Roadmap toward Effective Flood hazard Mapping in China

Concluding Report For
JICA region-focused training course on flood hazard mapping
Oct. 31~ Dec. 3 2005

Prepared by Luo Xiaoqing
Engineer, Office of State Flood Control and Drought Relief Headquarters
People’s Republic of China
Nov. 28, 2005

1. The role of flood hazard map to mitigate flood damages in China
1.1 Current flood situation in China
China is endowed with about 50,000 rivers, including 1,600 rivers with water basinlarger than 1,000 km2 each. The topography of China is characterized by high west part and low
east part, gradually descending in elevation from the west towards the east to form three steps. The
main river systems consist of seven major rivers, the Yangtze, Yellow, Pearl, Haihe, Huaihe,
Liaohe and Songhua rivers. Most rivers, including seven major rivers, flow from west to east,
directly or indirectly emptying into the Pacific Ocean. And the total annual average runoff isabout 2,800 billion m3.
China is subject to strong monsoon climate and most of the areas are under the impacts of thesoutheastern and southwestern monsoons. The average annual precipitation in China is 648 mm.

About 70% of annual rainfall is concentrated in the flood season lasting from June to
September in most area. The floods have the characteristic of high peak discharge and greatamount of flood volume. The water volume of one large flood may account for the annual
runoff of the river. The extremely uneven temporal and spatial distribution of precipitation
and river runoff constitute the fundamental cause of frequent floods and waterlogging inflood season.
Floods occurred frequently in China. According to statistics, in the past two thousand
years, nearly one thousand comparable large floods have occurred altogether, and one flood
disaster occurred in two years in average. During the 1990s, six out of 10 years witnessed
major floods taking place in the major river basins. In some areas, floods occur every year.
On average, there are seven typhoons that land on the mainland of China every year.
Torrential rains also cause mudflow and landslide problems. The total flood-prone areas areabout 1.06 million km2, nearly 11 percent of Chinese territory. In these areas there is a
population of 840 million people, and GDP is about 6562.8 billion RMB. These areas are
the major regions of Chinese social and economic activities.

Serious flood-prone area
Flash flood-prone area
Other area

Figure 1 Regions of different flood hazard1

In 1990s, annual economic losses caused by floods accounted for 1.7% of GDP. But indeveloped countries the flood damage rate to GDP is less than 0.5%. In 2005, up to October,
16.26 million hectares of farmlands were affected by flood and waterlogging, 212 million
people affected, 1404 people killed in flood and sediment disasters, and the direct economic
losses 160.7 billion RMB. Zhejiang, Fujian, Hainan, Guangxi, Sichuan, Anhui, Jiangxi,
Liaoning provicnes heavily suffered from flood disasters. Generally speaking, the loss fromflood and waterlogging disasters in 2005 was serious as compared with those in recent
years.
Affected persons by floods in 1992-2002

Economic losses by floods in 1990-2002

300

300.0

215

255.1

200

192

201
181

174

economic loss (billion RMB)

affected person (million)

