Abstract
There is a river called the Heihe River in western China. The Heihe River is an inland river that flows north across the Silk Road, which is famous as the intersection between Eastern and Western cultures. Further, there is also an important trade route running north-south from the Mongolian steppes in the north through Tibet to Yunnan, far in the south, along the Heihe River. In other words, the Heihe River basin is equivalent to the crossroads of major north-south and east-west trade routes, and viewed historically occupies an extremely important position. The problem of water shortages has occurred repeatedly many times throughout history in this arid region. Even today, the problem of extreme water shortages exists. It is said that the only solution is to import water from outside the country, virtual though it may seem.
Each time water shortages occur, sometimes people solve the problem by digging irrigation canals and at other times by building underground water courses, or by developing subterranean aquifers. In other words, people have overcome the problem by expanding the scope of their own system (the area in which they live, or their area of influence). Now, however, the way that people live is expanding into being on a global scale. We have now reached the stage at which there is no more space into which the system can expand. This is because the territory of the heavenly body known as the Earth is finite. The method employed by people to solve their problems by expanding the system has now become unusable. This can be considered as an aspect of the so-called global environmental problems that face us directly today.
Key words: history, water, arid region, Heihe River, globalization, global environmental problems
1. WATER PROBLEMS IN THE HEIHE RIVER BASIN
The Heihe River, which straddles the provinces of Qinghai and Gansu in western China, as well as of the Inner Mongolia Autonomous Region, is a typical inland river that starts in the Qilian Mountains fed by glaciers, and flows north across the Silk Road, where it is distributed into numerous oases from the foothills of the mountains, crosses the desert region and continues to the plains, before finally flowing into and being absorbed by the lake called Juyanze. Recently, the underground water levels around the downstream area centered on Ejina in particular have fallen dramatically. Wells that have always been in use before have suddenly run dry. Nearby vegetation is also on the verge of crisis. Juyanze is also a shadow of its former self. These facts are major problems for the people who live in the Ejina region in particular. The cause, basically, is the increase in the volume of water consumption for irrigation farming at the oases located midstream, such as Zhangye and Jiuquan in upstream Gansu Province.
Two countermeasures to this problem have been established: forestation, and limits to the water drawn from the river in the mid-flow basins. The volume of the flow downstream has increased due to the limits on water that can be taken, but oasis farmers, for whom the volume of water they can take has been reduced, have come to dig wells to use the subterranean aquifers to augment their shortages in order to maintain their arable land. For forestation, a policy of “Ecological Relocation”, in which herdsmen from the foothills of the mountains are moved to the area around the oasis, has been adopted. The displaced herdsmen, however, have to develop fresh arable land to graze their animals. Although only natural, their fresh farming regions need water. The Ecological Relocation Policy adopted to restore the downstream riverside forests has also invited the same results. In other words, the oases need more water now than ever, and shallow wells in the downstream area and even around midstream region of Zhangye have started to dry up. To supplement this, an abundance of deep wells are now being dug.
The cultivation of deep underground aquifers takes an unconscionable amount of time. In that sense, old aquifers are better thought of as natural resources that, once lost, are extremely difficult to regain, in the same way as oil. The water has started to be used in abundance.
To solve the current water shortage problem in the Heihe River Basin, it is essential to think of the upstream, midstream, and downstream basins of the river all as one. Further, not only the surface water in rivers and lakes that is visible to the naked eye should be considered. This problem will never be solved unless a comprehensive view is taken, including the subterranean water that is not visible to the naked eye. At any rate, currently there is a shadow over the efforts to both jointly preserve the environment and increase food production. There is a good idea for making both objectives work well together with limited water. It says that “it would be a good idea if China imported vast amounts of food”. This is because the limited water can be used entirely for environmental protection
2. WHERE THE PROBLEM LIES
Arid regions are blessed with sunlight. It can be said that all is needed is water to make them places ideally suited to growing plants. It is precisely because water is limited, however, that the regions are arid. Initially, people created products and supported themselves, in the arid regions of the central Eurasian Continent, using spring water and the slight area near rivers. During this time, it was thought that more water enabled more products to be made, and an irrigation system was created that drew water from the rivers. A wider area was then changed into arable land by drawing water from farther away through the construction of underground water canals due to the insatiable demand for water. This effort can be cited as a great success.
