Memorandum
To: Dr. Breck Bowden
From: Peter Dufault
Re: ENSC 285B; Engelsby Brook
Date: April 29, 2005
Cc: Evan Fitzgerald, Stacy Pomeroy, Mike Kline and Peter Spatz
This memo addresses and summarizes the issues and problems that I’ve had while using
the SGAT program for the Engelsby Brook, as per your request.
Stream Typing: I used Table 2.2 in the Phase I reference chart to determine what type
of stream pertains to each reach; and I found it somewhat difficult to determine exactly
what stream belongs to each stream type. This difficulty was due to the fact that this was
my first time seriously attempting this exercise and the small variations of my stream on
any given reach made it somewhat difficult to determine the stream type. I determined
the stream type by averaging small differences in a stream to match a stream listed in the
table.
Channel Widths: The channel widths varied substantially in the Engelsby Brook,
especially at the lowest reach where the stream often went into a divided channel. I used
an average distance when I entered the data on stream widths.
Channel straightening: In the urban setting, I found channel straightening somewhat
difficult to determine. The culverts and bridges were easy to recognize, however some
portions of the urban setting were difficult to determine the length of channel
straightening that has taken place.
Approximately 75% of the Engelsby watershed is in an urban setting, and I determined
that most of the urban portions of the stream have undergone some degree of channel
straightening, but I feel that my conclusions should be confirmed. The remaining portion
(~25%) of the Engelsby watershed is located in a golf course. The majority of the stream
segments have been straightened (or altered) in the golf course where numerous culverts
and several ponds were observed.
Channel Modifications: In step 5.4 of SGAT there were several options available from
the drop down menu regarding channel modifications and none of them pertained to what
I wanted to describe. I wanted to conclude that the channel was straightened, but I was
unable to select that on the SGAT program. (In some instances a comment box in SGAT
would be helpful). The T.01 tributary to the Engelsby Brook is straightened or modified
nearly 100%, yet I was unable to assign an accurate channel modification description in
the SGAT program.
As described in my Powerpoint presentation, the channel modifications were generally
described as ‘highly modified’, and this was determined without the RIT tool.
Meanders: I determined that the Engelsby does not contain any good meanders for the
entire length of the stream, as observed in the ArcView program. This made it difficult to
determine the Meander Width Ratio and the Wavelength Ratio in steps 6.5 and 6.6 of the
SGAT program. I made some measurements (with the measuring tool in ArcView) and
was able to complete steps 6.5 and 6.6; however these steps may need to be checked for
accuracy.
During my second windshield survey I did observe a few meanders at the lowest reach,
but I did not take any field measurements. Hopefully some field measurements of
meanders will be measured during the Phase II process.
Conclusion: In conclusion, I’d like to make a brief comment on the flow of the course
and its structure. I was impressed with the wide range of resources available to us and
the numerous people who contributed time and effort into making this class a success. I
think the only negative comment I have would be the timeframe in which the SGAT
process was completed. I wish there was more time to utilize the program we have been
developing in Phase I, rather than finishing it up in the last few weeks of class. I would
have liked to fully understand the program, as I feel that the first time through the setup
process took longer than we expected, and it did not allow time to work with the SGAT
product.