Author: Han Zhaoqing Wei Kai
Source: "Chinese Historical Geography Theory Series" WeChat public account
The original article was published in the "Chinese Historical Geography Theory Series" No. 1, 2022
Notes on the Water Classics, Tsinghua University, 20 years (1894) engraving (Source: CADAL)
A preface
Surface water and groundwater carried by rivers and lakes are an important part of the terrestrial watersphere and an indispensable source of material for the survival and reproduction of humans and other organisms. China has a vast territory and many rivers and lakes, with more than 50,000 rivers with a basin area of more than 100k square meters and about 1,500 rivers with a basin area of more than 1,000 square meters. There are 2693 lakes with an area of more than 1k㎡, of which 2557 have an area of 1-100k㎡, accounting for 95% of the total number of lakes, and there are 10 extra-large lakes larger than 1000k㎡. Affected by the terrain and climate, the geographical distribution of rivers and lakes is very uneven, the vast majority of rivers in China are distributed in the eastern climate of humid and rainy monsoon area, the largest number and area of lakes is the Qinghai-Tibet Plateau Lake Area, the Eastern Plain Lake Area ranks second.
In the historical period, the river and lake water systems in different regions will undergo changes to varying degrees due to the influence of natural and human activities, especially in the plains, deltas and other areas. These changes have also had different effects on the local natural ecosystem and human society, so China has a long tradition of recording water systems, which are mainly related to water conservancy. Duan Xizhong divides the traditions of Chinese water conservancy records into three categories, the first of which is the "Five Tibetan Mountains Classic" derived from the "Classic of Mountains and Seas", "The scriptures describe the mountains, describe the outflow of a certain water, where it flows, into a certain river, from the source to the direction of flow, to the return to the ruins must be remembered, and the passage in the middle is generally omitted." The second is the system of recording of the Shang Shu Yu Gong. The third is the "Book of River Canals" pioneered by Sima Qian in the "Records of History", which was inherited by Bangu's "Book of Han" and developed. In ancient times, yugong was regarded as the "book of ten thousand worlds", but forgot the common phenomenon of waterway migration, and Ban Shi created two systems: "Hanshu Geographical History" and "Hanshu Gugouzhi" in view of this.
The Classic of Water is a monograph on waterways that follows the Classic of Mountains and Seas, the Yugong, the Book of Canals, and the Geographical Chronicle, and records the source, direction, flow, flow, and return of 137 large and medium-sized rivers in China, but it is relatively brief. At the end of the 5th century and the beginning of the 6th century, Li Daoyuan recorded the sources and flow paths of the 1252 main tributaries in more detail, examined the "misunderstandings" of the original text of the "Water Classic" on a basis, and carried them forward, achieving the strange book of "Notes on the Water Classics".
Since then, on the basis of inheriting the above traditions, the historical documents on the water systems and changes of rivers and lakes in China have been divided into five categories: the "Geographical Chronicles", which inherit the "Geographical Records" of the "Book of Han" and simply record the water system veins in various places; the "Records of the Rivers and Canals" that inherit the recording method of the "History of the Rivers and Canals", which are preserved in the seven main histories, and the "Records of the Ditches" and "River Canals" that record the history of the Chinese people's prevention and control of water damage and the construction of water conservancy in history; the tradition of the "Notes on the Water Classics", the transcription and inheritance of various versions of the "Notes on the Water Classics" of the Ming and Qing Dynasties, belong to this category. In modern times, Yang Shoujing and Xiong Huizhen's disciples have made arrangements for the "Notes on the Water Classics", enriching the records and contents of the "Notes on the Water Classics" and enhancing the scientific nature; the last two are various water conservancy documents for the records and treatment of floods, as well as thousands of local chronicles written in historical periods.
These historical documents provide a rich and continuous historical basis for the study of the long-term change of China's river and lake water systems, and at the same time make this field quite Chinese, and flourish in the study of the history of geomorphological changes in the world's rivers and lakes. In the more than 70 years since the founding of New China in 1949, with the development of modern historical geography and the introduction of research methods and technical means in other disciplines, the study of the historical changes of rivers and lakes that belong to the field of historical geography has also made great progress and fruitful results. In the past, the introduction of research on the change of river and lake water systems has been included in the review of the achievements of the research direction of the historical physical geography branch of Chinese historical geography, which is divided into two kinds of reviews for many years and year by year, such as Hua Linfu's "Fifty Years of Chinese Historical Geography (1949-1999)", which includes the academic dynamics written by historical geographers from the founding of New China to 1999, in addition, Zhu Shiguang's "Review and Prospect of Chinese Historical Physical Geography", Zhang Xiugui's "New Progress in Historical Physical Geography Research in the Past Ten Years" and "Chinese Historical Geography Theory Series" ushered in the 100th issue of the organization of relevant scholars to compile a review and review of China's historical geography research from 2001 to 2010 are all multi-year reviews.
The writing of the annual research progress of historical geography began in 1981 and ended in 2015, except for Ge Jianxiong's "Progress in The Study of China's Historical Geography in 1982", the rest were published in "Trends in Chinese Historical Research". The above reviews on the study of river and lake changes are mainly written by scholars from the major of historical geography, limited by the title and style, most of the reviews are mainly based on listing the name of the paper, summarizing the abstract of the paper, and pay little attention to the research from other disciplines, especially geographers, and lack a comprehensive, systematic and in-depth introduction and evaluation of the entire research field in terms of research significance, content, methods and achievements in the past 70 years. In view of this, this paper will not repeat the content of the above review, but will add an introduction from the perspective of geography, and take the Journal of Geography, Historical Geography and Theory Series of Chinese Historical Geography as examples, first of all, through statistical methods, analyze the research themes, research methods and data utilization of river and lake changes in the past 70 years, and then introduce the content and significance of important research achievements in this field in four stages.
Two, three major journals include statistical analysis of research papers on the change of rivers and lakes
According to the traditional dichotomy, historical geography is divided into historical physical geography and historical human geography, and the changes in rivers and lakes belong to historical physical geography, and through the statistics of the number of relevant papers published in professional journals of this discipline, it can roughly reflect the proportion of this field in the entire discipline. From its inception in 1934 to the end of 2020, a total of 4760 papers have been published, according to the author's statistics according to the classification of the discipline code of the "Geographical Journal", of which 141 are related to river landforms, 42 are limnology, and 18 are related to river and lake changes and major floods in historical periods, accounting for 4.22% of the total published papers. This proportion seems to be very small, but if you calculate according to the classification of the "Geographical Journal", the papers published in the journal involve 305 topics, an average of only 14 per topic, and 201 papers are published in rivers and lakes, which is one of the topics published in the "Geographical Journal" of the Department of River and Lake Research. It is worth noting that not all articles on river landforms and limnology are related to changes in historical periods, while a small number of articles on changes in rivers and lakes are scattered in hydrology, sediment, paleogeography and tourism geography. The research methods on the change of rivers and lakes in the Journal of Geography are diverse, including field investigation, description, analysis of historical documents, sedimentary analysis, quantitative research, theoretical analysis, experimental operation and archaeological demonstration.
Historical Geography was first published in 1981, changed to a journal in 2019, and has published 1,339 papers by the end of 2020. According to the author's screening and statistics, there are 109 papers related to historical water system changes, of which 66 are based on historical changes, accounting for 60.55%, more than half of which include 37 riverbed evolutions, 13 lake and marsh evolutions, 4 historical flood disasters, and the rest involve estuarine evolution, sandbar evolution, canal changes, urban water system changes, sand content changes, pebble transport changes, waterfall erosion and other content of only one to two There are 37 articles on the topic of investigation and correction, accounting for 33.95%, including 20 articles on the examination of the records of the "Water Commentary", mainly for the examination of the name, location and source of rivers and lakes; there are 6 articles related to the changes of historical water systems in the history of water conservancy and shipping history, accounting for 5.5%. In addition, the journal has set up a "supplementary white" column since its inception, which includes some small short articles with literature research as the content, of which 14 articles involve the examination of rivers and lakes, mainly for the supplementary whitening of the study of "Water Commentary". If these additions are added, from 1981 to 2020, Historical Geography published a total of 123 articles related to the changes in historical water systems, accounting for 9.19% of the total number of articles published. The research methods are mainly based on historical document analysis methods, supplemented by field investigations, theoretical analysis and quantitative analysis methods, and in recent years, a small number of research using GIS methods has appeared. The research objects are mainly the Yellow River, Yangtze River, Pearl River and Haihe River and other large river systems.
