Evaluation of Water-Storage and Water-Saving Potential for Paddy Fields in Gaoyou, China

Abstract

In China, the stress on agricultural water resources is becoming increasingly severe. In response, a range of water-saving irrigation (WSI) policies and practices have been promoted to improve irrigation efficiency. In this study, a water-balance model in paddy fields was calibrated and validated using a 2-year field experimental dataset collected from an irrigated area in Gaoyou, China, in 2014–2015. The model was used to assess the effects of WSI practices and provides options for implementing water-price reforms. Results show that paddy fields effectively retain rainfall with utilization rates greater than 70% for both shallow wet irrigation (SWI) and shallow humidity-regulated irrigation (SHRI) scenarios. The estimated average water-saving rates from 1960 to 2015 using SWI and SHRI are 33.7% and 43%, respectively, which represent considerable reductions in water consumption. The benefits of WSI practices combined with water management policies are also evident. For example, conversion of irrigation water to industrial water yields a 3-year average water fee of 205.2 yuan/ha using SWI and 20.6 yuan/ha using SHRI, considerably reducing farmers’ financial burden for agricultural water supplies. In conclusion, we recommend the adoption of SWI and SHRI practices in southern China as a means of partially alleviating China’s water-shortage problem.