Texas Heritage, Volume 18, Number 3, Summer 2000 Page: 24
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Before these wild rivers were tamed with
several large dams (including Elephant
Butte, Amistad, and Falcon on the Rio
Grande, Redbluff on the Pecos, and Presa
de la Boquilla on the Conchos), snow melt,
combined with spring rains or exception
Sanderson sustained heavy damage in the flood
of the Rio Grande River in 1965. Above,
wool, which is raised and processed locally
covered bridges and buildings following the
flood. At right, railroad tracks that run
through Sanderson lay twisted and turned.
From the Terrell County Historical Museum.
By far the majority of floods on the Rio
Grande stay within a well-defined flood
plain, and people have generally avoided
risks to themselves and their property by
respecting the river's typical flood capacity.
Floods on the main stream move at
moderate speed, and people downstream
usually have anywhere from
several hours to a few days warning
of approaching flood crests. Exceptionally
high floods occasionally
occur and when they do, areas that
are usually safe from flooding may
experience high water. Fort Duncan
and downtown Eagle Pass are built
on land almost 60 feet above the
normal river level, but were flooded
in 1865 and again in 1954. Amistad
Dam, completed on the Rio Grande
above Del Rio in 1968, should prevent
such floods in the future. Although
spectacular and capable of
causing disruption of normal activities
and inconveniences for a few
days, large floods on the main Rio
Grande have rarely been responsible
for great loss of life.
FLASH FLOODS AND
Storms similar to those that
caused the Pecos River flood of 1954,
the Sanderson flood of 1965, and the
Del Rio flood of 1998 have occurred
some 25 times in the past 100 years
in a broad band of Texas from near Austin
to Sanderson along the eastern and south
ern margin of the Edwards Plateau. And,
they will occur again. This is widely known
as one of the top flood risk regions of the
United States. Most of these floods result
from downpours such as these along the
southern edge of the Edwards Plateau between
San Antonio and Del Rio:
* June 28-29, 1913; 21 inches of rain in
Montell and Uvalde County in 24 hours;
* May 31, 1935; 22-24 inches of rain in
D'Hanis and Medina County in 2-3/4 hours;
* June 14-15, 1935; 12.5 inches of rain
in Uvalde in 12 hours;
* June 23-24, 1948; 26 inches of rain in
Bracketville, Rocksprings, and Del Rio in
12 hours; and
* August 1-4, 1978; 48 inches of rain in
Medina in 52 hours.
There is a pattern to be seen in the climatological
attributes of such storms. Most
occur in the spring or fall. All of these floods
resulted from tropical moisture that flowed
from the Gulf of Mexico into the southern
part of Texas as fairly well-organized tropical
lows, tropical storms, hurricanes, or
their remnants. When such low pressure
masses of moist air move rapidly, they pose
comparatively little threat, but a slow-moving
or stalled tropical air mass has the capacity
to produce very heavy rains in a limited
area. Two quirks of Texas geography
and climate combine to stall tropical air
masses and trigger rain events. Air masses
moving in from the Gulf cross a broad,
nearly flat coastal plain until reaching the
Balcones Escarpment, where the land rises
abruptly to the Edwards Plateau. This to
ally heavy rainfall on a significant part of
the watershed, could produce severe flooding
along the Rio Grande in Texas. Since
the dams have been in place, flooding on
the main channel of the Rio Grande is far
less likely to occur.
Floods confined in the narrow canyons,
such as Santa Elena or Boquillas in the Big
Bend, are still dangerous to anyone who is
unfortunate enough to be caught there.
Such floods rise rapidly, generate high velocity,
and leave little place for escape. Risk
of sudden rises in the canyons has been lessened
but not been eliminated by the dams.
HERITAGE * 24 * SUMMER 2000
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Texas Historical Foundation. Texas Heritage, Volume 18, Number 3, Summer 2000, periodical, Summer 2000; Austin, Texas. (texashistory.unt.edu/ark:/67531/metapth45389/m1/24/: accessed January 17, 2018), University of North Texas Libraries, The Portal to Texas History, texashistory.unt.edu; crediting Texas Historical Foundation.