The theory series of Chinese historical geographies, also founded in 1981, has been a journal since 1988. By the end of 2020, a total of 2745 papers have been published. According to the classification in the general catalogue published by the journal from 1981 to 1993, articles related to rivers and lakes are mostly found under the classification of historical physical geography, historical transportation geography and geographical name research. According to the author's statistics, there are 109 papers related to the changes of historical water systems, of which 58 are based on historical changes, accounting for 53.21%, including 31 riverbed evolutions, 11 lake and swamp evolutions, 4 canal changes, 3 estuarine evolutions, and the rest of the sandbar evolution, urban water system changes, flow changes, sand content changes, river network density reconstruction, and loess landform erosion are one to two each; 36 articles are on the topic of investigation and correction, accounting for 33.03%, mainly for the names and locations of rivers and lakes. Of the source research, there are 8 articles with the "Notes on the Water Classics" as the research object, and the rest are the research on ancient books such as the "Classic of Mountains and Seas", "Yugong", "Hanshu Geographical History" and so on; there are 15 articles related to the changes of historical water systems in the history of water conservancy, shipping history, and migration history, accounting for 13.76%. In addition, this journal also includes a number of short articles on the content of literature research, of which 23 involve the examination of rivers and lakes. Therefore, from 1981 to 2020, the Chinese Historical Geography Theory Series published a total of 132 articles related to the changes of historical water systems, accounting for 4.81% of the total number of articles published. Compared with Historical Geography, the proportion of papers on river and lake water systems published in this journal is smaller, but the research area is broader than that of Historical Geography, mainly in the increase of research on western rivers and lakes and some tributaries, and the methods adopted are basically consistent with Historical Geography.
Based on the above rough statistical analysis of the papers included in the three journals, it can be roughly seen that in the past, the proportion of river and lake change research in geography and historical geography research was generally not high, and the research objects were relatively concentrated, and the research methods were relatively single, mainly for historical document analysis methods, combined with field investigation and description methods, in recent years, there have been research combining elevation data and GIS spatial analysis methods.
3. Introduction of important achievements
The study of river and lake system changes is not only an important part of historical physical geography, but also an integral part of geomorphology. Before the founding of New China, most of the research work on chinese geomorphology was carried out incidentally by geologists, and the research content was mainly regional landforms and the history of geomorphological development. After the founding of New China, along with the needs of socialist economic construction, Chinese geomorphological workers successively participated in railway construction, water and soil conservation in the middle reaches of the Yellow River, planning of river basins such as the Han River, Xiang River, and HaiHe River, and comprehensive investigation of Xinjiang, Tibet, Heilongjiang, and other frontier areas, accumulating a large amount of geomorphological data. The sub-disciplines of river landforms, desert landforms, loess landforms, karst landforms and other geomorphology have also developed to varying degrees with the needs of national economic construction. Contemporary geomorphological scholars' research on river and lake landforms mainly analyzes their geological basis and current pattern through field investigations, and the study of historical period changes is mainly based on the analysis of instrumental measurement data, and historical geomorphology is the link between ancient landforms and modern landform research. Historical geomorphology is largely developed by studying the changes of rivers, so the changes of river and lake systems are an important part of historical geomorphology.
If Shen Yuchang's "Hydrology of Dongting Lake" published in the Journal of Geography is taken as an indiscriminate work of historical rivers and lakes since the founding of New China, the research on the changes of rivers and lakes in the historical period of more than 70 years can be divided into four stages. In the meantime, the important results of this research are mainly concentrated in two collective works, one is the "Historical Physical Geography" subsection edited and published by the editorial board of "Physical Geography of China" of the Chinese Academy of Sciences in the 1980s. The other is the "Historical and Physical Geography of China" edited by Zou Yilin and Zhang Xiugui in the early 21st century, called the new edition, and the publication time of these two sets of books can be used as the main basis for periodization. Therefore, the first stage refers to 1949-1980, the scholars engaged in the change of rivers and lakes at this stage are mainly from geoscience, the research objects are mainly the Yellow River, the Yangtze River and its tributaries, the research methods are mainly on the basis of field investigation, the use of geology and geomorphological language for description and interpretation, partly the use of quantitative analysis and theoretical analysis methods, some of the change history beyond the fourth century, such as the discussion on the phenomenon of raiding the Jinsha River. At this stage, a small number of historical geographers have used historical documents to conduct research, such as Tan Qijun's research on the changes of the Haihe River and other waterways initiated by Tan Qijun to cooperate with the compilation of the "Historical Atlas of China", Shi Nianhai's restoration of the early lower reaches of the Yellow River, and Cen Zhongmian's "History of the Changes of the Yellow River" focusing on the changes in the yellow river before the Yuan Dynasty. The second stage is characterized by the compilation of "China's Historical Physical Geography" in the 1980s, which is a collection of works of research by many historical geographers, and also lays the foundation for the study of the changes in China's water system in the subsequent historical period, which is groundbreaking. The third stage is bounded by the advent of the new edition of "China's Historical Physical Geography" in the early 21st century, mainly for the revision and supplement of the old version, although this book was published in 2010, but the research content is mostly as of 2000 years ago, so the fourth stage can be used as the starting point in the early 21st century, which is mainly characterized by the application of new technologies, new methods and new materials such as GIS in the study of water system change.
In view of the different research perspectives, the previous achievements in the field of historical geography are mainly divided into four categories, namely, individual object research, comprehensive research, theoretical discussion and literature collation. Individual object research refers to the study object limited to a certain river or a certain lake, focusing on the restoration of its own evolution process, the summary of the law and the analysis of the causes; comprehensive research can also be called regional research, which comprehensively discusses the changes of rivers and lakes within a region and the relationship between them.
1. Individual object research
Over the past 70 years, the important achievements in the study of individual objects in the study of river and lake system changes in China have been mainly concentrated in the new and old editions of "Physical Geography of China". In the old edition, the water system change is the fourth chapter of the book, which is 190 pages, accounting for 73% of the book, which is the focus of the book, and the research objects are divided into the Yellow River, yangtze river, Hai river, Pearl River, Liao River, Tarim River and canal. Among them, the study of the Yellow River and the Yangtze River is the most comprehensive and in-depth, with the pioneering work of the blue wisp of the Yanlu Road, and the following will take the old version and the new version as the main line, interspersed with related research, and introduce the important individual object research.
In the historical period, the lower reaches of the Yellow River are typical wandering rivers, and their research focuses on the restoration and examination of the changes in the lower reaches of the river. The yellow river change is listed as the first section of the water system change, co-written by Zou Yilin, Tan Qijun and Shi Nianhai, after defining the criteria for major diversions, according to the analysis of historical documents, the characteristics of the changes in the lower reaches of the Yellow River are described in nine periods and six times. Of the nine periods, it is particularly noteworthy of the discussion of the first period, that is, before the Warring States built the embankment, the author creatively proposed that there were "Shanjing", "Yugong" and "Hejaz" rivers in the lower reaches of the Yellow River before the Warring States built the embankment, according to the name of the document that recorded the Yellow River, and examined the flow path of three ancient rivers. On this basis, Zhang Xiugui proposed that in the lower reaches of the Yellow River in the pre-Qin period, there was a diversion of the "Han Zhi" river of the northeast branch and the "Yugong" river of the north branch, and the above-mentioned "Shanjing" river and the "Yugong" river belonged to the "Yugong" river's Jiuhebei tributary system, and when the nine rivers of the "Yugong" river were fully developed and formed into the Bohai Sea, it was the time when the ancient Baiyangdian completely disintegrated and disappeared.
