Research

Coastal Systems

Coastal rivers are unique systems in that they connect terrestrial biomes to the marine environment. Much of my work in coastal rivers has centered on understanding fundamental hydrologic processes (flow pathways and sources) and disturbance responses (wildfire and wastewater).

Relevant Projects
Wildfire impacts on coastal watershed hydrology and biogeochemistry (California)
While small watersheds are globally ubiquitous, their hydrologic and material export behavior is often poorly understood, due in large part to the paucity of direct observations. We know even less about how disturbances, like wildfire, alter watershed processes in these systems. We are conducting a baseline analysis of near-term wildfire impacts on coastal stream water exports of metals, nutrients, and particulates in five watersheds affected by varying degrees of wildfire.


Geologic controls on summer baseflow dynamics (California) 

Snapshot sampling events of streamwater chemistry were collected across the summer dry down period in a geologically complex coastal Californian watershed to better understand spatial controls on baseflow generation and dissolved carbon geochemistry. Published in Water Resources Research

Land use controls on long-term river nitrate concentrations (California)
Records of discharge and nitrate concentrations from select central coastal California rivers are being used together to evaluate the evolution of nitrate inputs in these systems and their possible relation to land use metrics. 

Estuaries are hydrodynamically and biogeochemically complex ecosystems. California's coast is lined with ephemeral and perennial estuaries that range in size by many orders of magnitude. My work on estuaries has focused on large systems, like the San Francisco Bay and Sacramento-San Joaquin Delta, as well as small ephemeral estuaries, like Pescadero and Younger Lagoons.  

Relevant Projects
Long-term changes in particulate organic matter dynamics (California)
This project is using long-term records of carbon and nitrogen stable isotope data, along with existing records of related water quality parameters, to better understand multi-scale spatial and temporal changes in and master controls on carbon and nitrogen biogeochemistry in the San Francisco Bay and Sacramento-San Joaquin Delta.

High-frequency measurements of water quality in drained peatlands discharging into the Sacramento-San Joaquin Delta (California)
This project is using three high-frequency monitoring stations to better constrain water quality and material fluxes from islands in the Delta.

Lateral carbon loss in drained peatlands in the Sacramento-San Joaquin Delta (California)
This project assessed the hydrologic and biogeochemical processes that influence lateral carbon exports from peat-rich islands in the Sacramento-San Joaquin Delta in central California. Published in Journal of Geophysical Research: Biogeosciences

Nitrogen exports from drained peatlands in the Sacramento-San Joaquin Delta (California)
This project examines the dominant sources and biogeochemical processes that influence macronutrient, major dissolved ion, and trace element concentrations in agricultural drainage in the Sacramento-San Joaquin Delta using a suite of stable isotope tracers and geochemical parameters. Published in San Francisco Estuary and Watershed Sciences

Groundwater is a critical contributor to watershed hydrology and biogeochemistry. Nearly all of my work has integrated some component of terrestrial or nearshore hydrogeology. In Hawaii, we utilized deep production wells and shallow piezometers to link terrestrial groundwater nutrients from wastewater to submarine groundwater discharge nutrient fluxes into coral reefs. Similarly, we leveraged production wells in central coastal California to better understand deep groundwater contributions to summer baseflow regimes.

Relevant Projects
Nitrogen sourcing in coastal groundwater (Hawaii)
This project quantitatively examined wastewater signatures in groundwater emanating from two coastal aquifers on O'ahu, Hawai'i, using N and O stable isotopes and a recharge model. Published in Journal of Hydrology: Regional Studies

Coastal groundwater's influence on nearshore chemistry (Hawaii)
We investigated the relationship between coastal groundwater discharge and reef biogeochemistry to better understand how differences in groundwater geochemistry may drive changes in proximal marine carbonate chemistry. Published in Limnology and Oceanography
 
Geologic controls on summer baseflow dynamics (California)
Snapshot sampling events of streamwater chemistry were collected across the summer dry down period in a geologically complex coastal Californian watershed to better understand spatial controls on baseflow generation and dissolved carbon geochemistry. Published in Water Resources Research

The nearshore environment is home to diverse marine ecosystems, and coastal watersheds connect these systems to upland terrestrial processes. Some of my work has centered on understanding how terrestrial impacts cascade down to coastal ecosystems. In Hawaii, this ridge-to-reef continuum has led to widespread nutrient contamination of coral reefs from on-site sewage disposal systems, and some of my research has focused on trying to track nutrient sources from these inputs. In California, my work has focused on understanding material fluxes from both long-term disturbances (agriculture, wastewater) and, more recently, shorter-term disturbances (wildfire). 

Relevant Projects
Wildfire impacts on coastal watershed hydrology and biogeochemistry (California)
While small watersheds are globally ubiquitous, their hydrologic and material export behavior is often poorly understood, due in large part to the paucity of direct observations. We know even less about how disturbances, like wildfire, alter watershed processes in these systems. We are conducting a baseline analysis of near-term wildfire impacts on coastal stream water exports of metals, nutrients, and particulates in five watersheds affected by varying degrees of wildfire.

Nitrogen sourcing in coastal groundwater (Hawaii)
This project quantitatively examined wastewater signatures in groundwater emanating from two coastal aquifers on O'ahu, Hawai'i, using N and O stable isotopes and a recharge model. Published in Journal of Hydrology: Regional Studies

Coastal groundwater's influence on nearshore chemistry (Hawaii)
We investigated the relationship between coastal groundwater discharge and reef biogeochemistry to better understand how differences in groundwater geochemistry may drive changes in proximal marine carbonate chemistry. Published in Limnology and Oceanography

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