By repeating this process, however, too much water came to be used, to the extent that the river water no longer travelled downstream.
With the river water insufficient, then the next time wells had to be dug to enable the groundwater to be used. Irrigation systems that use well water can control the irrigation frequency and amount comparatively easily. As this is extremely convenient, the amount of water drawn up from underground increased sharply. Consequently, the subterranean water levels fell, and the wells in the lower stream as well as midstream basin dried up. This led to the current situation in which the deep underground aquifers, in which there is still water, have started to be used.
Due to recent global warming, the glaciers in the Qilian Mountains are shrinking rapidly. Consequently, excess water equivalent to the amount of glacial shrinkage is being fed into the Heihe River. That is to say, currently the flow amount of the Heihe River is greater than the total amount of precipitation that falls in the region of the river’s source. If this situation continues unabated, however, the glaciers will have completely disappeared in a few short centuries. If this happens, the natural resource of melted water concomitant with shrinking glaciers will cease to exist, and likelihood is great that the flow amount of the river will suddenly become very small.
Conversely, even if freezing occurs, the flow amount of the river will again be reduced. The glaciers will increase in size, and the water volume flowing into the rivers will be reduced by the same amount. In either case, the Heihe River water can be considered as likely to reduce in future. These facts need to be considered now.
When considered, however, this water shortage does not seem to have started yet. Evidently, the same phenomenon has occurred in the past.
To make this point clear, it is necessary to investigate how water was supplied to the same region in times past, and how the water was used by the people living in the region, and then clarify whether water shortages occurred as a result.
3. HISTORICAL RESEARCH OF THE HEIHE RIVER BASIN
The Heihe River Basin, including the Ejina region, is the intersection of the Silk Road, which is the crossroads of Eastern and Western Culture, and the north-south trade route, which is important for the exchange of the different cultures of north and south. It occupies an extremely important position historically that might even be called a cultural crossroads. As might be expected as a consequence, the region also became a vital military strongpoint. Numerous ancient records dating back 2000 years or more from the Han Dynasty called the Juyan Documents, written on wooden stripes, have been unearthed from this region, particularly downstream. Further, the fact that numerous documents written during the Xixia and Yuan Dynasties were excavated from the Kara Khoto, a historic site, is also well known.
These collections of major texts are undoubtedly a great clue in investigating historical changes in the region. It is impossible to determine from this alone, however, how much rain fell during the periods, how much runoff from the Qilian Mountains, which is the source of the water, there was, or how far the vegetation spread that caused water to evaporate from the surface of the land. These are many such facts that are not recorded in the texts.
Consequently, in addition to researching the texts、a comprehensive approach is also necessary that includes natural scientific research to recreate the environment of old using an analysis of the natural samples (proxies) hidden in the information described above.
Consequently, the historical relationship between people and water in the region was investigated jointly at the Research Institute for Humanity and Nature by numerous research institutions under the umbrella of the Chinese Academy of Sciences and the Chinese Academy of Social Sciences or Chinese universities, who in addition were also involved in setting up and running and comprehensive multi-discipline research project to recreate the environment of the past. The project title is the “Historical Evolution of the Adaptability in an Oasis Region to Water Resource Changes”, or the “Oasis Project” for short.
4. INVOLVEMENT IN THE OASIS PROJECT
The research is broadly divided into research to recreate the relationship between people and nature, and their history of interaction by deciphering the historical texts and proxies (natural samples called substitute record media, such as ice cores and dendrochronological samples, and lake bottom sediment cores, etc.), and research to make clear the elemental processes involved in the water cycle to interpret these historical data.
No matter whether texts or natural proxies, these historical data that remain today are scattered throughout both time and space. Consequently, it is necessary to supplement those places where the data are missing. To this end, knowing the individual elemental processes described below is indispensable. This is because, if the elemental processes are understood, the missing parts of the data can be interpolated and/or extrapolated using such methods as model calculations.
