Action plan toward effective flood hazard mappingin China

Concluding Report For
JICA region-focused training course on flood hazard mapping
Oct. 29~ Dec. 2 2006

Prepared by Xu Jing
Engineer, Office of State Flood Control and Drought Relief
Headquarters
People’s Republic of China
Nov. 28, 2006

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1.The role of flood hazard maps to mitigate flood damages in China
1.1The flood status in China.
Geography and meteorology.
The topography of China is characterized by high west part and low east part, graduallydescending in elevation from the west towards the east to form three steps. China isendowed with about 50,000 rivers, including 1,600 rivers with water basin larger than
1,000 km2 each. The main river systems consist of seven major rivers, the Yangtze,
Yellow, Pearl, Hai, Huai and Song Liao 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 is about 2,800 billion m3.
Table 1 Characteristics of seven main rivers in China.
Annual Average ValueRiver

DrainageArea(104km2)River
Length(km)

Annual Runoff(109m2)Depth of
Annual Runoff(mm)

Annual Average
Discharge(m3/s)

Yangtze R.

180.85

6300

975.5

539

30933

Yellow R.

75.24

5464

56.3

75

1785

Huaihe R.

26.93

1000

61.1

227

1937

Haihe R.

26.36

1090

22.8

86

723

Pearl R.

45.37

2214

336.0

741

10654

Songhua R.

55.72

2308

74.2

133

2353

Liaohe R.

22.90

1390

14.8

65

469

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 peakdischarge and great amount of flood volume. The water volume of one large flood
may account for the annual runoff of the river. The extremely uneven temporal andspatial distribution of precipitation and river runoff constitute the fundamental causeof frequent floods and waterlogging in flood 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 themainland of China every year. Torrential rains also cause mudflow and landslide
problems. The total flood-prone areas are about 1.06 million km2, nearly 11 percent ofChinese 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 andeconomic activities. The characteristics of the seven main rivers are given bellow.
The flood hazard damage is serious. In various hazard, flood hazard is one of themost serious one. From 1996 to 2005, the total casualties due to flood hazard areabout 24,540 persons. That means 2400 to 2500 persons died of flood hazard per year.
2The average economic is also serious with an average number of 125 billion RMB per
year. Damage of each year is given in the bellowed table. In 1990s, annual economic
losses caused by floods accounted for 1.7% of GDP. But in developed countries theflood damage rate to GDP is less than 0.5%.
Table 2. Annual flood hazard damage from 1996 to 2005.
year

affected field
4(10^ ha.)affected peoplecausualty

economic loss

(million)(person)(billion RMB)

