Abstract
Sapporo has relied on the Toyohira for most of its water resources. However, population increases have necessitated much water use. In recent years, some rivers have experienced drought and water quality deterioration.We researched the hydrologic and material cycles in Sapporo toward finding solutions to these water environment problems. The assessment revealed the following characteristics of the hydrologic cycle in Sapporo: 1) Sapporo depended on the Toyohira River for 80% of its water supply. However, 2/3 the volume of waste water discharge from its area is channeled into other rivers. 2) Two third of organic pollutant substance and total phosphorus and half of total nitrogen is drained to the other rivers. 3) We identified high-concentration organic pollutant and nutrient of the initial rainfall runoff water from sewerage system.
