Guadalupe River Basin

The Guadalupe River Basin begins in the Texas Hill country before crossing the Balcones Escarpment on its way to the Texas Coastal Plains and the Gulf of Mexico. Major tributaries to the Guadalupe River Basin include the San Marcos and Comal Rivers. The Guadalupe River Basin is relatively long and narrow, with a length of approximately 237 miles and a maximum width of about 50 miles. The basin has a drainage area of approximately 6,700 square miles (mi2).
 

Flash flooding is a frequent problem, especially in the northern part of the basin, as the steep topography produces rapidly rising river stages during storm periods, leaving residents with little warning time.

Although the climate over the Guadalupe River Basin is generally mild, the southern portion of the basin can be impacted from hurricanes that come through the Gulf of Mexico. The mean annual precipitation over the Guadalupe River Basin ranges from 26 to 40 inches, increasing from the west to southeast.

Available streamflow records show that major floods have occurred over nearly all sections of the Guadalupe River Basin. While there have been scattered floods throughout the basin’s nearly 150-year history, the last 20 years has shown an uptick in the frequency and magnitude of devastating floods, including major floods in 2002, 1998, and 2015.

Interactive Basin Map