267
250
186
152
150

130

129
110

100
50
0

250.0

220.8

200.0

179.7

165.3

150.0
93.0

100.0
50.0

77.9

93.0
71.2

64.2

83.8
62.3

41.3
23.9

0.0

1992

1993

1994

1995

1996

1997

1998

1999

2000

2001

2002

1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002

year

year

Figure 2 Flood losses of China in 1990-2002

The injury, death and property losses caused by floods, landslide and mudflow, rank thefirst among all natural disasters in China. Floods seriously threaten the social and economic
development. As a significant strategic issue, flood control and flood security attract highattention all over the country.
1.2 Outline of present countermeasures for mitigating flood damages in China
In the late 20th century, the floods in the Yangtze, Nenjiang and Songhuajiang rivers in1998 were the most serious natural disasters. China made great efforts to implement the
project to prevent floods. In China the flood control systems are composed of structural andnon-structural measures. Combined these measures, the main goal of flood management isprevention of casualties and reduction of economic losses to the least.
Structural measures are aimed at releasing, detaining, confining, diverting and storing
floodwater, to reduce the frequency and magnitude of flooding. Flood control facilities
construction in the river basin is the basic way to mitigate flood risk and damage. Thesefacilities include reservoirs, embankments, food detention areas, pumping stations, etc.
Reservoirs were constructed in upstream areas to store floodwaters and decrease flood peak,
to reduce flood magnitude. Levees and embankments along the rivers were constructed toconfine extents of inundation. Flood detention areas, for temporary storage of floodwaters
to control discharge to downstream, were built up in the lower rivers.
With the effort of fifty years, the comparable integrated flood and waterlogging
mitigation system, which can control normal flood disasters, had been accomplished. It canbe summarized as follows: about 246-thousand kilometers levees and embankments
constructed; more than 860-thousand reservoirs with a total storage capacity more than
475.1-billion cubic meters; 98 national specified flood detention areas with total capacity
near 100-billion cubic meters. According to incompletion statistics, the flood prevention
system that has been built has reduced losses of 1,500 billion RMB from floods.
Up to now, the key flood control projects were constructed up in seven major rivers in
China. The Xiaolangdi reservoir located at the lower Yellow River commenced its
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operation in 2000, to control floods and reduce aggradation rate in the lower Yellow River.
Three Gorges Project is under construction, it will be completed in 2009. In Huaihe River,
Linhuaigang hydraulic complex project will be completed soon, which will improve theflood control standard in the middle reach of Huaihe River to 100-year flood.
Non-structural measures play a very important role in China. These methods include
legal and institutional system, recovery of floodplain storage, flood forecasting andtelecommunication system, flood emergency planning and response, and post-flood
recovery, etc. These activities directly modify the vulnerability of communities exposed toflood risk.
Till now, China has set up a series of flood control legal and institutional system. FloodControl Law was adopted on August. 29 1997, and came into force on January.1 1998.
According to the law, all units and individuals shall have the obligations to protect flood
control works and to take part in flood control and flood fighting. The administrative headsof people's governments at all levels have the obligation to assume overall responsibility for
the work of flood control, this is the basic rule in Chinese flood management. So the local
government, such as province, city and county, should be in charge of flood facilities
construction and flood fighting. And central government and Ministry of Water Resources
provide capital and technical support separately to the local government. Defense planningfor the Seven Large Rivers are compiled by State Flood Control and Drought Relief
Headquarters, which comprise the operation principle of flood facilities and the floodfighting obligation of local government concerned.
Recovery of floodplain storage in river systems is also used to increase flood storage
capacity. After 1998 flood of Yangtze River, farmlands around the Poyang Lake andDongting Lake, the two largest lakes in middle stream of Yangtze river, are returned torecover lakes and rivers, 2.42 million affected populations were resettled to nearby places,
water area of 2900 km2 was recovered and flood storage capacity of 13 billion cubic
kilometers was increased.
Flood forecasting is another non-structure measure widely used in China. Hydrologicalinformation system can collect and disseminate hydrological information promptly, andmake hydrological forecasting. The real-time rainfall and flood information of the nationalhydrological stations can be collected within 30 minutes, and forecasting results can beobtained within 1 hour. The hydrological information is the most important data forflood-decision. Research is ongoing to maintain and improve technical capabilities.
In addition, China has formulated a compensation policy for the local people living
inside flood detention areas since 2000. Central and local governments share the expenses
on personal property and crop loss compensation due to flood detention in the national
flood detention areas. In the past five years, ten flood detention areas were utilized tostorage floods, nearly 200 million RMB capitals were compensated for the affected
residents.
In 1998, extraordinary severe floods occurred in the Yangtze River basin. Flood-control
system construction for rivers is oriented towards harmonious coexistence between man
and nature. In other words, floods should be provided a way out, and thoughts should be
gradually transformed from endless disorderly struggle for land between man and water toorderly and sustainable harmony between man and flood. A new flood thoughts, transferfrom the flood control to flood management, has been brought forward since 2003. So In
the process of flood management, flood, drought and water shortage issues are considered
concurrently, firstly to ensure the flood safety, and utilize the flood source to mitigate water
shortage.
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1.3 The function of flood hazard maps in China
Since flooding is a natural phenomenon, it’s impossible to prevent flood disasters
completely. Although structural measures can control the target floods, in a case where
floods exceed target level, the structure measures still could not prevent the occurrence offlood damage. So there is a need for non-structure measure to cope with the floods thatexceed the target level, and flood hazard map is a good example of such non-structural
measures. In China, flood hazard maps are developed as a multiple-purpose project,
expected to achieve several goals.
First goal is to enhance awareness of flood disaster prevention of the nation.
“Becoming aware is the step towards preparation”. When floods occur, disaster mitigation
not only relies on the government activities, but also community and self-help. In areas
where flooding has been decreased by flood control facilities, or not suffered from flooding
in recent years, the residents tempt to be too optimistic and believe there is no flood danger
in the area. It’s very necessary to offer flood disaster mitigation education to the public.
From flood hazard map, it can awake residents that they still live in the flood-prone area,
and the public can obtain effective flood and evacuation information, so it impels residents
to think for themselves, bearing in mind the danger of flood damage and to prepare
beforehand. As a result, in the emergency of flooding, residents can evacuate in time andreduce the damage loss by themselves.
Secondly, flood hazard map can serve for the flood control and flood fighting
decision-making at all levels of Flood Control Headquarters (FCH). In the process ofcompiling flood hazard maps, such as examining disasters or gathering various kinds ofinformation, FCH can collect more information about flood inundation, acquire experienceon how to evacuate residents promptly, enable prompt administration of action on theoccasion of the actual flood. And also flood hazard map can be used to offer basic data forassessing flood losses. In the emergency of flooding, important information, such asprevious inundation area, affected people, economic loss, can be estimated in advance, so
FCH can determine how to operate flood control facilities, such as reservoirs, flood
detention areas, and issue evacuation order in time.
Thirdly, flood hazard map can direct the land use plan and construction of safety
facilities in the flood detention areas. Flood hazard maps provide a principle for land use
plan. In the presumed deep inundation area, it’s restricted to develop industry immoderately,otherwise these factories should construct self-guard flood control facilities to ensure safety.
And the flood hazard maps can provide reference for land use plan, such as which area issuited for agriculture, industry, entertainment, wetland, etc. There are many people living
inside 98 flood diversion and detention areas in China. In order to safeguard their lives atflooding times, live-saving facilities have been constructed, and flood hazard map can
provide choose visual and reasonable way and place for evacuating people in emergency.
Finally, using flood hazard maps, flood damage can be reduced by the accurate
information and usual countermeasures. The residents know how to get flood information
and where, when, how to evacuate, it can shorten evacuation time effectively. Lives will besaved by early escape.
Recently, Office of Flood Control and Drought Relief Headquarters conduct a pilot
work to produce flood hazard maps, as a non-structural measure to mitigate the flood
hazard.
2. The allocation of roles in making flood hazard maps in China

