Streambed instruments that measure electrical resistivity were constructed and installed along the main channel in San Antonio Creek and along tributary streambeds in order to provide insight into intermittent streamflow not recorded by traditional stream gaging stations. These instruments can record high-resolution temporal and geographic responses of streamflow to precipitation in intermittent streams. Streambed electrical resistivity sensors (SERS) and stream temperature, intermittency, and conductivity sensors (STICs) are small, cost-effective, instruments that can be installed (and re-installed) along stream reaches to measure stream intermittency. These instruments employ water contact electrodes to record wet and dry periods—dry periods with no streamflow are characterized by no or small electrical signals, whereas wet periods with streamflow are characterized by large electrical signals due to the presence of water. SERS are constructed by repurposing commercial temperature sensors to record electrical conductivity by removing the sensor thermistor and replacing it with water contact electrodes (Blasch, and others, 2002). STICs serve the same function as SERS but are constructed by repurposing optical sensors so that a temperature and conductivity signal can be recorded (Chapin, and others, 2014).
Twenty one SERS and four STICS were constructed and installed in protective casings at bed level along the main channel in San Antonio Creek, and in tributary streams in order to provide insight into stream intermittency. The SERS and STICs were in use between August 2015 and February 2019; the period of record for each instrument varied depending on the date of installation and removal.