Globally, agriculture accounts for the largest share (72%) of total annual freshwater withdrawals, but the share varies significantly across regions and countries (World Bank 2019a). According to the World Bank, South Asia has the largest share of agricultural water use (91%), while the European Union has the smallest (31%). Among the countries with the largest agricultural production globally (measured in value terms in US dollars), the share of agricultural water use is highest in India (90%), followed by the People’s Republic of China (PRC) (64%), Brazil (61%), and the United States (40%) (World Bank 2019b). What is more, on average, water use in the agriculture sector in least developed countries (based on United Nations classifications) accounts for about 91% of the global total (Table 1).
Table 1: Share of Agriculture in Total Annual Freshwater Withdrawals, 2019
a Freshwater withdrawals as a proportion of available freshwater resources.
Source: Food and Agriculture Organization (FAO), AQUASTAT data (accessed 15 March 2023).
Another crucial issue is that despite rapidly increasing water demand from non-agricultural sectors, absolute demand for water will remain much higher in agriculture for the next 2 decades (Gruère and Shigemitsu 2021). This is primarily due to the necessity of satisfying food demand for the rising global population, which is projected to increase from over 7 billion people in 2017 to around 10 billion people in 2050 (United Nations 2022). Additionally, with higher economic growth in developing countries, per capita, food demand growth is more likely to be a driving factor behind food demand in 2050 compared to population growth alone (van Dijk et al. 2021). To meet the extra food demand in 2050, global production of crops and livestock is estimated to be at least 60% higher than it was in 2006. A more serious concern is that even with new advancements in farming practices and innovations in agricultural systems, the global food supply will face daunting challenges from the impacts of climate change on water resource availability and its spatial distributions (Boretti and Rosa 2019).
Water resource management in agriculture: Challenges
The unsustainable use of water resources in agriculture and other sectors, climate change, and inadequate institutional policies are some of the major challenges in agricultural water resource management, with severe implications for future food and water security.
Unsustainable use of water in irrigation
Although irrigated agriculture represents 20% of total cultivated land and contributes to almost 40% of global food production, it is highly unsustainable (Rosa et al. 2019). In some countries, such as the PRC, irrigated agriculture contributes nearly 75% of total grain production, indicating a critical role for irrigation water management in ensuring national food security and world grain market stability. It is predicted that irrigation water demand will rise by 13.6% by 2025, while about 15% of freshwater will be diverted from agriculture to domestic use and industry. This could cause acute water shortages for agriculture in the future. Given that almost 52% of global irrigation is unsustainable, current global food production is largely responsible for the depletion of freshwater stocks and environmental flows, leading to the unsustainable use of water (Rosa et al. 2019). These issues show the importance of improved water management in agriculture.
Unsustainable consumption of water in food systems
Globally, increases in the purchasing power associated with economic growth and urbanization have enormously changed the consumption patterns of a large segment of the population toward animal-based proteins (Rahut et al. 2022; Sans and Combris 2015). This has led to an increase in the production of livestock in many countries, thereby increasing pressure on water resources. For example, between 1985 and 1996, red meat, poultry, and egg production increased by almost 209% in the PRC (Fuller, Hayes, and Smith 2000).
Climate change
Climate change considerably affects the available water for agriculture and also contributes to water-related hazards, such as floods and droughts. As a result, water scarcity due to climate change and increased demand for water from other sectors of the economy can limit the agriculture sector’s capacity to ensure food security unless issues related to improved water management in agriculture are properly addressed (FAO 2017a). The global population at risk of hunger is also expected to be much larger when considering the impacts of climate change (van Dijk et al. 2021).
Institutional policy
Existing institutional policies, both at the national and international levels, cannot adequately address agricultural water management to secure future water and food security. For example, there is a massive trade in virtual water across borders. It is estimated that 60% of the global virtual transfers of unsustainable irrigation water consumption are driven by exports of cotton, sugar cane, fruits, and vegetables (Rosa et al. 2019). The mismatch between spatial water distribution and food production systems also exhibits the need for better institutional policy.
The way forward
Resolving future water challenges in agriculture requires a systematic reconsideration of water management in the agricultural sector and reassessment in the broader context of overall water resources management and water policy in agriculture.
Reconsidering the demand and supply side of agricultural water resource management
Better management refers to improving the water allocation system and enhancing efficiency in use. A proper water pricing mechanism is essential for improving water allocation in agriculture, while enhancing water use efficiency calls for better irrigation technology and practices and proper environmental regulations. However, socioeconomic and political issues and climate change impose several restrictions on water allocation in agriculture. Better water management in agriculture is, thus, not only related to technological issues but involves many other considerations, such as the social behavior of farming communities, economic constraints, and legal and institutional frameworks.
In agriculture, demand-side measures for water management refer to those methods that reduce the amount of water that is being used for agricultural activity. Several measures can be applied as demand-side measures: i) structural and/or operational changes, such as replacing inefficient water pumps, using drip irrigation, laser land leveling, etc.; ii) economic measures, such as financial incentives for reducing water waste in irrigation, or disincentives (or taxes) on overuse; and iii) the provision of training and education to farmers to change their behaviour and make them aware on the importance of using water-saving technologies. Due to a lack of proper demand-side measures, the groundwater in many developing countries largely suffers from a situation that resembles the “tragedy of the commons.” Existing rules in many developing countries give landowners the right to use the groundwater on their land, while the landowners are not legally liable for groundwater depletion due to unsustainable use. The lack of institutional rules and regulations to effectively enforce the rate of groundwater extraction has led to the severe depletion of groundwater tables in major food-producing regions of the world.
Supply-side measures for water management in agriculture are associated with alternatives that increase the amount of water available for agricultural use. This is done mainly by increasing storage capacities, recharging groundwater tables, using technology to clean water so that it can be used in agriculture, and finding new sources. Several supply-side management techniques can be expensive and, thus, their implementation may face financial barriers in developing countries. Yet, implementing small farm-sized dams that help reuse run-off water from other crops to irrigate crops can be a suitable option for small farmers in Asia. Additionally, growing crops based on water requirements and water availability is important. Both supply- and demand-side measures are crucial in water management, particularly in light of water depletion and given that demand-side measures such as water pricing are effective and easy to implement.
Prioritizing a food system approach rather than an agricultural production system approach only
Sustainable food systems depend on sustainable water management and vice versa. Therefore, rather than looking at agricultural water management as only an agricultural production system, we need to also consider it at the food-system level (FAO 2017b). This requires a better understanding of multiple domains, actors, and multiple aspects of food systems. Such a vision brings policy coherence and contributes to designing effective incentive schemes for systematic change in agricultural water use behavior that is required for the optimal use of water resources (Uhlenbrook et al. 2022). Moreover, policies and programs that create less-water-intensive supply chain processes, increase the consumption of less-water-intensive foods, and reduce food loss and waste may offer similar levels of effectiveness in reducing system-wide water consumption that is equivalent to improvements in irrigation efficiency (Lundqvist et al. 2008; Marston et al. 2021).
Reducing the mismatch between the spatial distribution of water and the production of water-intensive agricultural products
The uneven distribution of water and fertile land area largely affects agricultural production and water management in agriculture. In many regions of the world, water-intensive crops and livestock are not always grown in water-abundant regions. For example, the northern PRC, a water-scarce region, is a main exporter of virtual water (Cai et al. 2020). This is mainly due to the mismatch between the spatial availability of agricultural land and water resources. Therefore, more research is needed to reduce such a mismatch so that both land and water use efficiency can be attained in agriculture at an affordable cost (Xu et al. 2021).
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