UC Berkeley

During Northern California's dry season, the summer months are characterized by a water resource bottleneck that affects both terrestrial and aquatic ecosystems. Though the sensitivities of these summer-dry watersheds to environmental variability are frequently studied, spatiotemporal improvements in monitoring of watershed variables are undoubtedly beneficial in the context of ongoing climate change.

This dissertation presents innovative field methods to observe and record spatially heterogeneous and distributed watershed data that are essential for accurate evaluation of a Northern California watershed's water budget and thermal regime. This work focuses on two hydrologic fluxes providing dry season relief to vulnerable vegetation and freshwater species: fog water in the atmosphere and groundwater in streams. For each flux, a new field method employing a combination of commercially available sensors, remote sensing, and robotics is first developed and tested; the method is then used to describe or quantify the flux in a case study. Where appropriate, field studies are followed by modeling approaches that allow extensive analysis of a broader range of conditions than could be observed in the field. The direct observations made by employing the new field methods and subsequent analyses presented indicate the importance of improving accuracy of measurements of these hydrologic fluxes in understanding their watershed-scale effects. This dissertation also identifies operational and system constraints of the new methods, as well as key areas for further development, such that these methods may eventually be generally applied across all seasonally-dry, Mediterranean-type climate watersheds.