Flood drainage rights in watersheds based on the harmonious allocation method

Abstract Flood drainage rights (FDR) refer to the rights of all regions in a watershed to drain floodwaters into river reaches under the permission of law. FDR is an important measure used to manage the flooding in various regions of China. This paper explores the problem of flood drainage conflicts caused by regional competition for FDR during flood disasters. We designed an FDR allocation indicator system based on the principles of fairness, efficiency, sustainable development, respect for historical context, and flood resilience strategy. We used the interval multi-objective allocation model based on the projection method to create an FDR pre-allocation plan, and iteratively improved it until it exceeded the standards of a harmonious diagnosis method, thereby obtaining a harmonious allocation plan. The Jiangsu section of the Sunan Canal in the Yangtze River Delta region of China was taken as an example, using data from 2009 to 2018, to study the suitability of our approach and compare it with other indicator systems. Our results showed that: (1) in the FDR pre-allocation, the proportions of FDR obtained by Suzhou, Zhenjiang, Wuxi, and Changzhou were 32.81%, 19.83%, 24.68%, and 22.69%, respectively. However, the FDR pre-allocation scheme did not pass the harmonious diagnosis and would have been objectionable to some regions. (2) After two rounds of harmonious adjustment, the model yielded a final scheme that would promote the harmonious development of the region and improve the acceptability of the FDR allocation plan. In the harmonious distribution of FDR, the proportions of FDR obtained by Suzhou, Zhenjiang, Wuxi, and Changzhou were changed to 29.18%, 20.03%, 28.10%, and 22.69%, respectively. (3) The allocation results based on our five-principle approach were the most harmonious of the tested plans. Our method is geared toward solving the problem of flood drainage conflicts between regions to ensure an orderly flood drainage situation, reduce flood losses, and promote the harmonious development of the entire watershed. As such, it provides a reference for governments and agencies involved in FDR management.