensuring the dynamic balance of regional water resources' supply and demand, the water consumption of each industry and department is reasonably allocated among the regional total water (Zhang, 2010). This paper discussed the optimization of total water use as well as the optimization of production water.

The optimization of industrial structure is based on the optimal allocation of water-use structure under the control of total water resources. This paper discussed not only the optimization of the structure among three industries, but also the optimization of agricultural internal structure and industrial internal structure.

Results

Analysis on the supporting capacity of water resources

Under different scenarios of urban development, the population and industries of water utilization are different, which results in the difference between domestic water demand and industrial water demand. Even under the same urban development scenario, the adoption of different water utilization programmes also leads to changes in water quotas, which affect the industrial water demand and agricultural water demand, and thus the total water demand.

The simulation results of major indicators on water-resource demand under different scenarios are shown in Table 2. Urban-development scenario and water-use programme have different impacts on agricultural water demand, industrial water demand, domestic water demand and ecological water demand. The total amount of agricultural water demand is mainly influenced by the irrigation water quota, which is related to water-use programme, but has nothing to do with urban-development scenario; therefore, under different water-use programmes, the agricultural water demands are different, but under different urban-development scenarios, the agricultural water demands are the same. The ecological water demand is simulated by exponential function. The change processes under different scenarios are the same, so no matter under different urban-development scenarios or under different water-use programmes, the ecological water demand remains the same. The domestic water demand is mainly influenced by population. It has nothing to do with the water-use programme, and is related only to the urban-development scenario. So, the domestic water demands are different under different urban-development scenarios, but stay the same under different water-use programmes. The industrial water demand is affected by the change rate of the industrial output value and the water consumption of the 10,000 yuan industrial output value. These two factors are related to both urban-development scenarios and water-use programmes. So, the industrial water demands are different under different urban-development scenarios and water-use programmes.

Table 2.

Simulation results of water-resource demand under different scenarios.

Water utilization programme Year City development scenario Total demand (109 m3Agriculture demand (109 m3Industry demand (109 m3Domestic demand (109 m3Ecological demand (109 m3Water demand of per thousand yuan GDP (m3
 2010 Current 1.089 0.701 0.196 0.15 0.042 5.01 
Baseline 2020 High 1.737 0.533 0.925 0.197 0.081 4.15 
Medium 1.324 0.533 0.537 0.172 0.081 4.15 
Low 1.142 0.533 0.367 0.161 0.081 4.15 
2030 High 5.380 0.506 4.475 0.236 0.163 3.53 
Medium 2.358 0.506 1.509 0.179 0.163 3.53 
Low 1.531 0.506 0.705 0.156 0.163 3.53 
Water saving 2020 High 1.617 0.503 0.836 0.197 0.081 3.75 
Medium 1.242 0.503 0.485 0.172 0.081 3.75 
Low 1.077 0.503 0.332 0.161 0.081 3.75 
2030 High 4.530 0.446 3.685 0.236 0.163 2.90 
Medium 2.032 0.446 1.243 0.179 0.163 2.90 
Low 1.346 0.446 0.581 0.156 0.163 2.90 
Water utilization programme Year City development scenario Total demand (109 m3Agriculture demand (109 m3Industry demand (109 m3Domestic demand (109 m3Ecological demand (109 m3Water demand of per thousand yuan GDP (m3
 2010 Current 1.089 0.701 0.196 0.15 0.042 5.01 
Baseline 2020 High 1.737 0.533 0.925 0.197 0.081 4.15 
Medium 1.324 0.533 0.537 0.172 0.081 4.15 
Low 1.142 0.533 0.367 0.161 0.081 4.15 
2030 High 5.380 0.506 4.475 0.236 0.163 3.53 
Medium 2.358 0.506 1.509 0.179 0.163 3.53 
Low 1.531 0.506 0.705 0.156 0.163 3.53 
Water saving 2020 High 1.617 0.503 0.836 0.197 0.081 3.75 
Medium 1.242 0.503 0.485 0.172 0.081 3.75 
Low 1.077 0.503 0.332 0.161 0.081 3.75 
2030 High 4.530 0.446 3.685 0.236 0.163 2.90 
Medium 2.032 0.446 1.243 0.179 0.163 2.90 
Low 1.346 0.446 0.581 0.156 0.163 2.90 

