Ecohydrology of Semiarid Catchments with Woody Plant Encroachment:
Overview: Two watersheds have been instrumented with a high-resolution environmental sensor network consisting of rain gauges, soil moisture and
temperature profiles, channel 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 heavily instrumented watersheds to quantify the spatiotemporal ecohydrological dynamics and to parameterize physically-based distributed models. This will allow 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) and Schreiner-McGraw et al. (2016, 2017), among others.
- - Dr. Nolie Templeton is in charge of the observational and modeling activities conducted in a small watershed in the Santa Rita Experimental Range, AZ. This desert basin is representative of woody plant encroachment into desert grasslands and has been characterized by hydrologic and photographic observations over the last 30 years. The high resolution network will allow analyzing the temporal and spatial distributions of rainfall, soil moisture and temperature, channel runoff and land-atmosphere fluxes in the watershed. The field observations are also used for site simulations of the tRIBS model designed to explore the influence of the vegetation shifts on the landscape dynamics.
- -Dr. Adam Schreiner-McGraw conducts experiments and compiles data from the two instrumented watersheds with the goal of comparing the effects of shifting vegetation patterns on hydrologic processes and using the insight gained to inform and improve current hydrologic models. In addition, he is pursuing a new technology to measure soil moisture at intermediate scales (hectometers) using cosmogenically produced neutrons. The results from this study can be used to inform statistical downscaling of low resolution satellite data, estimate changes in biomass due to monsoon rains, and to compare intermediate scale soil moisture data to model-derived estimates.
- -Eli Perez-Ruiz (Ph.D.) studies the dynamic and response of arid and semi-arid ecosystem to changes in environmental factors, particularly, changes in precipitation and water availability. He focus in three main objectives: a) the analysis of the seasonal and inter-annual variation of carbon dioxide fluxes (Net Ecosystem Exchange, NEE) and evapotranspiration (ET) in two different arid landscapes and their relationship with meteorological and environmental measurements; b) the relationship between NEE and other components of carbon cycle, including soil carbon fluxes and storages and litter decomposition; and c) using process-based models (tRIBS-VEGGIE and tRIBS-Ecotone) to model relations between plant communities, environmental conditions and meteorological forcings that alter carbon storages and fluxes.
Land Surface Hydrology and Atmospheric Processes in Monsoon Ecosystems:
Overview: This project focuses on understanding the spatiotemporal variability of ecohydrological conditions in a large watershed of northwest Mexico influenced by rainfall during the North American monsoon. To assess the implications of the ecosystem seasonality, we combine remote-sensing observations of terrestrial conditions with the tRIBS model. Using the model, we evaluate the impact of dynamic greening on soil moisture, evapotranspiration and soil temperature fields, in comparison to cases where the phenological changes are withheld from the model (static leaf-on and leaf-off). The results provide a better understanding of the impact of dynamic vegetation on ecohydrological patterns and their nonlinear propagation to other hydrological variables of interest, including runoff generation mechanisms and channel network streamflow. 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) and Robles-Morua et al. (2012), Xiang et al. (2014, 2017, 2018), among others.
- - Dr. Tiantian Xiang investigates how land surface temperature (LST), a key parameter in watershed energy and water budgets, can be used as a validation metric for distributed hydrologic models. Spatiotemporal LST observations can serve as a strong constraint for distributed simulations and can augment other available in-situ data. In this study, we collect and process remotely-sensed fields from several satellite platforms to capture spatiotemporal LST dynamics at multiple resolutions and with frequent repeat visits. We focus our analysis of these fields over the Sierra Los Locos basin (~100 km2) in Sonora, Mexico, for a period encompassing the Soil Moisture Experiment in 2004. Results from the comparisons are discussed in light of the utility of remotely-sensed LST for testing distributed models in regions of complex terrain with seasonal changes in land surface conditions.
