Assessment of climate change impacts on agricultural sector in Vinh Long province

Climate change is one of the major challenges for humanity in the 21 century, has negatively affected many sectors. This work aimed at assessing impacts of climate change (CC) on agricultural sector in Vinh Long province till 2020 via data collection and processing method, Geographic Information System (GIS), risk assessment matrix, and SWOT. Flood, saltwater intrusion (SI), drought, landslide, storm, temperature, and precipitation were taken into consideration. Flood, SI, and temperature were found as main factors affecting on agricultural sector in Vinh Long province, especially rice. In Vinh Long province, Vung Liem, Long Ho, and Binh Tan districts were significantly effected. Besides, this work proposed some solutions to improve the adaptive capacity to CC of this sector, contributing to the local sustainable development. Index Terms – Agriculture, climate change, saltwater intrusion, flood


INTRODUCTION
limate change is one of the major challenges for humanity in the 21st century.Disasters and severe weather events are increasing in quantity, strength, and affecting scale, considered as top concerns of the world, including VietNam, especially in the MeKong Delta where would be in danger of flooding about 39% of the area under sea level rise 1 m [1].Therefore, both positive and negative impacts of CC need assessing to develop suitable adaption plans.
Agriculture is a sensitive sector to climatic conditions and disasters, such as temperature, precipitation, SI, drought, and flood, etc., thus can be seriously affected by CC [2 -6].
Many different methods have been used to assess impacts of CC on agricultural sector, based on the historical climate data [7], modelling as DSSAT Ver 4.0.2model (Decision Support System for Agrotechnology Transfer) [8 -10], AquaCrop [11,12], Cropwat [13], etc., lab-scale empirical methods for annual and perennial crops, pests, and epidemics [14], GIS and remote sensing [14], expert method, and community survey [15,16].In general, according to research objectives and scope, suitable individual or combined methods are used.
Vinh Long province (including Vinh Long city, Vung Liem, Mang Thit, Tra On, Tam Binh, Binh Tan, Binh Minh, and Long Ho districts), located in the Mekong Delta, on one hand has a thriving agriculture sector, especially rice, fruit, and freshwater aquaculture with about 79% of its natural area being agricultural land [17].On the other hand, it also would be one of the most flooding area in the context of sea level rise [1].Besides, natuaral disasters such as riverbank landslide, storm, drought, SI, etc. have occured quite frequently [18] and then seriously affected the local agricultural sector, especially in the context of CC.
Therefore, assessing CC impacts on agricultural sector is necessary to provide scientific basis for developing adaptive solutions in each specific condition, reducing risks, and contributing to the local sustainable development.

Impacts of CC on the agricultural sector of Vinh
Long province were assessed by the effects of flood, SI, drought, storm, temperature, and precipitation variations (called as CC factors in this work).

Data collection and processing method
Concerning data of the current status and development plans of the agricultural sector, the changing in disasters and climate, CC scenarios (developed by SIMCLIM software according to AR4 of IPCC), SI and tidal flooding scenarios, as well as response action plans, etc. was collected, C then processed by Excel software.For CC scenarios in VinhLong province in 2020, according to the average greenhouse gas emission scenario (B2), temperature and precipitation would be 27.64 o C and 1,491.80mm, respectively; water level would rise about 9 cm as compared to that in the reference period (1980-1999) [19].

Geographic Information System (GIS) method
Mapinfo 11.5 and ArGIS softwares were used to mapping impacts of flood, SI, temperature, and precipitation, etc. on agricultural sector in Vinh Long province to 2020.

CC risk assessment matrix
This method was used to determine areas needing to be paid special attention and respective causes based on the risk level due to CC which was evaluated by risk index as presented in Table 1.The risk index to CC was integratedly calculated by risk index to each CC factor (basically determined based on occurrence possibility and related damages) and its weight in relation to the agricultural sector.
The weight of each CC factor was determined as follows: -Ranking the importance of each factor based on 20 experts' opinions.The more important the factor is, the higher the ranking score will be.

