Today, anthropogenic influences are recognized to extend beyond the realm of flood
control structures. In many instances, man creates hazards that rival the most dangerous and
bizarre of natural flood conditions. Often man’s influences on natural systems are long-term and
go unrecognized until conditions gradually deteriorate to critical levels. Examples of this include
the transport of chemicals in floodwaters, creation or aggravation of extreme events, and dangers
associated with social works that are not related to aquatic systems.