Changing agricultural practices as a result of variable water resource availability in a hilly area of An Giang province, Vietnam

Located in the Southwest of the Mekong Delta in Vietnam, An Giang province is an important center of agricultural production, especially rice cultivation. Climate change impacts are one of several man-made factors affecting water resource availability for agriculture in the province. It is recognized that new solutions are crucial to adapt to the present and future conditions of a scarcer water supply. This paper explores climate factors affecting water resource availability in agriculture and some recent adaptations being adopted by farmers in one district of An Giang province. Hydro-meteorological data was collected together with in-depth interviews as a tool to point to proximate changes in water status and availability and to evaluate local inhabitants’ awareness of climate risks and adaptive strategies. The results noted that climate factors (temperature, humidity, annual rainfall) have altered over time, causing decreased availability of water supplies for agriculture. Recognizing this situation, both structural adaptation and non-structural solutions may occur simultaneously to maintain agricultural production efficiency. The types of crops, tolerant varieties, and irrigation projects suitable for various geographical areas were considered for more adaptive agriculture production locally. To address some of the problems that farmers face, water-saving technologies are an essential part of a range of potential solutions to maintain agricultural production and protect the environment in the future.


Introduction
Vietnam is recognized as one of the most vulnerable countries in the world to the impacts of climate change [1,2,3].The effects of climate change include rising temperatures, changes in the intensity of rainfall, more severe and frequent typhoons, increased flooding and erosion, raised sea levels and saline intrusion, and probably intensifd droughts that can lead to the degradation of the environment, the destruction of human communities and infrastructure and inevitably, reduced agricultural production capacity, with impacts most acute in developing countries [4,3].Tropical delta regions, such as the Mekong and Red River deltas, are at the frontline of anthropomorphic climate change, with impacts

Research site
A Giang is a border province (figure 1a) adjacent to the Cambodian provinces of Kandal and Takeo lying to the north.The province has some quite different natural characteristics compared to the rest of the provinces in the Mekong Delta, with the terrain comprised primarily of flat floodplains of the main distributaries of the Mekong and a few prominent hills [16].The hills, composed of volcanic rock, rise out of the wetlands landscape and have been settled by mostly Khmer ethnicity villagers for many centuries.A Giang is currently facing several challenges in the context of climate change, with generally rising temperatures, floods, droughts, and thunderstorms [17].Source: [18,19] Tinh Bien district was selected as the study site because it has been affected by climate change impacts, as have all provinces of the delta to a greater or lesser degree.The location of Tinh Bien district in An Giang Province is shown in Figure 1, b. Basic information about the study area is shown in Table 1.
Table 1.Some basic data of Tinh Bien district in An Giang Province.

Facts Description
Land area 35,459.1 ha, equivalent to about 10.03% of the provincial area.Population and Ethnicity 108,485 people (2019).Kinh (majority) and Khmer (minority) are the main ethnic groups of people.Density 306 people/km 2 (2019).Administrative units Three towns and 11 communes.Tide regime The Canal system is affected by the semidiurnal tide from Hau River (two high and two low tides of approximately equal size every lunar day).

Topography
Topography can be classified into three main areas titled as the alluvial field, the high field, and the hilly area.

Agricultural sector
The gross output (GO) of the agricultural sector in 2019 was 37,750 billion Viet Nam Dong accounting for about 97% of the total GO of the district.Source: [20,21]

Data Collection and Analysis
Climate change refers to any change in climate over time, whether due to natural variability or as a result of human activity [22].Locally, however, climate change impacts may be more difficult to perceive by people and, to a certain extent, to measure.The specific context is essential to appreciate a specific climate change event [23].In this case, the concept of climate risk is applied to describe the result of climate change and its effect.Water, as an indispensable agricultural input, is considered a climate risk variable.In this study, adaptation is defined as adjustments in ecological and social systems in response to actual climatic stimuli and their impacts [23, [24, 25].Adopted the science of adaptation concept for adaptive strategies [26], the theoretical framework has been created to guide the research as shown in Figure 2, displaying the relationships between climate risk effect and action to respond in the case study area. .

