Impervious surfaces change runoff
Less infiltration can increase the volume and speed of surface flow.
Drainage has finite capacity
Pipes, channels and inlets can be overwhelmed by intense storms or blockages.
Site design matters
Grading, detention, infiltration and green infrastructure can influence how water moves.
Downstream effects count
Managing one property or district can shift timing and volume elsewhere in the watershed.
Scope boundary. This page explains system relationships at a planning level. Real utility, transportation, emergency, structural, electrical, cybersecurity and public-safety decisions require local agencies and qualified professionals.