Ceiling & Roof Leak Water Damage Repair in Poughkeepsie, NY

A narrow ravine with a wide catchment does exactly that. The channel drains a large built-up area and has very little room to spread, so the level rises sharply rather than the water spreading out. It also drops quickly once the rain stops. The practical consequence is that the event is short and there is no time to move anything, so protection has to be permanent rather than something you do when the rain starts.

On a slope that is the expected pattern. The uphill side has saturated ground against it and the water arrives under pressure rather than running across the surface, which is why sealing the inside face does not hold. Interception above the house, with a drain that discharges to somewhere lower, addresses it at the source. On a hillside there is usually somewhere lower available, which makes a gravity drain possible and a pump unnecessary.

Enough that the drainage which handles the rest of the year is beside the point. Tropical remnants deliver in a day what the area would normally receive in a month, and the local creeks and storm system have no capacity for that. Design and preparation should be judged against the once-a-year event rather than the average one, because that is the storm that produces essentially all of the damage.