High-speed urban-development scenario

Under the high-speed urban-development scenario, the industrial water demand, domestic water demand, ecological water demand and total water demand of Urumqi will increase in 2010–2030, but agricultural water demand will not. In the baseline water-consumption programme, the total water demand will increase from 1.089 × 109 m3 in 2010 to 5.380 × 109 m3 in 2030. The rapid growth of industrial output leads to the rapid increase of industrial water demand, and industry becomes an important water-consuming department in Urumqi. Meanwhile in the water-saving programme, the total water demand in 2030 will drop to 4.530 × 109 m3, which saves 0.85 × 109 m3 water compared with the baseline water-consumption programme, and water-use structure has been optimized. The rapid development of society and economy brings increasing demand of water resources. When the water resources' demand exceeds the water supply capacity, an imbalance and water resources' deficit will inevitably occur. According to the baseline water-supply programme, by 2030, the total water-supply capacity of Urumqi will be 1.115 × 109 m3. Then, the water deficit under the ‘baseline water utilization’ programme and ‘water saving utilization’ programme will be 4.265 × 109 m3 and 3.415 × 109 m3, respectively, as shown in Figure 3(a). If the external water resources' supply is transferred, the total water supply in 2030 will be 1.515 × 109 m3, and then the water deficit under the ‘baseline water utilization’ programme and ‘water-saving utilization’ programme will be 3.865 × 109 m3 and 3.015 × 109 m3, respectively, as shown in Figure 3(b).

Fig. 3.

Simulation results of water deficit in different scenarios.

Fig. 3.

Simulation results of water deficit in different scenarios.

Medium-speed urban-development scenario

Under the medium-speed urban-development scenario, the agricultural water demand will decline, while all the amounts of industrial, domestic, ecological and total water demand will increase. In the baseline water-consumption programme, the total water demand of Urumqi will increase to 2.358 × 109 m3 in 2030, while in the water-saving programme the total water demand increases only to 2.032 × 109 m3 and the water shortage situation is greatly reduced. Under the baseline water-supply programme, water shortage starts in 2011 in Urumqi. In the baseline water-utilization programme, the water deficit will be 1.243 × 109 m3 in 2030, and in the water-saving utilization programme the water deficit in 2030 will be 0.917 × 109 m3. Under the water-transferring supply programme, water shortage starts in 2017 with the baseline utilization programme, and the water deficit will be 0.843 × 109 m3 by 2030; while with the water-saving utilization programme, water shortage starts in 2021, and the water deficit will be 0.517 × 109 m3 by 2030.

Low-speed urban-development scenario

Under the low-speed urban-development scenario, the agricultural water demand and domestic water demand will decline from 2011 to 2030, and the total amount of industrial water demand, ecological water demand, and total water demand will increase. Under the baseline water-utilization programme, the total water demand will increase to 1.531 × 109 m3 in 2030, while under the water-saving utilization programme, the total water demand increases only to 1.346 × 109 m3. In the baseline water-supply programme, water shortage starts in 2012 and the water deficit will be 0.416 × 109 m3 by 2030; if the water-saving utilization programme is adopted, water shortage starts in 2017 and the water deficit will be 0.231 × 109 m3 by 2030. In the water-transferring programme, the water resources are sufficient to meet the needs of social and economic development.

Optimization

Social and economic development brings about the increase in water demand; when the water demand exceeds the water supply capacity, water resources' deficit will inevitably occur as discussed above. Looking forward, Urumqi will have to face the tough task of how to maintain the balance between urban development and water resources' exploitation and utilization. We must change attitudes toward water supply and demand, adjust the relationship between water resources' supply and demand, take the coordinated development method by allocating water resources under the regulation of ‘plan the demand according to the supply’ and ‘limit the consumption of water’ (Chen et al., 2009). Before the water-transferring project can be substantially carried out, it is necessary to establish a relatively reasonable water-use structure based on the optimization of industrial structure as well as the optimization of local water resources' allocation. This can, to a certain extent, help to reduce the shortage of water resources in Urumqi, and to improve the sustainable development of society and the economy (Zhang, 2010).

