The flood control, irrigation and environmental improvement of rivers are important tasks in the development of infrastructure in Japan. Work in these fields protects the lives and property of people who live in river basins and plays a significant role in the development of our country through the supply of water for agricultural and industrial uses. Furthermore, the supply of high-quality drinking water via the public water system is an essential project for human activities and lends security to people's daily lives. The functions of ecological habitats that naturally spring up around rivers and the creation of good river landscapes are vital for the wildlife and people that live in river basins, and, at the same time, offer a sense of tranquility and abundance. On the other hand, Japan's economic situation and social structure have been going through dramatic changes with the recent financial crunch, declining birthrate, and rapidly aging population. The government has continued to reduce its investment in the public sector in recent years, and the drastic reduction in public investment is making it increasingly difficult to carry forward river improvement projects that originally need to be implemented and maintain river facilities that have traditionally been maintained. Amid these changes in Japan's socioeconomic conditions and changes in our awareness of the environment, we should view water and rivers as increasingly important resources in the construction of a society that can maintain and increase its economic vitality and improve disaster prevention, ensuring prosperity and peace of mind. At present, however, this awareness is not shared by all Japanese people. This may be due to an inaccurate or insufficient understanding of the natural characteristics of rivers in Japan, the history of flood control and water resource development, and the role of water in human activities. Ignorance of rivers and water is not limited to Japan, however. It seems that people's concern about, and awareness of, water are surprisingly low in countries throughout the world.

Against this backdrop, Paul Kennedy, a British historian, contributed an article entitled "A Universal Problem" (Japanese title: "Sekai Kyotsu no Mondai"; original title: "Water, Water Everywhere.") to the Yomiuri Shimbun column Reading the Earth (Japanese title: Chikyu wo Yomu), which was published on the front page of the newspaper's October 14 issue. In the article, Kennedy issues a warning concerning a worldwide shortage of water threatening the survival of the human race, saying, "Why not identify the loss of secure fresh water as by far the greatest challenge to humankind's longer-term security?" Later on, he continues, "Let us now return, therefore, to my original proposition. It is that the issues which obsess our contemporary strategic analysts, our armchair pundits on foreign affairs-issues like [the] Syria [crisis],.[and the hostility between] Israel and Iran-however important their protagonists believe them to be, pale in comparison to the global water crisis." As someone who studies hydrology, I couldn't agree more. Possible causes of the water shortage are a reduction in the flow of large rivers throughout the world and a reduction in water resources accompanying the retreat of glaciers-events which have (apparently) been triggered by global climate change related to global warming. Referring to some of these global changes or fluctuations, Kennedy remarks, "It sounds unbelievable to all but climatic scientists." In this case, however, it would be more accurate to say all but hydrologists. Hydrology (the study of water) is a field that is probably unfamiliar to most Japanese people. Hydrology is a term on the same level as astronomy; while the field of astronomy looks at the entire universe, the field of hydrology studies the water on all planets-especially that found on the earth. A researcher in the field of hydrology is called a hydrologist in English; this is a general term that commonly appears in the everyday speech of people with a certain level of education in the English-speaking world. As someone personally involved in the field of hydrology, I am continually irritated at the widespread lack of awareness about hydrology in Japan and the thoughtless attitude people in this country have toward not only the socioeconomic changes, but also the physical, meteorological and hydrological changes and fluctuating conditions of our world. In fact, the problems the world faces in securing enough water resources may sound completely irrelevant to our everyday lives due to the regular abundance of water in Japan-a country with typhoons, guerilla rainstorms (sudden, heavy rainstorms), a rainy season and about a third of its land mass located in one of the world's leading snowbelts. Another reason for this lack of awareness may be the absence, or shortage, of adequate educational materials that can guide and inform students and other members of the younger generation who wish to learn about and research topics such as the multifaceted roles and functions of rivers, wetlands and glaciers. As a resident of the Kanto area of Japan, I recommend that these would-be students of hydrology start out by studying the Tone River, Japan's largest river. They should study both the value of the water in this river, which has contributed to the development of the region and the entire nation, and its potential danger by looking at its river basin and channel characteristics, status of disaster occurrence, history of flood control, safe supply of drinking water and stable supply of water for agricultural and industrial uses, as well as the way good river environments provide habitats for wildlife. By doing so, these students will, perhaps, be better able to acquire the tools they need to figure out some kind of solution to the biggest problem facing our world, where an exponential explosion in the human population continues to unfold. To put it another way, learning about the current state of rivers located near us and the various issues surrounding them will provide us with insights into the biggest problem the world will face in the future-a shortage of fresh water that will not just be a problem in some countries, but a major global crisis.