The Impact of Construction on Dog River Watershed
Doni E. Thompson, Earth Sciences Department, University of South Alabama, Mobile,
Al 36688. E-mail: det601@jaguar1.usouthal.edu.
The Dog River Watershed consists of several streams and drainage ditches that
drain the Mobile, Alabama area and empty into Mobile Bay. More homes and businesses
are being constructed in the area to support the growing population. This construction has
a negative effect on the watershed. The lack of vegetation, due to land clearing, leads to
erosion. Building materials are also washing into the rivers and tributaries. This has a
huge effect on stream and river health. Repeat photography is used to determine how
long these construction sites affect the watershed. Older photographs were studied from
1997 to 2008. New photographs were taken of ongoing construction sites. These sites
included over twenty residential, commercial, and roadway construction sites. The
photographs were used to determine how long the sites affected the watershed. These
sites cumulatively impact the health of the Dog River and its tributaries. The sites may be
short term, but the impacts are huge and new construction sites are always opening. The
area takes a long time to recover. The length of time is crucial to overall health of the
watershed. This study provides education to the public and may stimulate ideas for
improvement. It also brings much needed attention to poor construction practices.
Keywords: Dog River Watershed, repeat-photography, construction
Introduction
The Dog River Watershed consists of several streams and drainage ditches that
drain the Mobile area and empty into Mobile Bay. It is also the key to estuarine health in
Mobile Bay. Forty percent of the Dog River Watershed is in Mobile County and the other
sixty percent is within the Mobile city limits (Fearn, 2009). All of Mobile County is
growing in population. The county grew by over 25,000 people between 1990 and 2007
(U.S. Census Bureau). As the population continues to grow, so do areas of construction.
More homes and business are being built in this area to support the growing population.
Construction can have a negative effect on the watershed. Some of these may be short
term, but some may be much longer. Poor land development practices have a longer term
effect on the Dog River Watershed. The lack of vegetation, due to land clearing, may lead
to erosion, which is simply the movement of dirt, sand, rocks, and other sediment. Rain
water may cause sediments and building materials to flow off of a hillside into streams
and tributaries. This affects the health of the river and streams.
By using repeat photography, it is easy to determine how specific areas contribute
to the degradation of the Dog River Watershed. Repeat photography refers to two or
more pictures taken from the same place with the same field of view, ideally with
cameras possessing the same focal characteristics, but at different times (Hanks, 2006). It
is often used to show change in geographic features over time. Whenever early
photographs are repeated, they become elements of continuous record (Skovlin, 1995).
Repeat photography shows approximately how long a construction site may affect the
area.
Research Question
How long do residential, commercial, and construction sites impact the Dog River
Watershed? Identifying this may lead to more stern enforcing of laws for construction
companies. It will also better educate the community about the impacts that construction
areas have on the Dog River Watershed.
Methods
Repeat photography is a simple research method that provides great results. First,
past photographs, taken by previous geography students, of the Dog River Watershed
were studied. Past photographs of construction areas in both residential and commercial
areas were located. Twenty locations were chosen for this research, all within Mobile’s
current city limits. The photographs were studied to see how the construction and
surrounding areas changed throughout the years and what kind of impact they show.
Areas are located on a map and photographs were taken at each of the locations. They
needed to be taken from the same field of view or angle as the original photographs,
which allowed better interpretation of changes to the areas. The period of time that the
watershed is degraded can be determined for commercial, road, and residential areas.
Field notes were taken to record any changes, the condition of the area and nearby
waterways, and any problems experienced while collecting research materials. A report
the overall changes and effects to the area is given. Repeat Photography is the best
research method to provide answers on this subject.
Figure 1: The map shows all of the study area. The orange dots represent each location visited to
repeat photographs.
Results
The results of this study are very interesting. Using repeat photography, it is easy
to see that many former construction sites still have issues. Years later, many of the
construction sites still play a role in the degradation of Dog River Watershed. Most of the
sites that showed significant poor construction practice still have problems now, with
erosion still being the dominant issue in the areas. A key example is a gas station located
at Azalea Road and Michael Boulevard (Fig. 2 and 3). The construction was underway in
January of 1997 and showed poor practices from the beginning (Appendix A). Twelve
years later, dirt and sand is still eroding from the area and silt is seen in the ditches
flowing downhill toward Montlimar Canal. Another example is the Lowe’s on Airport
Figure 2: 1997 image of Chevron
Figure 3: 2009 image of Chevron
Boulevard and Schillinger Road, in construction during 1999 (Appendix D). The
structure sits at the top of a hill. At the time of construction, improper use of silt fences
led to the erosion from the parking lot. At the present time, the eastern hillside is still
experiencing erosion very near Milkhouse Creek. Another example is a church located on
Schillinger Rd that was built on a hillside (Appendix Q). They had to cut into the hill and
this area still has major erosion issues. Day Springs Baptist Church on Cody Road is very
similar (Appendix S). All the hillsides are eroding away and the retention ponds are full
of silt. During this research, very few sites with previous poor construction practices were
without any problems currently. However, some were surprising. The Hampton Inn and
Suites on Interstate 65 Service Road was one of these sites (Appendix J). Poor
construction with excess erosion was underway in 2006. Presently, the site is well
maintained and shows no signs of erosion or any other construction related issues. The
sites with good construction practices seemed to have fewer problems then and show no
land disturbances presently. Other examples include a business on Montlimar Road and
Legacy Village on Dauphin Street (Appendix B and T).
