Wang Dong¹, Shi Yunliang²,Wu Jichun¹, Gong Zheng³

1. Dept. of Hydrosciences, Dept. of Earth Sciences, Nanjing Univ., Nanjing, 210093, China, 86-25-83595591, wangdongml@hotmail.com

2. College of Geography and Marine Sciences, Nanjing Univ., Nanjing, 210093, China;

3. Taihu Basin Authority of Ministry of Water Resources, Shanghai, 200434, China)

Abstract:Water resources possess both social attribute and natural attribute. water resources system is a complicated large system, which contains regional background, as well as specific framework, function and dynamic balance. The evaluation of the water resources system needs the measurement according to both water resources carrying capacity and water environment carrying capacity, and the supervision with the viewpoint of sustainable development. The water resources system of Lake Taihu basin experiences a degenerate period from 1960, and the year of 1980 is a turning point of the degeneration. Therefore, it demands to use the concept and theory of circular economy and to be based on the water resources system, to improve, harmonize and counterpoise water resources carrying capacity and water environment carrying capacity, to insist the “3R principle”, to save water and use water efficiently. Consequently, human can coexist with water harmoniously, and gain sustainable development, insuring the sustainable social-economic development with the sustainable use of water resources.

Keywords: water resources system, circular economy, water resources carrying capacity, water environment carrying capacity, Lake Taihu basin

Lake Taihu basin is located at the south end of the Changjiang River Delta, bordering the Changjiang River on its north side, facing the Hangzhou Bay to the south, with mountain.Tianmu immediately to its west and East China Sea to its east. Lake Taihu basin is a typical drainage network area, since it has a fairly big drainage density. The total length of its watercourse is added up to almost 1.2×10⁵ km, and besides Lake Taihu which covers an area of 2.338×10³ km², more than 189 lakes have a coverage bigger than 0.5 km². Taihu hydrographic net, which runs across Jiangsu Province, Zhejiang Province and Shanghai City, is the main part of the lower stretch of the Changjiang River. The key part of the whole net is Lake Taihu, whose main sources lays on stream Shao and Nan, and flow out through more than 70 channels on the east of the Lake. These channels combined with other runoffs in east areas finally flow into the Changjiang River and East China Sea by way of the Liu River and the Huangpu River.

Lake Taihu basin has long been regarded as a place rich in resources and ingenuity. GDP in the year 2002 of this place is as high as 1.24×10¹² yuan, which is almost 12% of the total amount of the country. In the year following, this percentage is added to 13% and the finance incoming of this area grow from 16% up to 19% of the total national incomings, accounting only 0.4% for the areas and 3% for the population. It became one of the most developing area of the country. How ever, with the rapid economic development, the water resources system of Lake Taihu basin experiences a degenerate period from 1960. The water quality standard lowered 1 level every 10 years, and this is obviously more serious in recent years. How to control the degeneration in order to use water recourses more scientifically and efficiently is drawing great attention among researchers both in China and overseas^[1]-[6].

2 Basic Concept of Water Resources System

2.1 Water resources and water resources system

According to the study both in and out of China, water resources can be defined as the renewable part of water body, which is adequate in amount and quality, and has been or can be made continuous use for man’s exploitation.

It has 3 attributes as following:

It is limited in amount.

It possesses both social attributes and natural attributes.

It is measured by quantity and quality standard.

The dualism of water resources determines the comprehensive characters of water resources system. It is a combination of both natural water and social water, as well as a mix of natural water resources, usable water resources, available water supply, and water demand and consumed by social economy, etc. Water resources system is also a complicated large system, which contains regional background, as well as specific framework, function and dynamic balance.