1996

2039

267

5840

220

1997

1313

181

2799

93

1998

2229

186

4150

255

1999

961

130

1896

93

2000

905

129

1942

71

2001

714

110

1605

62

2002

1238

152

1819

84

2003

2037

226

1551

130

2004

778

107

1282

71

2005

1497

200

1660

166

average

1371

169

2454

125

One important thing must be illustrated here is that the flood hazard damage
mentioned above include damages caused by flood of main river, land slide, mudflow
and typhoon. The injury, death and property losses caused by floods, landslide andmudflow, rank the first 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 high attention all over the country.
1.2The outline of the present countermeasures for mitigating flood damages in
China
Present countermeasures for mitigating flood damages in China can be divided into
two main groups. One is to construct flood control system which is composed ofstructural and nonstructural measures. The other is to restrain people’s action under
the concepts of integrated water resources management and integrated flood risk
management.
The flood control system can be summarized as follow:
Construct flood control works in main river systems. Flood control dams,
reservoirs, levees, detention basins, flood division ways, flood control sluices andpumping stations are constructed in main river systems. Structural measures are aimed
at releasing, detaining, confining, diverting and storing floodwater, to reduce thefrequency and magnitude of flooding. Reservoirs were constructed in upstream areas
to store floodwaters and cut flood peak, to reduce flood magnitude so as to relief theflood defending pressure downstream. Levees and embankments along the rivers wereconstructed to confine extents of inundation. Flood detention basins, for temporarystorage of floodwaters to control discharge to downstream, were built up in the lower
rivers. Sluices, water gates and pumping stations are used to discharge water from
retarding area.
3With so many years’ efforts, a comparable integrated flood prevention system has
been constructed. From statistics, about 246-thousand kilometers levees andembankments, more than 860-thousand reservoirs with a total storage capacity morethan 475.1-billion cubic meters, 97 national specified flood detention basins with total
capacity near 100-billion cubic meters have already been accomplished. With thepresent flood prevention system, normal flood can be defended in seven main river
basins. According to incompletion statistics, the flood prevention system that has been
built has reduced losses of 1,500 billion RMB from floods.
Set up non-structural measure system.
Outline on legal and institutional system. Law and institutional system has been set
up to guarantee flood mitigation activities being carried out. As have been introducedin country report, China has set up a series of flood control laws and regulations.
The water law (1998)
The law of flood control (1997). Flood Control Law was adopted on August.
29 1997, and came into force on January.1 1998.
Flood fighting regulation of PRC (1991, revised in 2005)
Regulation on dam safety management (1991)
Provisional compensation regulation for use of flood detention basins (2000)
The guide to safety building of flood storage and detention basins
Regulation of river course management
Framework of normal flood management and emergency management. 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 incharge of planning, construction and management of flood control measures. Office ofState Flood Control and Drought Relief Headquarters (OSFCDRH) is the special
department in charge of national flood affairs in MWR, and also 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 these commissions. For the convenient flood
management of river basins, the Yangtze, Yellow, Huaihe and Songhua River haveseparately established a basin-wide flood control organization, which is under theleadership 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.
Hydrology and meteorology monitoring and reporting stations are constructed toget data in time. Hydrological information system can collect and disseminate4hydrological information promptly, and make hydrological forecasting. The real-time
rainfall and flood information of the national hydrological stations can be collected
within 30 minutes, and forecasting results can be obtained within 1 hour. The
hydrological information is the most important data for flood-decision. Research is
ongoing to maintain and improve technical capabilities.
Flood forecasting is another non-structure measure widely used in China. Modern
technologies such as radars and satellites are used on weather and flood monitoring,
forecasting and assessment. However, modern technologies are not almighty. In somecases, traditional tools are more convenient and practical than radars and satellites. In
the whole procedure of flood reduction, we use radars and satellites for flood
monitoring and forecasting, use television, telephone, mobile phone, newspaper,
broadcasting and internet for flood alerts. Cooperation between the Bureau of
Meteorology of China and the CCTV has been set up to broadcast landslide andmudflow defending warning information whenever it is necessary. In some remoteareas where all modern measures are not available, even firecrackers and alarm gongs
are used to make flood alerts.
Flood defending plans in central, provincial and local levels are made for flood
preparedness and defending.
Under the concept of integrated flood risk management, more efforts are made. Floodissue is considered with the context of water resources and land resources. Giving
flood water more space and do not occupy river or lake spaces which means recoveryof floodplain storage in river systems has been carried out since 1998. Other methods
such like taking good use of flood water to relief the shortage of water resources,using flood water to clean river system in some areas like the downstream of the Huai
river so as to relief the issue of water pollution also are conducted. All those methods
are taken under the concept of integrated flood risk management. After 1998 flood of
Yangtze River, farmlands around the Poyang Lake and Dongting Lake, the two largest
lakes in middle stream of Yangtze river, are returned to recover 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 wasincreased.
1.3Do you think flood hazard maps will be useful in China? Why?
Flood hazard maps are sure to be useful for flood hazard mitigation in China.
Firstly, compared with structural constructions, our non structural methods are still
weak and not so effective. After long period of construction on flood control works,
we need an effective method for more effective flood disaster mitigation. Floodhazard map is a foundation and a useful tool for disaster mitigation. Maybe it can betaken as a breakthrough toward more effective flood disaster mitigation.
Secondly, public awareness on flood risk is not so strong. Their abilities ofself-helping in hazards need to be enhanced greatly.
Thirdly, land use in flood prone area lack guidance according to flood risk. Land use
plan and construction don’t take flood risk into consideration, hence increased thevulnerability to flood risk. Statistics show that, the economic losses due to flood
hazard are increasing.
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Finally, flood hazard map plays an important role in flood hazard mitigation.
Community based flood hazard mapping involves residents’ participants. Their needs,
their opinions are considered with other final users. In the process of user needinvestigation, making and dissemination, local residents’ awareness on flood hazard
are increased greatly. The flood hazard map also provides useful information on
inundation and evacuation. By good understanding and using of flood hazard map,
local resident can take proper method or carry out self-save on the first time whenflood occur. The vulnerability to flood hazard can be decreased sharply. To the sectorof land use planning and management, flood hazard map help them to make thedecision by providing related flood inundation information.
The purpose of making flood hazard in China may be the following:
serve for the flood control and flood fighting decision-making at all levels of
FCH;
enhance the consciousness of flood hazard mitigation of the nation;
direct the constructions of the safety facilities for the flood detention areas,
and to chose reasonable way and place for evacuating people in emergency;
offer basic data for assessing flood losses, and so on.
On the other hand, flood hazard maps are not almighty. It is a supplementary method
for flood hazard mitigation. So other methods must be considered in addition to flood
hazard map. Flood forecasting and warning mechanisms are most crucial. In coastal
areas and mountain areas multi-hazards map should be made for more effective
hazard mitigation. For better understand and usage of flood hazard map, propaganda
to the public and education to school students are necessary.
2.The allocation plan of making flood hazard maps in China
2.1Which organization should hold the main responsibility for making afundamental map such as an anticipated inundation area map?
According to the framework of water resources and flood mitigation management, theministry of water resources will be in charge of the flood hazard mapping. The officeof state flood control and drought relief headquarters will make the needed guideline
and criterion. The bureau of hydrological will be responsible for providinghydrological data. The institution of water resources and hydropower research aresupposed to give technical support. Fundamental map such as anticipated inundation
area map will be made by the IWHR.
The follow framework shows the responsibilities of each unit in flood hazard
mapping.
MWR

