Mitchell Dabling, Utah State University
Civil and Environmental Engineering
Water management and flood control are essential elements of civilization. Linear weirs (e.g. ogee crest, sharp crested, and broad crested weirs) are often used in irrigation channels or reservoir spillways to regulate the discharge and upstream water level during flood flows. As hydrologic data sets increase in size and accuracy, the highest probable maximum flood (PMF) discharge is becoming increasingly more accurate, and in many cases much larger than previous estimates. Because of this, an older weir may need to be rehabilitated to ensure it can pass the updated PMF discharge safely without upstream flooding. A nonlinear weir (e.g. labyrinth or piano key weir) can replace a linear weir in a channel or spillway to pass significantly more discharge without requiring increased channel width. The Utah Water Research Laboratory at Utah State University, with the help of Utah Mineral Lease Funds, has developed and published design data for multiple configurations of nonlinear weirs. In 2012, the Utah Division of Water Resources used this data to design a labyrinth-style nonlinear weir that will replace the spillway currently in use at Millsite Reservoir in Emery County. This rehabilitation project will significantly decrease the flooding potential of the surrounding area.