- - Eli Perez-Ruiz (PhD) studies the water, energy and carbon fluxes in three monsoonal ecosystems of northwest Mexico using the eddy covariance (EC) method. A multi-institutional effort in summer 2017 will compare the land surface turbulent fluxes in these ecosystems with atmospheric measurements of precipitable water and temperature/humidity profiles. The goal of the monsoon analyses is to identify the relative roles of synoptic water vapor transport and local evapotranspiration on precipitation recycling, including variations among ecosystems with different seasonal phenology. Results from the comparison of atmospheric and land surface datasets will be critical to address long-standing questions on the role of terrestrial ecosystems in sustaining the North American monsoon.
Regional Impacts of Changes in Climate and Land/Water Use on Hydrology and Water Resources:
Overview: This project assesses the potential future impacts of both climate change and land/water use change on hydrology and water resources, at a variety of scales, ranging from several metropolitan areas, through the Colorado River Basin (CRB), up to the entirety of the Continental US + Mexico. This project is part of two funded proposals: (1) Urban Resilience Sustainability Research Network (UREx-SRN) and (2) Decision Center for a Desert City (DCDC). UREx-SRN focuses on impacts of climate change on climate and hydrologic extremes in 10 urban areas throughout the US and Mexico; two cities of particular interest in our group at ASU are Phoenix, AZ and Hermosillo, Sonora, Mexico. DCDC III focuses on climate and land use impacts on the water resources of the CRB in general and Phoenix, AZ; Denver, CO; and Las Vegas, NV in particular.
- - Dr. Theodore Bohn is using the VIC model, remote sensing data, and government records to study the impacts of both short- (phenology) and long-term (land cover/use change) on hydrology and water resources, and comparing these to impacts of climate change, over the Continental US and Mexico over the period 1980-2013. This work builds on recent modifications to the VIC model (Bohn and Vivoni, 2016) and hinges on the development of VIC input parameters (land cover maps for 1992 and 2011; daily time series of LAI, NDVI, and albedo given by MODIS) over the domain. Once historical comparisons are finished, impacts of potential future climate change (given by several CMIP5 models) over the domain will be examined.
- - Zhaocheng Wang (Ph.D.) is using VIC study the impacts of climate change and potential changes in future land use on the hydrology of several major cities that depend on water from the Colorado River: Phoenix, AZ; Denver, CO; Las Vegas, NV; and Salt Lake City, UT. In the first phase, he is analyzing future land-use maps under Integrated Climate and Land Use Scenarios from US Environmental Protection Agency (EPA) up to 2100 in 10-years interval. He will then conduct dynamic downscaling of latest emission scenarios from Coupled Model Intercomparison Project 5 (CMIP5) to generate future climate projections using the Weather Research Forecast (WRF) model. Zhaocheng will eventually couple VIC to the Weather Research and Forecasting (WRF) model to more accurately capture the response of the urban environment to these changes.
Distributed Flood Forecasting with Advanced Rainfall Products:
Overview: In these projects, several types of precipitation products from radar, satellite and model estimates are being evaluated with the goal of producing spatially distributed hydrological forecasts. The assessment of their benefits and factors limiting their use in coupled hydrometeorological flood forecasting models and eventual adoption by flood forecasting centers is the main purpose behind these studies. These projects also open up opportunities to interact with stakeholders on flood hazard forecasting and mitigation. This project has resulted in a number of publications: Vivoni et al. (2006), Vivoni et al. (2007), Mascaro et al. (2010), Moreno et al. (2012) and Moreno et al. (2013a,b), among others.
- - Jorge Cazares (M.S.) is conducting a study applying tRIBS in the Santa Catarina basin of Nuevo Leon, Mexico, where Hurricane Alex in July 2010 led to catastrophic flooding of the capital city of Monterrey. The distributed model simulations were forced using meteorological forcing for the flood event based on multiple data sources, including three local gauge networks, satellite-based estimates from PERSIANN, and the North American Land Data Assimilation System (NLDAS). The overall goal of this project is to assess if the results from the hydrologic model can help bring consensus among diverse stakeholders in regional flood planning by producing quantifiable sets of alternative futures.
