Transport of nitrogen and phosphorus from
Rhode River watersheds during storm events
David Correll, Thomas Jordan, and Donald Weller
Water Resources Research, 1999. Vol. 35 No 8 pg 2513-2521
Why this paper?
•One of many papers from the SERC on
the Rhode River Watershed since the
1970s
•Effects of land use, season, and storm
characteristics on nutrient transport
Site Description
Land Use effects: 4 watersheds
Watershed 101 Mixed Use
Land Use
Watershed 109 Crops
Watershed 110 Forest
Watershed 111 Grazed
Forest
Row crops
Pasture and Hay fields
Residential
Old Fields
Site Description
Chemistry
• Phosphorus
– PPi, Dpi, POP, DOP
• Nitrogen
– NO3-, NH4, PON, DON
– Continuous baseflow samples and storm samples
– Collected and returned w/in 24 hr
– Filtered 0.45 m
Discharge
120° and 150 ° V notch weirs
Stilling wells, floats every 5 minutes
0.1
Loads: Linear interpolation
60
Discharge (cms)
50
0.06
0.04
40
0.02
0
6/12/02 15:30
6/12/02 17:10
6/12/02 18:49
6/12/02 20:29
Steps:
1. Connect the concentrations using a linear
interpolation
2. Integrate the instantaneous load for the period
between the first sample and the last using
equation (1)
6/12/02 22:09
Concentration (mg/l)
0.08
30
t
L   CiQi
to
(1)
Base flow vs. Storm
Storm Particulate + Dissolved Fractions added
Characteristic Storms (WS 101)
P and N Dynamics June storm
(WS 101)
P
N
Storm P & N Dynamics (all 4)
P
N
Seasonal P Comparison
WS 101: Mixed LU
WS 109: Cropland LU
Seasonal N Comparison
WS 101: Mixed LU
Summer: Particulates
WS 109: Cropland LU
P c-Q relationships
N/P Relationships
Mainly due to increases in Particulate P
Discussion
Particulate nutrients related to soil, soil erosion.
Discussion
Peak water discharge correlated to mean particulate
nutrient concentrations
– Eliminating need to know rainfall volume or intensity
– Smaller 1st order catchments
– Shorter, more intense storm discharges
[NH4] increased with peak water discharge
- slopes much lower
Discussion
• Sampling implications
• 1 large summer storm
– 24% of TP for entire
summer
– 18% of TPi for entire
summer
– 30% of TOP for entire
spring
– 18.5% of TON for
entire spring
• 1 large spring storm
– 39% of TP for entire
spring
– 41% of TPi for entire
spring
– 38% of TOP for entire
spring
– 12% of of TON for
entire spring
Questions?????
• Why do storms increase particulate nutrient
concentrations but do not influence dissolved
concentrations?
• If sediment related, why isn’t rain (detachment) as
important as flow?
• Implications for sampling: every storm? Or use
different load estimation?
• Internal validity- are differences really seasonal
and land use related
• External validity? – how is this applicable to other
watersheds