Characterizing the Influence of Fire on Hydrology in Southern California

Science Center Objects

The frequency of fire in southern California forests has steadily increased over time as a result of ignitions at the growing wildland-urban interface, as well as a result of warming due to climate change. Understanding the implications of increased wildfire on hydrologic conditions and water supply is particularly important given the increasing demands for water resources to satisfy growing populations and agricultural intensification in southern California. This study focuses on nine such fires in an area that encompasses the four southern California national forests (Los Padres, Angeles, San Bernardino, and Cleveland).

Image: A Wall of Fire in Southern California

A wall of fire in southern California

Problem

The Mediterranean climate region of southern and coastal California is a globally recognized biodiversity hotspot. In addition to its natural landscapes, it provides water to its high-density urban populations and agricultural lands. Such water is also critical to sustaining its ecosystem, including habitat for endangered species like the southern California steelhead. Given the importance of water in southern California, there is surprisingly little known regarding water supply vulnerability. Understanding the water/climate/fire relationship and having appropriate spatial data is critical for natural resource managers to implement climate-smart conservation.

Objectives

In order to increase the understanding of hydrologic regimes under current and future climates, and the interaction of fire on these regimes, the aims of this study are to:

  1. Quantify groundwater recharge, runoff, and climatic water deficit by refining and calibrating the Basin Characterization Model to current climates in the Santa Clara River watershed
  2. Project how the hydrologic regime is modified by future climates
  3. Assess the impact of fire on the hydrologic regime and measure the recovery post-fire 
  4. Collaborate with UC Davis to develop a management workflow and visualization and data output tool for natural resource managers

Science Plan

The California Water Science Cneter will collaborate with UC Davis and the US Forest Service to characterize pre- and post-fire hydrologic conditions in the Santa Clara River watershed and surrounding forests, as well as the impacts of projected future climates. We will leverage an ongoing project funded by the USFS to assess ecosystem services within the watershed.