FLOOD10133

• County: Statewide
• Community: State of North Carolina
• Basin: Statewide
• Title: Two Months of Flooding in Eastern North Carolina, September-October 1999: Hydrologic, Water-Quality, and Geologic Effects of Hurricanes Dennis, Floyd and Irene
• Date: 1/1/2000
• Prepared By: USGS
• Floodplain - Doc Type: Flood Documentation Report

Pamlico River estuary (fig. 20).
Following Hurricane Floyd, there

o

2

c
~ 4
'"
='
c
i= 6
~
w
~
~ B
~
'"
~
z
-10
~'
Z
~ 12
'"

Hurricane floodwaters also
affected dissolved oxygen con centra-

Near-surface-
salinity

.
'.
c
.
o

.
Iii
u
'E
.
"

14

16

Near.bottom-
salinity

14 15 1617 lB 19 2021 2223 242526 27 2B 29 30 31 1 2 3 4 5 6 7 B 9 10 11 12 13 14
AUGUST 1999 SEPTEMBER 1999

Figure 20. Near-surface and near-bottom salinity measured at Pamlico River at Light 5
(site 46, fig. 7) during August-September 1999.

was little salt in much of the Pamlico
River (fig. 21). Near-surface salinity
remained less than 2 parts per thou-
sand (ppt) in December 1999,
whereas salinity at this location
typically ranges from
7 to II ppt during October to
November (Bales and Robbins,
1995). As late as January 2000,
near-surface salinity at site 46
remained about I ppt, and near-
bottom salinity was about
5-7 ppt, demonstrating the con-
tinued effect of the high volume
of freshwater discharged to the
estuary. The effects of the flood-
ing on salinity seem to be more
extreme in the Neuse River
estuary. Both near-surface and
near-bottom salinity in the
Neuse River remained less than
2 ppt in January 2000 as far
do"mstream as Cherry Point,
where the estuary makes a 90-
degree bend from the southeast
to the northeast (fig. 7).

tions in the estuaries, although per-
sistent and extremely low dissolved
oxygen conditions were not

o

2

c
~ 4
'"
='
c
i= 6
~
w
~
~ B
~
~
z
~,10
Z
~ 12
'"

14

16

observed. Priorto Hurricane Dennis,
dissolved oxygen in the Neuse River
at New Bern (site 47, fig, 7) was
near zero at the bottom, but was
between 8 and 10 mglL near the
water surface. Following Hurri-
cane Floyd, the water column
was mixed, with only a small
difference between near-surface
and near-bottom dissolved oxy-
gen (fig. 22). Dissolved oxygen
gradually recovered during Octo-
ber, but was generally between 4
and 6 mg/L, which is somewhat
low for fall conditions. Dissolved
oxygen concentrations increased
with distance downstream from
New Bern during September and
October. Dissolved oxygen con-
centrations generally were
greater than 6 mg/L in the
Pamlico River estuary during
September and October, except
near Washington, where dis-
solved oxygen increased from
about 2 mg/L in late September to
6 mg/L by about mid-October.

Near-bonomsalinity-

212223242526272B2930311 234567 B 91011121314151617181920212223242526272829
OCTOBER 1999 NOVEMBER 1999

Figure 21. Near-surface and near-bottom salinity measured at Pamlico River at Light 5
(site 46, fig. 7) during October-November 1999.

Two ~'1onths of Flooding in Eastern North Carolina, September-October 1999