The evaluation of the water resources system requires the evaluation of water resources carrying capacity, and the supervision with the viewpoint of sustainable development. The term of water resources system carrying capacity has two meanings, one is water environment carrying capacity, and the other is water resources carrying capacity. The former, the carrying capacity of water environment refers to the ability carrying and containing pollutes and polluted water in certain water area, where the water resources is renewable and self-cleaning to be used continuously and maintain a good ecosystem. The latter, the carrying capacity of water resources refers to the ability supplying for the economic social development and maintaining a good ecosystem in certain drainage area or region. The carrying capacity of water environment and the carrying capacity of water resources are both depending on and restricting each other. And the co-relationship and matching of them determine the status of the function, structure and balance of water resources system.

2.2 Elements and relationship inside water resources system

The water resources system can be divided into two subsystems: the natural water subsystem and the social water subsystem.

For the natural water subsystem, the total water resources (including both surface and subsurface water) is made up of water resources in situ, passing by and diverted. While the ecological water requirement of natural system are supplied by natural water subsystem, the residual water are called usable water resources. There are great relationships between ecological water requirement and water environment carrying capacity, between usable water and water resources carrying capacity, as well as between water environment carrying capacity and water resources carrying capacity.

As to the social water subsystem, it is mainly social economical water requirement, using the available water supply from the usable water resources provided by natural subsystem. The social economic water requirement is including consumed water and surplus water. The surplus water has impact on water environment carrying capacity through Point-source, area-source and inner-source polluting ^[7]. Elements of water resources system and the relationship are shown in Figure 1.

For example, the mean annual water resources in situ of Lake Taihu drainage area has 1.62 ×10¹⁰ m³, including 1.37 ×10¹⁰ m³ of the surface water resources and 2.5×10⁹ m³ of the subsurface water resources. In the year of 2001, the water consumption has reached 2.85 ×10¹² m³, and water resources in situ of this drainage area could not meet the demand. Along with the rapid development, the sewage water is increased by years. At present, the sewage released by industry and living activities in the drainage area has reach 5.0×10⁹ m³/a. The conflict between supply and requirement and water pollution problem could be resolved by drawing water from the Changjiang River.

In the year of 2002, the test of diversion from the Changjiang River to Lake Taihu got to start^[8]. Water quality of Lake Taihu has been improved by regulating the still with the dynamic, diluting the polluted with the clean, and replenishing the exhausted with the abundant.

In 2002, from Jan 30^th to Mar 31^st, the total amount of water drawn from the Changjiang River to Changshu junction of the Wangyu River added up to 1.028×10⁹ m³, whereas 6.47×10⁸ m³ through Wanting junction into Lake Taihu, and 6.2×10⁸ m³ through Taipu Gate to the lower reach of the drainage area, among which 3.8×10⁸ m³ were supplied for Shanghai City.

In 2004, from Jan 1^st to Dec 21^st, the total amount of water drawn from the Changjiang River to Changshu junction added up to 2.2×10⁹ m³, whereas 1.012×10⁹ m³ through Wanting junction into Lake Taihu , and 1.429×10⁹ m³ through Taipu River to the lower reach of the drainage area.

In 2005, from Jan 1^st to Apr 30^th, the total amount of water drawn from the Changjiang River to Changshu junction of Wangyu River added up to 1.32×10⁸ m³, whereas 5.71×10⁸ m³ through Taipu River to the lower reach of the drainage area.

In 2006, from Jan 1^st to May 17^th, the total amount of water drawn from the Changjiang River to Changshu junction added up to 2.81×10⁸ m³, whereas 7.56×10⁸ m³ through Taipu River to the lower reach of the drainage area.

Figure 1 The relationship between elements of water resources system of Lake Taihu basin

Figure 2 Sketch map of diversion from the Changjiang River to Taihu Lake

By such diversion in the recent years, the water supplied for drainage area is effectively increased, and the water environment is also greatly improved.

For example, during the period from Dec 17^th to 21^st in the year of 2004, all kinds of water-quality index are improved, main index like COD_Mn and TP of water supplied for Suzhou from the Xitang River had met level Ⅱ～ Ⅲ. All these enhance the carrying capacity of water resources system of Lake Taihu basin.

