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,"Accumulation")

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)

http://water.usgs.gov/GIS/regions.html

Hydrologic Unit Codes

Sub-Catchments

Lakes

National Hydrography Dataset

• NHD

http://nhd.usgs.gov/

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