So what’s behind the propensity for floods in Ellicott City? Part of the problem is its vulnerable location: the town lies at the foot of a hill where river branches meet the Patapsco River. And, of course, climate change makes storms wetter and increases the frequency of severe, record-breaking weather. But there’s another thing people are pointing out: concrete. When hard, impermeable concrete replaces absorbent green spaces, it’s much easier for floodwaters to overwhelm stormwater drainage.