In addition to the three ancient rivers, the "Historical Physical Geography" also points out 11 other records in the "Hanshu Geographical Chronicle" and the 7 old ways of the main stream of the Yellow River or its diversion recorded in the "Water Classic". Based on the characteristics of the wandering river in the lower reaches of the Yellow River, hu Wei of the Qing Dynasty rejected the qing dynasty's statement that the fifth year of King Ding of Zhou (602 BC) was the first diversion of the lower reaches of the Yellow River, and that the flow path of the lower reaches of the Yellow River was extremely unstable, and it was not until the embankments on both sides of the river were built that a long-term stable situation appeared. The river channel fixed after the large-scale construction of the embankment in the lower reaches of the Warring States period is the great river in the "Book of Han and Geography", which has since ended the long-term situation of multi-strand diversion, which can be regarded as the first major diversion of the Yellow River in history.
The six major diversions were proposed on the basis of drawing on and revising the five major migrations proposed by the geographer Hu Wei in the early Qing Dynasty, pointing out that in 1128, in order to prevent the Jin soldiers from going south, the Song Dynasty decided to break the river in the southwest of present-day Huaxian County, and from then on the old road of the Yellow River leaving the northeast into the Bohai Sea was changed to the southeast into Sihuai, which was the fourth major diversion, and the river proposed by Hu Wei in the fifth year of Jin Mingchang (1194) was by no means a major diversion. In addition to the phased overview of the general trend of the yellow river changes in various periods, it is also summarized that there are 12 pan roads in the lower reaches of the Yellow River, namely the northern flow of The Water, the Tuotuo, and the Yuhe River, the East Stream of Luoshui, MaJie, and Jiqing, and the south-flowing Surabaya, Fenshui, Shuishui, Vortex, and Yingshui. Among them, the Luoshui Pandao and the Biaoshui Pandao are the longest, they are also known as the Eastern Han River and the Abandoned Yellow River Old Road, respectively, and the water travel time is as long as 10 and 7 centuries respectively. In addition, it also summarizes the three situations and reasons for the change of the lower reaches of the Yellow River, one is gradually from deep to shallow, from large to small, and even silted up to flat land, such as Guxingze in present-day Xingyang County, Putianze in Zhongmu, etc.; one is the lake area by the yellow river sand exclusion and siltation occurs from the upstream to the downstream low-lying areas of the change, such as Hebei's continental Ze; the other is from scratch, from small to large, such as Jiangsu's Hongze Lake, the fundamental cause of the change of the lower reaches of the Yellow River is flood and sediment.
Unlike the Yellow River, which mainly discusses the route change of the river, the chapter on the change of the Yangtze River focuses on the analysis of the evolution of the middle and lower reaches of the riverbed, written by Zhang Xiugui, Tan Qijun, Wei Songshan, and Yuan Fanfang. The evolution of the riverbed has always been valued by water conservancy workers, due to the lack of hydrological data in the historical period or even the lack of research on the evolution of the Yangtze Riverbed, mainly using historical documents, based on the theory of geomorphology to draw conclusions.
This chapter discusses the changes in the Yunmengze, Jingjiang riverbed, Dongting Lake, Chenglingji-Hukou section, Poyang Lake, Hukou-Zhenjiang river section, and Taihu Lake water system in descending order of the Yangtze River from top to bottom. In addition to making full use of historical materials, the Yangtze River changes also refer to the research reports of modern geographers and the archaeological results of archaeologists. The author first demonstrates the evolution of Yun Mengze, pointing out that there is a difference between Yun Meng and the area indicated by Yun Mengze, Yun Meng refers to the hunting area of the Chu King during the Spring and Autumn Warring States period, including mountains, hills, plains and lakes and other landform forms, Yun Meng's geographical scope is vast, almost including most of the southeastern provinces of present-day Hubei, but Yun Mengze, which is known for its lake and swamp form, is only an integral part of Yun Meng, and the southern part is bounded by the Great River, located in the present-day Jianghan Plain. Early literature often conflated the two, and since the Western Jin Dynasty, Yunmeng has been misunderstood as "crossing the north and south of the river", but in fact, Yun Mengze is not only in jiangbei, but also has nothing to do with Dongting Lake in jiangnan. Yun Mengze was filled by the sediment of the river water and the Han water flow, and the further expansion of the Jianghan land delta, until the Song Dynasty,the original large-scale lake water body was replaced by a dotted lake swamp, and Yun Mengze disintegrated and basically disappeared. Honghu Lake, the largest lake on the Jianghan Plain today, gradually converged into a lake due to poor drainage in the Jianghan Plain in the late Ming and early Qing dynasties, and expanded rapidly in the mid-to-late 19th century to develop into today's lake.
The evolution of the Jingjiang riverbed in the historical period is the most typical section of the yangtze riverbed evolution, the author takes the modern river geomorphology theory as the guide, through the analysis of historical documents, believes that the Yangtze River main hong roughly along the current Jingjiang River flow road throughout the historical period to the Chengling Jihe Dongting Four Waters. Pointed out that since the Ming Dynasty since the 5th century before the Yangtze River main Hongnan Zhudongting, today's Jingjiang River was only a Yangtze River at that time can not be established, the pre-Qin and Han Dynasties, the Yangtze River in the west of Jiangling to form a fendling river, south of the river, north of Tuo, to the Ming Jiajing years due to the two fencing river runoff changes, the original Tuo river runoff gradually exceeded the river channel, the original main Hong river channel became a channel, giving way to the original Tuo Road, resulting in the transposition of the river, becoming a major change in the Jing River for more than two thousand years, By the Wanli period, the Jingjiang River west of Gangneung was roughly formed.
The evolution process of the Jingjiang River section below Jiangling is closely related to the evolution process of Yun Mengze and can be roughly divided into three stages. The first stage is the jingjiang river flooding stage; the second stage is the pre-Qin and Han dynasties, due to the long-term sediment deposition in Yunmengze, the Jingjiang Delta with Jiangling as the apex is formed, called the Jingjiang Delta diversion stage; the third stage from the Wei Jin to the Tang and Song dynasties, is the shaping stage of the unified riverbed of the Jingjiang River. By the end of the Yuan Dynasty and the beginning of the Ming Dynasty, the vent stream gradually disappeared, Jiangxinzhou gradually docked, and a single riverbed was formed, and under the action of the curved circulation, the river curve developed rapidly. By the middle of the Ming Dynasty, due to the relationship between the water and the top of Dongting Lake, the typical river bend in the southeast of Jianli had developed and formed. In the Qing Dynasty, under the control of the boundary conditions of the riverbed and the artificial embankments of the river beach, the river curve in Shishou also began to develop from downstream to upstream.
Combined with archaeological data and literature analysis, it is learned that by the Jin Dynasty, the four waters of Xiang, Zi, Yuan and Li were directly injected into the Yangtze River in the Dongting Plain, and at this time the Dongting area was a plain landscape cut by a river network, with a small area of lakes, and did not form a large-scale water body, and it was not until the Southern Dynasty period that the scope of the present-day Dongting Lake was formed. Due to the slow subsidence zone of Dongting Lake and the formation of the unified riverbed of the Jingjiang River, since the Tang and Song Dynasties, the water area of Dongting Lake has continued to expand, and the Daoguang years are the heyday of Dongting Lake. During the Xianfeng and Tongzhi years, the Jingjiang River broke through, forming the Lotus Pond Mouth and Songzi Mouth respectively, and together with the previous Tiger Crossing and the Tune String Two Mouth, the situation of four diversions was formed, and a large amount of sediment was discharged into the Dongting Lake area, resulting in the rapid shrinkage of Dongting Lake in the past hundred years.