3 Degeneration of Water Resources System in Lake Taihu Basin

Lake Taihu drainage area is one of most densely populated areas in China and of the world. The mean individual water resources in Lake Taihu basin only account 18% of that of the country, and water resources for every unit of area only account 13% of that of the country. It is still under the national average level, even though it now has water diversion from the Changjiang River.

With the rapid development of economic society, water resources system in Lake Taihu basin has been degenerating ^[9]-[11].

Water quality of Lake Taihu in the 1960’s could be classified into classⅠ to Ⅱ. While in the 1970’s, it turned into class Ⅱ. And in early 1980’s, the water quality of Lake Taihu fell into class Ⅱ to Ⅲ, and in later 1980’s, it totally fell into class Ⅲ, some of the areas are even worse and turned into class Ⅳ and Ⅴ. In the 1990’s, water quality of Lake Taihu was more deeply deteriorated, becoming worse than class Ⅳ, and quality of 1/3 water even reached class Ⅴ.

Figure 3 Variations over past 25 years of total nitrogen (TN) in the Taihu Lake (unit: mg/L)

Figure 4 Variations over past 25 years of total phosphorus (TP) in the Taihu Lake(unit: mg/L)

Figure 5 Variations over past 25 years of chemical oxygen demand of Manganese (COD_Mn) in the Taihu Lake (unit: mg/L)

In general, water quality of Lake Taihu dropped one class every 10 yeas during the past 40 years, and the degenerating speed is most rapid in recent 10 years. It is thought that, the year of 1980 is a turning point of the degeneration of Lake Taihu. Before 1980, the index of TN (Total Nitrogen, TN) changed greatly, and the index of COD (Chemical Oxygen Demand, COD) increased a bit. While after 1980, the increase of the index of TN has been slowing down, instead, the indexes of COD and TP (total phosphorous, TP) have been steadily growing up. Figure 3, 4 and 5 show the variations over past 25 years of TN, TP and COD_Mn in the Taihu Lake respectively.

From 1950’s to 1970’s, except for the Suzhou River, Huangpu River and Jiangnan Channel, water quality of other river channels in Lake Taihu basin is fairly good. The water from whole network of other river channels could be regarded as good source. It is also since 1980, water quality of river channels in Lake Taihu basin started falling down. In 1983, water quality of 40% river channels fell into class IV or even worse, while in 1987, that percentage turned into 61.1%. And in 1992, that percentage turned into 73.1%, while in 1996, it even increased to 86.1%. In the year of 2000, that percentage got back to 80.6%. Table 1 and Figure 6 is the water quality of reaches evaluated in Lake Taihu basin over 20 past years.

Table 1 Water quality of river channels evaluated in Lake Taihu basin over past 20 year

Data from [12].

Figure 6 Water quality of river channels evaluated in Lake Taihu basin over past 20 years

4 Concept of Circular Economy

Circular economy is defined as the formation of the development of ecological economics, which follows the law of substance circle and energy flow of natural ecosystem and constructs economy system, making it bring into substance and energy circular utilization process of natural ecosystem. It is characterized by cleaner production, resources circular utilization and waste efficient recovery. The birth of circular economy develops the useful and discards the useless of traditional development patterns. It is the necessary result of the society progress. The essence of circular economy is to adjust production relations, and the target is to maintain sustainable development ^[13]-[15]. The difference between circular economy and traditional economy is shown in Table 2.

Circular economy has three operation principles: Reducing, Reusing and Recycling, also called 3R principles. They constitute the basic thought, but their significances are not the same. Only the Reducing principle has the first status. Circular economy first aims to avoid producing waste.

Table 2 the comparison between traditional economy and circular economy

The idea of circular economy is first germinate in 1960’s, when the environmental conservation movement is arisen. The American economist Kenneth Ewert Boulding has put forward the “spaceship theory” (The Economics of the Coming Spaceship Earth, 1966), which is considered to be a presentation of early circular economy theory. The emergence of circular economy has promoted research on resources and environment of 1970’s and widen the later study of sustainable development, as well as connect the circular economy to the ecosystem. In 1990’s, the study of intelligent economy had given the circular economy even more meaning in respect of high-tech industrialization and a learning type society.

