Cc Swat Qnam

8/4/2019 Cc Swat Qnam

1/12

Assessing Climate change Impacts and Adaptation in Central Vietnam using

Watershed and Community Based Approach:Case study in Quang Nam Province

Nguyen Kim Loi(1)

, Nguyen Van Trai(1)

, Hoang Thi Thuy(1)

, Nguyen Thi Huyen(1)

,

Le Anh Tuan(2)

, Suppakorn Chinvanno(3)

(1) Nong Lam University, Ho Chi Minh City, Vietnam(2) Can Tho University, Vietnam

(3) Southeast Asia START Regional Center, Bangkok, ThailandABSTRACT

With the changes in climate, biophysical, socio-cultural, economic and technological

components, paradigm shift in natural resources management are unavoidably

adapt/modified to harmonize with the global changes and the local communities needs.

This research focused on climatic change risk, vulnerability and adaptation in Dong Giang

district in response to climate change impacts as case study. The Soil and Water Assessment

Tool (SWAT) model was applied to assess climate, land use change and practice impacts to

soil and water resources in Dong Giang district as upstream of Vu Gia watershed, Quang

Nam province. This part focuses on the relationship between upstream and downstream in

Vu Gia watershed and using sustainable watershed management in response to climate

change in Quang Nam province, Vietnam. The research also concerns with changes inecological and socio-economic conditions driven by climate change and human activities in

Dong Giang; and adaptation measures in agricultural production and livelihoods to suit the

new conditions.

Keyword: Climate change, Watershed management, Community Base, Quang Nam

INTRODUCTION

Current climate change estimates indicate that major environmental changes are likely to

occur due to climate change in practically every part of the world, with majority of these

changes being felt through modification of hydrological cycle as e.g, floods, droughts and

storms. Climate change impacts are also estimated to be particularly severe in many

developing countries of the world and especially in Vietnam.. The recent studies (World

Bank Study, Dasgupta et al.: 2007, IPCC, 2007) have concurred that Viet Nam will be one

of most vulnerable countries to climate change in the world. Gradual changes such as sea

level rises and higher temperatures, more extremes of weather such as drought, and more

intense typhoons are all on the horizon and will have a potentially devastating impact on the

countrys people and economy.


2/12

Dong Giang District is one of eight mountainous districts that locate in western part of

Quang Nam province the centre of Vietnam, with 70 km far way from Da Nang city. The

area often have tremendous catastrophically natural hazard by flood and typhoon. Recently,the number of events occurring such as landslide, drought, flash flood, etc. has increased

rapidly. In addition, developing activities in the area such as hydropower construction, road

building, and deforestation contributed to changing of ecosystem in Vu Gia watershed.

Hence, this research attempts to assess climate change impacts on ecosystems and livelihood

in Dong Giang district, Quang Nam province and to make policy recommendations to

decision maker on climate change impacts to adapt to the new context.

STUDY AREA DESCRIPTION

Dong Giang District is one of eight mountainous districts located in western part of Quang

Nam province and upstream Vu Gia watershed the central Vietnam, with 107o

30 to

107o56 longitude and 15

o35 to 16

o10 latitude and 70 km west of Da Nang city. The region

occupies an area of approximately 81,000 ha as shown in Figure 1. The Dong Giang district

has been divided into 10 villages and 1 town. Dong Giang locates in mountainous area

associated with small valleys and distributed by small and middle stream networks. The area

is classified into 3 categories by height, i.e. the area of higher than 1000m over sea level

accounts for approximately 22,600 ha which is 27.81% of the total; from 500m to 1000m

height is about 38,400 ha ( 47.25%) and below 500m is 24.94%.

Statistically, the population of the district was 23,635 people in 2008, of which 73.21% wereCtu ethic-a minor group and the rest was Kinh people. Eighty percent of the local

population relied on agricultural production and forestry activities for their livings. The

value of Dong Giang district has been based on its diverse natural, cultural and historical

resources including forest and its products, ethnic culture, etc.

On the other aspect, the area often suffers from tremendous catastrophically natural hazard

causing by flash flood and typhoon. Recently, these disasters are in increasing trends. In

addition to natural disasters, developing activities such as hydropower construction, road

building, mining and stone exploitation have accelerate the hazard.


3/12

Figure 1. Vu Gia watershed map

METHODOLOGY

1. Brief description of SWAT model

The Soil and Water Assessment Tool (SWAT) has been widely applied for modeling

watershed hydrology and simulating the movement of non-point source pollution. The

SWAT is a physically based continuous time hydrologic model with Arcview GIS

interface developed by the Blackland Research and Extension Center and the USDA-ARS

(Arnold et al., 1998) to predict the impact of land management practices on water, sediment,

and agricultural chemical yields in large complex basins with varying soil type, land use and

management conditions over long periods of time. The main driving force behind the SWAT

is the hydrological component. The hydrological processes are divided into two phases, the

land phase, which control amount of water, sediment and nutrient loading in receiving

waters, and the water routing phase which simulates movement through the channelnetwork. The SWAT considers both nature sources (e.g. mineralization of organic matter

and N-fixation) and anthropogenic contributions (fertilizers, manures and point sources) as

nutrient inputs (Somura, H. et.al. 2009). The SWAT is expected to provide useful

information across a range of timescales, i.e. hourly, daily, monthly, and yearly time-steps

(Neitsch et al., 2002).