There were also areas that seemed to have once been cleared for construction.
There is a cleared site behind Wal-Mart on Schillinger Road, and it is unknown how long
the area has been cleared (Fig. 4 and 5). However, some photographs of the cleared area
date back to 1999 and 2003. There is no evidence of any preventative measures to stop
erosion. There is also no sign of any structures being built or land for sale. Access to the
rear of the site is not open, but the farthest area in view is less than a third of a mile uphill
from Milkhouse Creek (Appendix I). Some areas, such as a section of land behind
Knollwood hospital, were once cleared with no signs construction. The area experienced
erosion problems three years ago, but is now overgrown with vegetation (Appendix M).
An area around the former Cock of the Walk restaurant seems to have been cleared also
(Appendix K). Much of the sand flows into Halls Mill Creek during rain events. This area
was once run by the Army Corp of Engineers and has not been cleaned up. There is a lot
of erosion and old silt fence material in the area.
Figure 4: Behind Wal-Mart on Schillinger Rd
in 2003
Figure 5: Behind Wal-Mart on Schillinger Rd
in 2009
Another issue is silt fencing and other construction material being left behind after
the land has healed. The above mentioned area near Knollwood hospital is a good
example. Many silt fences were left behind even though they are no longer needed. They
are now torn and littering the area. This is seen in several other places, including the
Target shopping center on Schillinger Road (Appendix F). At this site, the only thing left
is the short wire fencing and the material is now ripped and torn off. It serves no purpose
and needs to be removed, because it only causes more pollution to the area. Silt fences
should be removed when they are no longer needed or required (Caltrans, 2003). Other
sites, such as Shadow Creek sub-division on Sollie Road, never finished construction
(Appendix N). They left a lot of materials and debris behind, but never built anything
other than roads.
It is difficult to say whether commercial or residential construction sites have a
longer effect on the watershed. Many commercial structures are built quicker, but the
land takes longer to heal, if it heals completely at all. Individual homes tend to be built
fairly quickly and have less long term effects. An example of this is the two homes in
Wimbledon Park sub-division (Appendix C). They were built quickly and did not affect
Eslava Creek for a long period of time. The sub-division is now running out of space to
continue building. However, some communities and sub-divisions may have long term
effects, because many homes are built in sub-divisions. Many of them continue to expand
through out several year periods, so the area as a whole may have longer effects than one
commercial site. Dawes Lake Estates is a good example of this (Appendix P). The first
homes were built in the late 90s. The sub-division has expanded farther since then and
new homes are being built on the lake using poor practices currently. Another example is
Stone Hedge sub-division (Appendix O). Many homes have been built here in the past
several years and some are still being built now. Some of these sites have poor
construction practices that affect Second Creek, which runs directly through this subdivision. Another site is the Brookside Retirement Community at the intersection of
Milkhouse Creek and Cottage Hill Road (Appendix G). This community has been
expanding for over ten years. The areas recover well from the poor construction, but it is
constantly affecting the watershed. They need to do more to protect Milkhouse Creek.
Minor road construction tends to be short lived. Most of the companies seem to
use decent construction practices more recently. An example is the road construction on
Government Street near Interstate 65 (Appendix H). It was a poor construction site, but
recovered quickly. Another example is the service road near I-65 and Halls Mill Road
(Appendix L). The site had poor construction practices also, but recovered well in less
than a year.
Discussion
There was some trouble faced while doing this research. Some previous photos
dated back to 1997. Over any amount of time, land and vegetation can change
dramatically. In several cases, vegetation had grown so much that repeating the photos in
some areas was nearly impossible and even dangerous (Fig. 6 and 7). In some instances,
Figure 6: Vegetation in 1997, behind Wal-Mart
Figure 7: Same location in 2009
fences were put up to enclose property, making it impossible to reach the previous
construction sites. Some sites are now surrounded by other structures, making it hard to
get the same camera angle. Updated photographs were originally taken in early March.
Due to technical difficulties, the process had to be repeated again in mid April. In that
small time period, much of the vegetation had grown. Many trees had new blooms and
new leaves, which prevented many photos from being replicated as easily as the previous
attempt.
Other problems included construction companies having issues with photos being
taken of there current sites. At one particular site, pictures were not allowed of a
developing area connected to a retirement community. Unless there is something to hide,
there should not be any issues.
