Research Themes

Intertidal Ecohydrology and Ecogeomorphology

Coastal wetlands are thought to function as buffers, filtering nutrient-rich terrestrial runoff and mitigating coastal flooding and storm surge damage; they are also thought to serve as bioreactors to help clean estuarine waters and nurture coastal fauna and food webs. However, the field evidence for the effectiveness of these hypothesized wetland functions remains sparse in many cases. While surface water flow in coastal wetlands and estuaries is a large and active area of research, flow through subsurface portions of the wetlands and interactions with plants in the root zone remains more of a black-box. Our research is documenting and quantifying this surface water-groundwater interaction, subsurface flow, and plant-water interactions and identifying the significance of these processes for overall coastal wetland hydrologic, ecologic, and geomorphologic function and resilience. Likewise, certain portions of the surface waters connected to coastal wetlands have fallen in the gap between riverine and estuarine science: specifically the tidal, most downstream freshwater portions of coastal rivers. Our research is assessing the role of these unique tidal freshwater river reaches as link or sink for carbon, nitrogen, and pollutants between land and sea. Major field areas include coastal wetlands of San Francisco Bay and of the Louisiana and Texas Gulf Coasts.

Urban Ecohydrology

As humans are becoming more concentrated in dense and expanding urban areas, the field of urban ecology has been identifying the new habitat niches established in the urban setting and the field of urban hydrology has been quantifying the effects of development and stormwater conveyance on rainfall and runoff impacts. The connection between these two fields has remained more of an open question, however, especially the bi-directional influence of landscaping and greenspace choices on the urban hydrological cycle, and the influence of regional hydrology on greenspace choices. Ecosystem-scale studies on plant-water interactions overwhelmingly focus on ‘simpler’ natural systems. Our research on urban ecohydrology tackles the complexity of urban systems head-on to answer such open questions as the role of plant-water interactions in total urban ecology and hydrology including surface water-groundwater fluid exchanges, the interactions between regional and urban ecology, hydrology, and social norms regarding landscaping, and the differential biophysical and social roles of landscaping and greenspace in neighborhoods of contrasting socio-economic and geological/topographic setting.

Biophysics of Plant-Water Interactions

Although most life on earth relies on the ability of green vegetation to store energy from sunlight in carbon-based molecules (splitting water and releasing oxygen in the process), there remain mysteries about the biophysical and hydraulic function of these organisms that range from the control/response of plant leaf stomata to changes in environmental conditions, to the processes that achieve refilling of vascular plant xylem after water flow has become blocked by an air bubble. Our research is teasing apart aspects of these and other mysteries of biophysical plant-water interactions via use of novel and cutting-edge technologies: e.g., new ways to use thermal remote sensing imagery to quantify spatial and temporal variations in stomatal control and application of micron-scale X-ray Computed Tomography (CT-scanning) to image root-water associations and root network development in 3D time-lapse.