Data collection:
A mixed-method approach using both qualitative and qualitative data sources was used.The main methods were a desk study, in-depth interviews, and direct observation.(1996 to 2020), namely rainfall, temperature, humidity, and highest flood level.Since Chau Doc is a regional station in An Giang province belonging to the national network of stations in Vietnam, there is no meteorological station in Tinh Bien, but Chau Doc (25 km away) is used as a proxy site.The framework indicates three main research foci, as follows: • Understanding the climate factors that affect water resource availability.• Exploring changing agriculture practices as adaptive solutions to variable water availability • Forms of adaptation and the relationship for better use of water for agriculture at different levels.In the study, the main focus was on the climatic factors affecting the change of water resources, while non-climate forces were not considered in any detail.
Data analysis: Climate data was collected and calculated to get the mean for the year (temperature, humidity), the total annual rainfall, and the highest flood level of the year.The extensive and raw qualitative data are condensed into a brief and categorized into different categories.They are selected to correspond to the research objectives.The findings were documented and discussed according to the outcomes of the research.

Variation of climate factors and Relationship to Agriculture
Climate data displays that average annual rainfall, temperature, humidity, and the highest flood water level have changed in An Giang over the past 25 years.
Figure 3 shows that the annual average temperature has tended to increase gradually over the last 25 years.The data coincides with a previous study showing that the average temperature in the Mekong Delta has fluctuated over the years, but the general trend has tended to be upwards [1].By contrast, the annual average humidity in An Giang has tended to decrease slightly over the same period (figure 4).The average humidity in An Giang varies from about 83 -84% in the rainy season and is slightly lower (77 -80%) in the dry season [27].The annual average rainfall in An Giang is about 1400-1500 mm [11].It is less than the average rainfall of Vietnam (which averages around 1,800 mm per year).However, the annual distribution is highly uneven because the country lies in a tropical monsoonal region.Typically, 80-85% of the total rainfall occurs in the wet season from May to November [28], which may affect the water resource available for agriculture.
The hydrological characteristics of An Giang province strongly depend on the water volume of the Mekong River.In the entire Mekong Delta, the annual flood plays a vital role in underpinning the productivity of the entire system (the flood season occurs in the rainy season from May to November), under normal conditions depositing a large amount of alluvium on the floodplain, maintaining water tables and providing a variety of ecosystem services, including enabling a high output of aquatic resources that have traditionally supported local livelihoods [29].The height of floodwater has an important influence on the alluvial deposition in the field [15].The results show that the flood water level in the past 25 years has tended to decrease sharply (figure 6).As Park et al. (2020) maintain, the main factor that has reduced the frequency of flooding has been river-bed mining of sand and extensive dyke construction, effectively cutting off the floodplain from the main river channels.Many large reservoirs and dams store vast quantities of water upstream in China, Cambodia, Laos, Thailand, and Vietnam, massively altering the annual hydrograph and reducing downstream water availability, with one outcome being that large floods now rarely occur, so floodwater and associated sediment and nutrients hardly ever reach farmer's fields [13,30].
Being considered a climate risk, water resource has influenced many sectors, especially agricultural production.Research on agriculture in the Delta of Vietnam has shown that farmers face a wide range of climate-related and eco-hydrological factors which threaten rice production [31].In Tinh Bien district, agricultural land accounts for 84.49% of the total area, and 71.69% of the population lives in rural areas and relies on agricultural production, so the change in water resources has a strong effect on the livelihood of local inhabitants.Ms H T Le, an officer of the Department of Agriculture and Rural Development of Tinh Bien district, expressed that "the rain has changed abnormally, prolonged rain or no rain for many days affecting the growth and yield of rice.At the sowing stage, rain may last many days, cause waterlogging, or delays the sowing time.If it rains a lot at the harvest time, the rice will fall over and loses yield" (KIP Interview, 2021).It is similar to the study conducted in An Giang noted that the variation of rainfall over the years is the most critical factor affecting rice yield [14].

