Water Crisis

Water scarcity is an urgent issue for humankind since the quantity of foods for people depends on water supply. In particular, agricultural use is the largest among various usage of water. Moreover, water shortage becomes more serious since the agricultural and industrial uses for people's need have also increased more due to future demand. In fact, many people especially in developing countries suffer from the shortage of water as well as the quality of water over a wide area in Africa, Central Asia and so forth. Furthermore, water shortages arising from the reduced rainfall during dry summers due to global climate change and flooding from concentrated heavy rain in restricted regions cannot be ignored. Therefore, dams and/or reservoirs are necessary for us and should be constructed at many places without destruction of nature. However, we forget how to manage water and just use it up. Furthermore, another fact that tremendous amount of underground water has been pumped up for agricultural and industrial use at many places in the world is much serious. We cannot see how much has disappeared in case of underground water. It is extremely important to find a way to preserve and to manage water in earnest now.

Generally, water is circulating resource which comes from precipitation through mainly evaporation of seawater and the amount of water on earth is definitely limited. About 60 % of rain water permeates into the ground such as mountains covered by forests and move slowly underground while a portion returns to the ocean through rivers. A recent serious problem is the felling of trees at mountains for human use like dam construction, demand for wooden materials and so on, leading to weakened water-keeping ability of forests.