1 Introduction
The workshop was initiated by Prof. Yu XIAOGAN, Nanjing Institute of Geography and Limnology, Chi- nese Academy of Sciences, and Prof. Volker HEIDT, Geographisches Institut, Universität Mainz and sup- ported by Sino-German Center for Science Promotion (NSFCand DFG), Beijing. Co-organizers and additional sponsors were World Wide Fund for Nature (WWF) and Hunan Water Resource Department.
Experts from various disciplines (geography, ecology, economies, water resources management and sociol- ogy) were brought together to exchange ideas and con- cepts of flood protection, for sustainable land use and on developing wetland ecosystem functions. The work- shop contributions were grouped into five sessions and covered a variety of topics from the Yangtze catchment.
The German contributions focussed on flood protec- tion and integrated concepts for land use (HEIDT, BUCK, QUAST, ROTHER, MEON) along the rivers Rhine, Elbe and Oder and on sociological aspects of large engineering projects (DOMBROWSKI). In addition, stud- ies on high resolution climate data modelling in China B E R I C H T E U N D M I T T E I L U N G E N
R E P O RT O N T H E S I N O - G E R M A N S Y M P O S I U M O N W E T L A N D R E G I O NA L I Z AT I O N O F E C O S YS T E M S E RV I C E S I N T H E YA N G T Z E R I V E R BA S I N
CHANGSHA, HUNAN PROVINCE, PR CHINA, APRIL 10–15, 2005 With 4 figures, 1 table and 3 photos
HARALDZEPP, VOLKERHEIDT, AXELTHOMAS, WERNERBUCKand GÜNTERMEON
The first task in administering a country is to prevent five disasters: flood; drought; wind;
fog and hail; plagues; and fire. Of these, the most serious is flood.1)
Guan Zhong, great political figure of Qi, Spring and Autumn Dynasty (770–476 BC)
Zusammenfassung: Bericht über ein Chinesisch-Deutsches Symposium zum Feuchtgebietsschutz und zur Hochwasservor- sorge am Yangtze, China. Changsha, Hunan Province, China, 10.–15. April 2005
Das chinesisch-deutsche Symposium diente der gegenseitigen Information und dem Erfahrungsaustausch zwischen Wissenschaftlern, Behörden und Vertretern von Nichtregierungsorgansationen über Hochwasserschutz, nachhaltige Land- nutzung und Feuchtgebietsschutz am Mittellauf des Yangtze. Auf einer Exkursion im Anschluss an die Vortragsveranstaltung wurden den Teilnehmern Demonstrationsprojekte gezeigt, die die Flutung zuvor eingedeichter Polder am Dongting-See um- fassen: Qingshan Polder, Xipanshanzhou Polder and Caishanghu National Nature Reserve. Im vorliegenden Tagungsbericht sind die während der Exkursion mitgeteilten Informationen zusammengefasst. Von den deutschen Teilnehmern wurden die Anstrengungen der chinesischen Wissenschaftler, Behörden und NGOs für den Hochwasserschutz gewürdigt. Während die chinesischen Wissenschaftler vor allem die Bedeutung der Öffnung von Polderflächen hervorgehoben haben, um Hochwas- serscheitelabflüsse zu senken, betonten die deutschen Tagungsteilnehmer die Notwendigkeit integrierter Hochwasseraktions- pläne unter Berücksichtigung der verschiedensten ökonomischen Erfordernisse und ökologischen Belange.
Summary:The symposium brought together Chinese and German experts from various disciplines to exchange ideas and concepts of flood protection, for sustainable land use and on developing wetland ecosystem functions in the middle reaches of the Yangtze River. During a post-conference tour the participants were shown key-areas for wetland restoration in the Dongt- ing Lake area: Qingshan Polder, Xipanshanzhou Polder and Caishanghu National Nature Reserve. Additional data provided during the field trip is compiled in this report. The achievements in mitigating flood hazards by a variety of measures were acknowledged. Chinese scientists strongly promoted the idea that flood peaks can significantly be lowered by opening polders and restoring wetlands, whereas their German counterparts stressed the need for integrated flood action planning taking into account various economic and land use needs as well as ecological functions.
1) From SEPA/UNEP/UNHABITAT(2004).
(THOMAS) as well as micro-scale results from hydrolog- ical investigations in SE-China (ZEPP) were presented.
The Chinese scientists and officials reported on wet- land studies (ZHAO, WANGand ZHU, CHANG, WENG, LI
and GAO), flood hazards (XUand WANG), ecosystem services (JIANG, YAN, N. and YU, YAN, B., YU), influ- ences of global change on the upper Yangtze catch- ment area (LU and ZHEN), fishery and ichthyology (CHANGand GU), nature protection (YUand ZHANG) as well as on regional planning (DENG, DUAN, ZHU, CHENand MA).