Shifting of agricultural practices in the rice field.Tinh
Bien district is different from other districts in the province due to a series of hilly outcrops, so Tinh Bien is termed a "hilly district ."It is also important to note that hilly is the concept in the context of the plains, not in comparison to the real mountainous regions of Vietnam.The three main sub-agricultural zones of the district are listed as follows: • The alluvial field is about 20,260 ha (average 2 -3 m above mean sea level).The area has been built up by sediment from Hau River, which is suitable for rice, aquaculture, and wet forest.• The highland field is about 8,953 ha (averages 5 -30 m about mean sea level).The area can grow fruit trees and rice and raise livestock.• The hilly area comprises about 6,330 ha.This region is suitable for minerals, construction materials, eco-tourism, and resorts due to its many hills and beautiful landscapes.
Viet Nam's national agricultural policy has long strived to increase domestic supplies and exports of rice through intensive production, and this is most apparent in the two delta regions of the Red River in the north and Mekong in the south, where about [32].Although crops in Tinh Bien are various, rice is the main crop in the district.The information on rice cultivation in Tinh Bien from 2009 to 2019 is described in Table 2.The table shows that the rice areas have changed from year to year, all part of a longer trend in increased production through more intensive cropping following government policy, but without an increase in rice yields, suggesting a sustainability limit has been reached.This significant increase in rice production, in itself, is putting water supplies across the delta under increasing strain, as most of it relies on both surface water and groundwater irrigation in the dry season (and, to a lesser extent, the wet season), increasing competition for a limited resource and decreases water quality for other ecosystem uses.Rice production jumped markedly between 2017 -2020 as a result of further construction of irrigation systems, adding to the complex network of existing dykes, dams, pumps, and canals that cover the Delta landscape.People switched from double rice cropping to triple cropping rice since the construction of more high dykes and pumps that isolate the paddy fields from the river channels, thereby theoretically protecting them from flooding but also denying the fields the benefits of floodwater, such as the ingression of sediments and nutrients from the Mekong River.Source: [21] In the case of cropping on the hilly slopes above the floodplain, many areas are unsuitable for rice fields due to limited irrigation water availability, so they are mostly dedicated to growing a range of upland crops [33].The total area converted from rice cultivation to growing vegetables and fruit trees in 2018 was 452.67 hectares; in 2019, up to now is 1,427.26hectares.Figure 7 shows the range of upland crops grown in Tinh Bien district over the past ten years, with a trend of crops using less water.Cassava is considered a drought-tolerant crop.Others can be listed as peanuts and beans.
In general, it is found that the agriculture of Tinh Bien district is mainly reliant on rice cultivation and, to a lesser extent, the cultivation of upland crops in the few hilly areas.The recent increase in rice production is due to an increase in the area of the third crop of rice.However, the district authorities have decided not to develop more rice cultivation areas due to water and soil limitations but to encourage farmers to switch to crops that consume less water.

is poor and that it cannot hold water for a long time together with the influence of climate factors contributes to causing water shortages in the area. Ms H T Le, an officer of the Cultivation and Plant Protection sub-department in Tinh Bien district, mentioned that the climate has been erratic, and it affects agricultural production.
The perceptions tend to be somewhat different among farmers.The results indicated that farmers' perceptions of climate effects are varied depending on the place where they live and cultivate.
Farmers living in areas with adequate irrigation systems are not aware of changes in water availability, while farmers cultivating in areas without irrigation are well aware of the effects of water shortages in cultivation areas.
Mr. V D Le, a farmer cultivating in the alluvial field, expressed that the water used in rice cultivation is supplied by the water cooperative.Farmers have enough water for their crops.
Mr. N Chau, a Khmer farmer cultivating the highland field, shared that local farmers are facing a severe shortage of water.Rice cultivation mainly depends on the rainy season (using rainwater).Soil is dry, infertile, and difficult to improve.Sometimes, it is abandoned for six months in the dry season.
In Tinh Bien district, rice is and will be continuously considered the main crop.Rice uses a lot of water than other crops, together with some farmers living in well-function irrigation areas, have not been aware of changes to water supply over time.Farmers can use as much as they want.All contribute to causing water supply decreases.Therefore, it is necessary to have adaptive solutions from the government and the people.

