Week 3 - Running Water: Delaware River

I was awakened early this morning by a loud knock (banging really) on my front door.  Imagine my surprise to see my 111-year-old great granny standing there.  I had no idea she was coming.  Apparently, she hitchhiked some 700 miles south, overnight, and arrived looking like she just came from next door.  “Let’s move,” she said, “we’re going to see a river.”  We jumped in the Jeep and headed for Pennsylvania’s easternmost border for a look at the Delaware River.

Later, while riding in a helicopter that Granny was piloting over the Delaware River, she explained the whole thing to me.  Following is the description she laid out for me.

The Delaware River originates from two branches in the upper portion of eastern New York. The west branch begins in the Jefferson, New York and the east branch begins in Roxbury, New York.  The two branches come together in Hancock, New York to form the Delaware River.  The Delaware River then flows south some 331 miles discharging into the Delaware Bay and then immediately into the Atlantic Ocean.  The two largest tributaries to the Delaware River are the Lehigh River and the Schuylkill River, both in Pennsylvania.  There are 214 lesser tributaries that empty into the Delaware River.  The Delaware River is the Northeastern border separating New York from Pennsylvania, the sole separator of Pennsylvania from New Jersey and finally, the separator of Delaware from New Jersey.  

The Delaware River is a perennial river flowing for many hundreds, if not thousands, of years.  It is made up of three main parts: the upper, the middle and the lower sections.  The upper and middle sections are in areas far less populated than the lower section which passes next to the highly populated city of Philadelphia. 

The upper section of the river is bounded by forested and rocky banks with the “V” shape valley effect in many parts, having a depth of 6.5-8.5 feet, an elevation of approximately 600 feet above sea level, and giving a discharge of 9000 – 18000 ft³/s., depending on flow rates of tributary dams in the upper section being opened.  The drainage area for the upper section of the Delaware River is about 2020 mi² (https://waterdata.usgs.gov/ny/nwis/uv/?site_no=01428500).

Upper Delaware River; 

Photo Credit: National Park Service

 The middle section of the Delaware River contains the Delaware Water Gap – a National Recreation Area.  A water gap is part of a trellis drainage pattern and happens when the river follows a steep-walled notch in the mountains surrounding the river.  This water gap also demonstrates some of the meandering aspects of the Delaware River as is makes many s-shaped curves at several points along its length.  

Delaware Water Gap;

Photo credit: National Park Service

The lower section is much wider, deeper and open to shipping.  In fact, the Delaware River lays claim to being the largest freshwater port in the world receiving fruit, appliances and many other items produced worldwide.  The lower section of the Delaware River near Philadelphia is used by large ships and has a depth of 40-45 feet deep with a discharge of approximately 50,000 ft³/s and approximately 39 feet above sea level (https://drbc.net/Sky/flows.htm).  

Lower Delaware River, Philadelphia;

Photo credit: Philadelphia Water Department

USGS gages provide much data using telemetry via satellite for many points along the river.  The Delaware River has a suspended sediment load of about 1.6 million tons according to data obtained from a USGS report (https://pubs.usgs.gov/wsp/1532h/report.pdf).  There have been ten major recorded floods in the Delaware River Basin since 1903 but as the only major river east of the Mississippi River not to be dammed, the Delaware River is able to drain water relatively quickly out into the Atlantic Ocean and as such does not represent a high annual flood risk (https://www.state.nj.us/drbc/hydrological/flood/drb-flood-events.html).  Most of the Delaware River has been designated a part of the National Wild and Scenic Rivers System created by Congress in 1968 (https://www.rivers.gov/wsr-act.php).