p.s. because I live in CA and did work for public agencies I'm familiar with the Caltrans Manual pertaining to Hydrology. For anyone interested:http://www.dot.ca.gov/design/manuals/hdm/chp0810.pdf
I will say that with climate change occurring we are seeing recurrent incidence of having 50, 100, and even 1,000 year storms at shorter intervals. This with ongoing channels filling in with sediment from reduced flows due to construction of dams and flood control features and also subsidence of land from elimination of regular winter floods the would historically deposit farm rich soils we are looking at looming infrastructure costs in the not to distant (geologically speaking) future.
Think about New Orleans, and most coastal areas and areas protected by levees in low-laying areas close to river outlets or junctions of rivers (or creeks). Add to increased frequency and duration of rainfall rates the potential of ongoing ocean level increase (glaciers and polar cap erosion) one can envision that the 40% (or a smaller ortion) of the worlds population may be looking ar relocation. It's said 1.5 million Chinese were or will be at completion of the Three Gorges Dam.
IDK if we will be impacted much in our lifetime, but know that all we (USA) have done to cut our impact other developing nations have done not so much.
I offer this not as a doom and gloom, but as a snapshot of the evolution of engineering and engineering economy that the planet faces. We actually study this stuff, but don't dwell on it too much as frankly it's pretty scary to think about.