Estimation of Climate Change Impact on Japanese Water Resources Part 2: Water Demand-Supply Balance, Rice Yield Changes, and an Adaptation Plan

Kotsuki, Shunji; Tanaka, K.; Kojiri, Toshiharu

doi:10.3178/jjshwr.26.143

Cited by 6 publications

(2 citation statements)

References 8 publications

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“…As a result of such changes in the seasonal variability of river flows, farmers' requests to shift the transplantation date may not be granted. Kotsuki et al (2013) evaluated the effects of shifting the transplantation date on rice yield and the water supply-demand balance. They calculated rice yield and water supply-demand balance by using a process-based model in an experiment in which the transplantation date of paddy rice was shifted by up to 30 days before and after the reference dates throughout Japan.…”

Section: Impacts Of Climate Change On Rice Cultivation and Water Reso...mentioning

confidence: 99%

Potential Barriers to Adaptive Actions in Water–Rice Coupled Systems in Japan: A Framework for Predicting Soft Adaptation Limits

Takada,

Yoshida,

Ishigooka

et al. 2024

Water Resources Research

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The changing climate makes it more difficult to manage water resources and food production sustainably. Various adaptation measures have been proposed to moderate the negative impacts of climate change; however, implementation of these measures may be hampered by other factors even if the benefits are acknowledged—a situation termed “soft adaptation limits” by the IPCC. We hypothesized that societal rules can be a potential barrier to adaptive action if they are too fixed, because such rules have coevolved with the interactions between the past climate and human activities. To test this hypothesis, we present a framework based on the assumption that associated societal rules of Japan's matured irrigation systems are potential barriers to adaptation. The framework consisted of two process‐based models, one to evaluate the water deficit risk and one to evaluate the benefits of optimizing rice yield and quality. We applied each model to an experiment in which we shifted the current transplantation date by 1 week for up to 5 weeks before and after the current date under the historical (1981–2000) and RCP 2.6 and 8.5 (2011–2030 and 2031–2050) scenarios. We revealed two contrasting development pathways in the study watershed. Soft adaptation limits imposed by water availability will occur by 2030 if farmers optimize for quality, whereas mutual benefits to farmers and river administrators will be achieved if farmers seek yield. We argue that more participatory research with stakeholder engagement, as well as policy discussions about these possible developments, is needed to ensure successful adaptation.

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Section: Impacts Of Climate Change On Rice Cultivation and Water Reso...mentioning

confidence: 99%

Potential Barriers to Adaptive Actions in Water–Rice Coupled Systems in Japan: A Framework for Predicting Soft Adaptation Limits

Takada,

Yoshida,

Ishigooka

et al. 2024

Water Resources Research

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“…A few studies have dealt with water resources assessments (Wada et al, 2005;Tachikawa et al, 2011;Kotsuki et al, 2013). However, these analyses were based on only one climate scenario; they did not consider uncertainty arising in the impact assessments.…”

Section: Introductionmentioning

confidence: 99%

Nationwide assessment of the impact of climate change on agricultural water resources in Japan using multiple emission scenarios in CMIP5

Kudo

Yoshida

Masumoto

2017

Hydrological Research Letters

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Abstract:The present study generated nationwide assessment maps for the impact of climate change on agricultural water resources throughout Japan, by using climate scenarios derived from global climate models and DWCM-AgWU, a hydrological model that incorporated irrigation water management. In addition, we analyzed the uncertainty of the assessment maps, investigating the ranges of the assessment indices in 11 climate scenarios used. For the assessment of drought discharge, we generated the assessment maps for two rice growth stages (puddling and heading) that are highly vulnerable to water shortages. The maps generated in this study provide a framework for assessing the impact of climate change on agricultural water resources in Japan and reveal the vulnerable regions to climate change. The uncertainty analysis suggested that the assessment uncertainty depended on the hydrological processes used to calculate assessment indices and on the magnitude of their natural annual variability. For a deeper understanding of the uncertainty in hydrological assessments it is necessary to investigate the impact on the assessment uncertainty of the natural variability of hydrological processes especially relating to extreme events.

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Assessment of the climate change risks for inflow into Sagami Dam reservoir using a hydrological model

Momiyama

Sagehashi

Akiba

2018

Journal of Water and Climate Change

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Adverse effects of future climate change on water supply systems are of concern. High turbidity caused by abrupt flood, and drought caused by continuous dry days are the major risks. To assess such risks, a comprehensive method to simulate hydrology with high spatiotemporal resolution should be developed. In this study, a series of methods from parameter estimation to future simulation using the Soil and Water Assessment Tool (SWAT) was demonstrated for Sagami Dam reservoir, which is a typical water supply reservoir in Japan. A proposed parameter calibration method by optimizing percent bias followed by optimizing Nash–Sutcliffe efficiency gave good performance of model prediction of the daily average reservoir inflow in the past. Using this model, the changes in inflow under expected climate change were simulated. Three predicted daily climates by the Model for Interdisciplinary Research on Climate version 5 (MIROC5) under three representative concentration pathways, i.e., RCP 2.6, 4.5, and 8.5, in 2081–2100 were used for the simulation, whereas observed daily climate during 1981–2000 was used as the past reference. The risks were discussed by considering their seasonality, indicating increases in flood and drought in June and July, and in February and April, respectively.

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Estimation of Climate Change Impact on Japanese Water Resources Part 2: Water Demand-Supply Balance, Rice Yield Changes, and an Adaptation Plan

Cited by 6 publications

References 8 publications

Potential Barriers to Adaptive Actions in Water–Rice Coupled Systems in Japan: A Framework for Predicting Soft Adaptation Limits

Potential Barriers to Adaptive Actions in Water–Rice Coupled Systems in Japan: A Framework for Predicting Soft Adaptation Limits

Nationwide assessment of the impact of climate change on agricultural water resources in Japan using multiple emission scenarios in CMIP5

Assessment of the climate change risks for inflow into Sagami Dam reservoir using a hydrological model

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