Linkages between local institutional and Farmers' Response
Reacting to environmental changes is not new; farmers have been doing it for centuries, almost since the dawn of history, since the climate is part of the landscape of human habitation [34], [24].In research about climate risks and adaptation strategies in the Lower Mekong River basin, other authors have indicated that there have been various structural and non-structural adaptation practices occurring at the local level.Most of the structural measures received direct or indirect support from government agencies, while non-structural options have been conducted by local inhabitants [35].The research has found that both government actors and farmers have responded to the changes in the availability of water resources in Tinh Bien district.

Building Infrastructure as structural adaptation
As mentioned in the previous part, the water source for rice cultivation in Tinh Bien district is divided into two main eco-regions: deltaic floodplains and several hills.The lowlands get water directly from manmade irrigation canals through pumping stations, and parts of the uplands get water from manmade canal systems, and the majority rely on rainfed agriculture (figure 8). Figure 8 shows a canal system built to serve intensive rice production.Due to the topography of Tinh Bien district with a lot of sandy soils and poor water retention, cement-lined canal systems have been built to limit water loss during transportation.In terms of irrigation system management, Decision No. 144/QD-People's Committee dated 22/01/2020 of the People's Committee of An Giang province approves the decentralization of management of irrigation infrastructure assets within An Giang province.The water pumping process is managed by different agencies depending on the type of equipment and energy source (electrical pumping stations are managed by district and provincial agencies, while diesel pumping stations are managed by local people).The length of canals in the district is shown in Table 3.
In Vietnam, irrigation schemes are managed by government institutions controlled by the Ministry for Agriculture and Rural Development [28].Faced with the current climate crisis, to manage water resources, the Department of Agriculture and Rural Development in Tinh Bien district has to coordinate with other state agencies to ensure enough water for agricultural production is supplied, especially during the dry season.3.3.2Farmer's Action as a non-structural Option.Tinh Bien district, farmers have taken many actions to improve their livelihoods by having a more reliable supply of water.They commonly switch to crops that require less water (e.g., cassava, peanut).They choose other rice varieties.The selected seeds are purebred, so farmers can follow one seasonal crop calendar provided by the local irrigation agency.They use more fertilizers to visit the fields regularly to detect pests since some diseases on rice are easy to develop either in wet or dry weather conditions.Two diseases that cause a lot of rice problems are Rice Blast and Sheath Blight has different growing conditions.Rice blast disease caused by the fungus Pyricularia oryzae lives well in conditions of cloudy weather, low temperatures from 22-30 0 C, and high air humidity of 90-95%.At the same time, Sheath Blight disease caused by the fungus Rhizoctonia solani grows strongly in higher conditions of temperature around 24-32 0 C and high humidity.Some households apply drip irrigation for orchards or vegetables.Other farmers dug fond or repaired canals in their farms to store water.However, the number of farmers who have a place to dig a pond or are eligible to maintain the canal to bring water to the field does not account for a large proportion because this requires investment.In addition, the area for ponds does not generate direct income.Therefore, most of the solutions farmers choose are selecting new varieties and techniques.This is also found in other places in Asia, Bastakoti et al. (2014) have found that local practices reflected the improvement in the management of water resources, such as the use of on-farm water management practices like creating farm ponds, rainwater storage, and dredging the field channels [29].The hope is that the transformation of crop structure shifts to growing more drought-tolerant crops in the district will bring about new and more effective directions in agricultural production for the people, contributing to improving people's lives.Experiences have been noted that in the process of crop restructuring, farmers' action needs the support of the local government for the implementation of measures to be effective [35].

