Environmental Effects Of Dikes And Revetments On Large Riverine Systems

A review of pertinent research, suggests that dikes and revetments have short-term and long-term effects on major riverine ecosystems. Short-term effects may be beneficial and include increases in aquatic habitat diversity physical stability which, in turn, results in high densities and diversities of fish and macroinvertebrates within the main stem of the river. Dike fields are intermediate physically, chemically, and biologically to the main channel and backwaters of rivers. Dike fields often support the most diverse fish and macroinvertebrate community of any habitat within the river. But community composition is less stable than backwaters and is dependent upon river stage and water velocity. Moderate and slow-water areas within dike fields provide important spawning and nursery areas for many lotic species of fish within the modified river. Revetments of broken rock stabilize banks and provide additional hard substrate for colonization by dense populations of invertebrates. Interstitial spaces between rocks may provide areas of moderate flow for juvenile and forage fish. Long-term effects of river training structures may be detrimental to the biotic integrity of the river.