Ecohydrology of Semiarid Catchments with Woody Plant Encroachment:
Overview: Two watersheds have been instrumented with high-resolution environmental sensor networks consisting of rain gauges, soil moisture and
temperature profiles, channel and hillslope runoff flumes, and eddy covariance towers with a complete set of radiation, energy, carbon and water fluxes. In addition, high resolution digital terrain models have been obtained from LiDAR measurements, UAV imagery and field dGPS surveys, allowing characterization of terrain and plant cover distributions. We use these watersheds to quantify the spatiotemporal ecohydrological dynamics and to parameterize physically-based distributed models. This has allowed us to gain insight on the impact of shifting vegetation patterns on the watershed-scale runoff patterns and explore implications on the site ecogeomorphology. This project has resulted in a number of publications, including Templeton et al. (2014), Vivoni et al. (2014), Anderson and Vivoni (2016), Mascaro and Vivoni (2016), Schreiner-McGraw et al. (2016, 2019, 2020) and Schreiner-McGraw and Vivoni (2017, 2018), among others.
- -Eli Perez-Ruiz (Ph.D. candidate) studies the long-term response of arid ecosystems to changes in environmental factors and water availability. Using data from the two instrumented watersheds, he focuses on the analysis of the seasonal and inter-annual variation of carbon dioxide fluxes and evapotranspiration and their relationship with environmental measurements and changing woody plant conditions.
- -Zachary Keller (M.S. candidate) is conducting hillslope runoff measurements at one study site to understand their contribution to streamflow generation. Using a new set of hillslope plots, he is characterizing the water and sediment yield through multiple methods and utilizing the field data to improve process modeling in tRIBS. He is also applying Structure for Motion (SfM) techniques to characterize the hillslope plot topographic and vegetation conditions.
- -Eric Escoto (Ph.D. candidate) is assessing rainfall characteristics at two sites to improve understanding of hillslope processes using rainfall disdrometers. These sensors measure the drop size distribution and kinetic energy of rainfall which can be linked to measurements of soil moisture, hillslope runoff and channel streamflow. This will allow a deeper understanding of the impact of rainfall intensity and antecedent moisture on runoff generation.
Regional Impacts of Changes in Climate and Land Use on Hydrology:
Overview: This project assesses the potential future impacts of both climate change and land use change on hydrology and water resources, at a variety of scales, ranging from the Phoenix metropolitan area, to the Colorado River Basin using the VIC model, remote sensing data and networks of field observations. It also includes interactions with water managers and stakeholders that are interested in the long-range scenario planning for the western U.S. This work builds upon recent modifications to the VIC model and the development of improved parameter sets and forcing products that are being provided to the scientific community. This work has resulted in several publications, including Bohn and Vivoni (2016, 2018, 2019), Bohn et al. (2018, 2019), and Bennett et al. (2018), among others.
- - Kristen Whitney (Ph.D. candidate) studies the impact of climate change in the Colorado River basin to understand the relative importance of temperature and precipitation projections on future streamflow. Based on improved VIC simulations, she is inspecting future changes in the chain of hydrologic variables that propagate warmer and drier conditions to explain underlying mechanism for different subbasins that contribute to Colorado River flows.
- - Zhaocheng Wang (Ph.D. candidate) is using VIC to simulate the impact of crop and urban irrigation on the land surface processes in Phoenix, AZ. He is also analyzing the impact of future land-use projections and future climate change scenarios in Phoenix and contributing to the simulations in the Colorado River basin. Current efforts also include comparisons of remote sensing products to VIC simulations at multiple scales for the purpose of model validation and enhancements.
Ecohydrological Interactions and Modeling in Urban Environments:
Overview: Given the growth of urban populations in desert areas, it is increasingly important we understand the relations between hydrological, biogeochemical, and ecological processes in arid cities. The advancement of ecohydrological approaches that explore those linkages is important to improve our ability to forecast environmental change. This project has resulted in a number of publications, including Chow et al. (2014), Volo et al. (2014, 2015), Templeton et al. (2018), and Perez-Ruiz et al. (2020), among others.
- - Mercedes Kindler (M.S. candidate) studies potential water savings in turf grass irrigation at three urban parks. Soil moisture content and precipitation are being continuously monitored in sections of the parks that have compost treatments of various levels. This information is being utilized to parameterize and test a soil water balance model will be used to quantify potential water savings from the compost application and from alternative irrigation scheduling.
- - Eli Perez-Ruiz (Ph.D. candidate) is involved in the analysis and deployment of eddy covariance systems in urban areas. The proportion of irrigated vegetation and the proximity to vehicular emissions have been identified as important controls. At one of the study parks, the surface energy balance and carbon dioxide fluxes are allowing an understanding of turf grass irrigation and landscape management.
