Many environmental and hydrological systems have been modified by human intervention. This intervention usually takes the form of constructions intended to change system behavior to better serve the needs of society. Some of these interventions result in structures that have a purely passive role (dikes, coastal defenses), others are have no moving parts, but use physical principles to regulate or divert flows, finally there are structures where the configuration can be changed. This last category can be under manual or automatic control. The design and management of such structures must take into account the need for the system as a whole to adapt to a heterogeneous and uncertain environment for one or more generations. Both tasks pose challenges that can only be answered by a multidisciplinary approach and new optimization techniques. These questions typically involve multiple decision criteria and constraints over a wide range of levels in time and space. Moreover, robust results at the larger scale depend on assumptions about the performance of smaller scale systems in operation.

The resulting interaction of human intervention and nature changes the hydrological system substantially. A proper understanding of the resulting water resource system is needed for all efforts to optimize its behavior.