Solutions for better water management.
In the district, there has been cooperation between the local state institutions and farmers in responding to changes in water resources.Local institutions have facilitated adaptation in different ways to meet the current needs.
One of the highlights is that the irrigation system has been developed for the difficult areas of the district for irrigation, so many farmers can now access water for cultivation.Advanced irrigation methods have been introduced to some farmers in the area.However, there are still difficulties in operating the pumping system for both farmers and officials.Understanding carefully the current situation for better cooperation is necessary for water resources management in agricultural production.Some recent problems and their solutions are stated in Table 4.The pumping plan should be prepared appropriately.When there is a change, it must promptly notify the people.
c Water-saving irrigation methods (mainly used on fruit trees and upland crops) are costly.
Current water-saving irrigation solutions are costly and not suitable for all farmers.High investment costs will mean they are mostly suitable for better-off households.
Opportunities exist to subsidize costs for lower-income households, therefore making them more affordable and widely adopted.d Water-saving approaches and technological solutions are not yet common at the community level.Savings solutions should be applied at the community level to improve water-saving efficiency for a bigger group of farmers.This is something that can be addressed by appropriate development policy and practical strategies.f People's awareness concerning the need to conserve water is still low and does not match the urgency of climate change and ecological crisis.
It is necessary to widely disseminate extension advice to the people about saving water approaches, and techniques in farming to both keep up with wider global trends and protect them from the impacts of worsening climate change.
This will require appropriate policy support from the government, as farmers are one of the most vulnerable groups to climate change but also are the major water consumptive sector in the delta.
The Climate change crisis has caused increasingly severe and complex effects over time across Southeast Asia, so a more ecologically rational and economical use of water resources for agriculture is essential, both as a major consumer of water also because farmers are at the front line of change and highly vulnerable to its impacts, having implications to wider food security issues.Since rice is still the main crop in the district, the water-saving techniques offer some potential to reduce usage and increase the adaptive capacity of farmers.It provides the ability to reduce and limit water consumption locally and the ability to apply water quantities according to the plant's needs at each stage of growth, limiting excess water but not affecting yield and plant quality.Among new techniques being trialed, the alternative wet and dry technique (AWD) has shown some potential to be useful in water conservation.In rice plantations in An Giang province, farmers adopting AWD realized not only water-saving effects but also improvements in rice yield and growth [37].AWD is a knowledge-intensive practice for optimizing watering amounts and timing in paddy rice farming.It requires no extra infrastructure, but it does require well-arranged irrigation conditions and additional labor to be effective [38].However, existing paddy irrigation conditions are a crucial factor influencing whether farmers decide to adopt AWD or not [37].Paddies suitable for AWD should be carefully considered from the viewpoint of irrigation conditions and present water scarcity.For further study, the criteria for choosing experience Situation Opportunities fields should be considered carefully in terms of soil structure, topography, and the current irrigation system.In addition, the role of collective action in facilitating adaptation is a key issue where lessons can be learned from successful interventions and good practices elsewhere [24].The willingness of the community is essential since local farmers need to understand the benefits and limitations of the technique for it to be accepted at the community and household levels.

Conclusion
Climate change and multiple impacts of human-related development, including poorly conceived and implemented hydraulic infrastructure development and excessive groundwater abstraction, have affected agricultural production in the Mekong Delta.Several recent papers have noted that the delta may have reached or be reaching a "tipping point" in terms of its socio-ecological sustainability, and food production systems could be significantly threatened in the future due to a range of anthropomorphicrelated causes.Farmers are facing an increasingly uncertain future as combined climate and ecological crises take hold in the region, being felt particularly acutely by smallholder farmers on marginal lands, such as those in the study area.Rice is still the main crop in the district of Tinh Bien, and farmers are heavily dependent on its production, despite it being a significant consumer of water and with relatively low-profit margins.Faced with this situation, the local government and farmers in the region have begun to take action to adapt to these changes.The state's support is mostly structural, mainly through the construction of irrigation systems to carry water to wider areas.However, this infrastructural expansion and redistribution of water can both increase demand, thereby putting additional stress on a limited resource in a time of climate change, but also increase inequalities between individual farmers and user groups.The government, while aware of climate change impacts, both now and in the future, is only beginning to address the multiplicity of problems faced in the complex Delta environment that will require all inhabitants, including farmers, to adapt rapidly in the coming years.Farmers need to be given the tools and education to make wise choices to adapt to change, which must include reducing water consumption and being more ecologically cognizant in their approaches to farming.Local agricultural officers have a vital role to play in raising awareness of farmers about threats posed by climate change and other factors on water resources use; through technological adaptation and resources, use should be enhanced.However, local farmers and officials alike in Tinh Bien district and elsewhere in the Vietnam Mekong Delta need to be facilitated and supported by appropriate policies and practical programs or interventions that focus on the most disadvantaged communities and provide appropriate support that will even up to existing inequalities and allow fair access to water resources for all.