Ecohydrological Interactions and Modeling in Natural and Urban Environments:
Overview: Given the importance of water-limited environments and the impacts of increasing demands on water supplies and other natural resources, it is increasingly important we understand the relationships between hydrological, biogeochemical, and ecological processes. The advancement of ecohydrological approaches that explore those linkages is important in order to improve our ability to forecast environmental change. This project has resulted in a number of publications: Vivoni et al. (2008), Mahmoud and Vivoni (2008, 2011a,b, 2013), Vivoni (2012), and Whitney et al. (2017), among others.
- - Dr. Taufique Mahmood studies Ponderosa pine forests to explore the switching between local (vegetative) and nonlocal (topographic) controls using tRIBS. This modeling effort is focused on identifying threshold behaviors in the hillslope response due to wetting during the North American monsoon (NAM). The water supplies in major river basins largely depend on ponderosa pine forest as it (1) receives a significant amount of rainfall and snowfall, (2) intercepts precipitation and transpires water and (3) indirectly influences runoff by impacting the infiltration rate. However, the temporal evolution of spatial hydrologic patterns in such systems is poorly understood which is why we try to investigate and provide a better understanding through our modeling efforts.
- - Kristen Whitney (M.S.) is studying how changes in climate and variations in vegetation type and biological soil crust (BSC) morphology/distribution alter soil water dynamics and water cycling in the desert grassland and shrub ecosystems of the Colorado Plateau. This work builds upon soil moisture observations currently underway by the USGS Southwest Biological Science Center in Moab, Utah, under different experimental manipulations of precipitation and temperature regimes. The first part of this project involves synthesizing and analyzing field data to describe the soil water availability and cycling in response to treatments across the range of vegetation types and soil conditions (including BSCs). Subsquently, Kristen is exploring the use of a dynamic ecohydrological model to represent the results of her field data analysis and simulate the dynamic feedbacks between vegetation/BSC development and structure, and the energy and water budgets under future climate scenarios.
Ensemble Generation of Downscaled Soil Moisture from Satellite Observations:
Overview: While satellite observations have improved knowledge of Earth’s surface, there is a critical need for high-resolution soil moisture fields at hillslope (10 m) to watershed (1 km) scales due to its importance in controlling the partitioning of energy and water. Despite a new generation of space-borne sensors, the resolution of satellite estimates is still too coarse for high-resolution hydrologic, ecologic, and climatologic applications. In this project, we will use a statistical downscaling model for generating high-resolution soil moisture fields from coarser satellite data. The model is based on scale invariance and multifractal properties exhibited by soil moisture fields obtained from aircraft-based sensors flown during NASA field campaigns and from simulations of a distributed hydrologic model applied to a set of study basins. This project has resulted in a number of publications: Mascaro and Vivoni (2010, 2012a,b) and Mascaro et al. (2011, 2012), among others.
- - Dr. Giuseppe Mascaro has characterized the statistical variability of soil moisture and how this is affected by terrain, soil texture and land use features. He has investigated the presence of scale invariance and multifractality and has calibrated a model that is able to statistically disaggregate satellite soil moisture products using data of NASA field campaigns located in contrasting environmental and climatic settings. The downscaling model has also been applied as a tool to generate soil moisture fields that are assimilated using a variety of methods into the tRIBS distributed hydrologic model to improve model predictions.
- - Ara Ko (Ph.D.) is analyzing the statistical variability of soil moisture through the scale invariance and multifractal theory and calibrating the downscaling algorithm to disaggregate coarse satellite estimates. She is collecting ground and aircraft-based soil moisture data and other ancillary datasets from different field campaigns, including the National Airborne Field Experiment 2005 (NAFE05) and 2006 (NAFE06). She is evaluating the effect of anthropogenic factors on soil moisture and strategies to include these in the downscaling scheme. Ara is also applying the tRIBS model to a set of study basins, with the goal of creating a database of high-resolution (up to 10 m) soil moisture data that will be used to refine the calibration of the downscaling algorithm.