Circular economy is a way to realize the harmony and balance between resources and environment, man and nature, and it is of great significance in realizing a new type of industrialization in our country.

5 Restoring and Improving the Water Resources System of Lake Taihu Basin Using Circular Economy Notion

Enhancing the utility of resources is of great significance to fulfilling sustained using of natural resources. Circulating economy can enhance the utility of natural resources to the greatest extent, and save large amounts of resources to be taken advantages of by later generations. At the same time, it can also reduce the discharge of contaminants and alleviate environmental pressure. It is believed that, to restore the degenerated water resources system of Lake Taihu basin and finally to solve the problem of water quantity-induced water shortage, circular economy notion, must be used and Scientific Developmental Concept must be insisted on. After that, based on the water resources system of Lake Taihu basin, the function of Lake Taihu basin according to its carrying capacity of the water resources system could be measured and identified. It relates to all kinds of measures such as law, administration, engineering, economy, science and technology, etc^[16-18].Here only two of them are emphasized as following.

5.1 Integrated management of water resources

Non-fluent administration management system of water resources is the root of low effectiveness of water resources utility and wastefulness, which greatly aggravated the water crisis of Lake Taihu basin and even of whole country. To the water resources system itself, implementing circular economy is implementing intergrated management of water resources system. It is mainly showed on two sides, one is the intergrated management of the drainage basin, the other is the integrated management of the water resources of the terrain, primarily the city. Therefore, the integrated management of the water resources institution (the committee of drainage basin management and the water resources bureau), which is comprised of drainage basin units and centered on the city, is urgently needed to be founded according to the principle of the combination of drainage basin management and area management, and the mode of “one pipe governing water, lots of pipes managing water”, so as to implement the integrated management of rivers, lakes and seas, cities and the countryside, the quantity and quality of water, the surface and ground water, water resources in situ, water transiting territories and transferred to other localities, water supplying and demanding, water using and contamination eliminating, etc., constructing the system related to the integrated management of water resources which includes the water source — water supplying — water using — water draining — contamination eliminating — water recycling, in order to facilitating using circular economy notion, coordinating diverse water resources projects, unifying planning, carrying out all kinds of water-saving measures, making the using and managing of water resources more scientifically.

5.2 Insisting on “3R Principle”, saving and using water scientifically

Lake Taihu basin must insist on the circular economy way and “3R Principle”, construct the society that saves water and prevents contamination. In this respect, Lake Taihu basin has tremendous potential and space to development. At present time, the general water consumption quantity per acre of the basin in the average year is 550 m³ or so. If we save water by 10 percents, mere water irrigation can save 9.0×10⁸ m³ water per year that is equivalent to one forth of living water consumption, area source contamination can also be reduced. In Lake Taihu basin, general industrial and living water consumption is 7.0×10⁹ t/a (not including industrial cooling water), contaminated water discharged to rivers and lakes is 5×10⁹ t/a, discharge quantity of the contaminant COD is 1.3×10⁶ t/a. Its effectiveness of water using is at leading position, which accounts for one half of our country’s average level 5045 m³ (data in 2000), but still falls far behind that of developed countries. At present, GDP consumption of water per 1.0×10⁴ U.S. dollars in Lake Taihu basin is 2689 m³, which is 5 times larger than 514 m³ of America and twice larger than the average level of the world. In industrial water recycling, Japan, America, the former Soviet Union had reached above 75% in 1980’s. Although the industrial water recycling of large quantity water-consuming factories in Shanghai City had arrived 79.2% in 2000, the basin as a whole is still of low level, which is merely 50% or so. The average living water consumption quantity per capita in the city in Lake Taihu basin is 358 L/d, whereas 15 European countries maintained at the level of 160 L/d.

The key is how to save and use water scientifically.