- - Zhaocheng Wang (Ph.D. candidate) is involved in quantifying urban land use and its changes using remote sensing observations, including from constellations of small satellites, through vegetation indices and land surface temperature. At one of the study parks, the phenology of turf grass allows quantifying decisions on irrigation, overseeing and maintenance, and its spatial variability within the park.
Impacts of Forest Thinning and Climate Change in Central Arizona Highlands:
Overview: Landscape management can have direct consequences on hydrologic functioning and water yields in catchments. This can be investigated through the application of numerical watershed models such as tRIBS and its use of remote sensing products and scenarios of land use and climate change. In the Central Arizona highlands, a principle concern is how forest conditions in ponderosa pine areas can impact watershed hydrological processes, including both cold and warm season conditions. Through interactions with local water managers, this work will help establish baselines for forest cover treatments. This project is based on prior efforts in such environments, including Mahmood and Vivoni (2008, 2011a,b, 2014) and Hawkins et al. (2015), among others.
- - Josh Cederstrom (M.S. candidate) is modeling cold and warm season processes in the Beaver Creek watershed to identify the how the interaction between simplified forest thinning and climate change scenarios will impact water yield. A particular focus is being placed on the rain-to-snow transition anticipated under warmer climates and how this can affect the overall runoff efficiency in the watershed. Local observations and remote sensing data are being used to test the model.
- - Xiaoyang Tang (Visiting Ph.D. student) is scaling up the forest thinning and climate change experiments using tRIBS from the Upper Verde River at coarser model resolutions. The goal is to understand how these interacting factors can impact an important region for streamflow production as a step toward modeling the entire Salt-Verde systems that provide water to the Phoenix metropolitan area. This work relies on a more sparse observational network.
- - Luisa Orci Fernandez (M.S. candidate) studies the interaction of forest cover and hydrological processes in experimental watersheds that are planned to have thinning experiments. This new effort is relying on the tRIBS model and its application in similar areas. Comparisons to experimental measurements will allow for understanding small scale variations in hydrologic processes influenced by spatial variability in geological conditions, forest tree density and catchment orientation.
Land Surface Hydrology and Atmospheric Processes in Monsoon Ecosystems:
Overview: This project focuses on understanding the spatiotemporal variability of ecohydrological conditions in large watersheds in the southwestern US and northern Mexico which are influenced by rainfall and flood events during the North American monsoon. We combine remote-sensing observations of terrestrial conditions with field observations and numerical modeling experiments. The results provide a better understanding of the impact of dynamic vegetation on ecohydrological patterns and the effects of storm events on hydrological variables of interest, including runoff generation mechanisms and channel network streamflow regimes. This project has resulted in a number of publications: Mendez-Barroso et al. (2009), Mendez-Barroso and Vivoni (2010), Vivoni et al. (2010a,b), Forzieri et al. (2011, 2014), Robles-Morua et al. (2012), Xiang et al. (2014, 2017, 2018), Mascaro et al. (2015, 2019), Ko et al. (2019), among others.
- - Eli Perez-Ruiz (Ph.D. candidate) studies the water, energy and carbon fluxes in northwest Mexico using the eddy covariance method to identify the relative roles of environmental conditions, access to groundwater and plant water use strategies. He also combines this with remotely sensed observations of vegetation conditions to determine ecosystem phenology and functional traits.
- - Danielle Smilovsky (Ph.D. student) studies streamflow regimes in dryland rivers in Arizona using satellite based remote sensing and GIS. These advanced technologies, including SmallSats, provides new insights on hydrological processes in river networks and groundwater aquifers which together form the basis for state-of-the-art water resources assessments.
Rainfall Properties and Hillslope Responses in Arid Engineering Systems:
Overview: Extreme flooding events is expected to increase as urban expansion continues in the southwestern US. A holistic understanding of rainfall characteristics and their hydrologic and erosive response can inform engineering design in this region. This project will use natural rainfall observations for the design and implementation of a large rainfall simulator and soil test bed at the Center for Bio-mediated and Bio-inspired Geotechnics (CBBG) at ASU’s Polytechnic campus. This simulator will be used to evaluate the effectiveness of geotechnical materials used in the built environment to mitigate current and future storm hazards.
- - Eric Escoto (Ph.D. candidate) is leading the development of a rainfall simulator facility to test the effectiveness of rolled erosion control products and other engineering solutions used in the built environment for erosion control. This involves design, fabrication, installation and testing activities.