Modeling Climate and Hydrological Extremes in Urban Environments:
Overview: This work is in collaboration with the Urban Resilience Sustainability Research Network (URex-SRN), an exciting program that integrates social, ecological, and technological systems to devise, analyze, and support urban infrastructure in the face of weather-related extreme events. ASU’s hydrosystems team is involved with the Climate and Hydrological Extremes Working Group (CHExWG). The goal of the CHExWG is to produce future scenarios of extreme climate and hydrologic events grounded on past conditions that have impacts on urban infrastructure. Through our modeling efforts, we aim to produce scenarios that resonate with urban decision-makers and promote better urban planning that addresses the vulnerabilities of each city.
- - Dr. Vivian Verduzco is working along with decision makers, government agencies and developers from Hermosillo on data acquisition, in order to identify urban infrastructure conditions and issues. She is also analyzing extreme climatic and hydrologic events through the use of the VIC model applied to the major basins in Sonora, Mexico.
- - Kristen Whitney (Ph.D.) is involved with selecting, processing, and analyzing downscaled global climate datasets for the urban regions involved with the UREX-SRN network. She is applying the recently-modified Variable Infiltration Capacity (VIC; Bohn and Vivoni, 2016) model forced with downscaled climate products using a statistical approach. Finally, she is analyzing the modeled storm water outputs from the projected extreme precipitation events over the urban areas.
Sociohydrological Interactions and Stakeholder Engagement in Water Resources:
Overview: With the importance of water resources to society, it is imperative that hydrologic science, engineering and sustainability be infused more directly into the sociopolitical processes that result in policy and decision-making. We are engaging in water resources planning and management projects in Arizona and New Mexico (USA), and Sonora, Nuevo Leon, Jalisco and Mexico City (Mexico) through stakeholder interactions and participatory modeling activities. This project has resulted in a number of publications: Robles-Morua et al. (2013), Mayer et al. (2017), Eakin et al. (2017), among others.
- - The group is studying how stakeholders perceive and utilize hydrologic models in participatory settings as a function of model complexity. We have carried this out with the HEC-HMS modeling system for the Rio Sonora under different levels of process, domain and forcing representation to assess differences in saliency, legitimacy and credibility in the modeling process among participants. Hands-on workshops were held in Hermosillo, Sonora, Mexico and focused on combined scenarios of water resources infrastructure and climate change impacts in the Rio Sonora basin in the context of the Sonora SI infrastructure program.
- - The group is also participating in stakeholder interactions related to sociohydrology in a range of projects with the School of Sustainability, the Decision Center for a Desert City and the Julie Anne Wrigley Global Institute of Sustainability at ASU. In these efforts, we are providing support in hydrologic data analysis, numerical modeling of hydrologic and water resource systems, remote sensing data and GIS visualization and the formulation of participatory exercises with a range of different modeling tools.
Rainfall Characteristics and Hillslope Responses in Arid to Semiarid Regions:
Overview: Havoc caused by 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 observations of rainfall characteristics 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 in addition to other research efforts.
- - Eric Escoto (PhD) is assessing rainfall characteristics in the southwestern US to improve understanding of soil and hillslope processes and assist in the development of a rainfall simulator facility. Along with the rainfall simulator, two rural sites in the Sonoran and Chihuahuan deserts will gather discrete rainfall characteristics as well as water and sediment fluxes. A particular focus is being placed on the drop size distribution (DSD) and kinetic energy (KE) of rainfall as a predictor of hydrologic and erosive responses at the hillslope scale. The experimental facility will also be used to test the effectiveness of rolled erosion control products (RECP) and other engineering solutions used in the built environment for erosion control.