During a post-conference tour the participants were shown key-areas for wetland regeneration in the Dongting Lake area.
2 Flood protection in the middle Yangtze region
The middle reaches of the Yangtze (Changjiang) River extend from the Three Gorges Dam near Yichang to Juijiang and cover a catchment area of 77,000 km2, including many lakes and tributary rivers (Fig. 1). The extremely low river gradient and the in- flow of numerous tributary rivers contribute to the dan- ger of flooding. Flood disasters are reported to have taken place at least from the first century AD. However, it seems that the floods causing loss of life and consid- erable damage are now happening more frequently than in the past (cf. Tab. 1 and JIANGet al. 2004).
Flood protection of the middle reach has a long tra- dition. The Yangtze River used to inundate many thou- sands of square kilometres almost every year, claiming
the lives of thousands of people. The flood control sys- tem consists of dikes and retention basins. The major flood defence along the river consists of the 3,570 km long grand levees north and south of the river, but of equal importance are the more than 30,000 km of lev- ees along the tributaries, riparian lakes and canals, and on a local scale, protective walls built by municipalities.
Retention basins also play an important role in the flood protection system. Their purpose is to protect the grand levees, whose breach would cause damage be- cause they protect the 126,000 km2plain on which 75 million people are dwelling and many industrial hubs such as Wuhan, Nanjing and Shanghai are located there (WANGa. PLATE2002).
The Dongting and Poyang Lakes play important roles in reducing crest flood discharge of the Yangtze River. Dongting Lake (Fig. 2) used to be China’s largest freshwater lake. During the younger earth’s history the lake was dammed by the alluvial sediments of the Yangtze River in the north of the basin area.
The Yangtze River supplies the largest portion of the total inflow into Dongting Lake through the Songzi, Taiping and Ouchi channels. An additional four rivers (Xiangjiang, Zijiang, Yuangjiang and Lishui) contribute to the lake waters entering the lake from the southwest and south. The total lake area during summer floods was reported to cover an area of 7,000 km2 in the middle of the 20thcentury, while during winter time the open water surface is restricted to comparably narrow channels.
In 1952 the lake was enlarged by a flood retention basin with 52 sluices at its northern and 32 sluices at its
Fig. 1: The Yangtze River (Jangtsekiang), its tributaries and riparian lakes (source: WANGa. PLATE2002) Der Yangtze (Jangtsekiang), seine Zuflüsse und Seeflächen (Quelle: WANGa. PLATE2002)
southern edge. “The mean annual runoff volume of the Dongting Lake is estimated at 301.8 billion m3with the flood waters discharging into the Yangtze River via Yueyang. The mean annual sediment yield into the lake is estimated at 129 million m3and an average of 100 million m3silts up in the lake every year” (HYDRO AND POWER DEPARTMENT OF HUNAN PROVINCIAL GOVERNMENT 1996, 1). Figure 2 shows the maxi- mum discharges of Dongting Lake’s major inlets and outlets.
Wetland reclamation and sedimentation led to a con- stant decrease of the lake’s area: 1825: 6,250 km2, 1935: 4,700 km2,1949: 4,350 km2, 1954: 3,915 km2, 1958: 3,141 km2, 1998: 2,623 km2 (WWF 2005b, cf.
Fig. 3). Since the 1950s Dongting Lake ranks only sec- ond in size following Poyang Lake in the neighbouring province of Jiangxi. In terms of water volume it is still the largest freshwater body in China. Since 1949 large scale construction (dikes, wetland drainage and recla- mation) have led to a total dike length of 5,812 km, dikes including 3,471 km along the Yangtze and other rivers for flood protection and 1,509 km along the floodways. The total installed electric irrigation and drainage pumping capacity amounted to 600 MW (HYDRO AND POWER DEPARTMENT OF HUNAN PROVINCIAL GOVERNMENT1996).
In 1998 an extreme flood occurred on the Yangtze River, which resulted in serious flood damage and Table 1: Flood disasters in Dongting Lake region
(source:HYDRO AND POWER DEPARTMENT OF HUNAN PROVINCIAL GOVERNMENT1996) Hochwasserkatastrophen im Gebiet des Dongting-Sees
(Quelle:HYDRO AND POWER DEPARTMENT OF HUNAN PROVINCIAL GOVERNMENT1996)
Flood disaster Waterlogging disaster
year Affected farmland Direct economic Affected farmland Direct economic (104 MU*) losses (108 RMB) (104 MU) losses (108 RMB)
