Ekpelikpeze et al. (2026) Water Scarcity Risk for Paddy Field Development Projects in Pre-Modern Japan: Case Study of the Kinu River Basin

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Identification

• Journal: Water
• Year: 2026
• Date: 2026-01-09
• Authors: Adonis Russell Ekpelikpeze, Minh Hong Tran, Atsushi Ishii, Yohei Asada
• DOI: 10.3390/w18020179

Research Groups

• Not specified in the provided text (typically associated with Japanese hydrological or agricultural engineering departments).

Short Summary

This study reconstructs pre-modern river flows in the Kinu River Basin to determine if historical irrigation success was due to natural water abundance or management practices. The findings indicate that while natural flows were insufficient for extensive management during droughts, intensive management could successfully prevent water scarcity.

Objective

• To evaluate the pre-modern water scarcity risk for six irrigation schemes in the Kinu River Basin (1603–1868) to distinguish the roles of natural water availability versus human water management.

Study Configuration

• Spatial Scale: Kinu River Basin, Japan (specifically six irrigation schemes developed during the Edo period).
• Temporal Scale: Pre-modern period (1603–1868), with quantitative analysis based on a 17-year reconstruction period.

Methodology and Data

• Models used: Hydrological reconstruction model involving the removal of modern dam effects, adjustment of conveyance efficiency, return flow calculations, and land-use change (paddy field area) corrections.
• Data sources: Present-day river discharge records, Japanese irrigation standards (5 mm/d for minimum demand and 20 mm/d for easy management), and historical rainfall/land-use data.
• Rules evaluated: Prior appropriation and Equal Water Distribution rules.

Main Results

• Flow Reconstruction: Modern dry season flow is approximately 25 m³/s, whereas reconstructed natural flow during drought years drops to 10–18 m³/s (averaging ~15 m³/s after rainfall adjustment).
• Scarcity under Easy Management (20 mm/d): Water scarcity occurred in four of the six schemes; for example, the third scheme faced scarcity in 2 out of 17 years, while the sixth scheme faced it in 7 out of 17 years.
• Scarcity under Intensive Management (5 mm/d): No water scarcity occurred in any scheme, even during low-flow conditions, when water demand was limited to the minimum necessary for evapotranspiration.
• Management Impact: The results suggest that drought damage was not avoided by natural abundance but by the capacity to switch from extensive to intensive irrigation management.

Contributions

• Provides quantitative evidence challenging the assumption that historical Japanese irrigation success was solely due to natural water abundance.
• Demonstrates that pre-modern water governance was robust enough to mitigate drought through intensive management practices that distributed minimum necessary water to all fields.

Funding

• Not specified in the provided text.

Citation

@article{Ekpelikpeze2026Water,
  author = {Ekpelikpeze, Adonis Russell and Tran, Minh Hong and Ishii, Atsushi and Asada, Yohei},
  title = {Water Scarcity Risk for Paddy Field Development Projects in Pre-Modern Japan: Case Study of the Kinu River Basin},
  journal = {Water},
  year = {2026},
  doi = {10.3390/w18020179},
  url = {https://doi.org/10.3390/w18020179}
}

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