Optimization of water-use structure

In general, the proportion of ecological water should keep increasing in order to guarantee the healthy cycle of the regional ecosystem, and will reach 0.163 × 109 m3 in 2030; domestic water consumption, which is determined by the urban (rural) population and urban (rural) residents' water quota, will also grow gradually and reach 0.179 × 109 and 0.236 × 109 m3, respectively, under the medium- and high-speed development scenarios by 2030.

Optimization of total water use

In 2010, the total water consumption is 0.985 × 109 m3, among which ecological water is 0.042 × 109 m3, domestic water is 0.150 × 109 m3, and production water is 0.793 × 109 m3. The demand for all three types of water will increase during the next 20 years. By 2030, the total demand for water will rise to 1.515 × 109 m3, among which the ecological, domestic and production water demands are 0.163 × 109, 0.179 × 109, and 1.173 × 109 m3, respectively, under the medium development scenario and 0.163 × 109, 0.236 × 109, and 1.116 × 109 m3, respectively, under the high development scenario, as shown in Figure 4. It is noted that during the optimization of water-use structure and industrial structure, only medium-speed and high-speed scenarios are considered. The reason is that the optimization should primarily meet the growth rate of socio-economic development needs, however, the low-speed scenario cannot meet the needs of socio-economic development and therefore is not taken into consideration. It is also noted that different development scenarios affect only the population and industry so that the domestic and production water demand are different between medium- and high-speed scenarios, while ecological water demand remains the same.

Fig. 4.

Optimization of total water use (total demand/amount).

Fig. 4.

Optimization of total water use (total demand/amount).

The optimization of total water use will change the water-use structure between ecological, domestic, and production water to a large extent, as shown in Figure 5.

Fig. 5.

Optimization of total water use (structure/proportion).

Fig. 5.

Optimization of total water use (structure/proportion).

Although ecological water still holds the smallest proportion among the total water demand, a dramatic increase can be seen from 4.3% in 2010 to 10.76% in 2030, in order to emphasize the importance of environment protection. The results of domestic water optimization are different under the medium development scenario and the high development scenario due to the difference in population. Under the medium-speed development scenario, the proportion of domestic water will decrease from 15.19% in 2010 to 11.84% in 2030; while under the high-speed development scenario, this proportion will slightly increase from 15.19% to 15.58%. For production water, the trend is more obvious. In 2010, the proportion of production water is as high as 80.51%; while in 2030, this proportion will be reduced to 77.40% under the medium-speed development scenario and 73.66% under the high-speed development scenario. In fact, the adjustment of the internal structure of production water is an emphasis of water-structure optimization, which will be specifically discussed in the next section.

Optimization of production water

Although the share of production water will largely decrease in the next 20 years, it still makes up the largest part of the total water use, so the optimization of production water is still the main focus of water-use optimization. The following results and discussion are mainly based on the reasonable allocation between industrial production water and agricultural production water. The optimization of production water is based on the fast development of water-saving agriculture and the restriction of high-water-consuming industries and inefficient industries. And then the internal structures of industry and agriculture are optimized according to the specific water demand.

Currently, the proportion of agricultural water is much larger than that of industrial water in Urumqi. After optimization, however, the proportion as well as the total amount of agricultural water will be substantially reduced while the proportion of industrial water will significantly increase. As shown in Figure 6, in 2010, the total amount of production water is 0.793 × 109 m3, among which industrial water (0.196 × 109 m3) and agricultural water (0.597 × 109 m3) account for 24.72% and 75.28%, respectively, of the total production water. In 2030, under the medium-speed urban-development scenario, the total demand of production water in Urumqi is adjusted to 1.173 × 109 m3, among which industrial water demand is 0.848 × 109 m3 and agricultural water demand is 0.325 × 109 m3. The shares of industrial water and agricultural water are 72.29% and 27.71%, respectively, a significant change compared with 24.72% and 75.28% in 2010. Under the high-speed urban-development scenario, the total demand for production water is adjusted to 1.116 × 109 m3, among which industrial water demand is 0.905 × 109 m3 and agricultural water demand is 0.211 × 109 m3; the share of industrial water will be even higher at 81.09% and that of agricultural water will be even lower at 18.91%. The change between the proportion of agricultural production water and industrial production water means the adjustment of water-use structure and shows that the water supply will follow the direction of industrial structure adjustment in Urumqi. It is noted that there is possibly a decrease in fresh-food production in Urumqi due to this change. The decreased production could be countered by receiving supplies from regions close to Urumqi, such as Changji.

