Abe590 Homework 3
This problem uses resources on the web. Go to this page,
http://www.crwr.utexas.edu/gis/gishydro04/index.htm
and do Exercise 4 and 5.
Exercise 4 is delineating a watershed.
Summary of Material to be Turned In – exercise 4 NOTE – skip tauDEM part, stop at
question 15.
1. Report the grid cell size in both N-S and E-W directions of a 1/3" grid cell at latitude 43oN.
2. Make a screen capture of the attribute table of Fdr and give an interpretation for the values in
the Value field using a sketch.
3. A layout showing the delineated Catchments and DrainageLines
4. How many DrainagePoints, DrainageLines and Catchments are there? What is the ID field in
each feature class that associates the appropriate DrainagePoint with its DrainageLine and
Catchment? Make a graphic showing how one associated DrainagePoint, DrainageLine and
Catchment are related.
5. A graphic showing drainage paths traced over the digital elevation model.
6. A graphic showing an Identify enquiry on the Flow Accumulation Grid
7. What is the flow accumulation in number of cells where the stream leaves this watershed. What
is the cell size? What drainage area does this correspond to in km2? Draw a series of 5 x 5 grids
on paper and based upon the template given fill in the following information

Initial elevation

AGREE conditioned elevation

Pit filled elevation

Flow direction (depict with arrows)

Flow accumulation area
8. A graphic showing the Region of Hydrologic Influence of your chosen catchment.
9. A graphic of the delineated subwatersheds, and a table showing the subdrainage area and the
total drainage area in km2 for each gage and for the basin as a whole.
10. Prepare a layout map of Reynolds Creek showing the TauDEM delineated channel network and
watersheds draining to each stream segment. On this layout indicate stream orders in different
colors or symbols.
11. Report the threshold selected by the constant drop procedure with the DEM curvature based
method for Reynolds Creek.
12. Report the contributing area threshold selected by the constant drop procedure with the
Contributing area method.
13. Report the drainage density identified from the constant drop procedure with the curvature
based and contributing area methods.
14. Report the drainage density from the channel network delineated using ArcHydro.
15. Report the drainage density from the NHD channel network. .
Hand in the following from Exercise 5:
Remember a map is a document with a scale bar, north arrow, author, and title.
To be turned in: A map showing the Arc Hydro framework dataset for the San Marcos Basin
To be turned in: A map of the features selected by the Trace Upstream task.
How many features are selected by this trace? (Look at the selected features in the attribute
tables)
To be turned in: A map of the features selected by the Trace Downstream task.
How many features are selected by this trace?
Make a table that lists the main five feature classes: HydroEdge, HydroJunction,
MonitoringPoint, Waterbody and Watershed and list the attributes that were added to these
feature classes by the process of applying the ArcHydro schema.
List all the fields in the UML class column even if they were already included in the class.
The gage on the San Marcos River at Luling is related to an adjacent HydroJunction, which is
in turn related to the Watershed draining to that location. List the HydroID’s of these three
related features.
To be turned in: What is the maximum flow distance from any HydroJunction in the San
Marcos network to its outlet?
What is the flow distance from the stream gage #08172400 (Plum Creek At Lockhart) to the
outlet?
How far downstream from stream gage #08171000 (Blanco River at Wimberley) is the stream
gage #08173500 (San Marcos River at Ottine) ?
Regards
Larry Theller