Long-term hydrologic research on the San Dimas Experimental Forest, southern California: lessons learned and future directions

The San Dimas Experimental Forest (SDEF) is located in the San Gabriel Mountains, about 45 km northeast of Los Angeles, California. The SDEF was originally established in 1934 to document and quantify the hydrologic cycle in semiarid uplands with intermittent headwater streams. New and innovative equipment was necessary to measure rainfall and streamflow in this mountainous terrain. Long-term monitoring has revealed a number of hydrologic patterns following land use change and wildfire. Water quality monitoring shows that the SDEF has had very high levels of nitrate due to its proximity to the heavily polluted Los Angeles Basin. These nitrate levels, which approach federal standards, are exacerbated by land use change and fire. In the future, evaluating the hydrologic response from climate change models and testing specific climate change predictions for southern California may be possible using the 80-year record of temperature, rainfall, and streamflow from the San Dimas Experimental Forest.