Abstract

Paddy field dams support both agricultural production and flood mitigation. However, their recovery after dam functionality, particularly within Land Improvement District-managed areas, has not been sufficiently studied. This study develops a hierarchical priority-zoning framework to guide recovery-based management in the Shin-Tonegawa Land Improvement District, Japan. Three key indicators – the actual drainage flow distance to the main drainage channel, the actual drainage flow distance to the final drainage point, and the potential storage volume – were calculated for individual paddy field plots and aggregated dam units. These indicators were then analysed using hierarchical clustering, decision-tree modelling, and analysis of variance to identify classes and assess the relative influence of each indicator. The findings show that hydraulic accessibility is the primary driver of recovery priority at both spatial scales. The plot-level results indicate that fields near the main drainage channel and outlet point can be drained quickly. At the dam level, downstream dams near the outfall must be prioritized to restore trunk-channel capacity and prevent upstream congestion. By integrating these two perspectives, this study proposes a nested recovery framework in which dam-level prioritization structures system restoration, followed by plot-level triage within prioritized dams.