Conclusion
All in all, new homes and businesses must be built to support the growing
population and people moving away from the metro area. There is constantly new
construction through out the area and the sites as a whole contribute to the degradation of
the Dog River Watershed. It is difficult to say how long the area has problems, because it
is constantly being affected. The sites cumulatively affect the health of the Dog River and
its tributaries. Sedimentation and erosion contribute significantly and some sites had this
problem in the beginning and it is still ongoing. Also, the poor construction sites built on
hills have the worst problems currently. The hillsides are still eroding and taking longer
to heal. The poor construction sites that were built on flat areas tended to heal quickly. To
put an actual time frame on it is impossible. Good construction practices are a necessity
to improve and restore the quality of the watershed. It is important for the people who
live and work in these areas to understand how the area is affected by the construction
sites. Strict laws need to be in place for the construction companies and need to be
heavily enforced. Preventative action needs to be taken at all times to reduce sediment
that flows into the river. Educating the public may also stimulate new ideas for improving
construction practices.
These photographs, old and new, will provide excellent records for the future. The
new photos will continue the sequence for further research and comparison. This project
can be repeated often to provide a better understanding of the effects the construction
sites have.
References
Alabama Department of Environmental Management. 1994. A Survey of Dog River
Watershed. Accessed on 28 March 2009.
Alabama Department of Environmental Management. 1995. A Survey of the Dog River
Watershed Second Year’s Findings. Accessed on 28 March 2009.
Caltrans. 2003. Construction Site Best Management Practices Manual. Section 4, Silt
Fence, SC-1. Accessed on 16 April 2009.
Cerney, Dawna L., J. Ronald Eyton, David R. Butler. 2008. Assessing Landscape Change
in Waterton Lakes National Park, Canada, Using Multitemporal Composites
Constructed from Terrestrial Repeat Photographs. Geocarto International, 23:
5,347-371. accessed on 26 February 2009.
Fearn, Mimi. Dog River Clearwater Revival. Last updated on 2 January 2009. Accessed
on 26 February 2009. http://www.usouthal.edu/geography/fearn/DRCR.htm
Hanks, Thomas C. Repeat Photography, Virtual Repeat Photography, and Earth Surface
Change in the Photographic Era. Copyright 2006. Accessed on 26 February 2009.
http://gsa.confex.com/gsa/2006AM/finalprogram/abstract_113487.htm
Previous Construction Photos: provided by all field work in geography classes between
1997 and 2008. All photos were taken in the Dog River Watershed. Accessed
between February 2009 and May 2009.
Skovlin, Jon M., Jack Ward Thomas. 1995. United States Department of Agriculture.
Interpreting Long-Term Trends in Blue Mountain Ecosystems from Repeat
Photography. Gen. Tech. Rep. PNW-GTR-315: p.1-15. Accessed on 26 February
2009.
United Stated Census Bureau. Population Finder. Accessed on 26 February 2009.
http://factfinder.census.gov/servlet/SAFFPopulation?_event=ChangeGeoContext
&geo_id=05000US01097&_geoContext=&_street=&_county=Mobile&_cityTow
n=Mobile&_state=&_zip=&_lang=en&_sse=on&ActiveGeoDiv=&_useEV=&pct
xt=fph&pgsl=010&_submenuId=population_0&ds_name=null&_ci_nbr=null&qr
_name=null&reg=null%3Anull&_keyword=&_industry=
Appendix A: Chevron at Azalea Rd. and Michael Blvd
1997
1998
2009
2009
Appendix B: Technical Suite on Montlimar Dr.
1997
2009
1997
2009
Appendix C: Wimbledon Park Neighborhood on McGregor Rd.
2004
2004
2004
2009
2009
2009
Appendix D: Lowe’s at Airport Blvd. and Schillinger Rd.
1999
2009
1999
2009
Appendix E: Christ United Methodist Church at Grelot Rd. and Hillcrest Rd
2003
2003
2009
Appendix F: Target shopping center on Schillinger Rd.
2001
2009
2001
2009
2005
2009
Appendix G: Brookside Retirement Community at Cottage Hill Rd.
1999
2009
2005
2009
1999
2009
Appendix H: Government St. near I-65
2003
2009
Appendix I: Behind Wal-Mart on Schillinger Rd.
1997
2009
2009
Appendix J: Hampton Inn on I-65 service rd.
2006
2006
2009
2009
Appendix K: Old Cock of the Walk Restaurant on Halls Mill Rd.
1998
2009
2000
2009
2003
2009
Appendix L: Government service rd. near Halls Mill Rd.
2003
2009
Appendix M: Former site of Mitchell Cancer Institute on Knollwood Rd.
2006
2009
2006
2009
Appendix N: Shadow Creek Sub-division on Sollie Rd.
2001
2009
1999
2009
2001
Appendix O: Stone Hedge sub-division on Grelot Rd.
1998
2009
2009
2009
Appendix P: Dawes Lake Estates on Dawes Rd.
1998
2009
1998
2009
Appendix Q: Church on Schillinger Rd. just south of Cottage Hill Rd.
2002
2002
2009
2009
Appendix R: Chevron at Schillinger Rd. and Three Notch Rd.
2001
2009
2001
2009
Appendix S: Day Springs Baptist Church on Cody Rd.
2003
2003
2009
2009
2009
2009
Appendix T: Legacy Village on Dauphin Street near I-65
2006
2009