BUILDING CANTHO CITY’S CLIMATE CHANGE RESPOND PLAN
8/18/2011 10:10:00 AM
Report of Third Scientific Conference in EIA and SEA, Hue City – Vietnam, 26 August 2011: Ky Quang Vinh - Cantho Climate Change Coordination Office.
Cantho Climate Change Coordination Office
TÓM TẮT:
Việt Nam là 1 trong nhóm 10 nước bị tác động của Biến đổi khí hậu(BĐKH). Thành phố Cần Thơ nằm giữa Đồng bằng sông Cửu Long (ĐBSCL) được UNDP xác định là 1 trong 3 đồng bằng bị tác động nặng nề của BĐKH. Tác động của BĐKH càng nặng nề hơn khi các hoạt động phát triển thượng nguồn sông Mê công sẽ trực tiếp hay gián tiếp, ít hay nhiều tác động đến chế độ thuỷ văn hạ nguồn gây bất lợi cho dân cư và môi trường đồng bằng sông Cửu Long của Việt Nam. Nguy cơ gây thiếu đói trên nhiều vùng của thế giới do tác động BĐKH tại đồng bằng sông Cửu Long là một thực tiển.
Kế hoạch hành động ứng phó BĐKH của thành phố Cần Thơ giai đoạn 2011-2015(Kế hoạch), được xây dựng bởi Ban chỉ đạo ứng phó BĐKH thuộc UBND thành phố Cần Thơ. Kế hoạch được hỗ trợ thực hiện từ chương trình mục tiêu quốc gia ứng phó BĐKH (NTP), cùng với quĩ RF và các tổ chức ngoài nước như: ISET, CtC và trong nước: Viện Chính sách Khoa học và công nghệ (NISTPASS), Viện Khoa học thủy lợi miền Nam (SIWRR) và Trường Đại học Cần Thơ (CTU). Trong lúc biên soạn Kế hoạch có tham khảo báo cáo kế hoạch hành động thích ứng BĐKH tại Thành phố Cần Thơ (LRAP) do WB thực hiện cũng như kết quả nghiên cứu về BĐKH khu vực ĐBSCL của Đại học hoàng gia Thái Lan và Đại học Helsinki, Phần Lan.
Tổng hợp các tài liệu và số liệu nghiên cứu cho thấy BĐKH làm cho thành phố Cần Thơ có các biểu hiện như: Nhiệt độ gia tăng ít nhất là 2oC vào cuối thế kỷ 21, số ngày có nhiệt độ trên 35oC tăng lên trên 240 ngày/năm; Thiếu nước do hạn khốc liệt hơn vào mùa khô; ngập sâu do nước biển dâng kết hợp nước lũ từ sông Mê công vào mùa mưa; Các hiện tượng thời tiết cực đoan gia tăng; Kèm theo đó là nước mặn xâm nhập sâu vào thành phố và hiện tượng sạt lở bờ sông rạch.
Cantho is a relatively young city (established about 120 years ago) located on the western portion of the Hau River in the Lower Mekong River Delta. Now, Cantho city is a first-class city of Vietnam. Cantho is considered the most important center for economics, culture, education and health in the Mekong Delta. It is also the national and international traffic hub of the region. It is 60 km from Longxuyen, 116km from Rachgia, 179km from Camau, 169km from Ho Chiminh City, and 75km from the East Sea.
Cantho's topography is flat and low-lying. Most of the land in Cantho is 0.8-1m above sea level. The land along the Hau River is slightly higher, between 1.0–1.5m above sea level. From Hau River, the topography is gradually drops from Northwest to Southeast.
Cantho has an area of 1,400 km2, it has an estimated population of 1,200,000 people. The average population density of the city is over 840 people/km2, but Ninhkieu has the highest population density of 7,392 people/km2, and Vinhthanh has the lowest population density (from 376to846people/km2).
Cantho’s climate is characterized as being tropical and monsoonal, with hot and humid weather nearly year around. The average annual temperature is 27oC. It is two seasons in a year, the rainy and the dry season. The annual average rainfall ranges from 1,600mm to 2,000 mm.