Poyang Lake, located at the mouth of the lake, like the aforementioned Dongting Lake, develops on the graben-shaped lake basin formed by the Yanshan Movement Fault. The differential movement of faults at the beginning of the Holocene has a large relative depression on the Nanchang-Hukou line, especially the Hukou fault is strong, and the Poyang North Lake develops here. Before the beginning of the 5th century, Poyang South Lake was a plain landscape with a network of rivers cut off. By the Northern Song Dynasty, Poyang North Lake (Peng Lize) rapidly developed to the east and south to form a vast Poyang South Lake, but the lake had the nature of a seasonal lake, and the morphology of the lake changed greatly during the flood and dry season. Due to the development of a series of extruded crushing belts in the lower reaches of the Yangtze River, the width of these crushing belts can reach more than ten kilometers to forty kilometers, and the Quaternary loose sediments are widely developed, which is very conducive to the lateral swing of the riverbed and the formation of the fencing channel. The author uses the literature to describe the river type and sandbar changes in the five sections of the river, namely Hukou-Jiyang and Nanjing-Zhenjiang.
The section on the change of the water system of Taihu Lake analyzes the relationship between the ancient Taihu Lake and its three rivers in the east, including the Wusong River, the Lou River and the East River. In the historical period of the coexistence of the three rivers, the downstream of Taihu Lake was drained smoothly, the area was smaller than today, due to the continuous sinking of the Taihu Plain, the three rivers that originally discharged the water of Taihu Lake into the sea became the main channel for the internal immersion of the seawater. In the 8th century, the Lou River and the East River were successively silted by the sediment brought by the back-irrigation of the seawater, and the central plain of Taihu Lake became a waterlogged area, and lakes of various sizes were formed successively, and the lake area was expanded. In order to eliminate stagnant water, the local people generally repaired river canals and formed a water network system. In the process, the Wusong River was also silted, and the Huangpu River, which was originally a tributary of the south bank of the Wusong River, was manually dredged, and after the 18th century, with the increasingly narrow and shallow of another LiuHe River that undertook to transport the water of Taihu Lake, it finally developed into the only large river in the lower reaches of Taihu Lake.
Zeng Zhaoxuan and Huang Shaoming used historical documents to outline the changes in the lower reaches of the Sanrong Gorge of the Xijiang River, the lower reaches of the Beijiang Feilai Gorge, the lower reaches of the Tianluo Gorge of the East River, and the pearl river channels in Guangzhou, and believed that the changes in the lower reaches of the Pearl River system were mainly caused by the delta-style radial water system, and since the Tang and Song Dynasties, after artificial reclamation, embankments and flood control, the tributaries were cut off, and the results of the reclamation of the main stream were retained.
Lin Tingshui and Zhou Weiyan believe that the change of the Liao River has the same law as the change of the sandy river in the general plain, and also has its own characteristics. Since the Qin and Han Dynasties, the downstream trunk roads have been increasingly affected by human activities, and with the enhancement of reclamation activities in the upper and middle reaches of the LiaoHe River, the sediment entrained by the Liaohe River and its tributaries has increased day by day, resulting in siltation of the riverbed, numerous branches, and the oscillation of the trunk roads. The swing trend of the north-south section of the Liao River is from west to east, the place where the swing occurs is often the confluence of the tributaries and the Liao River, and the sediment brought by the main stream is easy to silt up at the confluence of the tributaries, resulting in poor flow of the main stream, the emergence of branches, coupled with the role of delta extension, over time, the lower reaches of the Liao River will be changed to other roads, so the road often becomes a tributary section of the river.
Huang Shengzhang, Niu Zhongxun, Sun Zhongming, and Zhou Tingru used the literature to briefly sort out the changes of the four rivers of the Upper Tarim River, the Hotan River, the Yarkand River, the Kashgar River and the Aksu River, the main stream in the middle reaches from the mouth of the Aksu River to Qunke, and the changes in the lower reaches and lakes such as Lop Nur. It is believed that the Tarim River got its name late, previously also known as the Ergou River, which became the proper name of the whole river, which should be after Xu Song's "Records of the Waterways of the Western Regions" in the early years of Daoguang, and is related to the disappearance of the Ergou River. Swinging to the left and right is a common law of the change of the main stream of the Tarim River, and some of the original tributaries of the Tarim River, due to the reduction of water volume and the artificial drainage of water, cause the water downstream of these tributaries to be less than the mainstream, thus becoming a scattered stream. According to the analysis of satellite and aerial survey photos and geomorphological surveys, the change of Lop Nur is a process of gradual reduction, and the fundamental reason is the reduction of water sources, and there are natural and cultural reasons for the reduction of water sources. Lop Nur has never moved elsewhere, it has only moved and changed within its own range, in the form of a northward shift and a breakdown into a number of small lakes. It is incorrect to think that it was a wandering lake in the past. It is pointed out that the development of oases and the increase in agricultural water use are the leading reasons for the change of the Tarim River and Lake water system in modern times.
Ma Zhenglin, Huang Shengzhang, and Chen Qiaoyi used historical materials to reconstruct the canal routes artificially built since the end of the Spring and Autumn Period when Wu Guo used natural rivers and lakes to build a canal to communicate with Jianghuai, including the chasm connecting Huaiji in the Warring States period, and the Tongji Canal built by the Sui Dynasty to communicate with Huanghuai, which was mainly built by hand, that is, the Beihe River in the Tang and Song Dynasties. The Sui Dynasty excavated the Yongji Canal near present-day Beijing, and the Sui Emperor also widened the Hangou and Jiangnan Canal connecting Zhenjiang to Hangzhou. The Song Dynasty formed a network of canals centered on Kaifeng. The capital of the Yuan, Ming, and Qing dynasties was built in Beijing, and from the Yuan Dynasty onwards, in order to shorten the transport routes, avoid the Yellow River and solve the problem of land transport, a new road began to be opened in the territory of present-day Shandong, and the Yuan Dynasty successively opened the Jeju River from present-day Jining to Dongping in Shandong, the Huitong River that extended from Jeju Hebei to Linqing and the Yuhe River, and the Tonghui River that connected Tongzhou to Beijing today, and thus the Grand Canal connecting Hangzhou to Beijing was formed. However, due to the failure to solve the problem of insufficient water sources and inconsistent terrain between the north and the south in Shandong, shipping dominated the yuan generation. The Ming and Qing dynasties solved the problem of insufficient water source and separation of yellow transport in the Shandong Canal, and was committed to maintaining the smooth flow of the North-South Grand Canal. The cost of maintaining the canal in the Ming and Qing dynasties was extremely expensive, and the maintenance of the canal also affected the evolution of the South Four Lakes and the North Five Lakes.
In 2013, edited by Zou Yilin and Zhang Xiugui, "China's Historical Physical Geography" inherited the structure of the old version, the difference is that the evolution of the river system in the historical period is divided into two parts, the first part is composed of the evolution of the Yellow River and the Yangtze River, and the second part is less than the old version of the liao river change, adding the water system of the Hexi Corridor, and the researchers have also made some adjustments to the original, and all are independent authors. In addition to changes in content and authorship, the length has increased to 328 pages, but the proportion in the entire book has dropped to 47%, making the proportion between the various natural elements evener than in the older editions.
In terms of the older version of the Yellow River, the order of writing has been adjusted, and the flood and sediment of the Yellow River in the historical period originally located at the end of the text have been adjusted to the beginning of the article, and the content has been nearly doubled compared with the original version, increasing the evolution of the upper and middle reaches of the Yellow River, further improving the characteristics of the evolution of the lower reaches of the Yellow River and the environmental disasters of the lower plains of the Yellow River. The evolution of the middle and lower reaches of the Yangtze River in the new version of the historical period also adjusts the structure of the original river and lake intersection discussion, still in the order of the middle and lower reaches, but the evolution of the riverbed is described separately from the evolution of the lake, and in terms of the evolution of the riverbed, the middle reaches of the Yichang to Zhicheng river section, as well as the yangtze River estuary, especially the evolution of Chongming Island, are added, and the rest introduce the evolution of the middle and lower reaches of the Yangtze River according to different riverbed types.