42.1 Responsibility for making flood anticipated inundation maps (flood risk maps)
The Ministry of Water Resources (MWR) is the ministry of the State Council that is
responsible for water administration. One of main responsibilities of MWR is in charge ofplanning, construction and management of flood control measures. Office of State FloodControl and Drought Relief Headquarters (OSFCDRH) is the special department in chargeof national flood affairs in MWR, and also to take the daily work for its Headquarters.
Bureau of Hydrology (BOH) is another department of MWR, which provides hydrological,
precipitation information and technical support for OSFCDRH.
In China, seven major rivers flow different provinces, in order to coordinate andconduct water-related affairs, River Basin Water Resources Commissions (RBWRC) for the
Yellow River, Yangtze River, Hai River, Huai River, Pearl River, SongLiao River and Taihu
Lake, have been established. Specific functions for water management and flood protection,such as drafting out flood control planning for major rivers, are implemented through thesecommissions. For the convenient flood management of river basins, the Yangtze, Yellow,
Huaihe and Songhua River have separately established a basin-wide flood control
organization, which is under the leadership of SFCDRH. Flood Control and Drought Relief
Headquarters at local levels are in charge of flood emergency response affairs at the river
basin or the local level.
In my opinion, MWR, OSFCDRH, BOH and RBWRC should take the responsibility
for make anticipated inundation area maps of seven major rivers. These institutions havecollected the flood disaster information of these rivers, and also are familiar to the flood
control planning and facilities. So they can calculate and simulate the inundation area anddepths, compile the record and anticipated inundation maps and provide these maps to therespective provincial governments. Provincial Bureau of water resources, and Office ofProvincial Flood Control Headquarters are in charge of other rivers flood inundation maps
in the jurisdiction. China Institute of Water Resources and Hydropower Research will also
play an important role on technical support for the flood inundation and hazard maps.
Flood anticipated inundation maps are mainly used by officials and technicians
concerned and provide basic datum and flood information.
MWR

Publication

Guideline
and Criterion

OSFCDRH
Technical
supportHydrologicalinformation

BOH

RBRWC

IWHR

Compilation

Figure 3. Flowchart of compiling flood anticipated inundation maps of seven major rivers
MWR — Ministry of Water Resources
OSFCDRH — Office of State Flood Control and Drought Relief Headquarters
RBWRC — River Basin Water Resources Commission
BOH — Bureau of Hydrology