Figure 1 .
Figure 1.The Vietnamese Mekong Delta and location of An Giang province (a); the research site in Tinh Bien District and location of the Chau Doc meteorological station (b).Source:[18,19] Tinh Bien district was selected as the study site because it has been affected by climate change impacts, as have all provinces of the delta to a greater or lesser degree.The location of Tinh Bien district in An Giang Province is shown in Figure1, b.Basic information about the study area is shown in Table1.
• A desk study was conducted as a first step to gain access to the archives held at government institutions at different levels and reports relevant to climate factors affecting water resources, changing agricultural practices in the target area, and any future development strategies.• In-depth interview: Key informant interview was used to question local authorities in the Agricultural and Rural Development Department, Environment and Natural Resources Department, Cultivation and Plant Protection sub-department, Commune officers (KIP-Key Informant Panels), and farmers to get a general understanding of water resource, water management, current agricultural practices and solutions for future adaptation.A total of fourteen meetings were conducted.Fourteen people (six officers and eight farmers) were interviewed individually due to the effects of the Covid 19 Pandemic.• Field survey, the interdisciplinary team, went to the study area to observe the irrigation system, water management process, and crop structure at different times of growing time (land preparation, pumping water, and harvesting time).Three field trips were conducted in November 2020, March 2021, and June 2021.The trip lasted from 2 to 3 days; the research team went to the area to contact local officials for field reference.• To gather four types of climate data at the Chau Doc hydro-meteorological station in 25 years

Figure 2 .
Figure2.The framework to study changing agricultural practices to variable water resources in An Giang province Source: adapted from[26] The framework indicates three main research foci, as follows:• Understanding the climate factors that affect water resource availability.• Exploring changing agriculture practices as adaptive solutions to variable water availability • Forms of adaptation and the relationship for better use of water for agriculture at different levels.In the study, the main focus was on the climatic factors affecting the change of water resources, while non-climate forces were not considered in any detail.

Figure 3 .
Figure 3.Figure 3. The increasing trend in mean annual temperature from 1996 -202 0 at Chau Doc hydro -met station.

Figure 3 .
Figure 3.Figure 3. The increasing trend in mean annual temperature from 1996 -202 0 at Chau Doc hydro -met station.

Figure 4 .
Figure 4. Trends in mean annual humidity from 1996 -2020 at Chau Doc hydro -met station .

Figure 5 .
Figure 5.The trend in annual average rainfall at Chau Doc hy dro -met station from 1996 -2020.

Figure 6 . 6 Figure 5
Figure 6.The sharp decline of the highest flood water level on Hau River from 1996 to 2020 in An Giang province.

Figure 7 .
Figure 7. Status of upland crops in Tinh Bien district, including sweet potato and cassava, planted as crops that require less water than rice.

Figure 8 .
Figure 8. Canal under construction (left picture) and completed canal delivering water to the rice fields (right picture) in Van Giao Commune, Tinh Bien district.Figure8shows a canal system built to serve intensive rice production.Due to the topography of Tinh Bien district with a lot of sandy soils and poor water retention, cement-lined canal systems have been built to limit water loss during transportation.In terms of irrigation system management, Decision No. 144/QD-People's Committee dated 22/01/2020 of the People's Committee of An Giang province approves the decentralization of management of irrigation infrastructure assets within An Giang province.The water pumping process is managed by different agencies depending on the type of equipment and energy source (electrical pumping stations are managed by district and provincial agencies, while diesel pumping stations are managed by local people).The length of canals in the district is shown in Table3.

11 Table 4 .
1306 (2024) 012014 IOP Publishing doi:10.1088/1755-1315/1306/1/012014Current situation and opportunities for improved water use in Tinh Bien district.a The terrain of the district has different There is a need for closer cooperation between officials and topography, so water is inevitably farmers.Take advance of the natural topography, water hard to distribute equally to all moves from high to low fields (the pumping station should farmers' fields.Situation Opportunities operate continuously to supply enough water for the area for all areas).b Farmers sometimes have to spend more time getting water because the pumping program is not carried out as scheduled,

Table 2 .
Area, yield, and rice production in Tinh Bien district from 2009 to 2019.
a : It is calculated for all crops cultivated in the area year-round.

Table 3 .
The status and levels of the irrigation systems supplying agriculture in Tinh Bien district.