Publication

Guideline
and Criterion

OSFCDRH
HydrologicalTechnical

information

support

BOH

RBRWC
6
Compilation

IWHR

Figure 1. Flowchart of making flood hazard maps
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
IWHR — China Institute of Water Resources and Hydropower Research

2.2Which organization should hold the main responsibility for making anddisseminating flood hazard maps?
The framework of SFCH. The office of state flood control and drought relief
headquarters(the OSFCDRH for short) is a key organization that is responsible for the
management of emergency response on flood and drought hazards. The main
responsibilities will be described as to organize nationwide activities of flood control
and drought relief, undertake the day-to-day work of the State Flood Control andDrought Relief Headquarters and carry out unified control of water volume fromwater conservancy and hydropower facilities all over the country following thedirectives of the Headquarters.
Under a new ongoing action plan, the main purpose is to decrease the vulnerability
and the exposure to flood hazard. Flood here is specified as including flash flooding,dam-break floods, main river flooding, urban floods, debris flows and coastal flooding.
The OSFCDRH has the object to make flood hazard map in seven main river systems.
This will be a joint work with related ministries as the ministry of civil affairs,
ministry of construction, ministry of land resources and so on. As an important
foundation and a basic tool, flood hazard map are expected to play an important role.
So the need to make flood hazard map is pressing. The ministry of water resources
will be the administration to promote the task and the OSFCDRH will be in charge ofmaking and disseminating flood hazard maps.
In fact, the OSFCDRH has already done much work on flood hazard mapping. So far,pilot researches in seven main rivers including 36 experimental points have been
carried out. A guideline for flood hazard mapping was also issued last year. The
management system for digital flood hazard maps is under research. The project plan
has been made by the IWHR under the guide of the OSFCDRH. But much work
should be done to promote the developing and plan committee making the decision
since there are so many public affairs need financial support.
3.The action plan of making flood hazard maps in China
According to the project plan, in the next five years flood hazard mapping in sometarget areas will be carried out as schedule. The planned target areas are sure toinclude some important cities which have flood defending tasks and 97 flood
detention areas.
3.1Which area do you choose for the target river basin area? Why?
In my opinion, the middle and down-stream areas of Huai river basin should bechosen as the target area. The Huai river basin is an important agricultural base with
big cities along main river and counties along several important tributaries. The area7

