What determines whether water on earth's surface will seep into the ground or become runoff?

Well it depends on multiple things like the climate, amount of precipitation and so on like in a desert its gonna be hard to have run off because the water will just soak into the ground through its cracks because it doesn't get sufficient water supply. hope this helps.

Master planned communities outside of chicago. note: population density means people living in an area per square mile. chicago, an urban and highly populated area has a much more higher density than a desert, amish community, settlement, or nomadic region.