4/12

2. The Scenario Planning Process for watershed and community approach

2.1. The SWAT Model

The principal planning task is aiming at the efficient planning of future in Vu Gia watershed.

The objectives of each plan will assist in deciding upon the socio-economic, physical and

environmental data that required formulating the different planning scenarios. The derived

objectives are also used later in the methodology to evaluate the efficiency of each proposed

planning scenario.

The next step of the planning process is to formulate possible land-use scenarios. Two land-

use scenarios are formulated for Vu Gia watershed as input of SWAT model.

Scenario A: Vu Gia watershed Land use map in 2000.

Scenario B: Existing land use map in Vu Gia watershed in 2008.

Impact assessment of changes in land use practices and human practices in Vu Gia

watershed on surface water, sediment yield during the period from 2000 2008.

The SWAT model requires meteorological data such as daily precipitation, maximum and

minimum air temperature, wind speed, relative humidity, and solar radiation data. Spatial

data sets including digital parameter layers such as parameters (R, K, C, P) and topography

(LS) was digitized from the associated maps. LS factor of the watershed is derived from

digital elevation model (DEM) obtained from topography. The SWAT model was applied in

Vu Gia watershed as shown in Figure 3, 4.

2.2 PRA (Participatory Rural Appraisal) Method

In order to conduct a comprehensive assessment of climate change impacts on ecosystem

and livelihood in Dong Giang district, the PRA method (as shown in Figure 2) was applied

to collect data for additional analysis. Specifically, the PRA method in combination with

field visit were conducted in Dong Giang to collect information for an overall picture of the

district regarding concerns in livelihoods (including agricultural productions and other living

activities) in relation with climate change issues and natural disasters; and adaptation

capacity of local people to the new context. Especially, the discussion also aimed to identify

the perspectives of local people on climate change issues that affect their living conditions.

Participants in the PRA discussion comprised of research team members (from RCCC of

Nong Lam University, Dragon Institute of Can Tho University and SEA-START Center,

Thailand) who played a role of facilitators to guide the discussion and local authorities, other

stakeholders (Social Unions and farmers).


5/12

Figure 2. Photos of PRA discussion in Dong Giang District, Quang Nam

Province

Figure 3. The SWAT model


6/12

Figure 4. Application of SWAT model in Vu Gia watershed


7/12

RESULTS AND DISCUSSION

1. Evaluation of land use change effect on surface runoff and sediment yield

In Vu Gia watershed have 5 sub-basins as shown in Figure 5 based on SWAT model. In

order to develop sound management schemes of protecting the Vu Gia watershed and to

have clear picture of the impact of climate and land use changes specifically on surface

runoff, and sediment yield. The calibrated model was run to simulate two land use change

scenarios. Land use change scenarios are:

Scenario A: Vu Gia watershed Land use map in 2000.

Scenario B: Existing land use map in Vu Gia watershed in 2008.

For developing the scenarios, the key processes and related model parameters such as P

factor of USLE, infiltration rate were modified in the appropriate SWAT input files. AnUSLE P factor of 0.6 to 1.0 was used in simulations to reflect the condition of the watershed

with and without soil conservation intervention. The predicted surface runoff and sediment

yield in 2000 and 2008 were summarized in Table 1. The daily simulated surface runoff and

sediment yield in the watershed is shown in Figure 6, 7.

Figure 5. The Vu Gia watershed along with its sub-basin automatically delineated


8/12

Table 1. The SWAT output (monthly) with different land use scenarios

Rainfall (mm) Surface runoff Q(mm) Sediment yield(ton/ha)

Scenario A Scenario B Scenario A Scenario B Scenario A Scenario B

11.90 21.10 0.01 0.70 0.00 0.59

81.01 26.90 17.03 0.26 11.74 26.26

66.96 71.78 7.19 11.03 18.42 13.65

183.50 183.50 49.18 70.79 45.50 51.41

195.47 195.47 57.69 80.41 19.62 78.94

126.83 126.83 49.84 89.08 11.50 5.40

328.80 398.80 99.53 190.34 0.23 15.48

435.76 465.76 90.40 210.54 61.08 130.04

393.16 393.16 91.34 196.34 13.56 156.40

482.41 482.41 110.65 219.87 28.82 118.87

328.80 228.80 70.32 87.87 0.16 91.91

68.35 58.15 8.05 7.50 8.84 10.95

Figure 6. Simulated surface flow in sub-basin 1 (Dong Giang district) in Vu Gia watershed


9/12

Figure 7. Simulated Sediment yield loading to reservoir in Vu Gia watershed

To assess the effects of land use change in the study area, the SWAT model was run to

simulate two scenarios of land use changes on surface runoff, sediment yield. Results of the

simulation shown that surface runoff increase when forest converted to agricultural land. An

increase about 42.22% in surface runoff occurs when 21% of the forest area converted to

agricultural land. Meanwhile, sediment yield increase about 54.2% compared between 2000

(28.96 ton/ha) and 2008 41.66 ton/ha).

