The Rainfall Affect of Hurrican Rita on
the Neches River
The hurricane moved inland almost parallelling the Neches River dumping
a heavy rain 9/23/2005. A 5-15 mile-wide swath of cumulative rain
over 10 inches extended from near Beumont almost to Texarkana. In
response, the river rose 10 to 20 feet throughout much of its length.
Figure 1. shows the cumulative rainfall
over the area from Doppler
radar, the Neches River Drainage basin, some relavant USGS
streamflow gauges, and the location of the major reservoirs within the
Much of the lower Neches streamflow during normal periods comes from
the upper Neches and from the Angelina River drainage system.
These are measured by the USGS streamflow gauges at Rockland and Alto
respectively. Prior to the huricane, these upriver areas were
contributing water at only 130 and 20cubic feet per second rates
(see Fig. 2.) to the downstream rate
of 2600 cfs measured at
Evandale, (prior to the storm beginning 9/23/2005). The
difference between the 2600cfs rate and the
insignificant upstream rates was apparently mostly controlled discharge
from Lake Sam Rayburn.
During the storm, large runnoff rates were measured at the two
northerly streams feeding Lake Sam Rayburn (Fig.
Bayou has a larger drainage area and contributed more runnoff than
Downstream of the Angelina_Neches River junction Town Bluff USGS
stream gauge measured rates increasing from 2800 to 24000cfs and
the water rose over 20 feet. Some of that storm surge was water
arriving from drainage between Sam Rayburn reservoir and the Town Bluff
station, and some was
probably from Sam Rayburn and Steinhagen reservoirs themselves.
What is most interesting is the difference between the storm surge at
Town Bluff and at the Evandale gauging station further downstream close
to Beaumont. See Fig. 4. for
a comparison of those two
streamflows. Evandale received some runoff from the heavy rain
directly but the flow rate never rose as sharply as the Town Bluff
gauge. Furthermore, high flow rates of 24000 cfs have not been
seen yet a day and a half later at the downstream gauge.
Fig. 5. shows the area between
the Town Bluff and the lower, Evandale
gauging stations. A very robust bottomland forest and swamp
system exists between those stations and there are no man-made levees
in that stretch. Consequently those flood-prone forests and
swamps periodically absorb much floodwater temporarily, alleviating
downstream flooding. Those woods and swamps are functioning
as very effective protection against severe river flooding in the
Channelization and levee construction all along the Mississippi have
disastrous results downstream in that region. Fortunately the
Neches has not been channelized or leveed and the Neches woods and
swamps are working towards lessening downstream flood damage.