The changes of the haihe river system in the new version are divided into four stages, such as the embryonic period before the middle of the Warring States period, the formation of the Haihe River from the middle of the Warring States period to the early stage of the Western Han Dynasty, the late development period of the Western Han Dynasty to the late Sui Dynasty, and the late stage of the transformation of the Haihe River system since the Tang Dynasty. Different from the past, the article pointed out that as long as there is more than one water system in tianjin injecting into the main stream of the Haihe River, it can be considered that the Haihe River system was formed at that time, and it is not necessary to emphasize that the five major water systems are injected into the main stream of the Haihe River at the same time to confirm the existence of the Haihe River system, because the latter is only a phased product of the development of the Haihe River system, so in the middle of the Warring States, the embankment on the east and west banks of the "Han zhi" river led to the "Shanjing" River and the "Yugong" River breaking is a sign that the independent Haihe River system in the Haihe River Basin began to form. Since then, the Haihe River system, with the Haihe River as the channel to the sea, has separated from the lower Reaches of the Yellow River system and begun its independent local water system evolution process.
The changes in the new version of the Pearl River system inherit the framework foundation of the old version, and use new materials and methods to enrich and enrich the original content. With the help of historical documents, combined with the sedimentation of shells on the banks of the Xijiang River and the dating analysis of the tomb C14, it is believed that the main stream of the Xijiang River in the historical period is relatively stable below the Sanrong Gorge. The lower reaches of the Xijiang River began to build embankments since the Northern Song Dynasty, and the Yuan, Ming and Qing dynasties continued to build and strengthen them, which not only fixed the river channel but also defended a large area of farmland. Unlike the stability of the Xijiang River, the lower reaches of the Beijiang River today are no longer what they used to be. According to the analysis of historical documents and field investigations, the present-day Beijiang Waterway, originally a tributary of the Xijiang River, is today re-entered into Guangzhou's Drowning Valley Bay through Datang, Lubao, Hekou and Southwest. The river changes in the lower reaches of the East River are characterized by the development of Jiangxinzhou and the continuous generation of depressions on the banks of sandbars, and the evolution of the Pearl River estuary has also been added.
The new edition summarizes the characteristics of the change of the Tarim River system, the main stream of the Tarim River in the historical period in the south side of the Tianshan Mountains before the alluvial fan belt and the Taklamakan Desert between the alluvial plain migration swing, the section below the Qunke is radial swing, the process of the Nyaya River, the Kriya River and other tributaries are broken and separated from the Tarim River, and the Tarim River terminal lake Karakushun Lake and Lop Nur are analyzed. The study and study of the Evolution of the Shiyang River and its Tail Lu Lake in the Hexi Corridor, the restoration of the Ancient Juyan Sea, and the Underground Water Horizon have been added.
On the basis of the old version of the canal, the chapter on the evolution of the new version of the canal supplements a large number of historical materials, comprehensively discusses the historical and geographical background and natural conditions of the regional canal and the grand canal excavated through the north and south of the historical period, and the impact of the canal excavation on the natural environment of the area along the canal, enriches and deepens the research on the history of the canal, and the schematic diagram of the canal made on the basis of research greatly facilitates the reading and understanding of ordinary readers.
The new and old versions of the research on the change of Rivers and Lakes in China are the culminations of the research on the changes of river and lake water systems, which embody the highest achievements in the study of individual objects of rivers and lakes in the more than 70 years since the founding of New China, mainly based on the analysis of historical documents, guided by modern river geomorphology theory, combined with archaeological discoveries, stratigraphic analysis and other research results of other disciplines, for the characteristics of different river basin systems, put forward problems with regional characteristics, using original research methods and perspectives, comprehensively discussing the characteristics and causes of changes in China's major rivers and lakes. Draw more credible conclusions. Although its research objects are mainly large rivers in the eastern plains such as the Yellow River and the Yangtze River, and some rivers and lakes still need to be deepened and improved, there is no doubt that its research methods and perspectives are pioneering, providing a research paradigm for future related research and laying a good foundation.
In addition to these two monographs, there are still some representative papers that deserve attention. The above-mentioned yellow river change research mainly focuses on the summary of the characteristics and laws of the yellow river change, in addition to the characteristics of the Yellow River itself, the geographical environment in which the Yellow River itself is located, there are many man-made reasons, Tan Qihua's "Why the Yellow River will have a long-term flow situation after the Eastern Han Dynasty - from the history of the rational use of land in the middle reaches of the Yellow River is the decisive factor in eliminating the downstream water damage" is a comprehensive discussion of the causes of the change of the lower reaches of the Yellow River. He realized that although the Yellow River was downstream, the pathogen was serious sand erosion on the middle reaches of the Loess Plateau, and the severity of soil erosion was closely related to the quality of vegetation, and the land use pattern of the local people was the determinant of vegetation. Therefore, he grasped this key factor and discussed the root causes of the different severity of river disasters in the historical period from the perspectives of political district examination, population migration, and land use methods.
The pioneering work on the relationship between the changes of rivers and lakes and the relationship between human social activities in the historical period is Hou Renzhi's "Topographic Waterways and Settlements Near Haidian, Beijing - The Geographical Conditions of the Newly Designated Cultural and Educational Area in the Capital Urban Plan and Its Development Process", which starts from the introduction of the current situation of contemporary terrain and hydrology, analyzes the relationship between the formation process of the Yuquan Landscape System and the Wanquanzhuang Water System near the area and the development of nearby settlements, this article is for the planning of the Beijing Education New Area since the founding of New China, which has strong practical significance. It is the first important paper on the change of water system and the relationship between man and land since the founding of New China.
Another noteworthy article is Man Zhimin's article on the study of the Huangpu River system. When exploring the reasons for the formation of the Huangpu River system, he fully considered the theory of river geomorphology, and also took into account the sea level rise caused by the small warm period in the Middle Ages, which led to the flooding of the entire eastern coast of China, and the resulting series of river and lake changes, and pointed out that the Huangpu River water system was formed in the context of this large climate change. Although this conclusion is still debatable, the approach he adopted in the method of geographical environment analysis is undoubtedly worthy of recognition.
It is worth mentioning that in recent years, the advent of the "Atlas of Historical Changes of Dongting Lake" represents the trend of concentrating the research results of a certain river and lake into an atlas. The atlas is composed of eight major atlases and appendices, including the Agricultural Atlas Group, including 93 special topics, which concisely and intuitively show the laws and characteristics of the historical changes of Dongting Lake.
2. Comprehensive research
Zou Yilin's analysis of solving water sources along the canal is a model of comprehensive research, not only analyzing the different measures taken to solve the problem of canal water sources at different times in history, but also discussing the interference of canal excavation on the drainage system of the eastern plain. The canal runs from south to north, through different geomorphological zones and climatic zones, and changes in topography and water sources contradict artificial waterways that require a stable water surface at all times, and different engineering measures need to be implemented in different sections. Canal construction from the initial full use of natural rivers and lakes terrain, to the later use of engineering technology methods, so that the canal gradually separated from the natural river and lake channel, become a fixed channel of artificial embankment. While solving the water source of the canal, it often causes changes in the distribution pattern of the natural water system.
Wu Chen's "Research Theory on Paleochanic Channels in North China Plain" and "Collection of Paleochands in North China Plain" are the culminations of the restoration of paleochannels in The North China Plain, reflecting the work of the Hebei Institute of Geography for 30 years, using a variety of means to restore more than 300 paleohe channels in the Hebei Plain, more than 20 shallow buried ancient rivers, on the basis of restoring the paleochannel, the formation conditions and environmental changes of the paleochannel in the North China Plain, as well as the relationship with human activities, were also analyzed.
