Mapping and Delineating Watershed

Since my focus has been in landscape architecture and urban planning, it is interesting to me to study an urban watershed in a very well planned community, in terms of planning building of hundreds of years of history that they seem to do it well. Arlington County is one of those urban communities that I found out. Four Mile Run stream is a nine-mile long stream, a direct tributary of the Potomac river, located in a highly urbanized area in Northern Virginia with several tributaries.

Its 19.6 square mile watershed covers portions of Arlington and Fairfax Counties and the Cities of Alexandria and Falls Church. One of the initiatives has been to a better job of daylighting streams, so as I learned in my major, most of our watersheds in urban areas are all underground in streets sewers. The four mile run actually does not a good job of keeping things day lighted, that has a couple of components which I have not ever noticed this matter. Right there where the stream comes out from underground it smells bad, which causes getting bacteria that live underground and they are not affected by the darkness or they are not vulnerable the daylight and sunlight. But once it is day lighted, the stream is healthier and we have macroinvertebrate and all sorts of other organisms they are living in the stream so it is healthier. I would like to make an emphasis on these upper parts of the tributaries of four mile run. Rather than focus on just one of the tributaries, I am going to do comparisons on Doctors Branch and Lubber Run of the four mile run, as well as study these areas from where they come out from underground until they join four mile run which has direct impact on landscape architecture because storm sewers are parts of the purpose, they minimize flooding, they minimize damage to property but when done well they can be very attractive.

 

Watershed: Four Mile Run

Area: 19.6 mi²

Significant Tributaries:  Lubber Run, Long Branch (upper), Doctors Run (Doctors Branch), Lucky Run, Long Branch (lower)

Counties: Arlington, Fairfax, City of Alexandria

Impervious: 41%
Non-Impervious: 59%

 

SubWatershed	Area(mi2)	County	Elevation Change(ft)	Permeability	Significant Feature
Doctors Branch	1.4	Arlington	152 (82-234)	41% impervious	Bacteria Monitoring Site
Lubber Run	1.4	Arlington	266 (160-426)	37% impervious	Macroinvertebrate Monitoring Site

 

 

Map 1. Four Mile Run Watershed

Map 2. Lubber Run and Doctor's Branch Subwatersheds

Map 3. Slope Analysis