1949 172.4 0.54 325.8 1.40
1952 48.1 0.76 162.6 0.71
1954 385.0 18.17 514.2 2.86
1964 25.1 0.71 355.8 2.93
1965 22.9 2.15 101.0 0.62
1979 19.5 1.72 119.6 0.81
1980 38.6 1.17 307.6 7.61
1983 28.8 1.63 332.5 7.19
1988 22.5 0.99 522 6.79
1991 2.9 0.65 688 2.87
1949–1991 total 971.3 32.13 8054.7 65.09
* 15 Chinese mu equal 1 ha
71100 The Changjiang River
78800
57900
1 1970
1030 Songzi River 3210 Hudu River 19610 Ouchi River
Xiangjiang R. 20300 East Dongting
Lake Yichang
Shashi City JianLi
Luoshan
Chenglinji
Yueyang
Changsha
Xiangtan Taojiang
Yiyang TaoyuanChangde
Jinshi Shimen
Songzi
Notch Taiping
Notch Ouchi Diaoguan
17600 Lishui River
29000 Yuanshui River
15300 Zishui R.
South Dongting Lake West Dongting Lake
Fig. 2: Dongting Lake river system: mean annual through- flows (m3/s) (source: HYDRO AND POWER DEPART- MENT OF HUNAN PROVINCIAL GOVERNMENT1996, 4, modified)
Gewässersystem des Dongting-Sees: mittlere Jahresdurch- flüsse (Quelle: HYDRO AND POWER DEPARTMENT OF HUNAN PROVINCIAL GOVERNMENT1996, 4, ver- ändert)
affected 8 million people. The return period of the flood was about 100 years in terms of flood volume.
The flood stages in the middle reaches of the river were even higher than those in 1954 although the flood crest discharge was smaller.
The capacity of the Dongting and Poyang Lakes, lakes to reduce the crest flood discharge, was much smaller than in 1954, and heavy rainfall in the lake watersheds caused high water levels in the lakes and
reduced the retention capacity for Yangtze floodwater.
The two lakes retained 65 billion m3 of water and reduced the peak discharges in the river by 28–56%.
In the middle and lower reaches of the river and in the area of the two lakes, dikes of 1,075 polders were broken and 321,000 ha of land were inundated, of which 197,000 ha were farmland (WANG a. PLATE 2002).
The main reasons for the high flood levels are the
Fig. 3: Dongting Lake: reduction of lake area between 1825 and 1958 (source:WWF2005 b, modified) Dongting-See: Verkleinerung der Seefläche zwischen 1825 and 1958 (Quelle:WWF2005 b, verändert)
much smaller areas available for inundation. In 1954 the total diversion of flood volume to detention basins and through levee breaches was 102.3 billion m3. In 1998 only about 10 billion m3were retained on flood- plains, partly because of fewer levee breaches. Also, the regulating function of the Dongting and Poyang Lakes was much reduced. In the past 40 years sediment deposition and reclamation in the riparian lakes have reduced the lake area, so that in comparison with con- ditions in 1954 the volume of the Dongting Lake in 1998 was reduced by 10.1 billion m3. The flood prob- lem was aggravated by silting up of the river channel.
The 1998 flood has given reason to rethink the strat- egy of flood control of the river. The new strategy rests on the following actions: construction of the Three Gorges reservoir; reinforcing and increasing the height of the levees; conversion of some polders back into river channels ; increasing the size of Dongting Lake by returning farmland to the lake area to increase its flood detention capacity; dredging the main channel of the river; relocating people from flood detention polders;
reclamation and reforestation in the upper reaches of the catchment area (WANG a. PLATE 2002;SEPA/
UNEP/UNHABITAT2004; ZENGet al. 2002). Follow- ing the flooding of polder areas wetland reclamation programmes have been assisted by WWFChina.
3 Wetland restoration projects
On a post-conference field trip the participants were shown key localities of wetland restoration projects around Dongting Lake. The central Yangtze region is one of 200 eco-regions worldwide as identified by WWF. It includes two Ramsar sites (Fig. 4) of wetland ecosystems with international significance (WWF2005a).
Xipanshanzhou Polder has an area of 110 ha with a population of 580, established in 1972: “Flooding oc- curred three times between 1996 and 1999 and people suffered significant property losses. After the launch of WWF Yangtze Programme in 1999, Xipanshanzhou Polder was chosen as a pilot site for wetland restoration.
The farmers moved to higher ground and allow the floodwater to flow into the polder. Four years passed, and people wasted no time in building dikes and resist- ing flood. They have learned to breed aquatics” (WWF 2005b, 2).