"Research on the Relationship between Huanghuai and Its Evolution" discusses the changes of the Huaihe River system that occurred on the Huaibei Plain in the context of the long-term seizure of the lower reaches of the Yellow River into the sea from 1128 to 1855, and comprehensively analyzes the relationship between the mutual influence and interaction between the Yellow River, the Huaihe River and human activities during this period, which is the earliest monograph in China to comprehensively discuss the regional river and lake changes and the relationship between man and land.
Lu Xiqi and Pan Sheng's research on the river change and embankment construction of the main tributaries of the upper and lower reaches of the Han River is also another important result of comprehensive research, mainly relying on historical documents, supplemented by field investigations, dividing the upper and lower reaches of the Han River into the process of restoring the river channel change and the construction of artificial embankments in the upper and lower reaches of the Han River, summarizing the spatio-temporal characteristics of the changes in the upper and lower reaches of the Han River, and believing that the fundamental factor restricting the change of the upper and lower reaches of the Han River is the valley landform, but it is also affected by climate change and human activities.
3. Theoretical discussion
In 1985, Zeng Zhaoxuan and Zeng Xianshan systematically summarized the study of historical geomorphology, put forward an independent framework from a theoretical height, created historical geomorphology, a sub-discipline of historical physical geography, and authored the book "A Brief Treatise on Historical Geomorphology", which is of pioneering significance. Zeng Zhaoxuan pointed out that historical geomorphology has a broad sense and a narrow sense, the broad sense of historical geomorphology refers to the history of geomorphological development, and the narrow sense is limited to the development of landform since the Quaternary Holocene, and the age is only about 10,000 years. The book's "historical geomorphology" refers to historical geomorphology in the narrow sense. The two tasks of historical geomorphological research are the restoration of ancient landforms and the determination of geomorphological ageing. It is pointed out that the research methods of historical geomorphology include the documentary evidence method, the cultural relics archaeology method, the ancient map comparison method, the field investigation method, the application of remote sensing technology, the application of dating technology, the geographical environment analysis method, and the paleoclimate method.
In recent years, Zhang Xiugui's "Research on China's Historical Landforms and Ancient Maps" is a leading work for studying the changes of water systems from the perspective of historical geography. Regarding the research period of historical landforms, he believes that the historical geography community usually pays attention to the study of the evolution process of landforms in the past 2,000 years, and on the lower limit of "historical periods", he believes that it should be judged by "yesterday". He believes that the evolution process of historical landforms can be divided into two connecting stages, one is to study the geomorphological process, and the other is to systematically analyze the results of the geomorphological research in accordance with the historical development sequence, to clarify the development and evolution process of the geomorphological form in the entire historical period and the formation of today's geomorphological form, from which to find out the basic law of the whole process of evolution, and further predict the future development trend, and the study of the evolution process is the basic task of Chinese historical geomorphology.
On this basis, Zhang Xiugui took the principles and theories of modern geomorphology as the guide, comprehensively applied various methods of historical geomorphology, especially historical documents and ancient map analysis methods, to conduct a comprehensive, systematic and in-depth study of the historical evolution of the landforms of the Huang-Huai-Hai Plain and the middle and lower reaches of the Yangtze River in eastern China, and put forward many creative ideas, which greatly enriched the relevant theories and practices of river landforms, lake marsh landforms, coastal landforms and man-made landform evolution.
4. Literature collation
As mentioned above, the tradition of recording water systems on the mainland has a long history, providing a continuous and rich historical basis for the study of water system changes in historical periods. Therefore, sorting out relevant historical documents is the basic and necessary work in the study of water system changes.
The full text of "Shangshu Yugong" is only 1193 words, representing the geographical understanding of people in the pre-Qin period, and its record of the river and lake system has had a profound impact on future generations. Because the book was so old and difficult to read, successive hermenists spent a lot of effort to annotate it. In the Qing Dynasty, Hu Wei wrote the "Yugong Cone Finger", which systematically summarized the research results of dozens of hundreds of "Yugong" in the past. Zou Yilin sorted out and proofread the book, which is a representative achievement in the collation of "Yugong" after the founding of New China.
Compared with "YuGong", since the founding of New China, the results in the collation of "Water Classics" have been more remarkable. The author believes that the first recommendation of Duan Xizhong's "Water Classics Commentary" by Chen Qiaoyi.com. The original work of the "Water Classics Commentary" is Yang Shoujing and Xiong Huizhen in the late Qing Dynasty and the Republic of China, who not only attached importance to the analysis of the geography of mountains and rivers in the shuwen, but also drew a set of "Water Classics Annotation Maps", which are representatives of the geographical school in the study of Li. Yang Shoujing died in 1915, and his student Xiong Huizhen spent more than twenty years on the manuscript, changing its manuscript six times. Unfortunately, because Xiong Huizhen committed suicide, the final draft is still unknown. This book was based on the 1957 Beijing Science Publishing House published "Photocopy of "Water Sutra Annotations"" as the working base, with reference to the various inscriptions of the researchers of "Water Classics Notes" since the Ming and Qing Dynasties and the classics, histories, sub-texts, and collections of historical materials to be proofread, added, deleted, and errata, and then, according to Chen Qiaoyi's photocopy of "Yang Xiong's Co-authored "Water Classics Annotations" published by the Taipei Zhonghua Bookstore in 1971, referring to Zhong Fengnian's "Water Classics Annotations and Corrections", taipei photocopied "Water Classics Annotations" Fu Weiping proofreading, combined with personal research results, The lead typesetting printed after the proofreading of Duan Xizhong's school base was re-proofed, added or deleted, and errata. Therefore, this can be said to be the best version of Yang Shoujing and Xiong Huizhen's "Water Commentary" at present, which has high academic value. In addition to their outstanding contributions in revising and supplementing Yang Shoujing and Xiong Huizhen's original works, Duan and Chen's "Notes on the Water Classics" are included in the "Explanation of Typesetting the Water Classics Commentary", Li Daoyuan's "Notes on the Water Classics", Yang Shoujing's "Notes on the Water Classics", Xiong Huizhen's own opinions on the revision of the "Notes on the Water Classics", Duan Xizhong's "Notes on the Water Classics", Wang Peijiang's "The Total Achievements of the Compilation of the Water Classics notes in the Ming and Qing Dynasties", Chen Qiaoyi's "Discussion on different versions and origins of the Water Classics Notes" and "On the " The whereabouts of the final manuscript of the Water Sutra Commentary, as well as the explanation of He Changqun's photocopy of the Water Sutra Commentary, play a role as an introductory guide for posterity to understand the compilation process and the source flow of the version of the strange book of the Water Classic, especially Duan Xizhong's "Six Treatises on the Water Classics" for readers who are new to the Water Classics, which is even more enlightening for readers who are new to the Water Classics, and Duan Xizhong's discussion on the age of the "Water Classics" can also be described as exploring the pearls.
Regarding the collation and research of the "Water Commentary", Chen Qiaoyi's achievements are the most abundant and outstanding, in addition to the re-proofing of the above-mentioned new edition of the "Water Commentary", he has also continuously published monographs such as "Study of Water Commentary", "Second Collection of Water Commentary On Annotation", "New Theory of Li Xue" and so on. Subsequently, on the basis of the "Annotation and Interpretation of the Water Classics" published in 1999, in addition to participating in more than thirty versions of the "Notes on the Water Classics", the research results of modern Li Studies were supplemented, and the "Water Classics Annotation Proofs" were published.
In addition to inheriting the tradition of annotations to the Water Classics, the most important thing is that his research introduces theoretical knowledge of historical geomorphology and riverbed evolution. He believes that the Zhijiang-Shaxian river section is the most typical and most researched section of the river in the "Water Classics and River Water Notes". Using the same research method, he also annotated and restored the Xiangfan-Wuhan river section of the "Water Classic-ShuiShui Note" and the Dongting Lake water system of the "Water Classic".