Current status and the development plan of the agricultural sector in Vinh Long province till 2020
Current status: for the period of 2005-2015, reverse with the planting sector, the proportion of the breeding sector and service agricultural activities was increased.However, the planting sector still held the leading role, accounting for 67.78% of the agricultural sector in 2015 (followed by breeding sector and service agricultural activities, according to 26.46% and 5.76%), including major crops such as rice, annual crops, fruit and perennial plants.The largest areas of rice and fruit in the province were mainly located in Vung Liem, Tra On, Tam Binh, and Mang Thit districts [17].
Development plan: The agriculture, forestry, aquaculture sector of Vinh Long province has strived to achieve the growth rate of 4.0-4.5%/year in the period of 2016-2020, reducing the proportion of planting sector but conversely for the breeding sector.By 2020, the proportion of planting sector, breeding sector, and agricultural services are 61.91%,32.92%, and 5.17%, respectively.Besides, it is oriented to reduce the rice land instead of fruit land, to reduce the third crop of rice, to increase the alternation of crops, to exploit the strengths of fruit and aquaculture [20].

Temperature
Maximum temperature fluctuated in 35 o C-36.5 o C (in the period of 1986-2005) and affected about 5,000 ha of agricultural land, corresponding to 65.9% and 34.1% of the annual and perennialplant land, mainly distributed in Binh Tan (about 2,000 ha), followed by Long Ho, Mang Thit, Vung Liem districts (about 500-600 ha).
By 2020, temperature will be increased but the affected agricultural land could be decreased due to the change in agricultural land-use planning as mentioned: about 3,163 ha, mainly in Binh Tan district (about 32% of affected area).

Precipitation
Heavy, erratic, and unseasonal rain create favorable conditions for pest development.In the context of CC, the epidemics are increasingly complex, such as brown backed plant hopper, rice blast disease, sheath blight disease, leaf roller disease, twisted leaf disease, yellow leaf disease, yellow dwarf disease, etc. and affect the ability of intensive farming in Mekong Delta as well as VinhLong province [21].

Flooding
Flooding has the most impacts on rice-land and perennial-plant land in the province (Table 2).On one hand, it causes the decrease in agricultural yield and product quality, consequently provincial gross domestic product.On the other hand, it results in alluvium and then fertility for soil, etc.
Current status: rice-land (LUC) and perennialplant land (CLN) have been significantly affected by flooding: about 24,500 ha (accounted for 27% of agricultural land of the province), mainly located in Vung Liem (about 7,327 ha, accounted for 40.7% of agricultural land of the district), Long Ho (about 3,867 ha, 37.4%) and Tam Binh district (3,175 ha, 16.8%) (Table 2).
In 2020, flooded agricultural land could be decreased due to the change in rice land-use planning: about 23,394 ha, 29.8%.Vung Liem, Long Ho, and Tam Binh districts would be still affected the most, thus need suitable adaption measures (Fig. 1, Table 2).

Saltwater intrusion
Sea water entering inland can impact crops as making flower and fruit loss during blooming and fruiting periods, even killing plants due to high salinity of water.Besides, salinity reduces planting area, leading to the decrease in crops yield.Calculated results showed that VungLiem district is always the most affected in the current status and 2020 -B2 scenario (Fig. 2, Table 3)

Drought
Drought often occurs at the end of winterspring crop and prolongs until the end of summer-autumn crop -low tide period (end of April).In 2015, drought affected about 30% of summer-autumn rice area (about 17,600 ha), most in Vung Liem (5,000 ha) and BinhTan (5,000 ha), followed by Tam Binh (4,600 ha), and Tra On district (3,000 ha).In 2020, the increase in temperature and decrease in precipitation in Vinh Long province would result in drought risk with undesirable impacts on agricultural sector (water shortage, SI, reduction of productivity, etc.).