Located along the Hau River—a branch of the international Mekong River, one of the 2 biggest river of Mekong delta—Cantho has a dense network of canals and rivers with a total length extending approximately 3,405 km this means there are more than 2km length of river or canal per 1 square km of land, about 6,800 hectare water surface area. The hydrologic regime of this river and canal network is dominated by the Hau River’s flow, the diurnal tidal movement of the East Sea, local rainfall regimes...
In 2008, Cantho has the GDP per person was 709USD. The main agricultural products of the city are rice and fish. Yield of paddy is about 1.2 million tons annually. Aquaculture production is about 198,000 tons, and is the key section of the local economy.
Cantho develop a Master Plan in which the basic macro indicators in 2020 are as follows:
− It attempts to reach the target GDP goal of 4,611USD per capita by 2020.
− Agricultural land will be reduced to 70%, non-agricultural land will increase to 26% and water surface area will be 4% of total area.
− Population size wills over 1.8 million, in which the mechanical population grows about 25%. Inner-city population will reach 70%. Non-agricultural population will be 1.355 million people.
− Master Plan also indicates the target to reduce poor households from 5% of the population in 2010 to basically eradicate poverty by 2020.
2. Climate change in md and Cantho
Weather
Air temperature
From 1978 to 2008, the average air temperature in Cantho increased of about 0.5oC.
Figure 1. Average air temperature in Cantho
Annual rainfall
From 1978 to 2008, a decline in annual rainfall is not visible. But during 10 years from 1998 to 2008 annual rainfall tended to reduce 200mm. This decline is well within the natural variability of Cantho’s historical weather. Only time will tell if this decline will continue or be exacerbated by climate change.
Air humidity
The air humidity tended to decrease 1% during the period from 1978 to 2008 but during the last 10 years, the air humidity decreased 2%. Again, these decreases in humidity could be due to changes in plant type or loss of planted area for city expansion, or possibly due to changes in climate.
Wind speed
The average of highest wind speed per year tends to decrease. According to existing data of Cantho center for Meteorology and Hydrology Monitoring, the wind speed was 10.4 m/sec in 1998; 9.084 m/sec in 2004; and just over 3.0 m/sec in 2008.
Hydrology
Hydrology regime of Mekong delta was changing very much in the recent year. Increase in temperature is likely lead to reduced amounts of snow accumulation in the upstream reaches of the Mekong River in the Tibetan Plateau; it is affecting the hydrological regime of the Tien and Hau Rivers. According to a 30 year (1977-2008) hydrological data from Cantho Hydrographic Station shows that the highest water level on Hau River in Cantho increased nearly 50cm.
Figure 2. Chart of the change of the highest water level at Cantho station
On the other hand, during the 2000-2007, the crest of the annually flood at Tan Chau, where Mekong River go into Vietnam, decreased by 0.8m, even while the highest water level in Cantho increased by 0.3m. In addition, there was no flood at Mekong in the rainy season of 2010, but at Cantho city highest water level reaches 3rd alarm level. These phenomenon demonstrate seawater intrusion into the Mekong Delta, especially since rainfall was declining during that time.
Now, the water flow of the Hau River was only 800m3/sec rather than the 1250m3/sec it was 30 years before. Decreased water flow creates conditions for saltwater intrusion. The observed water quality data shows an increasing in salinity of 1‰ only 15km away from Ninhkieu Quay in April, 2004 to 8km in April, 2010.
In the framework of Asian Cities Climate Change Resilience Network project, a research on the vulnerability with the participation of local communities (including Bobao hamlet, Vinhthanh district, and Con Son, Binhthuy district) was carried by Challenge to Change (CtC), in collaboration with Cantho University and Steering Committee of Decision 158 of Cantho city,. Some key hazards were identified and are summarized as follows:
− Air temperature increase
− Drought in dry season
− Floods caused by heavy rains combined flood-tide and water released from the upstream reaches of the Mekong River;
− Saltwater intrusion
− The extreme weather phenomena like storms, lightning, cyclones
− River erosion due to the change of flow regime.
