Takao Masumoto

An index for evaluating the flood-prevention function of paddies

Urbanization is expanding in and around small to medium-sized cities as well as in large cities, and the expansion includes low-lying areas where the flood risk is high. Flood risk in small watersheds has been evaluated using precise mathematical models. However, these models cannot be applied to larger basins due to the complexity of data collection and analysis. As a result, quantitative evaluations of flood risk at macro scales and the flood-prevention function of paddies around urban areas have not been made. This paper proposes a method and an index that can be used to evaluate the flood-prevention function of paddies on a regional scale. In addition, the use of this system for basin-wide management is illustrated by an example for the Kinu and Kokai rivers, which are tributaries of the Tone River of Japan. The applicability of the approach is evaluated using data from a major flood that occurred in the study area.

Paradigm Shift in the Evaluation of Water Storage Function of Paddies and in Watershed Management

洪水処理技術における歴史的な流れとこれからの方向性を示すとともに,21世紀に水田地帯が果たす役割ならびに水田の持つ洪水貯留機能を水資源の流域管理にどのように活用したらよいかについて述べた.まず,水田の洪水貯留機能を水田固有のポテンシャルとして評価することが重要であることを指摘し,都市近郊におけるその機能をマクロ的に評価する方法を示した.また,それを踏まえて,その機能を水資源の流域管理にどう活かすかを検討した.次に,洪水管理や氾濫原管理に関する21世紀の課題は歴史の中に見いだせることを明らかにした.すなわち,ダムと堤防による「集めて迅速に流す」方式の洪水対策は,治水と利水の両面からの流域管理へと変化しており,その目標はまさに日本の江戸初期の河川や現在の東南アジアの流域で行われている方向であることを示した.さらに,世界の各地域における水環境の違いにより個々の技術の適用方向が異なることを,オランダの排水管理,オーストラリアにおける森林伐採や草地開発による地域水資源の変化,メコン河の下流地域での氾濫と潅漑の共存などの事例を用いて論述した.

Features of the AFFRC model for evaluating the relationship between the water cycle and rice production

This paper introduces the Agriculture, Forestry and Fisheries Research Council of Japan (AFFRC) model, an integrated model that predicts future rice production in the Mekong River basin by taking into account the effect of global warming on both the water cycle and the rice economy. The model focuses especially on the water balance of paddy fields for different farmland water use systems. We defined six categories of irrigated paddies and three categories of rain-fed paddies on the basis of their systems of water usage. We included a process-based model to predict future rice production, accounting for daily changes in available water resources such as precipitation. Many models of crop production treat rice in the same way as other crops; the particular characteristics of rice farming are considered in more detail in our model. Our results show that it is possible to estimate future rice production in the Mekong River basin by taking into account changes in available water, and to model the resultant effects on the grain market.

Assessment of changes in water cycles on food production and alternative policy scenarios

This special issue deals with water and food as it applies to water resources and rice production in the Mekong River Basin. The range of papers reflects not only the broad interest but also the complexity of the topic. These reports are mainly based on the research carried out by the project, “Assessment of the Impact of Global-Scale Change in Water Cycles on Food Production and Alternative Policy Scenarios”. Hence the special issue gives a brief overview of the structure, goals, outcomes, and future direction of the above project. What we do in this paper are: (1) giving an overview of the project’s structure and goals, (2) stating the five common outcomes and several more specific results, and (3) looking forward to the future direction of the project. The aim of our research is to draw up scenarios for optimum water-resource distribution and to develop social guidelines, measures, and policies to help solving food and environmental problems by developing a world water–food model that emphasizes rice production in Monsoon Asia. We have integrated all of the data gathered and the research results into a food supply and demand model combined with a water-cycle analysis. We included operational factors, such as water-cycle change, water demand, water supply, and water distribution in the model. Emphasis is placed on the use of efficient resource-management technologies for proper use of water resources in agricultural and other sectors. The water–food model has been developed as a tool for evaluating technical decisions derived under various policy scenarios.