now produces 18 percent of the country's food grain and 15 percent of coal. From 11
century, Huai River was disturbed by Yellow river for about 600 years, and several
hundred billion tons of soil and sand have taken into Huai River. The river courses
were disturbed, and the serious influences were very difficult to be eliminated. So theflood discharge capacity is not adequate and flood and water logging hazard
frequently occur. In recent years, it has a trend that the flood in this river occur
frequently. In 2003, 2005 and 2006, severe flood disasters and water logging disasters
occurred in both urban and rural areas. In 2003, about 6 flood detention basins wereused for storage flood water.
3.2What do you think is necessary to make flood hazard maps in the chosen area?
Do you have data, maps, budgets that is necessary for making flood hazard
maps?
Firstly, flood hazard in this area occur frequently. As has been introduced above, theHuai river is notorious for its frequent floods, endangering the local people in theriver basin. And also, in this area people’s awareness on flood hazard are weak, whenfloods occur they don’t want to evacuate because they are familiar with this riverhence increase the exposure to flood in another way.
Secondly, exposure to flood hazard in this area is high. Along the Huai river, fromupstream to down stream, are Henan, Anhai, Jiangsu and Shandong provinces. These
provinces are large in population. Henan ranks the top one among all provinces in
China with a population of up to 100 million. The high density of population in thisarea increases the exposure to flood hazard.
Thirdly, the flood control system is not so perfect compared with that of other mainrivers like the Yangzi river. Which means the vulnerability in Huai river the also high.
The Huai river system is complex especially in the middle and down stream. The
heavy flood along the Huai River in the summer of year 2003 caused 18.17 billion
yuan (2.2 billion US dollars) of direct economic losses in Anhui, Jiangsu and Henan
provinces. The flood prompted harness of Huai River from 2003. Although the large
scale harness of Huai river is being carried out people living there still face the highrisk of flood hazard since the construction is time taking.
Based the above reasons, I choose the Huai river area to be the target areas for flood
hazard mapping. Since the river system is large, complex it is necessary to divide thesystem into several sub-areas according to its main tributaries. Fortunately, the Huai
river is in the flood hazard mapping plan. If the project is approved, there will beabundant fund. The hydrology data are supposed to be provided by the Bureau of
Hydrology.
3.3Propose your own action plan within the next five years.
Dec 3,2006 ~ Dec 31,2006: report to my organization about what I havelearned from this traing course; set up a network among those people whohave participated in flood hazard mapping in the past 3 years.
January ,2007 ~ May,2007: conclude the flood hazard pilot researches;
help with the affairs of flood hazard mapping project.
June, 2007 ~Dec, 2007: survey in Huai river, prepare and participant inflood hazard mapping in this areas; if possible, carry out training course for8management staff in flood hazard mapping.
January 2008 ~ Dec, 2010: carry out the flood hazard mapping project intarget areas.
3.4What seems a problem in making flood hazard maps in China?
According to the training course, there are four basic elements to make a flood hazard
map, the technique standard, basic maps, hydraulic data and models like run-off
model and overflow simulation. Besides these, financial fun is another crucial element
for effective flood hazard mapping. As far as I know, problems will occur in thefollowing aspects:
Lack of large scale basic map. Large scale, simple and easy tounderstand designed, necessary information compose an effective flood hazard
map. But in China, large scale maps are expensive. Sometime, it is notavailable for security reason.
Lake of DEM.
Lack of enough hydrology data. The hydrology and meteorology stations
are far from enough. Can’t get rainfall and hydrology data for every hour.
Lack of budget. Compared with developed countries, China still needmuch more investments on both public works and public services. Budget
should be planned on each level of governments to supplied much more andbetter public services including flood hazard mitigation.
4.My own flood hazard map on Ise city.

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