2.2 modeling-based on average data of 1980-1999 period. Climate change
Ministry of Natural Resources and Environment-modeling 2009
Table 1. Increase of average temperature (°C) compared to the average temperature of period 1980-1999
|
Scenarios
|
Periods in year (Month)
|
Milestones of the 21st century
|
|
2020
|
2050
|
2070
|
2100
|
|
Highest scenario of the high - scenario group (A1FI)
|
Dec – Feb
|
0,5
|
1,5
|
2,5
|
3,6
|
|
Mar – May
|
0,5
|
1,7
|
2,7
|
3,9
|
|
Jun – Aug
|
0,4
|
1,1
|
1,7
|
2,5
|
|
Sep – Nov
|
0,5
|
1,5
|
2,6
|
3,7
|
|
Year
|
0,5
|
1,4
|
2,4
|
3,4
|
|
Medium scenario of the high - scenario group (A2)
|
Dec– Feb
|
0,5
|
1,2
|
1,8
|
2,9
|
|
Mar – May
|
0,5
|
1,3
|
2,0
|
3,2
|
|
Jun – Aug
|
0,4
|
0,9
|
1,3
|
2,0
|
|
Sep – Nov
|
0,5
|
1,2
|
1,9
|
3,0
|
|
Year
|
0,5
|
1,1
|
1,7
|
2,8
|
|
Medium scenario of the medium - scenario group (B2)
|
Dec – Feb
|
0,5
|
1,1
|
1,5
|
2,1
|
|
Mar – May
|
0,6
|
1,2
|
1,7
|
2,3
|
|
Jun – Aug
|
0,4
|
0,8
|
1,1
|
1,4
|
|
Sep – Nov
|
0,5
|
1,1
|
1,5
|
2,2
|
|
Year
|
0,5
|
1,1
|
1,4
|
2,0
|
Source: HMECC, 2009.
Temperature
In all emission scenarios from medium (B2) to high (A2) and to highest (A1FI), the trend of change in average annual temperature of Cantho city shows a gradual increase. For the near-term (2050), the range of average annual temperature increase according to all 3 emissions scenarios is 1.1 to 1.4°C compared with annual temperature over the period 1980-1999, with a range of 2°C to 3.4°C increases by 2100. The rate of temperature increases is highest during the March through May period.
Rainfall
According to the three emission scenarios, A1F1, A2 and B2, rainfall in the dry season decreases, while rainfall during the rainy season increases when compared to the average annual rainfall over the period 1980-1999. But in overall, the rainfall increase in all climate change scenarios from 0.7% (B2) to 1.2% (A1FI) by the end of the 21st century.
Sea level
On the base of 3 scenarios (A1F1, A2 and B2), at the end of 21st century, the sea level related to Mekong delta will rise from 74 to 100 cm.
Chulalongkorn University-Sea START
The Sea START’s projections suggest that temperature may increase by 4 to 5oC; rainfall may also increase, but the number of days with more than 3mm of precipitation will decrease. This means less rainfall but rain with high precipitation amounts in the rainy season.
Rainfall amount in dry season are likely to decrease. In addition the study suggests that during the rainy season, if the East Sea level is rising higher than current level by 1 m, as a result, the inundation on the Mekong Delta and Cantho city may be higher than double (2 m). But in the dry season, the water level of Hau River decreases significantly, leading to saltwater intrusion farther inland into areas of agricultural production.
The World Bank
As part of the World Bank’s “Economics of Adaptation Study”, under the IPCC emissions scenario A2 (median of the highest scenario group) for projections up until 2070, the temperature of Cantho is projected to increase 2.5oC compared with that of 1970. Urban areas will face the hot sun, causing an increase in water consumption, disease, and cooling requirements. Therefore, it seems logical for infrastructure design to plan ahead for such occurrences.
