Asessing CC impacts and adaptation ìn cnetral VN using water shed and comunity based approach

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, Thailand
ABSTRACT
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 in
ecological 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
country’s people and economy.


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 15o35’ to 16o10’ 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% were
C’tu 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.


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 channel
network. 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).

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 landuse 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).


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

Figure 3. The SWAT model


Figure 4. Application of SWAT model in Vu Gia watershed


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. An
USLE 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

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

Surface runoff Q
(mm)
Scenario A Scenario B

Sediment yield
(ton/ha)
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


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
2008
2000

Precipitation (mm)
2652.66
2702.95

Surface runoff (mm)
41.89
29.44

Sediment yield
(ton/ha)
41.66
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.


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 key
sectors 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

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 model
performed 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 Gia
watershed, 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 further
attention from the authority for more appropriate policies and strategies to support local
people for better livelihoods.
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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.