Rice is one of the most important food crops in China and is also the largest user of agricultural water. Experiments were conducted for two consecutive years at two locations of Jiangsu province to study the effect of four irrigation methods with four replications (shallow water irrigation (FSI), wet-shallow irrigation (WSI), controlled irrigation (CI), and rain-catching and controlled irrigation (RCCI)) on drainage, rainwater utilization rate, pollutant load of N and P, irrigation water, grain yield, and water use efficiency. The results show that FSI treatment used the largest irrigation amount, which is significantly higher than the other three irrigation methods, but the southern part of Jiangsu province especially Nanjing and riverside areas are relatively rich in water resources. It can be seen from our findings that FSI and RCCI are the best irrigation methods in Nanjing area to get a higher yield. However, the yield of CI treatment varies greatly; the annual and seasonal yield changes of CI treatment are higher than those of other treatments; and the risk of yield reduction is greater. Thus, considering water saving and high efficiency, RCCI is a better irrigation strategy than FSI. Combined with the following analysis, it can be seen that RCCI irrigation treatment has less nitrogen and phosphorus pollution load with no significant difference in yield in Lianshui and in 2017 in Nanjing area. Therefore, RCCI is more suitable for irrigation in Lianshui and similar areas.

In this study, an FDR allocation scheme based on synergetic theory was designed to alleviate the drainage conflicts caused by the grabbing of flood drainage rights (FDR) in each region of the basin. An FDR allocation index system was constructed by employing synergetic theory and following the principles of safety, equity, efficiency, and sustainability. A new multi-criteria decision-making method, called FBWM-Grey-TOPSIS, was developed, which is based on the integration of the fuzzy best–worst method (FBWM) and Grey-TOPSIS. Among them, the FBWM method was used to distinguish the importance of subsystems and order parameters, and the Grey-TOPSIS method is applied to obtain the optimal FDR assignment results. Taking the Jiangsu section of the Sunan Canal as an example, the FDRs of the four regions in the basin were allocated. The results reveal that the proportion of FDRs obtained in descending order is Changzhou (32.69%), Suzhou (24.88%), Wuxi (23.01%), and Zhenjiang (19.42%). In addition, the performance of the proposed method is demonstrated by sensitivity analysis and comparative analysis with the existing methods. The methodology and research results presented in this paper can help governments and agencies achieve a scientific allocation of FDR in watersheds, thus promoting harmonious watershed development.

Under the background of the worsening global food and water crisis, efficient agricultural practices have become increasingly important. This study investigated the impact of different irrigation and cultivation modes on rice growth parameters, gas exchange, rice yield components, and water footprints in Jiangsu, China. Four treatments were employed in a randomized complete block design with three replications: (i) transplanted rice with frequent shallow irrigation (T-FSI), (ii) transplanted rice with rain-catching and controlled irrigation (T-RCCI), (iii) direct-seeded rice with frequent shallow irrigation (D-FSI), (iv) and direct-seeded rice with rain-catching and controlled irrigation (D-RCCI). The results revealed that the D-RCCI treatment significantly improved growth and physiological parameters. The D-FSI treatment drastically increased rice yield whereas T-RCCI increased the stem bending resistance and reduced lodging risk. The water footprint analysis showed significant water savings by optimized management practices. Compared to T-FSI, the T-RCCI, D-FSI, and D-RCCI treatments reduced the blue-green water footprint by 33%, 25%, and 25%, respectively. Additionally, water production efficiency increased by 13%, 106%, and 154% for T-RCCI, D-FSI, and D-RCCI respectively. The water footprint per unit yield of T-RCCI, D-FSI, and D-RCCI treatments was significantly reduced by 12%, 5,3%, and 63% compared to T-FSI. Overall, D-RCCI is the optimal strategy for rice cultivation in Jiangsu province and similar climatic areas due to its positive impact on yield, water savings, and environmental benefits.