Table 2. The SWAT simulated statistics for Vu Gia watershed using land use scenario A

(2000) and land use scenario B (2008)

Scenario Precipitation (mm) Surface runoff (mm) Sediment yield

(ton/ha)

2008 2652.66 41.89 41.66

2000 2702.95 29.44 28.96

2. Effect of extreme weather phenomenon on natural and socio-economic conditions of

Dong Giang District.

Result from the PRA discussion is presented in Figure 8.


10/12

Figure 8. Ecological and socio-economic changes caused by extreme weather conditions and

adaptation to suit the new context.

The above flow chart conveys a key message that the destructive phenomena including

extreme weather conditions that occurred recently in Dong Giang was partially caused by

climate changes. For instance, more landslide incidences were due to heavier rainfall and

torrent that occurred at higher frequency in the district recently. Similarly, higher

temperature events and more frequent storm tend to increase in the last few years. In spite of

human activities such as construction of hydropower plants and gold mining were also keysectors caused adverse impacts on the environment, climate change phenomena are believed

to significantly contribute to the livelihood changing.

Most of the mentioned phenomena caused adverse effects on local people in various aspects

such as ecological changes, socio-economic disruption and some other gender issues. In

terms of ecological changes, the most frequent reported events included loss of agriculture

land, disease occurrence in human and agricultural productions, change in water quality and


11/12

current pattern leading to loss of fish species. Other concerns were that custom and

livelihood changes due to home loss and resettlement.

In order to adapt to new conditions, local people have adjusted their farming calendar and

changed varieties for cultivation and husbandry. For example, cow has been raised instead of

buffalo because it can tolerate better in hotter weather. However, eco-tourism has been

further developed because it benefit from a longer dry season and drought which prompt

tourists to searching such environment in the District.

CONCLUSIONS

This research is just the first step apply SWAT in Vu Gia watershed. The SWAT modelperformed well in simulating the general trend of surface runoff, sediment yield, at

watershed over time for daily, monthly time intervals. The results shown that the land use

change and practices was affected surface runoff, sediment yield. Results of the simulation

shown that surface runoff increase when forest converted to agricultural land. An increase

about 30% in surface runoff occurs when 21% of the forest area converted to agricultural

land. Meanwhile, sediment yield increase about 54.8% compared between 2000 (24.96

ton/ha) and 2008 (38.66 ton/ha).

These simulated effects of forest conversion to agricultural crops clearly indicate an

alarming situation of watershed elsewhere having the same land use pattern. In Vu Giawatershed, we recommend that policies addressing this problem should be formulated both

at the local and national level. Parallel to this, an intensive information and education

campaign on the consequences of forest conversion and ways of rehabilitating the watershed

should likewise be done. Finally, alternative livelihood opportunities for upland farmers

should be considered in policy implementation. While simulation results are subject to

further validation, this study showed that the Soil and Water Assessment Tool (SWAT)

model can be a useful tool for modeling the impact of climate and land use changes in

Vietnam watershed.

The recent adaptation to deal with changes in ecology and socio-economics requires furtherattention from the authority for more appropriate policies and strategies to support local

people for better livelihoods.

REFERENCES

Arnold, J.G., Srinivasan, R., Muttiah, R.S. and Williams, J.R. 1998. Large area hydrologic

modeling anh assessment part I: model development. J. American Water Resources

Association 34: 73-89.


12/12

Dasgupta, S., Laplante. B., Meisner, C., Wheeler, D., and Yan,J. (2007). The Impact of Sea

Level Rise on Developing Countries. A Comparative Analysis. World Bank Policy Research

Working Paper 4136, February 2007.IPCC (2007). Climate Change 2007: Impacts, Adaptation, and Vulnerability. The Fourth

Assessment Report of the Intergovernmental Panel of Climate Change. Cambridge

University Press.

Loi. N.K., and N. Tangtham. 2005. Decision support system for sustainable watershed

management in Dong Nai watershed Vietnam. Paper presented in International

Seminar on Synergistic Approach to Appropriate Forestry Technology for

Sustaining Rainforest Ecosystem, March 7 - 9, 2005, Bintulu Kinabalu, Malaysia.

Neitsch, S.L., Arnold, J.G., Kiniry, J.R., Srinivasan, R. and Williams, J.R. 2002. Soil and

Water Assessment Tool. Users Manual. Version 2000. GSWRL Report 02-02, BRC

Report 2-06. Temple, Texas, USA.

Somura, H., Hoffman, D., Arnold, J.G., Takeda, I. and Mori, Y. 2009. Application of the

SWAT Model to the Hii River Basin, Shimane Prefecture, Japan. Soil and Water

Assessment Tool (SWAT) Global Applications. World Association of Soil and Water

Conservation. Special Pub. No.4.

ACKNOWLEDGEMENTS

The authors acknowledge the APN (Asia-Pacific Network for Global Change Research)

funded Building research capacity on assessing community livelihood vulnerability to

climate change impact in central Vietnam and Mekong River delta project for funding this

research.

Documents

Cc Swat Qnam