First of all, to built up and strengthened the notion of saving water that country of water is terribly short of water and urgently needs to save water in the whole nation through school education, professional training and mass media.

Secondly, to encourage water-saving and clean production, to put the system of using water by ration into practice, to strengthen the management of water demanding, and to set up the base for the production system that is characterized by circular economy.

Thirdly, Exploit and utilize non-traditional water resources, such as rainwater using, seawater desalting, waster water recycling, flood water using, etc.

Fourthly, to adjust measures to local conditions, to lift water price moderately and to change gradually the condition that water price deviates from water value.

Fifthly, to advocate rational and clean consumption, and to incorporate the consumption process into the circular economy system.

In this way, the aim of “two taking-the-lead” of Lake Taihu basin can be fulfilled, healthy life of the river and lake can be maintained, and the sustainable social-economic development with the sustainable use of water resources can be ensured.

Acknowledgement

Pure-hearted thanks to the academician of Chinese Academy of Science, Professor Wang Ying in Nanjing University, and Professor Zhu Yuansheng in Hohai University.

References

[1]       Wang Y., Healy T., Chen W., Wang D. & Bishop A. (2004) Water resource capacity, regulation, and sustainable utilization of the Changjiang River Delta. J. Coastal Res. SI43, 75-88.

[2]       Liu C. & Chen Z. (2001) Analysis on China Water Resources Status Quo Evaluation and Trends on Demand and Supply. China Water Power Press, Beijing, China.

[3]       Wang S. (2001) Resources Water Conservation: Human Coexisting with Nature Harmoniously. China Water Power Press, Beijing, China.

[4]       Sun J. (2005) Discussions on water - saving society establishment in the Taihu basin. China Water Resour. (13), 189-192.

[5]       She Z. (1997) The Water-Land Resources And The Regional Development In Yangtze River Delta. University of Sciences & Technology of China Press, Hefei, China. (in Chinese)

[6]       Huang X. (2000) Layout and Improvement of Lake Taihu basin. China Water Power Press, Beijing, China.

[7]       Wang D., Shi Y., Wang L. (2003) On water resources system of the Changjiang River Delta. J. Nanjing Uni. (Natural Sci.), 39(6): 822-830.

[8]       Gao Y., Mao X., Xu W. (2006) Analyaia of the influence on the Taihu Lake and the aera around: diversion from the Yangtze River to Lake Taihu. J. China Hydrol. 26(1): 92-94.

[9]       Qin B., Wu Q., Gao J., Fan C., Xu G., Chen W., Mao R. & Chen Y. (2002) Water environmental issues in Lake Taihu: problems, causes and management. J.Natural Resour. 17(2), 221-228.

[10]   Huang Y. (2003) Water Environment and Pollution Control of Lake Taihu Basin. Science Press, Beijing, China.

[11]   Yang G., Wang D. (2003) Economic Development, Water Environment and Water Disaster of Lake Taihu Basin. Science Press, Beijing, China.

[12]   Ye S., Zhu W., Lin Z. (2002) Water resources and water environment of Lake Taihu basin. www.hwcc.com.cn

[13]   Niu W. (2004). Circular economy: an ideal mode gaining sustainable development. J. Chinese Academy Sci. 19(6): 408-411.

[14]   Wu J. (2004) Diversion from the Changjiang River to Lake Taihu being the base of develping circular economy system of Lake Taihu basin. China Water Resour. (10), 10-11, 22.

[15]   Feng Z. (2004) On circular economy. Soft Sci. China. (10): 1-9.

[16]   Ye S. & Huang W. (2001) Research on water saving of Lake Taihu basin. China Water Resour. (8), 75-76.

[17]   Qian Z. & Zhang G. (2001) The Integrated and Special Reports on Sustainable Development of China Water Resources Stratagem Research. China Water Power Press, Beijing, China.

[18]   Wu H., Zhang Y. (2005) Making efforts on a full operation of diverting water from Yangtze to Taihu Lake. China Water Resour. (7), 50-51, 49.