On the basis of the research of their predecessors, Li Xiaojie and others rediscovered the publication of Ming Chongzhen Chen Renxi's "Compilation of Ancient Texts of Qixiang Zhai" now in the National Diet Library of Japan, discovered the value of Wang Jun's schoolbook, which had been buried since Qianlong, and successively published such achievements as "Illustrations of The Annotations of the Water Classics -- The Chapters of the Weishui River Basin" and "The Illustrations of the Notes on the Annotations of the Water Classics-The Articles of the Fenshui Shushui River Basin."
In addition to the collation and research of important ancient books, the compilation of large-scale books has also yielded fruitful results, and the two most important ones are organized and compiled by the Ministry of Water Resources, namely the "Chinese Water Conservancy History Dictionary" and the "China River and Lake Dictionary". The former is the first comprehensive and systematic collation of large-scale reference books of water conservancy historical documents since the establishment of the People's Republic of China, and is also the first batch of projects supported after the establishment of the "National Publishing Fund", the time range of the collected documents is from the beginning of written records to 1949, divided into 10 volumes such as comprehensive volumes, Yangtze River volumes, Yellow River volumes, etc., using punctuation, proofreading, annotation and other methods, and adding collation instructions, prefaces, afterwords and other content. The project will be completed in two phases, with 50 volumes planned to be published, the first phase publishing 20 volumes, and the second phase passing the acceptance at the end of 2021. The latter consists of 10 volumes and 11 volumes, including a total of 5960 rivers, lakes and important water bodies above the national scale, and draws accurate water system maps, which provides a reference for the study of water system changes, and is known as "Contemporary "Water Commentary".
The compilation project of the "Great Dictionary of China", which began in the 1990s, extracted relevant materials from the vast ancient books on the mainland and classified them and punctuated them, and its "Agricultural Codex", "Geological Code" and "Historical geography codex" contained many historical materials related to rivers, lakes and water conservancy. The "China Water Conservancy Chronicle Series" edited by Ma Ning et al. collects more than 90 kinds of water conservancy books in mainland China, including the general theory of water conservancy, the examination of waterways in various provinces and the study of specific rivers. Under the organization of the relevant state departments, the compilation of hydrological data related to the continental rivers and lakes has also been fruitful, including the geography and water conservancy records in the newly revised fangzhi of the provinces since the 1980s, as well as the water conservancy yearbooks regularly compiled by the national, provincial and municipal water conservancy departments. In addition, a number of large-scale river chronicles such as the Yellow River Chronicle, the Yangtze River Chronicle, and the China Canal Chronicle have also been published. These achievements have facilitated the reading and use of river and lake water system materials in mainland historical documents.
Fourth, the application of new technologies and new materials and the proposal of new ideas
As early as the 1990s, Hou Renzhi pointed out: "The modern scientific and technological means that can be used to study current geographical problems, how to cite the study of geographical problems in the past era, is the key to the future development of Chinese historical geography." "In terms of the geomorphological changes of rivers and lakes, Man Zhimin earlier used modern remote sensing data, combined with the records along the Yellow River in historical documents, through new technologies and translation methods, restored the rivers above the Yang Liu Gu Dao of the Jingdong Ancient Road in the Northern Song Dynasty, corrected the misunderstanding of the Jingdong GuDao since Hu Wei, greatly improved the accuracy of the restoration of the ancient river channel route, and provided new ideas for future research. Since then, he has discussed the application of the grid system in historical geography, and put forward a preliminary idea of the relationship between man and land in a small area. On this basis, he cooperated with Pan Wei to take the Qingpu District of Shanghai as an example, on the basis of correcting the 1:50,000 military topographic map in 1918, and conducting spatial superposition analysis with the topographic map of the same scale in 1978, and studied the density of the river network and the change of lake area. The introduction of this method has greatly promoted the quantitative study of the change of river and lake water systems in historical periods, improved the credibility of the conclusions, and is worth promoting.
The use of new methods and new materials has also deepened the study of canals. Under the background of the South-to-North Water Diversion Project and the Application for world heritage of the Grand Canal, Sun Tao et al. combined with historical documents, public opinion maps, and 1/50,000 Japanese military topographic maps, etc., through on-site investigation and measurement, reconstructed the elevation of the Grand Canal in the Shandong section by GIS method, with a resolution of up to 0.5 meters. Some new research ideas are also worthy of attention, such as Zou Yi reconstructing the population sequences of Huangmei County, Guangji County and Susong County in the Longgan Lake-Taibai Lake Basin from 1391 to 2006 through historical methods, and then using the sedimentary index sequences of the two lakes in the same period for testing, and found that the sedimentary records can well reflect the trend of population fluctuations in the same period, which is refreshing.
Old maps drawn by measurement have an important place in the study of river and lake change, providing a difficult to describe the flow of rivers, the shape of lakes, and the distribution pattern of a regional water system. As some scholars have advocated, early maps are probably the most important source of information for the study of natural element transitions, as they facilitate the analysis of the characteristics of natural elements within a specific temporal and spatial context. Zhang Xiugui pointed out that comparing ancient maps with contemporary maps is the most effective and simplest way to study the historical evolution of landforms. In recent years, with the continuous publication of old maps, new materials have been provided for our future research. However, unfortunately, the ancient map of the mainland mostly uses the drawing method of landscape painting, and the characteristics of the natural geographical elements in the map are mostly completed by the diagram, so some of the spatial information we need is difficult to measure directly from the map, and can only get the general orientation, so most ancient maps cannot be fully utilized for us. It is worth pointing out that Kangxi's "Imperial Public Opinion Overview Map" is the first official surveyed and map of the country with longitude and latitude coordinates in Chinese history, and it is also the first time in Chinese history to use longitude and latitude coordinates to draw a map of the river and lake system, although its scale is 1:140-150 million, it is still relatively rough, but it can be digitized by GIS means through appropriate registration methods and appropriate corrections. It can provide a comparative data platform for the study of the changes of related elements on the topographic map drawn by Western surveying and mapping methods today, and through spatial comparative analysis, the accuracy of the research on the change process of China's water system and coastal geomorphology in the past three hundred years can be greatly improved, which has certain practical significance. In view of this, Han Zhaoqing has led students to carry out the digitization of Kangxi's "Imperial Public Opinion Overview Map" in recent years, and its impact on the mapping of the water system of the Public Opinion Map in later generations, and some recently published articles have used the digitization of this set of maps for case papers on the study of river and lake changes.
In addition to the application of new technologies and new materials, in recent years, research has gradually shifted from focusing on the changes of large rivers and large river systems in the east to focusing on the study of the middle and small river systems in the central and western regions. For example, Fu Linxiang's "New Solution to the Evolution of the Lower Reaches of the Wusong River" believes that the evolution of the Wusong River to today's Suzhou River is the result of natural evolution. Zhang Li and Li Lili's "Research on the Changes of Manas Lake in Xinjiang in the Past 300 Years" uses the historical geography reverse deduction method to gradually determine the location of Manas Lake and the change process of manas lake in different eras and the change process of the water system entering the lake in the past three hundred years, and analyzes the influence of regional natural and human factors on the hydrological changes in the Manas Lake basin in different historical periods. Song Lizhou used historical documents to restore the cognitive process of the Yeerqiang River Basin from the Qing Dynasty to the Republic of China, and talked about the changes of the river in various historical periods.
