In the heart of Spain’s Lower Guadalquivir Marshes, a battle is being waged against water scarcity and salinity, and a new study led by Blanca Cuadrado-Alarcón of the Institute for Sustainable Agriculture (IAS) and the University of Córdoba is providing valuable insights into how to win it. The research, published in the journal Agricultural Water Management, focuses on the rice-growing region on the right bank of the Guadalquivir River, a area that spans approximately 22,500 hectares and is crucial for both local economies and the energy sector, which relies on stable agricultural practices for bioenergy feedstocks.
The Guadalquivir Marshes are a vital rice-growing region, but they face significant challenges due to high water demand and salinity issues. Each year, rice cultivation in this area requires around 1,000 millimeters of flood irrigation at the district level. However, individual fields often receive up to four times this amount due to high surface drainage and water recirculation rates. This excessive water use is not only environmentally unsustainable but also economically costly, impacting both farmers and the energy sector, which depends on stable agricultural practices for bioenergy feedstocks.
To address these challenges, Cuadrado-Alarcón and her team developed a district model to explore management options that can help mitigate water scarcity and salinity. The model, a ‘bucket’ mass balance system with circulation rules and capacity constraints, analyzes daily water and salt balances in the rice-growing area. This innovative approach conceptualizes the system as a mesh layout of the distribution network, where connection nodes, consisting of drains, collect return flows from irrigation units and provide reused water for irrigation.
“The interaction between irrigation units is crucial,” explains Cuadrado-Alarcón. “By understanding how water and salt move through the system, we can identify opportunities for improvement and develop strategies to enhance water use efficiency and reduce salinity impacts.”
The model’s effectiveness was validated by comparing its outputs with measured values of discharge volumes and salinity at specific points within the rice-growing area. The results showed a good agreement, indicating the model’s reliability. Subsequently, the team simulated two groups of alternative scenarios. The first group focused on the benefits of upscaling on-farm irrigation practices and their effectiveness in saving water. The second group explored strategies for minimizing salinity-related constraints.
One of the most compelling aspects of this research is its potential to shape future developments in the field. By providing a tool to simulate different water management practices and evaluate their impact, the model offers a roadmap for improving the performance of the entire district. This is particularly relevant for the energy sector, which relies on sustainable agricultural practices for bioenergy feedstocks.
“The model has proven to be a useful tool for simulating different water management practices and evaluating their impact,” says Cuadrado-Alarcón. “This can help us make informed decisions and implement strategies that enhance water use efficiency and reduce salinity impacts, ultimately benefiting both farmers and the energy sector.”
As the world grapples with increasing water scarcity and salinity issues, the insights from this study are more relevant than ever. By providing a comprehensive understanding of water and salt dynamics in rice-growing areas, the research offers a blueprint for sustainable water management practices that can be applied not only in the Guadalquivir Marshes but also in other regions facing similar challenges. The study, published in Agricultural Water Management, which translates to English as Agricultural Water Management, underscores the importance of interdisciplinary collaboration and innovative modeling in addressing complex environmental and economic issues.