Fig. 6.

Adjustment of production water demand and structure in Urumqi.

Fig. 6.

Adjustment of production water demand and structure in Urumqi.

Optimization of industrial structure

There are two main goals of the industrial structure optimization: one is to achieve the balance between water supply and demand, and the other is for economic growth to meet the needs of urban development. These two goals can be achieved by the optimization and adjustment of the three industrial structures, the internal structure of agriculture and internal structure of industry in Urumqi. And the optimization also improves the evolution to a more efficient and water-saving industrial structure in Urumqi.

The adjustment of three industries' structure

In order to meet the requirements of the overall development speed of the city, the speed and structure of three industries in Urumqi over the next 20 years are optimized. In 2010, the GDP of Urumqi was 30.38 × 109 yuan (calculated at comparable prices in 1978), among which the primary, secondary, and tertiary industries accounted for 1.49%, 44.86%, and 53.65%, respectively, a typical ‘tertiary, secondary, primary’ industrial structure, with the primary industry having an extremely low proportion. Urumqi is the social and economic centre of Xinjiang, and it is a new comprehensive industrial city, which is in the historical stage of new industrialization. During future development, the primary industry will continue to decline, while the secondary and tertiary industries will continue to grow rapidly. In the medium-speed development scenario, the GDP of Urumqi in 2030 will be 260.56 × 109 yuan, an average growth rate of 11.34% per year compared with 2010. The proportions of primary, secondary, and tertiary industries' output are adjusted to 0.37%, 54.04%, and 45.59% with secondary industry considered as the main direction of development in the future of Urumqi. In the high-speed development scenario, the GDP of Urumqi reaches 889.56 × 109 yuan in 2030, with an average growth rate of 18.39% per year. The proportions of primary, secondary, and tertiary industries' output are adjusted to 0.09%, 49.68%, and 50.23%, still maintaining the ‘tertiary, secondary, primary’ structure (Table 3).

Table 3.

Industrial restructuring of Urumqi in different scenarios.

Index Year Medium-speed urban development
 
High-speed urban development
 
GDP Primary industry Secondary industry Tertiary industry GDP Primary industry Secondary industry Tertiary industry 
Output value (109 yuan) 2010 30.38 0.45 13.63 16.30 30.38 0.45 13.63 16.30 
2015 51.78 0.62 24.43 26.73 70.40 0.59 32.52 37.28 
2020 88.50 0.76 43.80 43.93 163.65 0.68 77.59 85.37 
2025 151.68 0.89 78.54 72.25 196.08 0.74 185.00 195.34 
2030 260.56 0.96 140.80 118.80 889.56 0.81 441.90 446.85 
Proportion (%) 2010 100 1.49 44.86 53.65 100 1.49 44.86 53.65 
2015 100 1.19 47.19 51.62 100 0.84 46.20 52.96 
2020 100 0.86 49.49 49.64 100 0.42 47.41 52.17 
2025 100 0.59 51.78 47.63 100 0.19 48.57 51.23 
2030 100 0.37 54.04 45.59 100 0.09 49.68 50.23 
Index Year Medium-speed urban development
 
High-speed urban development
 
GDP Primary industry Secondary industry Tertiary industry GDP Primary industry Secondary industry Tertiary industry 
Output value (109 yuan) 2010 30.38 0.45 13.63 16.30 30.38 0.45 13.63 16.30 
2015 51.78 0.62 24.43 26.73 70.40 0.59 32.52 37.28 
2020 88.50 0.76 43.80 43.93 163.65 0.68 77.59 85.37 
2025 151.68 0.89 78.54 72.25 196.08 0.74 185.00 195.34 
2030 260.56 0.96 140.80 118.80 889.56 0.81 441.90 446.85 
Proportion (%) 2010 100 1.49 44.86 53.65 100 1.49 44.86 53.65 
2015 100 1.19 47.19 51.62 100 0.84 46.20 52.96 
2020 100 0.86 49.49 49.64 100 0.42 47.41 52.17 
2025 100 0.59 51.78 47.63 100 0.19 48.57 51.23 
2030 100 0.37 54.04 45.59 100 0.09 49.68 50.23 