The research into elemental processes tried to elucidate through on-site measurements and Q&A surveys how fluctuations occurred in the amount of water supplied by air temperature, precipitation, and glacial contribution with climatic fluctuations on a global scale, the process of outflow due to water supplied from rivers and subterranean aquifers, and how water was used in irrigation farming and nomadic activities, as well as the process of water cycle by evaluating the amount of evaporation caused by these other factors.
As a result of the project research, the following facts were learned.
5. REPETITIVE HISTORY
Due to the recent policy of the “Great Western Development”, investment and the population migrating to western China have grown sharply. The population of the Heihe River Basin has grown to around 1.8 million people. Sudden increases in the population of the Heihe River Basin, however, are not a new phenomenon. In reality, this is a region where farming was developed by numerous colonial soldiers sent there to confront the Xiongnu during the Han Dynasty 2000 years ago. It is thought that even then, the population exceeded one million. Thereafter, the region’s population fell temporarily, but increased during each of the following dynasties: Tang, and Xixia･Yuan. Today, in the middle of this desert of nothingness, there remain many castle ruins that recall those ancient times, and all around spread the vast agricultural lands. Further, after the Ming Dynasty had passed, the great prosperity of the Qing Dynasty arrived.
At the Oasis Project, for example, three-dimensional views were created of photos from a satellite called “Corona” of the ruins of the agricultural lands that extend around Kara Khoto, and their geographic extent was determined by combining the photos with on-site investigations. As a result, the agricultural lands around Kara Khoto during the Xixia and Yuan Dynasties in the period that Kara Khoto flourished, were determined to be of approximately the same scale or more than the modern Ejina Oasis.
Further, the results of analyzing the ice cores extracted from the Qilian Mountains showed that the air temperature from the end of the Yuan through the early Ming dynasties gradually fell. This is thought to have been the start of the Little Ice Age. This era contrasts favourably with the modern era of global warming. In other words, the volume of river flow per annum became less than the total annual precipitation concomitant with the growth of the glaciers due to the cooling effect. Even with the ancient textual information, there are many remaining records that hint that whereas during the Xixia Dynasty there was a greater threat of floods than of water shortages, from the end of the Xixia and throughout the Yuan Dynasties, water was in short supply.
Moreover, it also became clear that the flow path of the Heihe River, which pours into a lake at the end, moved westwards from Kara Khoto at that time. Previously, Heihe River water ultimately emptied into a vast lake called Juyanze after irrigating Kara Khoto and its surrounding agricultural lands. This is because the flow path gradually moved westwards. Although dried up today, Heihe River water flowed into a lake called Gashon Lake, which still existed until several decades ago, and the time this lake started to form coincides exactly with the era when Kara Khoto began to decline.
Which water canals were created during which periods can be understood by matching the names of the irrigation routes at the Zhangye Oasis in Gansu Province. Many of the original water routes are still in use today. As a result, it is clear that many large-scale water routes were constructed during the Yuan Dynasty, and were used to develop vast tracts of agricultural land. This development of farmland definitely increased the volume of water drawn from the river around the oases, and consequently the downstream region of Kara Khoto was visited with water shortages. Further, this fact can also be thought of as a factor in Kara Khoto being abandoned and ultimately buried in sand.
That from the end of the Yuan Dynasty through to the start of the Ming Dynasty, the once proud and prosperous Kara Khoto become buried in the sand can be considered to be due to the multiplied effects of both so-called natural phenomena such as a reduction in glacial runoff due to the period of cooling and human activities such as drawing an excess of water from the oasis region. There are also written reports left by bureaucrats who performed on-site inspections that during the Qing Dynasty as well, downstream areas frequently suffered water crises due to excessive water drawing midstream. It is thought that a similar phenomenon also occurred during the Qing Dynasty.
The regions described above experienced repeatedly the phenomenon similar today of the increase in acute water consumption due to a rapid artificial increase in the population and the concomitant agricultural development in addition to natural fluctuations. Furthermore, it is clear that the modern phenomenon of downstream water shortages also occurred many times in the past. The only thing to say is that history has been repeating itself.
6. THE HISTORY OF WATER SUPPLY
As described in the early section of “Where the Problem Lies”, the arid and semi-arid regions of western China were transformed by the use of irrigation water into a massive land of agricultural production. This also brought great blessings to the people of the region.
