1. Cooperation, Public Relations
  2. Press Release
  3. 2024

研究成果

Overcoming Challenges in Drainage Measurement: Clarifying Paddy Field Drainage Characteristics in Lowlands with Cyclic Irrigation Systems
—Contributing to the Design of Efficient Irrigation Systems for Lowland Paddy Fields—

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March 27, 2025

Main Points

  • A rare case of successfully measuring drainage volumes in paddy irrigation, where such measurement is typically difficult.
  • In the cyclic irrigation system of the Inbanuma lowland area, more than 50% of irrigation water was reused drainage, with rainfall conditions significantly influencing drainage characteristics.
  • The findings contribute valuable knowledge for designing efficient and environmentally friendly irrigation systems in lowland rice fields.

Overview

A joint research team from JIRCAS, Tokyo University of Agriculture and Technology, and the Kanto Regional Agricultural Administration Office of the Ministry of Agriculture, Forestry and Fisheries has clarified the drainage characteristics of a cyclic irrigation system in the Inbanuma Second Phase National Land Improvement Project area in Chiba Prefecture, Japan.

In paddy field irrigation, calculating water use efficiency requires knowledge of both water inflows and outflows. However, measuring outflows is difficult due to the need for monitoring at all branching drainage channels. This study overcame that challenge by focusing on a cyclic irrigation system, where drainage is reused as irrigation water, enabling quantification of drainage volume at the paddy-field district level.

Field surveys conducted in 2021 and 2022 revealed that over 50% of irrigation water came from reused paddy drainage, including not only surface runoff but also part of the lateral flow (subsurface percolation), which was recaptured and reused.

These findings provide the first quantitative data on the volume of reused paddy drainage in this setting. This data will allow for:

  • Quantifying the water quality conservation effects at water sources
  • Developing optimal pump operation strategies based on drainage behavior
  • Designing environmentally sound and efficient irrigation systems for lowland paddy fields

This research was published in the online version of the Journal of Hydrology: Regional Studies on December 19, 2024 (Japan time).

Related Information

Funding

Publication

Authors
OKURA Fumi, KAMEI Asuka, and KATO Tasuku
Paper Title
Water balance analysis of hydrological processes in cyclic irrigation: A case study of the Imbanuma irrigation area in Chiba, Japan
Journal Title
Journal of Hydrology: Regional Studies
DOI: https://doi.org/10.1016/j.ejrh.2024.102111

For Inquiries

JIRCAS President: KOYAMA Osamu

Program Director:
HAYASHI Keiichi
Research Staff:
OKURA Fumi (Rural Development Division)
Press Coordinator:
OMORI Keisuke (Head Information and Public Relations Office)
Email: koho-jircas@ml.affrc.go.jp

Tokyo University of Agriculture and Technology (TUAT)

President:
CHIBA Kazuhiro
Research Staff:
KATO Ryo (United Graduate School of Agricultural Science)
Public Relations:
Public Relations Office, General Affairs Division
Email: koho2@cc.tuat.ac.jp

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