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IWHR — China Institute of Water Resources and Hydropower Research

2.2 Responsibility for making and disseminating flood hazard maps
In China, governors of local governments, such as province, city and county, arestipulated as the executive official in charge of the local disaster prevention and floodfighting. So the local governments are authorized to issue evacuation orders and supply
accommodation for the affected residents. Local governments are familiar to the residents’
distribution and topography of its jurisdiction. So it’s the local government responsibility tomake and disseminate flood hazard maps. Flood hazard map are aimed at the public livingin the flood prone areas, to prevent casualties by providing residents with flooding andevacuation information a easy-understanding way.
In detail, Bureau of water resources and Office of Flood Control Headquarters of thelocal government bear the concrete works, in close cooperation with the local residents,
qualified experts, non-governmental organizations and other pertinent bodies.
Province
City
CountyLocal Government

Publication
Dissemination
Organize
Provide information
etc.

BWR/OFCH
Technical
Consultation

Advice and
Suggestion

Residents

Research Institution

Experts

Compilation

Figure 4. Flowchart of compiling flood hazard maps of administrative jurisdiction
BWR — Bureau of Water Resources of local government
OFCH — Office of Flood Control Headquarter of local government

3. The Action plan of making flood hazard maps in China
3.1 Target river basin areas for flood hazard maps
In my opinion, there are three principles to select the target river basin areas. Firstly,
floods occurred in the river in the past years, and some area was submerged, so it’s urgently
essential to produce flood hazard maps to evacuate residents and reduce loss in emergencyof flooding. Secondly, current flood control standard of this area is low and probability offlooding is more frequent. So if flooding occurring, the effectiveness of flood hazard map
can be demonstrated in the recent years. Thirdly, the target area is relative with our daily
work. Because my division is in charge of Huaihe and Pearl River flood management,
different types of target areas are selected from these two rivers. According to my pastexperience of flood management, I plan to choose mengwa flood detention area to produce
the flood hazard maps, and Li river and Wuzhou city as optional targets.
(1) Mengwa Flood detention area
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In July. 2003, Mengwa flood detention area, which is located on the north bank of
middle Huaihe River, Anhui Province, was utilized to storage floodwater. Nearly 200,000
people have been evacuated to the earth platforms and embankment village polders. During
the past 52 years following, this area has been used 12 times in ten years.

Figure 5.Mengwa flood detention inundated in July. 2003

After the flood disaster map completed, we’ll disseminate to every household. Whenflooding, if the flood detention area is determined to utilize, the local government issues
order to organize residents to evacuate to designed shelters involved in flood hazard maps.
It can shorten evacuation time, ensuring life safety. Local government can assess theinundation extent and damage beforehand, and promptly carry out damage prevention plan.
Residents are aroused to adjust plant category to reduce crop losses according toanticipated inundation duration and depth, such as appropriate places to plant grain,
vegetables or fruit.
(2) Li River Basin

In July, 2004, severe flood occurred in
Li River, a tributary of Huaihe River, Henan
Province. For the floods has exceed thedesigned flood control standard of levees,
nine sites on the embankment were broken.
The flood submerged some farmlands, andnearly 20 thousand people were affected.
The embankment of Li River only can
defend the target flood which occurs once in
10 years. So the flooding is frequent in thisarea.
Figure 6 Levee break on Li River in July, 2004
(3) Wuzhou City

Wuzhou city is located on north bank of West River, a tributary of Pearl River, Guangxi
Province. It is the national important flood control city. In June, 2005, heavy floods withoccurrence over 100 years hit Wuzhou city. Since east district of Wuzhou only reaches to
10-year flood control standard, inevitably floods overtopped the top of levees, and nealy
2~3 km2 area was inundation. West district of Wuzhou the flood standard is 50-year, but theflood level still reached the top of wave-proofing walls. Through sub-embankment
construction with sandbags, inundation of west district was successfully avoided. About
200 thousand residents were evacuated to the safe places.