Other disasters
Storm affected crops in Long Ho (about 102 ha) and Tam Binh (1 ha), resulting in damage of 7 billion VND, as well as fruit area in Tam Binh district (0.4 ha) [18].
To sum up, there has been the impacts of CC on the agricultural sector, especially (rice) planting sector in Vinh Long province till 2020.

Determining CC factors of concern and hotspot areas
Table 4 presented risk index to CC of the agricultural sector in Vinh Long province, especially due to flooding and SI, where Vung Liem and Long Ho district had the highest values corresponding to 1.96 and 1.89 (Fig 3a), By 2020, flooding and SI tend to increase, leading to the increase in risk level of the agricultural sector.Risk index of other factors would not be significantly changed.Vung Liem and Long Ho district should be taken into pay special attention (Fig 3b , Table 4).Strenghts, weaknesses, opportunities, and Threats of the agricultural sector in the context of CC The relationships of S, W, O, and T of the agricultural sector in Vinh Long province in the context of CC (Table 5) are following: (i) S1, S2, S3 + O1: Maximizing the strengths of natural conditions and geographical position to maintain the growth rate of agricultural sector.
(ii) S6 + O3: Promoting the cooperation with research institutes, universities, companies from other provinces in studying and constructing seed and animal farms able to adapt to CC (increasing tolerance to salinity ...).
(iii) S7 + O2: When restructuring the agricultural sector, CC should be taken into consideration; promoting capital mobilization, creating financial sources in order to effectively respond to CC.
(iv) S8 + O2: Leveraging national and international funds to improve CC adaptive capacity of community via communication programs.
(v) S4, S5 + T1, T2: Maintaining and constructing new irrigation systems to prevent salinization and inundation; investment in developing water supply infrastructure; enhancing closed and proactive irrigation area in the context of salinization increase.
(vi) S8 + T1, T2: Enhancing communication activities to improve the awareness, responsibilty, and participation of communities and authorities in the mission of CC response in the province.
(vii) W4 + O2: Strengthening and taking full adventages from support capitals to increase the investment in plant and animal varieties adapting to CC and infrastructures for agricultural development.
(viii) W5 + O3: Strengthening the mechanization of production, harvest; applying advanced technologies to improve quality of agricultural products and increase market competitive capability, especially in the context of CC.
(ix) W6 + O2: Taking full advantages from support capitals to increase the capability of community in accessing information of CC via communication activities.
(x) W7, W8 + T1, T2: Proposing solutions and timeline to implement CC response action plan, focusing on flood and SI impacts on the agricultural sector and cooperations among related organizations.
Besides, the following solutions are needed considering and applying: (xi) Improving management capacity of local agencies in response to CC.
(xii) Cooperation of 4 important parties, including farmers, government, scientists, and entrepreneurs in agricultural production and consumption; strengthening trade promotion and agricultural product brand.
(xiii) Developing policies to attract the investment in the agricultural sector, large-scale and high-tech agriculture development, and CC adaptation.Focusing on studying and applying scientific and technological achievements, especially in bio-technology to produce crops and livestock breeds suitable to local climate conditions.
(xiv) Mobilizing social resources to invest in agricultural infrastructure, taking into account CC factors.
(xv) Take advantages of high temperature to diversify the ways of processing agricultural products and to save energy.
(xvi) Applying science and technology, cleaner production technologies, fewer greenhouse gas emissions in preliminary processing, storage and processing stages to enhance the brand of agricultural products as well as to contribute to CC mitigation.
In summary, solutions to increase the response capacity to CC of the agricultural sector in Vinh

Fig. 3
Fig. 3 The max CC risk index of the agricultural sector in Vinh Long province: (a) current status, (b) 2020

Table 1 .
Risk index scale due to CC

Table 2 .
Area (ha)having the risk of flood in current status and 2020 -B2 Scenario

Table 3 .
Area (ha) of rice land and perennial plant land affected by SI

Table 4 .
CC risk index of agricultural sector in Vinh Long province