By Dr. Praneet Ngamsnae
Water resource management is a pivotal factor directly influencing sustainable development across various societal and economic dimensions, particularly within an agricultural sector which necessitates a substantial continuous water supply. The water footprint serves as an effective metric for quantifying and evaluating the volume of water utilized in diverse agricultural production processes, including crop cultivation and livestock farming. Effective management of the water footprint is crucial to reduce excessive water use and enhance water use efficiency.
An implementation of efficient water footprint management strategies not only aids to reduce water consumption within the agricultural sector, but also bolsters long-term water security and environmental sustainability, thereby benefiting both farmers and the broader society. Investigating and analyzing appropriate water footprint management practices will foster a deeper understanding and practical application within Thai agriculture in the future.
Definition of Water Footprint
The water footprint is a metric employed to quantify the volume of water utilized in the production of all goods and services within an economic system or a specific production process. This encompasses both direct and indirect water use associated with all production activities. Calculating the water footprint provides insight into the actual water consumption, facilitating the development of sustainable water use strategies. The water footprint comprises the following components.
Blue Water Footprint: Refers to the volume of surface and groundwater consumed directly in the production of goods and services, including irrigation, industrial production, and household use. The blue water footprint is significant as it involves water that can be directly controlled and allocated.
Green Water Footprint: Denotes the volume of rainwater absorbed and utilized by plants for growth, particularly in agricultural systems that do not employ irrigation. Green water use represents the utilization of naturally occurring water resources. It plays a crucial role in the cultivation of crops in many places.
Grey Water Footprint: Indicates the volume of water required to dilute pollutants produced during the production process to meet acceptable water quality standards. The grey water footprint reflects the impact of production activities on natural water quality.
Concepts for Managing Water Footprint in Agriculture
Managing the water footprint in agriculture entails a multifaceted approach that considers all three types of water usage (blue, green, and grey). The process commences with an analysis and an assessing of the water footprint in production processes to identify water usage volumes and their environmental impacts. This is followed by the development of an efficient water use plan.
The principal concept is to enhance water use efficiency and to minimize water loss through modern irrigation technologies, such as drip or sprinkler systems. Additionally, the judicious application of fertilizers and chemicals is crucial to mitigate the grey water footprint and reduce water pollution.
Conservation and restoration of natural water ecosystems, such as creating buffer zones around water bodies and cultivating drought-resistant and low-water-use crops in water-scarce areas, are methods that help reduce water use in agriculture.
Effective water footprint management will improve water security and long-term environmental sustainability, benefiting both farmers and society.
Water Footprint in General Aquaculture Production
The water footprint associated with aquaculture and food production comprises primarily of blue water and green water (Falkenmark 2006). The grey water, or wastewater, remains in the environment, and a portion of the rainwater returns to the atmosphere through evaporation without direct use. So, aquaculture relies heavily on blue and green water sources, making their acquisition critical for aquaculture production.
Blue water sources account for 39% of the water used (Molden 2007) and are derived from rainfall, surface water, and groundwater. This includes water from runoff, storage, and irrigation found in canals, lakes, ponds, reservoirs, rivers, fields, and wetlands. Blue water is used in inland freshwater aquaculture and brackish water aquaculture along the coast. Green water sources account for 60% of the water used and they come from rainwater and soil moisture, plus the water stored in estuaries, lakes, mangroves, seas, and oceans used in marine aquaculture. Blue and green water cannot be separated.
The water footprint in aquaculture systems is a measure of both direct and indirect water use. The water footprint of a product (e.g. fish) is the volume of water used to produce it, measured and summed up throughout the entire supply chain (Hoekstra 2011). Although aquaculture uses water efficiently, the water footprint includes water lost from ponds through seepage and evaporation, and water used to produce fish feed. Moreover, aquaculture can negatively impact water resources by causing water pollution, known as the grey water footprint. The water footprint for aquaculture varies significantly depending on the type of aquatic species farmed and the farming system employed (Guzmán-Luna 2021).
Water Footprint (WF) and Water Productivity (WP)
Water Footprint (WF) is measured in cubic meters of water per kilogram of product. It is the inverse of Water Productivity (WP), which is measured in kilograms of product per cubic meter of water. The water footprint for aquaculture includes water lost, polluted water, and water used in feed production. The water footprint of fish production varies depending on the fish group and culture system used. For example, carp and catfish have high WF values of 61.4 and 52.2 cubic meters per kilogram, respectively, while shrimp and tilapia are more water-efficient, with WF values of 4.4 and 15.9 cubic meters per kilogram, respectively (Ahmed 2018).
Regarding the three main aquaculture systems, it seems that extensive systems require the most water (77.2 cubic meters per kilogram), followed by semi-intensive (36.0 cubic meters per kilogram), and intensive systems (33.5 cubic meters per kilogram). The global average water footprint for aquaculture is 40.4 cubic meters per kilogram (Waite 2014).
Water Productivity (WP) refers to the physical output per unit of water used, measured as the weight of the product per unit of water (kilograms’ worth of product per cubic meter of water). Water productivity in various aquaculture systems, measured in kilograms per cubic meter of water, shows that intensive recirculating systems have WP values between 0.71-2 kilograms per cubic meter (Verdegem 2006). General aquaculture WP depends on the production process and type of aquatic species, ranging from 0.01-1.6 kilograms per cubic meter (Lemoalle 2008). Intensive systems range from 0.05-1 kilogram per cubic meter (Molden 2010). These data illustrate the varying efficiency of water use in different aquaculture systems and their production capabilities according to the systems and processes employed.