Academics are innovative, and sometimes it is necessary to reflect and question traditional views, such as Zhou Hongwei speculated according to the geophysical data of geologists and geographers that there was once a lake formed by faults and falls in the Chengdu Plain, combined with historical documents to examine, put forward a new theory that "Dianchi Lake" was originally examined in the Chengdu Plain. Later, it was also proposed that before the beginning of the Han Dynasty, the upper reaches of the present-day Jialing River were originally the upper reaches of the ancient Han River, due to the great earthquake of Wudu Province in 186 BC, which caused a huge landslide. Landslides block the Guhan Water and form an extremely large-scale dammed lake in the upper reaches of the Guhan River, so it is concluded that the water system change in the upper reaches of the Guhan River is not due to the traceability erosion of the river, but the result of overflow erosion of the dammed lake water after the river is blocked by a major earthquake. Although these new theories have been questioned by other scholars, in my opinion, both the proposer of the new views and the scholars who have discussed them should be respected as long as they are reasonable. Normal academic discussion is the driving force of academic progress and a symbol of academic prosperity. Related articles include Ren Boping's "The Reasons for the Long-term Flow of the Yellow River After the Eastern Han Dynasty—Discussing with Mr. Tan Qijun", Zou Yilin's "After Reading Ren Boping's "Reasons for the Long-term Flow of the Yellow River After the Eastern Han Dynasty", and Zhao Shuzhen's "Re-discussion on the Long-term Flow of the Yellow River After the Eastern Han Dynasty".
V. Research characteristics and future research prospects of China's water system changes in the past 70 years
Looking at the four different stages and achievements of the study of water system change in China since the founding of New China, its characteristics can be summarized as follows: the first stage can be regarded as an individual exploration stage, which is mainly based on the restoration of the river change process and the description of the characteristics of the river environment, and the research of this stage is related to the compilation of the "Historical Atlas of China" and the needs of national construction. The second phase, which was devoted to the compilation of a series of books on the physical geography of China, was both a summary of previous research and the emergence of new research, which included not only the restoration of the process, but also the interpretation of the process. The third stage is characterized by the emergence of a new version, and on the basis of inheriting the old version, it not only pays attention to exploring the reasons for the change of the research object and the law of change, but more importantly, pays attention to the introduction of new achievements from other disciplines. The fourth stage is the new version so far, the application of new technologies and new materials has become the driving force for the development of this field, and the research object has also shifted from the traditional research of large rivers to the study of small and medium-sized rivers in the region, which has been further broadened.
In short, since the founding of New China, the research of water systems has been pioneering and innovative, self-contained, and remarkable achievements. With the joint efforts of many scholars, at present, the changes in the historical period of the major rivers and rivers in the mainland academic circles have been roughly outlined, and the relevant major problems have been solved one by one, and regional and small-scale research has also achieved continuous results. In recent years, with the application of new technological means such as scientific and technological archaeology, sediment analysis, remote sensing, and GIS, and the rediscovery and utilization of a large number of ancient maps, the study of water system change has broken through the limitations of qualitative research methods based on traditional evidence of textual literature and achieved a certain degree of quantitative analysis.
At the same time, it should be noted that the current research on the change of river and lake water systems is still facing many difficulties. First of all, the study of water system changes in the historical period has long been limited by the lack of historical records, and there is a large vacuum period in some periods, affected by the content and method of historical documents, qualitative analysis is still the main research method; secondly, although the current research on the Yellow River, Yangtze River, Haihe River, Pearl River and other major river systems has achieved more results, regional comprehensive research and other water system research is still weak; third, the study of water system changes in historical periods requires familiarity with geography-related theories and knowledge. The ability to correctly interpret historical documents is also required, which puts forward higher requirements for the knowledge background of researchers. How to better realize the combination of humanities and natural disciplines in research is not only an urgent problem to be solved in the study of historical water system changes, but also a major problem facing the discipline of historical geography for a long time; finally, it is worth paying attention to the fact that the study of river and lake water system changes showed a thriving and vigorous development trend at the beginning of the founding of New China.
The change of river and lake water systems is closely related to human society, especially in ancient societies, water management is related to the rise and fall of the country. In recent years, with the increase of extreme flood disasters caused by global changes, and with the establishment of ecological civilization construction as a national strategic policy, how to provide background knowledge, experience and lessons from a historical perspective has gradually attracted people's attention, and the relationship between rivers and human beings in the relevant historical period should undoubtedly also attract attention. To this end, the author puts forward the following four suggestions for the future study of river and lake system changes:
First, the research method should strengthen quantitative research. From the above introduction, it can be seen that due to the analysis of historical documents in the past, most of the research is qualitative research due to the limitations of the way and content of the data are recorded, but in order to fully grasp the law of river and lake change, more quantitative research is needed. To this end, the era can be extended downwards, with the help of the digitization of ancient maps and modern geographical survey data, to strengthen quantitative research.
Second, the content of the study should strengthen the comprehensive study of the western region, small and medium-sized rivers and lakes, including the change of urban water systems. In the past, due to data limitations, the study of the changes of rivers and lakes in the west was still relatively weak, but the western plateaus and mountainous areas were mostly the source of major rivers on the mainland, although the rivers in these areas were constrained by the boundary conditions of the riverbed and the influence of topographic factors, and the historical period did not change much, but exploring the cognitive process and changes of these rivers in the historical period also contributed to our understanding of the relationship between man and land in the historical period. Small and medium-sized rivers and lakes are often part of large and medium-sized rivers and lakes, and with the help of new materials and means such as aviation, remote sensing photos, and expedition reports produced in modern times, some areas with these data can be studied. Urbanization is the trend of future social development on the mainland, whether it is future urban planning or the solution of the increasing urban waterlogging problem in recent years, etc. all require the participation of historical geographers.
Third, we should absorb the perspective of environmental history, make suggestions for the harmonious development of today's human society and rivers and lakes from a historical perspective, and enrich the content of ecological civilization construction. In the past, the study of river and lake water system change only focused on the river and lake system itself, human activities are often considered as the driving force of river and lake change, is a one-way consideration, rarely pay attention to the impact of river and lake water system changes on human society, in fact, river and lake water system changes are often two-way, the first author of this article has been involved in this. Zhang Ling's Rivers, Plains, regimes: An Environmental Drama in Northern Song China is a comprehensive and in-depth study of the changes in the Yellow River and its effects, telling the intricate story of the Yellow River, the Hebei Plain, and the Northern Song government that took place between 1048 and 1128. Two English books published at the same time to study the changes and governance of the Yellow River in the historical period from the perspective of environmental history are also worth learning. In addition, there is another perspective of environmental history, which focuses on the dramatic changes that humans have brought to rivers with the advancement of science and technology. In Organic Machines, White takes a fresh look at the Columbia River and its relationship to human history. The reason for calling a river a machine is that the river is no longer a natural flowing river on its own riverbed, but is divided and distributed according to different uses, so it becomes an organic machine, an energy system, and a part of the artificial product, and people have largely reorganized the natural space of the river. The relationship between today's human society and rivers and lakes has undergone tremendous changes compared with the historical period, which needs our attention and thinking.
Fourth, strengthen the training of relevant researchers. Compared with other sub-disciplines of historical geography, in recent years, there have been few practitioners and weak research strength in the study of the changes of river and lake water systems. This phenomenon has been paid attention to by relevant experts, and on many occasions, it has been proposed that historical geography needs to "walk on two legs" of humanities and nature, so that historical geography can be better developed. The study of river and lake system change is one of the core issues that need to be solved in historical and physical geography, and I hope that more young scholars will join this field.
It can be seen from the above that the change of rivers and lakes is a discipline that has been applied through the ages, and the research of scholars of previous generations is mostly carried out in response to the needs of national economic construction, and our research should also be the same, to find problems in reality, and to find the wisdom and enlightenment of predecessors from history. Actively cooperate with water conservancy departments, planning departments and relevant units, strengthen field investigations, and give full play to the practical value of research.
The author, Han Zhaoqing, is a professor at the Research Center for Historical Geography of Fudan University, and Wei Kai is a doctoral candidate at the Research Center for Historical Geography of Fudan University
Comments from omitted, the full version please refer to the original text.
Editor: Xiang Yu
Proofreader: Water Life
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![Yang Shoujing and his great work "Water Commentary"[fig]](data:image/gif;base64,R0lGODlhAQABAIAAAP///wAAACwAAAAAAQABAAACAkQBADs=)