Network Examples Distance to schools in Gambia Puerto Rico Streams Determine water availability for Nuclear Reactors in Russia Invasive fish moving “up stream”
Gambia
“Hydrology”/Stream Paths Fill Sinks Find direction Find Accumulation SetNull(“Accumulation”<Desired, ”Accumulation”) Stream Feature Make a network?
Fill Sinks
Direction
Flow Accumulation
Null Non-Stream Pixels SetNull("Accumulation"<10000,"Accumul ation")
Stream To Feature
What happened here?
Goes “straight” through lakes
A stream network?
Puerto Rico Streams
Missed Connections
Be Careful with “Near”
Islands and Channels
Natural Earth: Oregon
Stream Ordering
Stream Order
Gauge & Tidal Stations Gauge Data: USGS –Flow at a point on a stream/river Tidal Stations: NOAA –Tide and/or current at a location
Hydrologic Unit Codes (HUCs)
Hydrologic Unit Codes
Sub-Catchments
Lakes
National Hydrography Dataset NHD
Next Steps? Create a stream network –Combine streams from multiple rasters –Compare the accumulated pixels to gauge station measurements Create watershed –Point along the stream can be a “pour” point Create lakes? –Constant elevation above the “pour” point Get other software?
HEC-RAS
Hydrologic Flow