China has a long history of irrigation. It is written in The “Hanshu” (History of the Former Han Dynasty) that in the Heihe River basin, the irrigation paths that channel the waters of the Heihe River already existed during that far-off Han Dynasty a small distance downstream from modern-day Zhangye. According to the Q&A surveys conducted in old days around Zhangye, irrigation paths seem to have already been created by the Tang Dynasty.
Even at the farthest point downstream, it is not difficult to imagine that during the Han Dynasty, man-made irrigation canals were built for agricultural activities by the numerous colonial soldiers sent to oppose the Xiongnu. We have not yet, however, been able to ascertain on site any water routes created during the Han Dynasty. Ancient irrigation canals whose ages have been measured have all yielded results from the Xixia or Yuan Dynasties only. In truth, canals made during the Han Dynasty might merely have continued to be used during the Xixia and Yuan Dynasties, and the Han Dynasty canals might be buried under the later Xixia and Yuan Dynasty channels. Alternatively, it might be that we have not yet examined any irrigation channels from the Han Dynasty. At any rate, the remains of irrigation paths spread out on a scale roughly equivalent to that of the modern Ejina Oasis.
It is recorded in ancient documents that during the Ming Dynasty, in the midstream area around Zhangye, for example in Hongsuihe, long underground canals, Xidong, and Dongdong, were built to draw water up the high terraces far from the river bed. These remains can be confirmed using satellite photos to be a row of elevated land (i.e., a row of shafts in case of “karez”) excavated from underground. Subterranean channels resembling these of “karez” have been repeatedly repaired and used over and over again, starting in the 14th century, and then again in the 18th century and also the 20th century. Moreover, they are still used today as underground canals that follow almost exactly the same route. Advances in construction technology have led to the underground construction of buried iron pipes today, which is the only difference from the past.
The praises of Tong Hua, who succeeded in excavating these underground water routes during the Qing Dynasty, are extolled in a memorial tablet that was erected at the time. Although not concurrent, the memorial tablet that praises his great work has been re-erected recently. In ancient China, people who succeeded in controlling river water were praised as saints and great men.
7. ONE ASPECT OF GLOBAL ENVIRONMENTAL PROBLEMS
As described above, when the Heihe River Basin was pressed by the need to increase food production concomitant with the increase in population, the need was met by developing agricultural land using Heihe River water for irrigation. In addition, when the need to increase farmland arose, a larger agricultural area was assured by constructing underground channels to draw water from even further away. Moreover, recently, water from the Heihe River alone has finally become insufficient, and the water shortage has been solved by drawing up water from subterranean aquifers.
In other words, people have solved the problem of water shortages caused in the region (system) where they live, by expanding the area of the system. Drawing irrigation water from upstream of the Heihe River is to expand the area on which their livelihoods depend.
Even so, if a water shortage occurred, the problem has been solved by building underground channels to expand the range of the system towards the mountains upstream, and using that water. Even more, recently surface water has all been used up, and the system has been expanded to include the subterranean world as well.
That being said, currently there is still a water shortage. The solution is said to be to “import foodstuffs”. The tendency is to think that if food is imported from abroad, the problem will be solved. As has been said before, the importation of food is nothing more than the importation of virtual water. It is equivalent to importing the water needed to produce the food that is imported.
This fact means that the range of the system on which people’s livelihoods depends has expanded to a global scale. This can also be rephrased as meaning that the methods used by people to solve their problems under the idea of expanding the scale of the system have reached their final destination. The meaning of so-called “globalization” lies herein.
There are, however, limits to the global system. This is the era of globalization, in which the whole world is used as part of the system. When a problem occurs, the system has no room into which to expand further to solve the problem, even if an attempt at further expansion is made. Expansion to the Moon and to Mars is still a far-off conversation. That is to say, our system has expanded as far as it can go, and it can only be said that we have now reached an era in which existing methods for solving problems by expanding the range of the system can no longer be used.
This fact is one aspect of the issue called global environmental problems. We have to find completely different methods for solving problems that do not rely on solutions based on expanding the existing system. We are living in just such an age.
（Presented at the first International RIHN symposium , held in Kyoto, Japan, in November, 2006. ）