The adjustment of agricultural internal structure

The proportion of agricultural output value in Urumqi is small, but the proportion of water used in agriculture is very high and the utilization rate is very low. Moreover, irrigation water accounts for more than 90% of the total agricultural water consumption, while the output value of the planting industry makes up only about 50% of the whole. It shows that the proportion of planting water is too high and the efficiency is too low. To adjust the agricultural structure, appropriately reducing the consumption of agricultural water, and gradually increasing the proportion of forestry, animal husbandry, and fishery, and reducing the proportion of crop planting are key to the control of total water resources during the development of Urumqi. As shown in Table 4, in 2010, the total output value of crop planting, forestry, animal husbandry, and fishery in Urumqi was 0.85 × 109 yuan, among which crop planting and animal husbandry dominate. Under the medium-speed scenario of urban development, the agricultural structure is optimized as following: the total output value of agriculture, forestry, animal husbandry, and fishery reaches 1.64 × 109 yuan by 2030, with an average increase of 0.04 × 109 yuan per year. The proportion of crop planting's output value decreases with an average rate of 1.05% per year, and the proportion of forestry, animal husbandry, and fishery increases slightly. Under the high-speed scenario of urban development, the total output value of agriculture, forestry, animal husbandry, and fishery reaches 1.38 × 109 yuan by 2030, an average increase of 0.03 × 109 yuan per year. The proportion of crop planting's output value will decrease by an average rate of 1.68% per year and the output value of animal husbandry will exceed that of crop planting in 2017.

Table 4.

Adjustment of agricultural structure in Urumqi under different scenarios.

Urban development Year Total output value (109 yuan) Structure of output value (%)
 
Crops Husbandry Forestry Fishery Other 
Current 2010 0.85 53.32 42.05 0.95 1.96 1.72 
Medium 2015 1.05 51.05 44.10 0.99 2.06 1.80 
2020 1.30 48.94 45.99 1.04 2.15 1.88 
2025 1.52 43.53 50.87 1.15 2.37 2.08 
2030 1.64 32.28 61.00 1.38 2.85 2.50 
Annual change 0.04 −1.05 0.95 0.02 0.04 0.04 
High 2015 1.01 49.01 45.93 1.04 2.14 1.88 
2020 1.16 42.94 51.39 1.16 2.40 2.10 
2025 1.25 31.43 61.77 1.39 2.88 2.53 
2030 1.38 19.64 72.39 1.63 3.38 2.96 
Annual change 0.03 −1.68 1.52 0.03 0.07 0.06 
Urban development Year Total output value (109 yuan) Structure of output value (%)
 
Crops Husbandry Forestry Fishery Other 
Current 2010 0.85 53.32 42.05 0.95 1.96 1.72 
Medium 2015 1.05 51.05 44.10 0.99 2.06 1.80 
2020 1.30 48.94 45.99 1.04 2.15 1.88 
2025 1.52 43.53 50.87 1.15 2.37 2.08 
2030 1.64 32.28 61.00 1.38 2.85 2.50 
Annual change 0.04 −1.05 0.95 0.02 0.04 0.04 
High 2015 1.01 49.01 45.93 1.04 2.14 1.88 
2020 1.16 42.94 51.39 1.16 2.40 2.10 
2025 1.25 31.43 61.77 1.39 2.88 2.53 
2030 1.38 19.64 72.39 1.63 3.38 2.96 
Annual change 0.03 −1.68 1.52 0.03 0.07 0.06 

