Unit name: Research Unit on Hydrologic Science

Key words: hydrologic science, water cycle, water environment, land area, global environment

http://www.geoenv.tsukuba.ac.jp/~hydro/index-e.htm

     Although there are significant amounts of water in the sea, most of it cannot be used as water resources. When water in the atmosphere has fallen to the ground in the form of rain or snow, humans can utilize the water to support the lives of people, for agricultural production, and industrial activities only until it flows into the sea or vaporizes into the atmosphere. If people wish to benefit from water infinitely, they need to correctly understand the water cycle and appropriately utilize water. The research unit: “Hydrologic Science”, aims to clarify the process of the water cycle to address environmental issues at regional and global levels, and promote the development of basic science as the basis of these issues.

Comprehensive understanding of regional- and global- scale water environments in the past, at present, and in the future

Figure 1: Water cycling process

       Water is essential for our lives. Furthermore, disasters and famines caused by excess or scarcity of water significantly influence the lives of people. Hydrologic science aims to understand water cycles and the processes of their changes comprehensively to identify the underlying causes of various problems and keys to their solutions (Figure 1). The unit examines water cycles in the past and their current status, and models them to predict their future changes. For example, in Mongolia, one of our research fields, we assess the flux, storage and residence time of water to understand the statuses of the regional environment and water cycles, examine the reason why grazing has long been conducted in the region, and predict changes expected to occur in the future due to global warming and increased grazing pressure.

Water cycles as the key to the solution of environmental problems at regional and global levels

       Water cycles are an important key to the solution of not only global environmental problems, such as global warming, desertification, and acid rain, but also regional environmental problems. For example, there has been little improvement in the quality of the water of Lake Kasumigaura. Since foreign substances from the surrounding area are transported into the lake primarily by water, it is important to accurately understand its flow to improve lake water quality. Furthermore, studies have suggested that the absorption and emission of CO₂ by lakes and swamps, including Lake Kasumikaura, influence atmospheric CO₂ levels. To clarify this point, we have been conducting on-site observations and modeling to determine the quantities of water and CO₂ transferred (Figure 2). Researchers of the research unit collaborate with each other to study hydrological processes through estimation of fluxes, storage and residence time and examine the status of interaction between hydrological processes and environments on both regional and global.

Figure 2: Results of the measurement of the water vapor flux from Lake Kasumigaura (left) and a scene of a survey of the river flow rate (right)

Interviewed on July 9, 2015