7Figure 7. Inundated east district of Wuzhou City (left) and the urgent crisis of west district (right)

3.2 Thoughts of making flood hazard maps in the chosen area
I have collected some datum of these three areas, such as topographical map. But thework of producing flood hazard maps should be done by office of municipal flood control
headquarters concerned. I plan to impel Guangxi, Anhui, Henan office of flood control
headquarters to develop this work, provide capital budget.
And also I will strive for financial support from the fund of flood control works
maintenance and construction. My role is to organize, promote this work, and can also offer
technical support and experience obtained from Japanese flood hazard maps.
3.3 My action plan within the next five years
Now, China is formulating the Eleventh Five-year Plan of water-related affairs. Floodmitigation is one important part in the plan, the primary Eleventh Five-year Plan of flood
mitigation contains the context of setting up the flood risk maps of the seven largest rivers,
and producing the flood hazard maps in partly important flood prone areas.
So my plan is corresponding with Eleventh Five-year Plan of flood mitigation. There
are two stages in the process of producing flood hazard maps, first stage is to compile theflood risk maps of seven largest rivers, and second stage is to compile flood hazard maps on
basis of flood risk maps. The following is a draft of my action plan: Nov. 2005
Report to my office.
Introduction of history, procedure, method, effectiveness, practice, etc ofJapanese flood hazard maps.
Bring forward target areas, to acquire the approval and support of my office.
 Jan. ~ Jun. 2006
Produce record flood maps
Cooperate with related provinces office of flood control headquarters.
Choose research institutions.
Collect past floods information, topography data, flood damage, etc.
Compile history inundation maps
 July. ~ Dec. 2006
Produce flood risk maps
Through hydraulic calculation and simulation, estimate the anticipatedinundation areas (such as extent of inundation, water depth, flow rate, arrival
timing etc.)
Compile flood risk area
 Jan. ~ April. 2007
Produce flood hazard maps
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Calculation population required to evacuate, accommodation provided byshelters.
Formulation of an evacuation plan
Inquire the public suggestion
Compile flood hazard maps
 May. ~ Jun. 2007
Publication and dissemination of flood hazard maps
Approval by the local government
Dissemination
Flood prevention education in schools
 July. 2007~ 2010
Verification and actual application
Survey report and verification the effectiveness of flood hazard maps in theemergency of flooding
Modify and improve the flood hazard maps
I also take charge of related woks about flood hazard maps involved in Eleventh
Five-year Plan.
3.4 Problems of making flood hazard maps in China
According my cognition, there is no unsolvable technical problem in producing flood
hazard maps, but it is time and capital consuming work. The most important things arewhether we can collect detailed datum and develop advanced hydrological numericalcalculation, and also the experience is also indispensable.
There are three problems we may probably encounter in the process of producing flood
hazard maps.
(1) Lack of laws support. Flood Control Law of People’s Republic of China came into
force as of January, 1998, but no such provision about flood risk and hazard maps were
stipulated in the law. So it’s not an obligation for local governments to produce flood
hazard maps, if local governments are lack of enthusiasm or capital, they may not impel
this work.
(2) Large Flood inundation area. Some important embankments of lower major rivers
protect wide lands and many residents, and the flood level is several meters higher than theinland ground level. Residents live sporadic in this area and the transportation is notconvenient, the farthest evacuation routine may exceed 10 km, so the evacuation time will
be very long. In these protective areas, if the levees are broken, large areas and thousands ofresidents will be inundated, how to estimate the inundation area and establish theevacuation plan is a difficult problem. We should estimate the anticipated inundation areaaccording to the volume of flood water discharging from the levee breaks.
(3) Low flood control standard. Because flood control standard of many levees canonly prevent the flood which occurs once in 10 years, in my opinion, 10-year, 20-year,
50-year, 100-year flood, and maximum flood inundation areas should be drawn out in themaps with different colors, so and risk of different flood magnitude can be displayed.
(4) Lack of detail information and experience. Although China Institute of Hydraulicand Hydropower Research is pursuing in the flood risk study, they have taking several pilot
study about flood risk, yet this study has not been demonstrated by actual floods. And
production of flood hazard maps just starts, now there is no flood hazard map completed.
4. Advices and suggestions
I should express my sincere thanks to JICA, TBIC, PWRI and ICHARM. This training
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greatly improves my knowledge of flood hazard maps, and will also benefit flood
management of China in the future. There are two suggestions: If possible, please arrange trainees to visit MLIT, let trainees further get to know thewater-related administrative management in Japan.
 Now PWRI is preparing another training course “Tsunami Disaster Prevention”.
China is one of the countries suffered the heavy cyclones, and we hope to exchange
information and experiences about cyclone and tsunami prevention. We are
expecting JICA, TBIC and PWRI will offer a chance for Chinese participants toattend that course.

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