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Virginia DEQ

Virginia Water Science Center

 
  Duration Plot and Table of 7-Day Average Streamflow
 
01646000 DIFFICULT RUN NEAR GREAT FALLS, VA
LOCATION.--Latitude 38°58'33", Longitude 77°14'46", North American Datum of 1927,
                    Fairfax County, VA, Hydrologic Unit 02070008.
DRAINAGE AREA.--57.8 square miles.
PERIOD OF RECORD.--October 1934 to current year. Monthly discharge only October to December 1934, published in WSP 1302.
DURATION STATISTIC COMPUTATION PERIOD.--All data through September 2015.
REGULATION.--No known regulation.
GAGE OPERATION.--Virginia Department of Environmental Quality - Water Division.

     Duration Plot with 7-Day Average Streamflow Conditions
Provisional Data Subject to Revision
01646000 plot. 
DIFFICULT RUN NEAR GREAT FALLS, VA
Provisional Data Subject to Revision

                    

The current 7-day running-average value for 03/22/2017 is 55.29 cubic feet per second.

  explanation   Percentile Description Duration Plot Description 28 Day 14 Day 7 Day Daily


      Duration Table of 7-Day Average Streamflow
           
Flow values in cubic feet per second


                01646000     DIFFICULT RUN NEAR GREAT FALLS, VA

   Minimum daily flow
   5th percentile
 
   10th percentile
 
   25th percentile
 
 
   Median
 
 
   75th percentile
 
 
 
   90th percentile
 
 
 
   95th percentile
 
 
 
 
   Maximum daily flow
         
Years of record
January
10.5
19.0
25.0
35.4
56.1
85.1
139
178
481
 
80
February
11.7
27.4
32.9
43.3
59.1
91.1
143
189
578
 
80
March
16.7
34.0
39.7
50.3
72.7
105
165
209
612
 
80
April
21.0
32.2
37.6
47.0
65.6
100
152
207
503
 
80
May
15.4
24.9
29.1
38.3
56.6
89.4
138
194
602
 
81
June
6.04
16.3
19.2
28.4
44.6
67.0
115
175
4,830
 
81
July
1.67
8.63
12.2
19.1
31.1
49.0
97.3
139
930
 
81
August
0.29
5.81
8.31
13.9
24.6
43.9
82.0
130
445
 
81
September
0.16
5.04
6.86
11.7
21.0
35.1
84.5
154
1,110
 
81
October
0.57
7.12
9.84
14.6
23.4
41.7
82.7
132
950
 
80
November
5.74
11.9
16.1
22.0
32.6
58.6
111
147
405
 
80
December
7.23
18.4
22.3
30.7
45.3
80.0
130
174
507
 
80
 
       

The current 7-day running-average value for 03/22/2017 is 55.29 cubic feet per second.

---- Provisional Data Subject to Revision ----

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