Artificial flood levees and navigational channels increase the current velocity, the creation of crevasses serves to divert some of the water volume thus decreasing velocity. Crevasses can be built in to rectify a detrimental situation created through anthropomorphic modifications of the fluvial system. When artificial levees are built, marshlands are cutoff from the freshwater sediments and nutrients they had been receiving. Determination of the rate of subsidence dictates the guidelines for construction of the crevasses. A higher rate of subsidence calls for bigger crevasses thus a larger volume of water and sediment.
Larger crevasses are only different from smaller ones in terms of the width.
The U.S. Army Corps of Engineers have determined that the depth of a crevasse is to kept above 8 feet, for flood control. A successful example of marsh sedimentation through use of a crevasse is found in a modification done by the U.S. Army Corps of Engineers at the South Bend of the Mississippi River. A crevasse was formed through the excavation of 42,000 cubic yard of material, which was placed adjacent to the opening of the crevasse. The crevasse is 125 ft wide by 1,265 feet long with a depth varying uniformly from 8 feet. It has a flow rate of approximately 1,265 cfs, depositing nearly 6.5 acres per year.