Assessing the potential of domestic reclaimed water for agricultural irrigation in Taiwan

Taiwan experiences significant variability in its water resources, with uneven rainfall distribution leading to challenges in water management, particularly in agriculture. This study investigates the potential of reclaimed water as a supplementary source for agricultural irrigation to address water shortages and improve resource efficiency. The study analyzes data from Taiwan's irrigation management offices and explores two scenarios: the current reclaimed water production capacity and the maximum potential supply. Results indicate that under current conditions, reclaimed water could reduce the overall irrigation water deficit from 28.1 to 20.1%, with a further reduction to 15.4% under maximum capacity. The northern region, in particular, could eliminate its water deficit entirely under both scenarios, while the central and southern regions could see significant improvements. Furthermore, reclaimed water has the potential to irrigate an additional 49,759.7 ha of paddy fields under current capacity, expanding to 82,836.3 ha under maximum capacity. However, the use of reclaimed water must be carefully managed to prevent increased ammonia nitrogen concentrations in rivers, which could lead to water pollution. This study highlights the critical role of reclaimed water in mitigating the impacts of drought and improving water resource sustainability in Taiwan's agricultural sector.

• Central Taiwan experiences the most significant irrigation water shortages.

• Water shortages peak during rice-growing seasons, varying across regions.

• Recycled water can significantly alleviate irrigation demand, particularly in northern Taiwan.

• Recycled water reduces ammonia nitrogen loads, mitigating river pollution.

• Reclaimed water can expand irrigated farmland, especially in northern and southern Taiwan.