In the heart of China’s rapidly urbanizing landscape, Nanjing City has become a focal point for sustainable agricultural water management. A recent study led by Jingchi Si from the School of Forestry at Nanjing Forestry University, published in the journal *Ecological Indicators* (translated as “生态指标”), sheds light on the city’s crop water footprint and offers insights into optimizing planting structures for better water use efficiency.
The research, which spanned two decades from 2002 to 2022, employed the CROPWAT model and Mann-Kendall trend analysis to assess the spatiotemporal changes in the crop water footprint (WF) of major crops in Nanjing. The findings reveal that over 90% of the crop WF was concentrated in the new industrial and ecological agricultural areas, with a notable decrease of 11.67% in the total crop WF from 1.08×1012 m³ in 2002 to 0.959×1012 m³ in 2022.
“Our study highlights the critical need for comprehensive evaluation of crop water use efficiency to achieve sustainable agricultural water management,” said lead author Jingchi Si. “By understanding the spatiotemporal dynamics of crop water footprints, we can make informed decisions that balance crop production and water consumption.”
The study also introduced several key indicators to assess water use efficiency. The Agricultural Water Footprint Intensity (AWFI) remained stable, while the Agricultural Water Scarcity Index (AWSI) showed a downward trend. The Blue Water Scarcity Index (BWSI) averaged 0.108, and the Water Use Efficiency Index (WUEI) was 0.365. The Comprehensive Agricultural Water Use Indicator (CWI) stood at 0.311, indicating a moderate level of overall crop water use efficiency in Nanjing City.
One of the most compelling aspects of the research is its potential commercial impact on the energy sector. By optimizing planting structures, Nanjing City could reduce crop water consumption by 0.91 billion m³ and save arable land equivalent to 7,148.58 hectares. This not only benefits agricultural sustainability but also has implications for water and energy management, as reduced water consumption can lead to lower energy demands for water pumping and treatment.
The findings provide a scientific basis for informed agricultural water governance in rapidly urbanizing regions like Nanjing. As cities continue to expand, the pressure on water resources intensifies, making studies like this crucial for sustainable development.
“This research offers a roadmap for other urbanizing regions to follow,” Si added. “By adopting similar methodologies, cities can achieve a balance between agricultural productivity and water resource management, ensuring long-term sustainability.”
The study’s insights are particularly relevant for the energy sector, where water and energy are intrinsically linked. Efficient water use in agriculture can reduce the energy footprint associated with water extraction, treatment, and distribution. As such, the research not only contributes to sustainable agriculture but also supports broader energy conservation efforts.
In conclusion, the research led by Jingchi Si and published in *Ecological Indicators* provides a valuable framework for assessing and optimizing crop water use efficiency. Its findings offer actionable insights for policymakers, agricultural practitioners, and energy sector stakeholders, paving the way for more sustainable and efficient water management practices in urbanizing regions.