In the continued quest for increased economic benefits from our water
resources, numerous structures and operating policies for controlling
the river flow have been built and implemented. These structures and
associated operating policies can facilitate navigation; they can
provide greater quantities of reliable water supplies to meet
agricultural, industrial and municipal water demands; they can generate
hydroelectric power and energy; and they can provide increased flood
protection, recreation, and other benefits. Over the past half-century
we have converted many of our rivers into engineered waterways. These
straightened, often periodically dredged, engineered rivers are complete
with dikes, reservoirs, weirs, and diversion canals. All this
engineering has enhanced economic development. However, as rivers and
their floodplains become stressed from the excessive use and misuse of
their resources, their contribution to economic development can be
threatened. Evidence of economic and ecological degradation, especially
in relatively large river systems such as the Danube, the Mississippi,
the Rhine, and the Volga, has increased our appreciation of beneficial
roles natural aquatic and terrestrial ecosystems play in water quantity
and quality management. We have recognized the need to pay more
attention to letting nature help us regulate water quantity and quality
rather than working against nature and its variabilities and
uncertainties. Today there are efforts underway in many developed river
basins to 'de- engineer' or return these straightened and controlled
rivers to a more natural state.