The total rainfall in Cantho may increase slightly, but there is a deeper change in the rainfall variability by month. This means that rain may be concentrated in a shorter time and drought may be longer. These will create serious impacts on urban flooding and agricultural production.
Figure 1. Map shows amount of days with air temperature more than 35oC
Cantho University and SIWRR
The research of Cantho University and SIWRR show that temperature and rainfall did not have great influence on rice, fish raising and the lives of people, but severe drought in dry season and deep flooding during the rainy season are the special risk factors for the agriculture, aquaculture, construction and livelihoods of community. Some suggestions for adaption.
− Within 50 years, the city of Cantho should have response measures such as crops reducing; seasonal calendar shifting, growing short-time rice varieties; to raise dikes ... To protect the infrastructure from water inundation the foundation of 2.5 m above current sea level has been suggested.
− After 50 years, the city should pay attention to these problems: the sanitization of soil and water; economic losses due to deep water; and increase the spread of disease as well as those affected by the disease climate change; the social problems arising from increasingly difficult in people's livelihoods and causing migration from rural to urban;
Figure 2. Map show inundation area and depth when SLR 100cm and big flood in Mekong
− Since Cantho is located between the Mekong Delta, the local city and provinces has close ties together to the ecological environment and livelihood, so there should be a response plan for the entire region, based on which the new local planning to be established for the provinces.
Table 2. The depth and flooded area in October of Cantho city under three sea level rise
|
Inundation depth
(cm)
|
Inundation area (km2)
By the sea level rise
|
|
30 cm
|
50 cm
|
100 cm
|
|
10
|
2,44
|
1,13
|
0,06
|
|
20
|
6,79
|
2,62
|
0,08
|
|
30
|
5,16
|
2,56
|
0,24
|
|
40
|
22,04
|
14,61
|
0,31
|
|
50
|
16,40
|
13,05
|
0,48
|
|
60
|
76,22
|
24,48
|
2,83
|
|
70
|
126,08
|
53,36
|
2,87
|
|
80
|
45,62
|
32,39
|
7,98
|
|
90
|
130,53
|
215,67
|
20,85
|
|
100
|
36,42
|
41,98
|
16,87
|
|
110
|
182,28
|
138,04
|
26,54
|
|
120
|
46,07
|
40,20
|
167,5
|
|
130
|
154,56
|
123,55
|
50,16
|
|
140
|
298,14
|
299,51
|
175,49
|
|
150
|
43,45
|
54,85
|
122,98
|
|
160
|
162,87
|
257,05
|
47,96
|
|
170
|
18,32
|
23,20
|
271,24
|
|
180
|
46,51
|
79,44
|
232,86
|
|
190
|
1,54
|
2,96
|
47,13
|
|
200
|
1,05
|
1,06
|
162,35
|
|
210
|
1,23
|
1,37
|
15,85
|
|
220
|
0,41
|
0,66
|
41,42
|
|
230
|
0,42
|
0,57
|
6,36
|
|
240
|
0,20
|
0,38
|
2,05
|
|
250
|
0,00
|
0,00
|
2,03
|
3. Climate change resilience activities plan in Cantho
3.1. Planning methods
Communities, especially poor people will be vulnerable group due to climate change. Thus the climate change resilience activities plan must come from the community and to be screening, assessment by the scientists and specialized agencies for selection.
We base on the request of current Cantho city’s master plan, historical climate data, the results of vulnerability assessment with the participation of communities, the results of climate change modeling to draft the necessary documents for 3 sharing, learning and dialogue workshops (SLD). These workshops are the forums for scientists, government officials and community discussion of substantive issues, developments and impacts of climate change at the local measures necessary to respond effectively, immediate and long term.
The minutes and general conclusions of the workshop to share, learn and dialogue are key documents to draft the climate change resilience activities plan to submit to the People's Committee of Cantho city for approval and promulgation.
3.2. Cantho Climate change – vulnerabilities
The characteristic of climate change in Cantho
We can get some conclusion about the impacts of climate change in MD and Cantho city:
− Average temperature will be higher 2 to 3oC in comparison with current temperature. The days with temperature more than 35oC will increase to 240 days/year of 2050s, instead of about 100days for the years being.
