Author(s): Shinji Fukuda

Linked Author(s): Shinji Fukuda

Keywords: Irrigation canals; Fish assemblages; Aquatic vegetation; Data-driven analysis; Habitat assessment

Abstract: Urban and peri-urban waterways play an increasingly important role in sustaining aquatic biodiversity under intensive human regulation. Irrigation canals and spring-fed streams represent contrasting but interconnected flow regimes, where anthropogenic flow control and natural groundwater inputs jointly shape ecohydraulic conditions in these systems. Despite their ecological importance, long-term and integrative ecohydraulic assessments of such systems remain limited. This study presents a synthesis of long-term ecohydraulic observations collected from two adjacent peri-urban waterways in Tokyo, Japan: a regulated irrigation canal monitored over six years and a spring-fed urban stream monitored over five years. The datasets integrate repeated monthly field measurements of physical habitat characteristics and fish assemblages across multiple seasons and hydrological contexts. Data-driven analytical approaches, including machine-learning-based species distribution models, were employed to quantify species–habitat relationships and their temporal variability. The synthesis highlights consistent ecohydraulic drivers governing fish distributions across both flow regimes, while also revealing regime-specific responses associated with flow regulation and hydrological stability. The results demonstrate that regulated irrigation flows can supplement spring-dependent baseflows and enhance flow variability and habitat heterogeneity, thereby supporting aquatic ecosystems in peri-urban waterways. These findings highlight the value of long-term, observation-based ecohydraulic datasets for improving the understanding and management of aquatic ecosystems in human-dominated landscapes.

DOI: https://doi.org/10.64697/iahr.proc.ise2026.abs.343

Year: 2026