Local Climate Change in Pasadena, Calif., and the Impact on Streamflow

Abstract

Pasadena, Calif., has used the Arroyo Seco as a source of water for more than 100 years. During this period, local air temperatures have risen dramatically, resulting in a significant increase in streamflow. The median streamflow in the period 1962–2016 was 30% higher than the median streamflow in the period 1910–1961. A substantial portion of that increase has been in the form of extreme flow episodes, with flows greater than 1 m3/s. If the data from the recent drought (2011–2016) are eliminated, the increase in streamflow is even greater. This increased water flow in the Arroyo Seco might seem to indicate that there is a greater supply of water in the stream. However, because of the high velocities and destructive forces associated with the extreme flows, this may not be the case.