 DEM from USGS ◦ Digitized version of 1:24,000 topo quadrangle ◦ Vertical accuracy  5m, 30m resolution  KML files, digitized from Google Earth ◦ Lake perimeter ◦ Drain line for dam  Drain depth estimations in 400ft increments  BING aerial imagery Drain LineDepth 1 st 400 ft~ 1 ft 2 nd 400 ft3 ft 3 rd 400 ft4 ft 4 th 400 ft~ 6 ft 5 th 400 ft~ 8 ft Remaining~ 10 ft

Lake perimeter and drain line depths (m)

Edit DEM  bottom topography Translate depth to elevation Create DEM of Lake Bottom Edit DEM  2 surfaces Identify elevation of 2 surfaces Create DEM of Lake Surface (normal/ flood) Raster subtraction = depth values Volume Estimations in Excel Generate Depth Raster, Volume Estimations

 Convert 30m raster DEM to center points  Edit points within the lake perimeter to reflect drain depth estimations Center-point values edited to reflect the lake bottom. Values are based on drain line depth estimations.

 Points file  mass points for terrain creation  Interpolate terrain to raster DEM with cell size 6.35m*

 Kml shoreline doesn’t make ‘elevational’ sense...  Modified using aerial imagery, DEM  Flood level established from photos taken in Summer

 Select all points within lake perimeter at each height  Assign new value to selected points  Create terrain from points and interpolate to raster

 Raster subtraction using Lake bottom DEM and Lake surface DEMs DepthExpression NormalNormal Surface – Lake Bottom FloodFlood Surface – Lake Bottom Normal HeightFlood Height

 Performed in Excel  Normal and flood depth rasters converted to ascii and imported to Excel  Volume: Cell Length x Width x Height (depth) ◦ 6.35m x 6.35m x (depth)  Sum all volume calculations Normal Water Level: 85, m 3 (112,095.6 yd 3 ) Flood Water Level: 190, m 3 (249, yd 3 )

 Data: ◦ 30m DEM from topo contour digitization/ interpolation  poor quality for scale of analysis ◦ Lake depths  estimations from lake users  Terrain to Raster ◦ Raster grid size (6.35m): questionable  Should match input size (30m), but too coarse for lake perimeter—excludes large amounts of lake area  ESRI default: based on the overall dimensions of the minimum bounding rectangle and the number of input elevation points