Comparison of Water Use in Rice-Fish Farming and Monoculture Rice Farming
In monoculture rice farming, the traditional system typically uses water with a depth of 2.5-7.5 centimeters to ensure optimal growth of the rice. However, the overall water usage remains high due to the reliance primarily on blue water, which includes surface and groundwater. The average water productivity in monoculture rice systems varies based on water usage, evaporation, and agricultural practices that affect total water consumption.
Conversely, rice-fish farming requires more water than monoculture rice farming, since it must maintain water levels in the fields to support fish growth. Rice-fish farming efficiently uses both blue water and green water (rainwater absorbed into the soil). Fish farming does not deplete water, but recycles it within the system. The physical water productivity in rice-fish farming is higher than in monoculture rice farming, estimated at around 1.21 kilograms per cubic meter compared to monoculture rice farming’s average of approximately 0.74-1.09 kilograms per cubic meter (Ahmed 2018).
Thus, rice-fish farming uses more water in terms of total volume, but achieves higher water efficiency due to increased yields of both rice and fish. Rice-fish farming effectively and efficiently utilizes both blue and green water without excessive use of blue water, while significantly increasing food production. The water use in rice-fish farming is more sustainable and reduces evaporation and water loss compared to monoculture rice farming.
The Role of Water in Rice-Fish Farming Systems
The cycle and the role of water in rice-fish farming systems are centered on the balance between blue water (surface and groundwater) and green water (soil moisture from rain). Rainwater acts as the primary source, contributing to surface runoff, groundwater recharge, and soil moisture retention. Blue water is used to irrigate the rice fields, while green water stored in the soil is crucial for the combined growth of rice and fish.
Incorporating both rice and fish in the same area creates a sustainable agricultural practice. This system effectively utilizes rainwater and optimizes the use of surface and groundwater, enhancing the productivity and sustainability of the farming practice (Ahmed 2022).
The control of water evaporation from watersheds and terrestrial ecosystems, the soil saturation, and the return flow of water to aquatic and terrestrial ecosystems, are all crucial for maintaining balance. By enhancing the efficiency of blue and green water resource use, integrating fish farming with rice cultivation can not only improve water efficiency and agricultural productivity, but also promote environmental conservation and sustainability in integrated farming practices.
Challenges in Managing the Water Footprint in Integrated Rice-Fish Farming Systems
The integrated rice-fish farming system, which combines rice cultivation and fish farming in the same area, optimizes resource use and increases farmers’ income. However, managing the water footprint in this system poses several challenges.
Water Quantity Control: Maintaining an optimal water level for both rice and fish requires meticulous management, as rice needs a significant amount of water while fish require high-quality water. Balancing the two requires knowledge and skills in water management.
Water Quality: Fish farming in rice fields can increase organic matter in the water and potentially cause turbidity or chemical accumulation, which can affect both rice and fish. Close monitoring of water quality is essential.
Fertilizer and Chemical Management: The use of fertilizers in rice fields can impact the fish. Selecting non-toxic fertilizers and chemicals, and applying organic farming practices, are good alternatives.
Disease and Pest Control: Both rice and fish are susceptible to diseases and pests. Effective planning and execution of prevention and control measures are necessary.
Adaptation to Climate Change: Changing climate conditions affect rainfall patterns and water levels. Planning and adapting appropriately are crucial.
Managing the water footprint in this system requires careful planning and execution. Studying and learning appropriate methods will help farmers manage water efficiently and sustainably.
Reducing the Water Footprint in Rice-Fish Cultivation
Reducing the water footprint in rice-fish cultivation can be achieved through the following methods.
Maximizing the Use of Rainwater: Build small reservoirs or embankments around the fields to store rainwater, reducing the need for blue water irrigation. Plant rice and rear fish during the rainy season when there is sufficient rainwater, thus decreasing reliance on other water sources.
Improving Soil Structure: Use organic fertilizers or compost to enhance the soil’s water retention capacity, and thereby reduce water loss from evaporation and seepage. Grow cover crops to maintain soil moisture and reduce water evaporation.
Managing Irrigation Efficiently: Implement drip or sprinkler irrigation systems that use less water and are highly efficient. Utilize soil moisture sensors to accurately control watering based on the specific needs of the crops and fish.
Managing Floodwaters and Water Storage: Prevent external floodwaters and minimize internal water loss. Use ponds or reservoirs to store excess water during periods of abundance for use during dry periods.
Selecting Appropriate Plant and Fish Varieties: Choose rice and fish varieties that are resilient to environmental conditions and require less water. Select varieties that are well-suited to the local climate and seasons to reduce water needs.
Training and Knowledge Promotion: Promote and train farmers on efficient water management techniques and sustainable rice-fish farming practices. Develop water management plans and offer advice on using technology to reduce water usage.
Implementing these strategies will effectively reduce water usage in rice-fish cultivation, resulting in sustainable farming practices and increased productivity.
Conclusion
The water footprint in aquaculture systems is a critical issue that affects surrounding ecosystems and the sustainability of food production. Aquaculture food production systems can negatively impact the environment by discharging waste into the environment, leading to water pollution. Traditional production systems place high demands on natural water resources and can cause ecological and environmental impacts through wastewater discharge.
Reducing the water footprint in integrated rice-fish farming requires proper management and system design to ensure efficient water use and balance between water used for fish farming and water used for rice cultivation. This ensures water efficiency and nutrient cycling. Additionally, measuring water usage and adopting efficient water use methods are essential.
Integrated rice-fish farming can enhance water use efficiency and sustainability and increase food production while reducing water use compared to traditional monoculture rice farming. However, despite the environmental and economic benefits of integrated rice-fish farming, challenges such as water scarcity and the need for effective water management remain. Collaboration among stakeholders, including farmers, government agencies, researchers, and policymakers, is crucial to support the widespread adoption of rice-fish farming systems and enhance their potential for sustainable food production globally.
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