The series shows how urbanization has increased the chances of flooding along the already flood-prone Raritan River and its tributaries, the major watershed in the Courier-News circulation area. They found, through statistical analysis of data covering more than 60 years, that the Raritan reacts more quickly and severely to rainfall today than it did in the past. The reason is development and urbanization. Water that previously was absorbed into the ground, then gradually seeped into the watershed, is instead running off parking lots, driveways, roofs and streets and into the river. This is a trend experts say could lead to more frequent and severe flooding.