Flood and Drought Data

Flood Data

Four Mile Run is a direct tributary of the Potomac River. The Potomac River Basin cradles the Four Mile Run watershed and ultimately drains it to the Chesapeake Bay. Four Mile Run rises in Fairfax County and flows downstream through the City of Falls Church and on to Arlington County. The final 2.3 miles of the run, before it opens to the Potomac River, are contained in a flood control channel designed in the early 1970s by the US Army Corps of Engineers (USACE). Although a USGS monitoring station within the Lubber Run and Doctor’s Branch watersheds could not be located, the USGS 1652500 gaging station on Four Mile Run located at the Shirlington Road Bridge has collected stream flow data since 1951.

 

USGS Gage 1652500 Location

 

View of Four Mile Run near gauge

 

The location of the gage allows capture of flow data from a 13.80 square mile sub-basin of the watershed, about 70% of the entire watershed (USGS website). Although the lower portion of Four Mile Run is impacted by the tidal influence of the Potomac River, the USGS gage location is roughly 6,000 feet upstream of the extent of those impacts.

 

Collapse of the Walter Reed Bridge in Arlington County – Just Upstream of the USGS Gaging Station. Flooding on June 22, 1972 was due to the remnants of Hurricane Agnes.

 

The USGS website provides continuous stream-flow, precipitation and temperature records which can be found in the graphs below:

 

   

Also, the information on National Weather Service website indicates that the latest observed water level in four mile run is 4.14 ft at 12:25 PM EDT 7-Oct-2020 and flood stage is 12 ft.

                          

Historic Flood Crests

-	Water Year	Date	Gage Height (ft)
1	2006	06/25/2006	20.20
2	2019	07/08/2019	15.30
3	1975	09/26/1975	13.07
4- Hurricane Agnes	1972	07/21/1972	12.40
5	2018	09/01/2018	12.26
6	2003	09/23/2003	11.83
7	2011	09/08/2011	11.29
8	2008	09/06/2008	11.19
8	1985	09/10/1985	10.36
9	1993	11/28/1993	10.23
10	2011	09/08/2011	10.13
11	1987	06/26/1987	10.12
12	2000	06/22/2000	9.79
13	1990	10/23/1990	9.66
14	2004	09/28/2004	9.29
15	2005	06/29/2005	9.28
16	2009	05/29/2009	9.03
17	2001	05/22/2001	9.01
18	1992	07/24/1992	8.90
19	1999	06/14/1999	8.58
20	2007	06/13/2007	8.56
21	1974	08/30/1974	8.55
22	1990	05/09/1990	8.38
23	1979	09/05/1979	8.36
24	1989	05/05/1989	8.25
25	1982	06/01/1982	8.20
26	1986	07/20/1986	8.15
27	1992	11/23/1992	8.10
28	2010	06/28/2010	8.01
29	2011	09/07/2011	8.00
30	1981	07/04/1981	7.96
31	1998	09/22/1998	7.94
32	1983	06/21/1983	7.92
33	1984	03/29/1984	7.90
34	1988	05/06/1988	7.87
35	1979	10/01/1979	7.49
36	2002	04/19/2002	7.48
37	1992	03/08/1995	7.28
38	2010	01/19/1996	7.18
39	2011	09/06/2011	7.02
40	1981	03/10/2011	6.85
41	1998	03/06/2011	6.84
42	1983	08/28/2011	6.73
43	1984	04/17/2011	5.76

Source: National Weather Service, Advanced Hydrological Prediction Service

 

 

Four Mile Run flooding, 1960s 

It is apparent from the table that there is a grouping of flooding events during the late 1960s and early 1970s. In recent years, particularly the summers of 2018 and 2019, brief, intense rains have caused flash flooding and significant property loss. The impact of flash floods like those in 2006 and 2019 can equal or exceed that of a hurricane requiring state and national emergency declarations. On July 8, 2019, rain fell fast and hard. Arlington suffered flood damage in the millions of dollars and declared a local state of emergency.

Source: Arlington County website

 

Flood damage, Arlington, 2006

 

Flood damage, Arlington, 2019

 

Based on the map below, Lubber Run suffered severe flood damage on July 8 in comparison to the doctor’s branch which suffered less damage.

Source: Arlington County website

 

Flood in Media

Videos capturing the July 8 2019 flood’s ferocity are:

https://www.youtube.com/watch?v=AB9QNP1rh7Q

https://www.youtube.com/watch?v=Y3rbANh1QaM

 

Drought Data

The U.S. Drought Monitor (USDM) is a map that shows the location and intensity of drought across the country. The data is updated each Tuesday and released on Thursday. This map shows the Virginia state drought conditions on October 06, 2020, and it is obvious that the Four Mile Run watershed is not currently in a Drought.

 

 

Drought History in Virginia
from 2000-2020

Since 2000, the longest duration of drought (D1-D4) in Virginia lasted 103 weeks beginning on May 1, 2007 and ending on April 14, 2009. The most intense period of drought occurred the week of August 20, 2002 where D4 affected 30.53% of Virginia land. (USDM)