Boston Globe: Last summer, Peter van Veelen led me on a hydraulic tour of Rotterdam, an excursion along the canals, dikes, sluice gates, and cisterns that keep residents dry in an island of a city that's mostly below sea level. Under a leaden sky, van Veelen, an urban planner, pedaled his battered three-speed. I trailed behind on a rental bike. He pointed at the red stones paving a plaza by the new central train station. A chamber below stores storm water gushing from the building's 7-acre roof, delaying drainage...