The internal structure of the planting industry is the key point of agricultural structure adjustment in Urumqi. The planting structure is the dominant factor affecting the quota of irrigation water (Wang et al., 2004). Since the change of irrigation water quota has taken water-saving factors into account, the control of irrigation water consumption is mainly through adjusting the planting structure and irrigation area. The total amount of regional water supply is limited, and the increase of water demand brought about by the growth of urban population and industrial development results in a decrease in the total amount of irrigation water, which requires the reduction of the irrigating area. Under the medium-speed and high-speed urban-development scenarios, the effective irrigating area of cultivated land in Urumqi is adjusted to 42.18 × 103 and 25.57 × 103 ha, respectively, in 2030, which is reduced to 69.41% and 42.07% of the level in 2010 (60.77 × 103 ha), respectively. Calculated according to the average level of effective tillage coefficient and multiple cropping index during 1995–2010, the crop planting area under medium-speed and high-speed urban-development scenarios is 49.21 × 103 and 29.83 × 103 ha, respectively, in Urumqi by 2030.

The basic planting structure of Urumqi presents a vegetable-food-based layout (Chen et al., 2004). The status of Urumqi's suburb agriculture determines that vegetable planting will be dominant in the future development. And the first goal of the planting industry is to meet the demand for vegetables required by the growing population. In order to reduce irrigation water and improve economic efficiency, and to implement the ‘grain compressing, structure adjusting and water saving’ project, it is necessary to compress the present irrigation area while, at the same time, reduce the grain planting area and expand the production of vegetables and fruit. In 2010, the vegetable planting area of Urumqi is 18.42 × 103 ha and will increase to 22.58 × 103 ha and 29.70 × 103 ha in 2030, respectively, under the medium- and high-speed urban-development scenarios. The decrease in the area of crop planting caused by the reduction of irrigation water will lead to a more obvious increase in the proportion of vegetable acreage. The acreage of grain, oil, and other crops will be reduced. In the case of high-speed urban development, the available irrigated arable land in 2029 can no longer meet the needs of the urban population for vegetables, so it will be used almost totally for vegetable planting (Table 5).

Table 5.

Adjustment of planting structure in Urumqi under different scenarios.

Urban development Year Effective irrigated area (103 ha) Planting area (103 ha)
 
Proportion of planting area (%)
 
Total Grain Vegetable Oil Other Grain Vegetable Oil Other 
Current 2010 60.77 65.88 30.7 18.42 5.65 11.11 45.63 24.91 7.70 21.76 
Medium 2015 67.98 79.30 37.05 18.33 6.26 17.67 46.72 23.11 7.89 22.28 
2020 70.54 82.29 38.07 19.65 6.43 18.15 46.26 23.87 7.81 22.06 
2025 64.08 74.75 32.63 21.06 5.51 15.56 43.65 28.17 7.37 20.81 
2030 42.18 49.21 16.18 22.58 2.73 7.72 32.89 45.88 5.55 15.68 
High 2015 61.08 71.26 31.38 19.63 5.30 14.96 44.03 27.54 7.43 20.99 
2020 52.95 61.77 23.84 22.53 4.03 11.37 38.60 36.48 6.52 18.40 
2025 35.59 41.52 9.51 25.87 1.61 4.54 22.91 62.30 3.87 10.92 
2030 25.57 29.83 0.08 29.70 0.01 0.04 0.27 99.57 0.04 0.12 
Urban development Year Effective irrigated area (103 ha) Planting area (103 ha)
 
Proportion of planting area (%)
 
Total Grain Vegetable Oil Other Grain Vegetable Oil Other 
Current 2010 60.77 65.88 30.7 18.42 5.65 11.11 45.63 24.91 7.70 21.76 
Medium 2015 67.98 79.30 37.05 18.33 6.26 17.67 46.72 23.11 7.89 22.28 
2020 70.54 82.29 38.07 19.65 6.43 18.15 46.26 23.87 7.81 22.06 
2025 64.08 74.75 32.63 21.06 5.51 15.56 43.65 28.17 7.37 20.81 
2030 42.18 49.21 16.18 22.58 2.73 7.72 32.89 45.88 5.55 15.68 
High 2015 61.08 71.26 31.38 19.63 5.30 14.96 44.03 27.54 7.43 20.99 
2020 52.95 61.77 23.84 22.53 4.03 11.37 38.60 36.48 6.52 18.40 
2025 35.59 41.52 9.51 25.87 1.61 4.54 22.91 62.30 3.87 10.92 
2030 25.57 29.83 0.08 29.70 0.01 0.04 0.27 99.57 0.04 0.12 

