Watershed urbanization strongly affects a river which has close relation to the cities in
these days. Increase of uninfiltrated area together with the expantion of urban area causes
serious flood disasters in terms of increase of peak discharge and decrease of
concentration time of flood runoff.
Above this, concentration of population to cities will give rise to water pollution and
decrease of average dischrage of river.
With this point of view, our laboratory have been examined the effection of watershed
urbanization to the river with whole understanings of the existing state of urvanization and
hydrologic cycle in urban area on the basis of observed data.
Water circulation in urban area is classified roughly into
1 Natural cycle,
2 artificial drainage cycle for precipitation,
3 artificial drainage cycle for supplied water.
When we want to analyze an amount of river discharge, we shoud remind this
character of water circulation
because these three circulations are complicatedly mixed in urvan area.