Wednesday, October 24, 2012

The Wide View

Graduate students capturing images of the native grasslands
How often, on an absolutely perfect autumn day, do you have to spend the day outside as part of your job?  I know I rarely have that good fortune, but the stars were aligned on Monday, October 22.  That day, I escorted thirteen Rutgers University landscape architecture graduate students and their two advisers on a tour of our watershed.  The students' studio project this term is to develop a master plan for a watershed in central New Jersey.  The advisers were aware that the watershed in which I work has a long history of fairly sophisticated land use planning, natural resource conservation, and ecological restoration, so they brought the students to southeastern Pennsylvania to get a feeling for what can be done if government entities, nonprofit organizations, and municipal agencies can work in concert.

The upper third of the watershed has largely been given over to standard suburban development; much of it is already a "lost cause."  So, instead of starting at the source of the creek, we began the tour at "my" preserve in the central portion of the watershed and worked our way downstream over the course of the day.

After touring a portion of the protected land we have set aside and reviewing the forest restoration and native grassland creation projects underway, we enjoyed a picnic lunch then headed south into the city of Philadelphia for an overview of the lower third of the watershed.  Within the city, the creek flows through a protected corridor of parkland, but the corridor only protects the steep slopes directly alongside the stream, not the creek's tributaries.  Outside the park, development crowds right up to the edge of the woods.

Seasonal marsh occupying the site of a former parking lot
Our first stop in the city was a wet weather marsh constructed a few years ago on the site of a former parking lot.  The parking lot was only usable part of the year because it was frequently flooded--either by stormwater overflowing from the adjacent creek, or from runoff in the watershed.  The park district scooped out the parking lot and replaced it with a seasonally-wet marsh.  The basin was dry on the day of our visit.

Residential stormwater outfall restoration project
Our second stop was at a stormwater outfall draining a large, mostly paved residential neighborhood.  The park district had recently completed an engineered restoration of the stream channel, replacing a severely eroded 12-foot-deep gully with a wider, boulder-lined swale designed to accommodate the stormwater outfall.  Further downstream, the park had installed a series of check dams and step pools to further slow and attenuate the flow before the stream re-entered its natural channel.  The engineered intrusion into the forest looks raw and unnatural, but the outfall becomes a raging torrent during heavy rains--like a water cannon blasting the streambanks--so anything less than a major retrofit would soon have washed away.

Check dams and step pools in the stream valley
Our third stop was at the fall line--the line at which a stream "falls" off the hard edge of the continent (often at a waterfall or rapids) and flows out onto the unconsolidated sediments of the coastal plain.  The fall line also represents the landward limit of the tides; downstream of this point, the creek becomes tidal.

Rapids at the creek's fall line
Students at the fall line, with the King's Road bridge in the background
Just a few hundred feet downstream of the fall line, the creek is spanned by the oldest bridge in the United States--the King's Road bridge, built in 1697.  The King's Road connected Philadelphia with New York.  The bridge is still in use and bears a heavy load of vehicular traffic.

Our final stop of the day was on the coastal plain at the mouth of the creek.  Here, the creek adds its flow to the Delaware River, which is also tidal.  We arrived at low tide, and the mud flats flanking the mouth of the creek were fully exposed.  The wetlands around the mouth of the creek are home to a pair of Bald Eagles, which started building a nest two years ago and have fledged chicks successfully each summer since.

Mud flats exposed at the creek's mouth at the Delaware River
The Philadelphia skyline, about seven miles distant
Students spread out in the maze of trails near the mouth of the creek to explore its wetlands.  As I came around a corner of a paved walking path, I found two students sprawled on the asphalt, clearly intent on something in the center of the trail.

A really hard day, or something exciting...?

They were getting up close and personal with a preying mantis that had caught a sulfur butterfly and was making quick work of the victim.

After we returned to our vehicles, I sent the students back to New Brunswick, New Jersey, and I headed back to the 'burbs.  A good day was had by all.


Carolyn H said...

Forced to work outside on a gorgeous fall day, eh? You don't have my sympathy at all! It does sound like a great way to spend the day, too, and I suspect the students enjoyed it just as much.

Seema said...

great pictures...
specially the photographers lying on the road to capture the insects is very interesting..

robin andrea said...

I loved reading this post and seeing the work being done to help restore some of the natural wetlands and grasslands in such an urban area. Pretty great stuff. As a New Jersey native, I like knowing that there are young people wanting to work on such restorations. That's hope for the future!

I wish I had known about the Kings Road bridge before I moved west. Such a history!

Haddock said...

Like that picture of them taking the picture of the praying Mantis.
Realised that you like watching movies.
Have you seen English Vinglish? (see my second last blog on the same movie)

Scott said...

Yeah, Carolyn, it's a tough job but somebody's got to do it. (Let me just add, though, that the field trip day way very atypical; usually, I'm stuck inside and can only wish I could escape like this.)

Scott said...

Thanks, Seema! At first, I have to admit that I just joined the two close-up photographers on the ground, but when I stood up and saw the potential for an interesting image, I just had to get the guys sprawled there. Their lenses were able to focus much more closely than mine, so they got some really great close-ups.

Scott said...

Robin Andrea: These students will be unleashed upon the natural world after one more semester, so I'm glad that I had a chance to get into their heads before they set off on their professional careers. Actually, Rutgers' program focuses very heavily on being respectful of native landscapes, so I think that these students will do as good a job as they can when they find work.

The King's Road/Frankford Avenue bridge has been widened with another lane to accommodate more traffic, but the original bridge is still in use. It's been recognized as an engineering landmark by the Society of Civil Engineers.

Scott said...

Haddock: I have not seen "English Vinglish." I'll check out your post. Thanks for the heads-up.

Gail said...

HI SCOTT - fascinating work-adventure and great pictures and explanations, I felt I was there. Wow!
Brace yourself for the storm, as are we.
Love Gail

Scott said...

Gail: I'm pretty much as prepared as I can be. Thanks for the good wishes!

packrat said...

I really enjoyed reading this post, Scott, and getting insight into the fascinating work being done in restoration. I'm certain those grad students were impressed by your grasp of the pertinent issues.

Scott said...

Thanks, Packrat. I host about a half-dozen classes each year, and these students seemed more motivated and interested than most. There's definitely a difference between undergrad and grad students; guess which are the more engaged.