Estimating Future Flood Frequency and Magnitude in Basins Affected by Glacier Wastage: March 2015

Climate Change Clearinghouse2015PDFTech ReportLiljedahl, AnnaDebolskiy, MatveyYoucha, EmilyArendt, AnthonyDavis, JenniferHock, RegineRoth, AuroraWolken, GabrielZhang, JingAlaska University Transportation CenterUnited States. Federal Highway AdministrationAlaska. Department of Transportation and Public Facilities. Research, Development, and Technology TransferAlaskaUnited StatesBridgesGlobal warmingFloodsGlaciersRunoffStreamflowHydrologic cycleWatershedsResearch HubHydraulics and HydrologyPlanning and ForecastingTransportation (General)I26: Water Run-off - Freeze-thawI72: Traffic and Transport PlanningForecastingGlaciersRiver basinsINE/AUTC 15.044000(119)S16806T2-12-11Final Report Sep 2012-2014We present field measurements of meteorology, hydrology and glaciers and long-term modeled projections of glacier mass balance and stream flow informed by downscaled climate simulations. The study basins include Valdez Glacier Stream (342 km2 ), Jarvis Creek (634 km2 ) and Phelan Creek (32 km2 ), Alaska, that represent distinctly different climates and glacier coverage. At Phelan Cr., the decadal-averaged peak annual mean daily runoff was projected to increase 114 % from 14 (2000-2010) to 30 cms (2090-2099) with an 87 % increase by mid-century (2050-2059). At Jarvis, the decadal-averaged peak annual mean daily runoff was projected to decrease 14 % from 24 (2000-2010) to 21 cms (2066-2075), while the glacier contribution increased (from 37 % to 43 %). However, at Jarvis Cr., the flow at the 1% exceedance probability level was projected largest (~30 cms) during the mid-century time period (2035-2050). The highest flood events tended to have less glacier contribution, indicating that rainfall or snowmelt generated events may have a greater influence than glacier melt during peak flows (only Jarvis analyzed). The differing trends in projected runoff between the Jarvis and Phelan Cr. may be attributed to the differing climate forcing and glacier coverage representation, i.e. dynamic and static for Jarvis and Phelan Cr., respectively.109