Review of Existing Hydrologic Studies of the Vermillion River Watershed

In order to update flood hazard data for the Vermillion River and its tributaries, it was necessary to make a decision regarding the use of the available hydrologic data for the entire watershed. Therefore, the two most recent hydrologic studies on the Vennillion River watershed, the US Anny Corps of Engineers (COE) Watershed Hydrologic Study and the Montgomery-Watson- Harza (MWH) Volume Study, were reviewed and compared. The results ofthis review showed that the calibration perfonned by MWH improved the model in simulating streamflows within the watershed. The improvement, however, was small. In order to simulate the 100-year flood in the Vermillion River watershed, it is recommended to use the 4-day frequency stonn as input, which was used by COE in projecting the 100-year flood.Barr Engineering Company; Dakota County, M