Review of the Probable Maximum Flood (PMF) Snowmelt Analysis for Success Dam

• Main Author: Daly, Steven F
• Other Authors: ENGINEER RESEARCH AND DEVELOPMENT CENTER HANOVER NH COLD REGIONS RESEARCH AND ENGINEERING LAB
• Format: Text
• Language: English
• Published: 2015
• Subjects: Hydrology; Limnology and Potamology; Snow; Ice and Permafrost; Civil Engineering; *DAMS; *FLOODING; *SNOW COVER; DISTRIBUTION; MELTS; MODELS; REMOTE DETECTION; RUNOFF; SATELLITE IMAGERY; SCENARIOS; TEMPERATURE; TOPOGRAPHY; WATERSHEDS; MODIS TERRA SNOW COVER DAILY L3 GLOBAL 500 M GRID; *PMF(PROBABLE MAXIMUM FLOOD); SNOW MELT; SNOW MODELING; SCA(SNOW-COVERED AREAS); SWE(SNOW-WATER EQUIVALENT); *SUCCESS DAM WATERSHED; AIR TEMPERATURE; Ice; permafrost
• Online Access: http://www.dtic.mil/docs/citations/ADA624268; http://oai.dtic.mil/oai/oai?&verb=getRecord&metadataPrefix=html&identifier=ADA624268

This report reviews the initial snowpack distribution assumed to be in place and available for melt in the probable maximum flood (PMF) analysis of Success Dam conducted by the Corps of Engineers. This project reviewed two aspects of the initial snow distribution: the snow-covered area (SCA) distribution and the snow water equivalent (SWE) distribution. We analyzed satellite imagery to determine the daily SCA of the Success Dam watershed from 2000 to 2014. This analysis was based on time-domain filtering of NASA's daily snow product. The SCA of the Success Dam watershed is highly dynamic with large day-to-day variations. The maximum 95th percentile SCA for each elevation band was selected to describe the initial snow cover in place at the start of the PMF analysis. We next reviewed the initial SWE distribution. Above 5000 ft, the initial SWE distribution was greater than the snowmelt that occurred during the PMF and was therefore heat transfer limited. In this region the snowmelt runoff during the PMF was insensitive to the amount of SWE. Below 5000 ft, the snowmelt was limited by the initial SWE. Runoff from this region is sensitive to the amount of initial SWE. The original document contains color images.