The adjustment of industrial internal structure

It is assumed that a water-saving programme is widely adopted in the future water resources' utilization of Urumqi. The reuse rate of water resources is increasing, water-saving technologies are widely used, and water-use efficiency is greatly improved. So the optimization of industrial water will not consider the water-saving measures within industrial enterprises, but mainly consider the structural adjustment among different water-consumption industries under the certain amount of water supply. The industrial sectors are classified into low-water-consuming industry, medium-water-consuming industry, and high-water-consuming industry according to their water-consumption levels using the average water consumption of all industry sectors in the country (Macroeconomic Research Institute of the State Planning Commission, 2001). From 1995 to 2010, the average water consumption for every 10,000 yuan output value of low-water-consuming industry was 1.380 m3 in Urumqi, however, for middle- and high-water-consuming industries, the figures are 6.662 and 65.373 m3, respectively, which are 4.83 and 47.37 times those of low-water-consuming industry, respectively. However, in the industrial internal structure of 2010, high-water-consuming industry takes as high as 76.29% of the output value while low-water-consuming industry takes only 19.54% of the output value, and medium-water-consuming industry takes 4.17%. This situation does not suit the water shortage condition in Urumqi, and is the opposite to Urumqi's function as a capital city, which needs to be adjusted and optimized urgently.

The adjustment of industrial internal structure shows that the proportion of high-water-consuming industries will sharply decrease in the next 20 years in Urumqi, and the proportion of low-water-consuming industries will gradually increase. The industrial structure will change to water-saving type (Table 6).

Table 6.

Adjustment of the internal structure of industry in Urumqi (%).

Year Medium-speed of urban development
 
High-speed of urban development
 
Low-water- consuming industry Medium-water- consuming industry High-water- consuming industry Low-water- consuming industry Medium-water- consuming industry High-water- consuming industry 
2010 19.54 4.17 76.30 19.54 4.17 76.30 
2015 18.55 12.56 68.88 26.05 16.31 60.13 
2020 24.04 13.37 62.59 39.04 20.87 45.09 
2025 29.52 14.19 56.29 52.02 25.44 30.04 
2030 35.00 15.00 50.00 60.00 25.00 15.00 
Year Medium-speed of urban development
 
High-speed of urban development
 
Low-water- consuming industry Medium-water- consuming industry High-water- consuming industry Low-water- consuming industry Medium-water- consuming industry High-water- consuming industry 
2010 19.54 4.17 76.30 19.54 4.17 76.30 
2015 18.55 12.56 68.88 26.05 16.31 60.13 
2020 24.04 13.37 62.59 39.04 20.87 45.09 
2025 29.52 14.19 56.29 52.02 25.44 30.04 
2030 35.00 15.00 50.00 60.00 25.00 15.00 

Under the medium-speed development scenario, the proportion of output value for low-water-consuming industry will increase from 19.54% in 2010 to 35% in 2030, the proportion of output value for medium-water-consuming industry will increase from 4.17% to 15%, and the proportion of output value for high-water-consuming industry will drop from 76.30% to 50%. Under the high-speed development scenario, the proportion of output value for low- and medium-water-consuming industries will increase to 60% and 25%, respectively, while the proportion of high-water-consuming industry will drastically drop to 15%. The adjustment of industrial internal structure in Urumqi will also bring changes in industrial water quota. According to the current industrial structure, the industrial water quota in Urumqi is 2.904 m3 per thousand yuan by 2030. However, through industrial structure adjustment, which speeds up the development of low- and medium-water-consuming industries, and limits the high-water-consuming industry, by 2030, the industrial water quotas will be reduced to 1.980 m3 per thousand yuan and 0.713 m3 per thousand yuan under medium- and high-speed urban-development scenarios, respectively. The adjustment of industrial internal structure and the increase of industrial water reuse rate will slow down the total industrial water consumption.

