ArcHydro Presentation

Josh Jones & Alyssa Weatherford
EGEO 451, Winter 2011
ArcHydro is used mainly by hydrologists or GIS
professionals interested/working in the field of water
resources. Even if you are not directly interested in water
resources, it is at least beneficial to know some basic
processes within a very powerful and extensive set of tools.
Watershed analysis is used by many others because of
how dependent humans and animals are on water. If a
watershed becomes contaminated many problems can arise
because of this watershed conservation is a big deal.
This presentation outlines the necessary steps to
develop stream network flow in regards to a Digital Elevation
DEM: J:\GEO\GEO_data\WA_USGS\DEM_10_MOSAICS\Bham_Whatcom_Co\w_wc_dem
Hydrology: USGS, National Hydrography Dataset,
This step creates linear features between the
raw DEM and the hydrography layer, which is
needed to develop flow on the stream network.
Each pixel in the resulting DEM
is assigned a direction of the
path of steepest descent. Each
number, although seemingly
nonsensical values have been
chosen, represents a direction.
1=E, 2=SE, 8=S, etc.
Drainage Lines, usually located on higher
order streams or on high topography
Watershed delineation did not always reflect the
watersheds in their true form. Lake Whatcom was
showed draining out of a channel in the Northeast instead
of through Whatcom Creek at first.
After trying numerous DEM’s and different stream
networks, it did finally show the correct drainage path.
This type of analysis is very picky, when you think you
barely changed something it ends up not doing the
analysis correctly.
Whatcom Watershed
There are two groups of people, one who want to develop
the watershed and other who want to make the Whatcom
watershed DNR land.
The Whatcom watershed is the main drinking water
source for over 95,000 people.
Development and allowing to log can lead to
contamination of water and landslides due to the areas
steep slopes and high rain fall.
By Josh Jones
• Vaddey Sesgu & Harman, Rhett. Basics of Arc Hydro: Building a New Foundation for Water
• Conservation Northwest. Next Step for a Whatcom watershed Preserve. November 9, 2009. Retrieved Feburary 28, 2011
For more Whatcom Watershed Information
About Our Drinking Water
About Development
About Conservation

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