Multifunctionality of paddies

This special issue deals with multifunctionality as it applies to paddy rice production in east and southeast Asia. The range of papers reflects not only the broad interest but also the complexity of the topic. These reports are based on the research supported by a range of national agencies (e.g. National Institute for Rural Engineering) and the International Water Management Institute headquartered in Sri Lanka. The term “multifunctionality” entered agricultural policy discussions in the early 1990s and its use has spread to trade policy discussions in recent years (Bohman et al. 1999). While the term is relatively new, the concept it represents is not. The basic idea is that agriculture, or in our case paddy rice production, is more than just producing and selling commodities. There are important non-commodity attributes associated with agricultural production. Some views of multifunctionality encompass a wide range of attributes, including those related to land use such as wildlife habitat, biodiversity, and landscape amenities as well as social attributes such as agriculture’s contribution to cultural heritage, the viability of rural communities, and food security. In other cases, the focus is primarily on the environmental attributes of agricultural production.

Message from the new Editor-in-Chief of Paddy and Water Environment

As the new Editor-in-Chief of the international journal Paddy and Water Environment, it is my pleasure and honor to inform you that successful, efficient, and timely publication of the first 14 years of the journal are now nearly complete. I am grateful for the persistent effort and involvement of the former Editors-in-Chief, namely, Drs. Yohei Sato, Yoshiki Nakano, and Masaru Mizoguchi. On behalf of the journal’s board of directors and staff, I express my sincere thanks and appreciation for the recent editorial work by Editorial Board members, and especially by Drs. Yoshiyuki Shinogi and Jin-Yong Choi as Chief Managing Editors. We are also grateful for the ongoing support from our publisher, Springer Japan. On the occasion of the new Editorial Board’s commencement in July 2016, I am taking this opportunity to review the journal’s status and clarify the challenges as well as the aims of the new Editorial Board. We have already received a large number of contributions from Asia, Africa, Europe, and the Americas. We are pleased that the number of contributions has continued to increase steadily, reaching about 180 manuscripts submitted annually in recent years. The total number of manuscripts already published in the journal’s 55 issues (including 9 Special Issues) recently has exceeded 550. While submissions are expected to increase, we recognize the challenges in maintaining the scientific quality required for an international journal. Aiming at continuously producing high-quality publications while increasing the efficiency of peer review, we have expanded the Editorial Board and made use of Managing Editors as well as a Chief Managing Editor to support the journal’s growth. In 2011, Paddy and Water Environment was selected for inclusion in the Science Citation Index Expanded (i.e., SCI searches) published by Thomson Reuters as well as in the Engineering Index of the Scopus database. Many articles published in other journals have cited papers published in Paddy and Water Environment. These journals include Agricultural Water Management, Hydrological Processes, Ecological Engineering, Plant and Soil, Irrigation and Drainage, Irrigation Science, Water Resources Management, Soil Science Society of America Journal, Field Crops Research, Journal of Hydrology, Journal of Irrigation and Drainage Engineering, Soil Science, and Transactions of the ASAE. These results are encouraging for the editorial team to keep up our efforts in delivering useful contents to the research field. To improve external evaluations of Paddy and Water Environment, we have proposed additional measures, such as shortening the submission-to-publication time, solicitation of scientific review papers by prominent researchers, the promotion of special issues, and reform of the Editorial Board’s roles. We would be grateful to receive additional suggestions from our readers. Finally, I am pleased to announce that the new Editorial Board, including Chief Managing Editor Dr. Yu-Pin Lin from National Taiwan University and five Managing Editors, namely, Drs. Jin-Yong Choi, Chihhao Fan, Nobuyoshi Fujiwara, Kimihito Nakamura, and Andrew Whitaker, will strive to continue the smooth operation of Paddy and Water Environment. We very much appreciate your continued support for the journal. & Takao Masumoto masumoto@affrc.go.jp