Main conclusions and suggestions

Urban-development scenarios and water-utilization programmes jointly affect total water demand. Water resources' deficit will occur in most cases, but the amount of water deficit varies under-different urban-development scenarios and water-utilization programmes.

According to the baseline water-use programme, by 2030, the total water demand of Urumqi will reach 5.380 × 109, 2.358 × 109 and 1.531 × 109 m3 under high-, medium-, and low-speed urban-development scenarios, respectively. If a water-saving programme is adopted, which means water-saving technology would be widely used in industrial and agricultural production and the recycle rate of industrial water be increased, then the amount of total water demand will be 4.530 × 109, 2.032 × 109 and 1.346 × 109 m3 under high-, medium-, and low-speed urban-development scenarios, respectively. Under the baseline water-supply programme, the total water supply in Urumqi in 2030 will be 1.115 × 109 m3; the water resources cannot support even the low speed of socio-economic development of Urumqi. If the water-transferring project could be adopted, the water demand of low-speed urban development could be met but in accordance with the medium-speed development scenario, water shortage will occur in 2017; in addition, by 2030, the water resources' deficit will reach 0.843 × 109 m3. If water-saving measures are carried out, water shortage will be delayed until 2021, and the water deficit in 2030 will be reduced to 0.517 × 109 m3. However, the baseline water-transferring projects and water-saving programmes still could not meet the water needs of rapid socio-economic growth. Water transferring and water saving must be strengthened; otherwise the water resources' constraints will inevitably limit the healthy development of Urumqi's society and economy.

In the case of a relatively stable water supply, it is necessary to adjust and optimize the water-use structure and industrial structure in order to maintain the regional balance between water supply and demand.

First of all, the regional ecological and domestic water demand should be satisfied and the utilization structure of production water should be adjusted. The industrial water demand should increase significantly, while agricultural water demand decreases rapidly, and the decrease in agricultural water consumption is mainly due to the reduction of irrigation water. Regarding the adjustment of the industrial structure, it is mainly to reduce the proportion of the primary industry's output value, and to focus on the development of secondary industry. In this regard, the adjustment of agricultural internal structure is mainly to increase of the proportion of forestry, animal husbandry, and fishery and to reduce the proportion of crop planting. The main goal of the planting area is to ensure the supply of vegetables, while the areas of other crops gradually decrease. The optimization of industrial water is mainly achieved through the adjustment of industrial structure. To limit the development of high-water-consuming industry, it would be necessary to increase the low- and medium-water-consuming industries' proportion of output value. The focus is to limit the development of high-water-consuming industries such as food and beverage production, and actively support industries with comparative advantages, such as those of electronics and machinery, and selectively develop high-tech industries relying on the ‘high-tech park’, strengthen policy support, and create a good environment for industrial development.

In order to improve the optimization of water-use structure in Urumqi and realize the efficient utilization of water resources, appropriate countermeasures and suggestions are proposed: (1) appropriately slow down the speed of urban economic development, to improve the regional industrialization level and urbanization level through promoting product quality, upgrading the technology and developing high technology, enhance the quality of urban expansion and ensure a sustainable urban development; (2) strengthen the construction of water-conservancy projects, appropriately improve the exploitation and utilization rate of surface water resources, reasonably construct the water supply network and layout of water-conservancy projects. To guarantee the implementation of water-transferring projects, and effectively increase water supply, improving the extent of water supporting capacity and ensuring the security of regional water supply; (3) change attitudes towards water supply, from ‘determine the supply according to the demand’ to ‘determine the demand according to the supply’. To enhance the overall allocation ability of water resources, and adjust the total water demand through technological progress and industrial restructure, give priority to domestic and ecological water, and achieve a virtuous circle of regional ecological environment, continuous efficiency of ecosystem and gradual improvement of living standards; (4) change the way of water utilization, significantly promote efficient water-saving technology and adjust the industrial structure, optimize the industrial layout. Finally, optimize the industrial structure according to the water resources and water environment bearing capacity; convert the industrial structure to the efficient water-saving type, to achieve the optimization and upgrading of industrial structure and improve the sustainable as well as rapid growth of the economy.

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