Qingshan Polder in the Western Dongting Lake cov- ers an area of 30,000 ha and is managed by the WWF as a nature protection area. The former polder had been established in 1976 and 5,021 people were settled thereafter. Repeated floods caused severe damage, and after the disastrous floods in 1996 and 1998 the inhab- itants, mostly farmers, were resettled in safer neigh-
Photo 1: Qingshan Polder: Concrete buildings are the remains of the former village. Brick-stone buildings were deconstructed prior to flooding (Photo:BUCK2005)
Qingshan Polder: Die Betonbauten sind die Überreste des ehemaligen Dorfes. Aus Ziegelsteinen errichtete Gebäude wur- den vor der Flutung abgetragen
bouring areas. The WWFpromotes the idea of a land use concept with different primary functions of the for- mer polder area. 30,000 primarily migratory birds have found their way back to an area where they had not been sighted for many years. “In 2003 West Dongting Nature Reserve started to consider co-management with local communities and dialogue between the two parties is focussed on bilateral benefits. An agreement
was reached on wetland conservation and a sustainable use plan by the two sides. In the plan spawning areas for fish and water bird habitat were strictly sited, and except for the official fish-banning period April 1 – June 30, an additional fish-banning period for wintering birds has been set. From the end of 2003 to the begin- ning of 2004, altogether 180 families participated in the Co-management Association and a Commission of
Photo 2: Qingshan Polder: Water Bird Habitat (Photo:BUCK2005) Qingshan Polder: Wasservögel-Habitat
Photo 3: Dwelling mound in the vicinity of Junshan islet (Photo:BUCK2005) Warft in der Umgebung des Junshan Insel
Co-management is formed, composed of 7 members including fisherman, NGOs and local Government officers” (WWF2005a, 3).
In the Eastern Dongting Lake area the Caishanghu National Nature Reserve was visited. Here a monitoring station was set up on the dike to monitor the populations of migratory birds. The dike has a height of 36.3 m a.s.l.
and is designed to withstand a flood with a recurrence
interval of 10 years. Smaller dikes with heights of 34 m a.s.l. offer less safety and thus do not fully protect agri- cultural fields and dwellings. Between the Caishanghu National Nature Reserve and the newly built bridge across the northeastern Dongting Lake to Yueyang, large fields belong to state farms. They stand in contrast to the small fields of individual farmers and their fami- lies that prevail in the lake region.
Fig. 4: Dongting Lake: polders, some wetland restoration sites and National Nature Reserve Caishanghu (source:WWF2005 a, modified and supplemented)
Dongting-See: Polderflächen, Lage von Feucht- und Naturreservaten (Quelle:WWF2005 a, verändert und ergänzt)
Datong Lake
Changsha Wangeli Lixian River
Lake, river Polder
Town, village Changde
Xiangjin Xiangjin Xiangjin
Yuanjiang YangtzeR
iver
Hanshou Yuanyang
Yiyang Taojiang
Shishou
Linli
Jingshi Lixian
Gongle Gongle Gongle
Shasi
Yueyau Yueyau Yueyau East
Dongting Lake
South Dongting Lake Nuping
Lake
Nanpichong River
River 3
1
2
Polder for flood defense Dyke
Provincial border Lake, temporary dry
Highway, road
Pilot sites:
Xipanshanzhou Polder Quingshan Polder Caishanghu Nature Reserve3
2 1
In the vicinity of the polder the Junshan islet is fa- mous for its green tea. Every year during flood periods the island (0.96 km2, maximum height 55 m above the lake level) is surrounded by the lake waters covering the marsh lands. Artificial earth hills rise as safety platforms within the marsh land in the foreland of the large dikes.
They are important structures to reduce the risks for human life and properties. As an interesting cross-cul- tural convergence they resemble the dwelling mounds on the Friesian coast of northern Germany.
4 Conclusions
The German group was impressed by the huge chal- lenge the Chinese society has to face in terms of flood protection. The achievements of Chinese scientists and the administration in mitigating flood hazards by a variety of measures was acknowledged. Chinese scien- tists strongly promoted the idea that flood peaks can be significantly lowered by opening polders and restoring wetlands. German counterparts stressed the need for
integrated flood action planning taking into account various economic and land use needs as well as ecolog- ical functions. The complexity of flood protection for sustainable development in the middle reaches of Yangtze River is so immense that the short visit could not by far illuminate all aspects of the problem. It is obvious that further research and investigation is needed and organizational structures adapted to the regional requirements have to be developed. In the future the effects of the Three Gorges Dam and of the river diversion to North China on discharge and mat- ter flux (solid matter and solutes) have to be studied thoroughly. The German participants were impressed by the openness of the Chinese colleagues from the fields of science and administration to discuss details of water quality issues and the public discussion and con- troversy concerning large water engineering measures.
A complementary workshop in Germany is planned to introduce the Chinese colleagues to the German handling of similar challenges and to continue dis- cussions, which are expected to evolve into future co- operation projects.
References
HYDRO AND POWER DEPARTMENT OF HUNAN PROVIN- CIAL GOVERNMENT(1996): Dongting Lake (= informa- tion brochure). Changsha.
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(= information brochure). S. l.
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