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.
- - Nolie Pierini (Ph.D.) 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.
- -Adam Schreiner-McGraw (Ph.D.) 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.The work is performed in two highly equipped and characterized small watersheds in Santa Rita Experimental Range (SRER) and Jornada Experimental Range (JER),
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), among others.
- - Dr. Luis Mendez-Barroso studies the role that seasonal vegetation changes have in semiarid regions by modifying water, energy and momentum fluxes. In addition, he investigates the impacts of seasonal precipitation pulses during the monsoon on land surface conditions. In this study, we coupled a set of vegetation parameters derived from the Moderate Resolution Imaging Spectroradiometer (MODIS) with the tRIBS model for two semiarid mountain ecosystems in northern Sonora, Mexico. The results indicate that dynamic greening conditions represent well the transition in ET partitioning which is shown to vary for each season. The results from this study will help understand biosphere-atmosphere interactions under complex topography in the region and improve hydrologic model parameterizations in semiarid forest ecosystems.
- - 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.
Hydrological Modeling for Land Cover and Climate Change Impacts:
Overview: These projects are part of multidisciplinary efforts aimed at understanding the impacts of climate variability in large watersheds in the southwest US. Watershed management is challenged by rising concerns over climate change and its potential to interact with land cover alterations to impact regional water supplies and hydrologic processes. The inability to conduct experimental manipulations that address climate and land cover change at watershed scales limits the capacity of water managers to make decisions to protect future supplies. As a result, spatially-explicit, physically-based models possess value for predicting the possible consequences on watershed hydrology. In these studies, we apply the tRIBS model to analyze the spatiotemporal distributions of precipitation, soil moisture, runoff generation, evapotranspiration and recharge at high resolution for an assessment of sustainable water supplies.
- - Dr. Agustin Robles-Morua is working on estimating basin hydrological fluxes using tRIBS in the Santa Cruz and San Pedro basins. With the distributed model, we will evaluate a set of climate change and population scenarios to quantify future conditions in these two river systems and their impacts on flood peaks, recharge events and low flows. The Weather Research Forecast (WRF) model is used to specify historical and two future conditions (2031-2040 & 2071-2080). The results will help better understand the distribution of precipitation, soil moisture, runoff generation and recharge and assess the value of the tRIBS-WRF products for assessing hydrological impacts of climate change.
Land Use Change Effects on Atmospheric Moisture and Rainfall Generation:
Overview: This project examines the influence of land cover and land use on atmospheric moisture transport in the North American Monsoon, both within Mexico and from Mexico to the US. Southern Arizona and New Mexico receive 30-50% of their annual rainfall in the summer, as part of the North American Monsoon (NAM). Modeling studies suggest that 15-25% of this rainfall first falls on Mexican land, is transpired by vegetation, and subsequently is transported northward across the border to the US. The main source regions in Mexico lie in the subtropical scrub and tropical deciduous forests in the foothills of the Sierra Madre Occidental, in the states of Sinaloa and Sonora. A key characteristic of these natural ecosystems is their rapid greening at the onset of the monsoon, which maximizes the amount of moisture transpired from the soil into the atmosphere in the days immediately following rainfall. These ecosystems are under threat from a number of human activities, including expansion of rainfed and irrigated agriculture, deforestation for grazing activities and urbanization. These changes in land use result in dramatically different seasonality and magnitude of evapotranspiration.
- - Dr. Theodore Bohn studies the influence of land cover and land use on atmospheric moisture transport in the North American Monsoon (NAM), both within Mexico and from Mexico to the US. To this end, he employs the Variable Infiltration Capacity (VIC) land surface model at 1/16 degree resolution, driven by gridded meteorological observations and MODIS-derived time series of LAI and NDVI, across the NAM region (Arizona, New Mexico, and northern Mexico). In the first phase of the project, he is examining the differences among various land cover/land use conditions in the seasonality of ET and its relationship with monsoon onset. In later phases of the project, he will couple VIC to the Weather Research Forecast (WRF) atmospheric model to examine the roles played by the different land covers/uses, via their ET “signatures”, in modulating moisture transport.
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), Mahmood and Vivoni (2008, 2011a,b, 2013) and Vivoni (2012), 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.
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), among others.
- - The group is studying how stakeholders perceive and utilize hydrologic models in participatory settings as a function of model complexity. Her work applies the HEC-HMS modeling system 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 are held in Hermosillo, Sonora, Mexico and focus 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. See workshop website at: Hermosillo Workshops
- - 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.
Socio-hydrological Risks under Climate and Land Use Change in Megacities:
Overview: The project is a collaboration between ASU and the Universidad Nacional Autonoma de Mexico (UNAM) to understand the dynamics of hydrological risk in a complex social-hydrological system with dependencies in water-resource management and urban development in the Mexico City Metropolitan Area (MCMA). This megacity with over 20 million people and has a complex water management system with drainage, water scarcity, and flooding issues. Four case studies considered for this project are: Magdalena Contreras, Xochimilco, Iztapalapa, and Texcoco. Regional upland watershed modeling will be accomplished through distributed hydrologic modeling using tRIBS to provide flood and water supply predictions. Model outputs will provide GIS layers used to predict flood hazards, water quality and public health risks in combined stormwater and sewer systems that can inform decision-making and urban planning activities.
- - The group is working with modeling techniques for the Magdalena River upland watershed as one case study. Data sets for model setup will be obtained from various sources including meteorological stations, CONAGUA and INEGI, among others. Climate change predictions will be obtained from a numerical weather model as model input. In addition, hydraulic infrastructure in the upland watershed will be considered. The results from the hydrologic model under climate change and infrastructure scenarios will be used in a multi criteria decision analysis framework to evaluate the relationship between actors’ decisions and its effect on land cover and/or water infrastructure.
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 new program that integrates social, ecological, and technological systems (SETS) 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), one of six working groups composing the URex-SRN. 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. See UREx-SRN website at: UREx-SRN Homepage
- - Dr. Vivian Verduzco is working along with decision makers, government agencies and developers from Latin American cities on data acquisition, in order to identify urban infrastructure conditions and issues. Another important goal of her work is to recognize vulnerable areas based on the analysis of extreme climatic and hydrologic events through the use of existing datasets and relate those to socioeconomic conditions. She is collaborating with the City Comparisons and Scenarios working group as well.
- - 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.