Quantitative assessment of improvements in hydrological water cycle in urbanized river basin

Abstract

Urbanization generally causes expansion of urban areas, improvement of lifestyles, high population density and high levels of land utilization. Those urbanization processes have resulted in an expansion of impermeable areas such as roofs and pavements, an increase in water demand, an increase in industrial and domestic waste water and a reduction of water surface areas and green lands. The above-mentioned phenomena tend to distort the appropriate hydrological water cycle and derive the six issues to be solved which were pointed out in our previous paper Imbe et al.(1995). Six issues were described as: 1) Maintenance of Ordinary Water Discharge; 2) Flood Control; 3) Conservation and Development of Water Resources; 4) Conservation and Revival of Ecological System; 5) Pollution Control; 6) Improvement of Heat Environment. In order to prevent the deterioration of the hydrological water cycle, many relevant measures are taken into account and the effect of those measures should be evaluated before the implementation. This paper presents a practical example of the evaluation procedure through a case study of the actual urbanized river basin called Azuma River.