− Increasing water stress, droughts during the dry season and deeper inundation in the rainy season. Salinity intrusion crises will be the consequence of these phenomena.
− The others extreme events: typhoon, whirlwind, lightning, landslide... will happen more steadily
Double impact: climate change and unsustainable activities in the upstream of Mekong
Mekong Delta and Cantho city was ill effects of global climate change also affected from upstream activities, especially activities that are not sustainable, such as deforestation, urbanization and construction of the dam...
Activities such as building dams will exacerbate the effects of climate change due to local: changing the flow regime, changes in water quality, exacerbate the saltwater intrusion into paddy land and freshwater fish.
More importantly, the dam will certainly lead to the destruction of wetland ecosystems, which has a dry season during the months in the beginning of the year and the flood season lasts from the end of the year, being long time in the past to now. This loss is enormous and cannot be permanently replaced. The result is reduced food production; a large number of people in the world would be starving.
Vulnerabilities
− Decreasing of freshwater availability for households using and production demands,
− Decreases in crop yield due to soil moisture reducing; evapotranspiration increasing land degradation.
− Health affected by: Heat stress, increases in endemic morbidity and mortality due to diarrheal, cholera and dengue...
− Deep inundation will likely to seriously affect the aquaculture industry and infrastructure.
3.3. Resilience activities plan
The resilience activities plan depends on 2 main solutions:
Non-structural solutions-capacities increasing
− Climate change awareness strengthening includes: Establish of Climate Change Coordination Office; Enhancement awareness of dealing with CC for Cantho communities, and government’s staff; Identifying the extent of climate change impacts on subjects, sectors and areas in Cantho to make long-term (from 2015 to 2030) resilience plan.
− Establishment of Climate change database and applying information technology on forecasting meteorological and hydraulic risks, and distributing the information to communities;
− Research for integration the climate change resilience activities into the approved programs, projects of Cantho city;
− To draft and issue regulations to support activities to respond to climate change
− Negotiations for legally binding protocol to manage, share, rational use of water resources Mekong River through MRC.
Working solutions
− Building resilience capacity for local communities and the system of preventive health care to deal with CC in Cantho city;
− Improving Cantho city into the eco-city to combat the rise of air temperature;
− Making decentralized system water reservoirs and manage exploit of groundwater and surface water;
− Building the system of altitude landmark and promulgate regulations for construction works in Cantho city;
− Enhancement poor families by resettlement base on providing livelihoods;
− Building multifunctional school in communes;
− Building decentralized water supply and waste treatment plants to mitigate negative impacts of climate change;
− Mapping the bottom and banks of rivers and their change to propose appropriate measures avoiding bank erosion;
− Building a center for researching agricultural production methods, plants and animals resilience to salinity and drought to increase food production in climate change;
− Applying clean production processes in the industrial sector;
− Building solar energy plant for Ninhkieu district;
Advantages and difficulties
- Advantages
− The fluctuations of weather and hydrology are suitable for social awareness campaign on climate change;
− The leaders of city government is very supportive of the plan to adapt to climate change;
− Rockefeller Foundation and other organizations within and outside the country are enthusiastically planning climate change adaptation
- Difficulties
− Climate change is a field related to all sectors, localities and social components in order to plan appropriate adaptation to the level of knowledge of many areas of expertise, local, and different people
− As required by the state to complete too big resilience plan to cover the whole society in a time just less than a year, time is too short.
− Little budget for research and completion of plans to adapt to climate change
− Communities must prepare plans to adapt to climate change in local general plans of the unreasonable. Local is subject to any actual impact due to climate change adaptation plans of localities to do before, plan to according to the support of the local plan.
− Assessing the effectiveness of the response to climate change are difficult
− Choose actions consistent with local and meet the criteria for "no regrets" is a very complex job, requiring more time and experience is that local conditions difficult to meet.
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