Alfonso Torres-Rua

Alfonso Torres-Rua
Utah State University | USU · Department of Civil and Environmental Engineering

Doctor of Philosophy

About

68
Publications
15,954
Reads
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1,104
Citations
Citations since 2017
57 Research Items
1044 Citations
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Introduction
I am an Irrigation Engineer interested in the use of remotely sensed products that support water balance at farm and larger scales. This interest involves UAVs, satellites and spatial models for quantification of ET, rainfall, soil moisture, and yield. Physical- and data-driven models are necessary due to complex and not fully understood processes at small scales.
Additional affiliations
July 2016 - December 2020
Utah State University
Position
  • Professor (Assistant)
April 2013 - June 2016
Utah Water Research Laboratory
Position
  • Engineer
Description
  • Satellite based research for farm management
Education
January 2007 - May 2011
Utah State University
Field of study
  • Water Resources
August 2005 - December 2006
Utah State University
Field of study
  • Irrigation Engineering
April 1996 - December 2000
Universidad Nacional Agraria La Molina
Field of study
  • Agricultural Engineering

Publications

Publications (68)
Method
The images generated by high-resolution spectral and thermal sensors equipped on small unmanned aerial vehicles (sUAV) make possible estimation of energy flux for California vineyards via the two-source energy balance (TSEB) model. Temperature (thermal) image plays an important role in the TSEB model, and the high-resolution provides an opportunity...
Method
This is a project aiming at using python program to generate fractional cover, canopy height, and canopy width over canopy height for the TSEB model based on images collected via the AggieAir small unmanned aerial system (sUAS) platform over California vineyards.
Article
Full-text available
Accurately estimating and forecasting evapotranspiration is one of the most important tasks to strengthen water resource management, especially in desert areas such as La Yarada, Tacna, Peru, a region located at the head of the Atacama Desert. In this study, we used temperature, humidity, wind speed, air pressure, and solar radiation from a local w...
Article
Full-text available
Assessment of water consumption is a crucial task for irrigation management in grapevines, especially in areas with limited water resources, which is the case of California Central Valley. This study evaluated the utility of the Simple Algorithm for Evapotranspiration Retrievement (SAFER) model to estimate daily and seasonal actual evapotranspirati...
Article
Full-text available
Monitoring evapotranspiration (ET) is possible through land surface temperature (LST) measured by satellites and unmanned aerial vehicles (UAV). The assumption that the higher resolution of LST may improve the performance of remote sensing ET models was verified in a recently published article showing that higher resolution LST led to increased per...
Article
Full-text available
Remote sensing estimation of evapotranspiration (ET) directly quantifies plant water consumption and provides essential information for irrigation scheduling, which is a pressing need for California vineyards as extreme droughts become more frequent. Many ET models take satellite-derived Leaf Area Index (LAI) as a major input, but how uncertainties...
Conference Paper
Full-text available
Leaf water potential (Ψl) in vineyards and orchards is a well-known indicator of plant water status and stress and it is commonly used by growers to make immediate crop and water management decisions. However, Ψl measurement via the direct method presents challenges as it is labor and time intensive and represents leaf-level conditions for only a s...
Presentation
Evapotranspiration (ET) is a crucial part of hydrological cycling, and its (ET) partitioning allows separate assessment of soil and plant water, energy, and carbon fluxes. ET partitioning plays an important role in agriculture since it is related to yield quality, irrigation efficiency, and plant growth. Satellite remote-sense-based methods provide...
Article
Full-text available
In agriculture, leaf area index (LAI) is an important variable that describes occurring biomass and relates to the distribution of energy fluxes and evapotranspiration components. Current LAI estimation methods at subfield scale are limited not only by the characteristics of the spatial data (pixel size and spectral information) but also by the emp...
Article
Full-text available
Crop evapotranspiration (ET) is a crucial component of energy and water budgets. The accurate determination of ET is vital for agricultural water management. Several satellite-based ET models have been developed to map ET at the field to regional scales. The spatial resolution of the satellite observations, particularly thermal-infrared imagery, is...
Article
Full-text available
Water conservation efforts for California’s agricultural industry are critical to its sustainability through severe droughts like the current one and others experienced over the last two decades. This is most critical for perennial crops, such as vineyards and orchards, which are costly to plant and maintain and constitute a significant fraction of...
Article
Full-text available
Understanding the spatial variability in highly heterogeneous natural environments such as savannas and river corridors is an important issue in characterizing and modeling energy fluxes, particularly for evapotranspiration (ET) estimates. Currently, remote-sensing-based surface energy balance (SEB) models are applied widely and routinely in agricu...
Article
In the present study, remote sensing techniques are used using a Remotely Piloted Aircraft System (RPAS) to estimate crop evapotranspiration (ETc) in olive trees (Olea europaea L.) on the southern coast of Peru. The objective of the experiment was to estimate the evapotranspiration of the olive cultivation by means of the METRIC model, from multisp...
Article
Full-text available
COMPARAÇÃO DO NDVI OBTIDO POR MEIO DE DRONE E SATÉLITE NAS FASES FENOLÓGICAS DA VIDEIRA MARYJANE DINIZ DE ARAÚJO GOMES1; RODRIGO MÁXIMO SÁCHEZ ROMÁN2; ALFONSO TORRES-RUA3; ÉLVIS DA SILVA ÁLVES4 E MAC MCKEE3 1 Instituto Federal de Ciência e Tecnologia do Pará, BR 316, km 65, Campus Castanhal, s/n, CEP. 68740-970, Castanhal, Pará, Brasil, maryjane.go...
Method
Leaf area index (LAI) plays an important role in land-surface models to describe the energy, carbon, and water fluxes between the soil and canopy vegetation. Indirect ground LAI measurements, such as using the LAI2200C Plant Canopy Analyzer (PCA), can not only increase the measurement efficiency but also protect the vegetation compared with the dir...
Method
Accurate leaf area index (LAI) estimation through machine learning (ML) algorithms is a channel for better understanding and monitoring the existing biomass and it relates to the distribution of energy fluxes and evapotranspiration partitioning. In order to support the ML algorithm for accurate LAI estimation, the supporting data (or features) gain...
Method
The widely used two-source energy balance (TSEB) model coupled with AggieAir (https:// uwrl.usu.edu/aggieair/, a type of small Unmanned Aerial System) data can provide high-resolution modeled energy components, evapotranspiration partitioning, etc., at a subfield scale. When the research area is equipped with eddy-covariance (EC) towers, researcher...
Method
Energy flux and evapotranspiration modeling via the widely used two-source energy balance (TSEB) model at a subfield scale for vineyards based on the high-resolution images gained by the small Unmanned Aerial System (sUAS) is a critical tool for vine-growers and researchers to better understand the water and energy exchange between the land surface...
Article
Full-text available
Daily evapotranspiration (ETd) plays a key role in irrigation water management and is particularly important in drought-stricken areas, such as California and high-value crops. Remote sensing allows for the cost-effective estimation of spatial evapotranspiration (ET), and the advent of small unmanned aerial systems (sUAS) technology has made it pos...
Conference Paper
Full-text available
Accurate quantification of the partitioning of evapotranspiration (ET) into transpiration and evaporation fluxes is necessary to understanding ecosystem interactions among carbon, water, and energy flux components. ET partitioning can also support the description of the atmosphere and land interactions and provide unique insights into vegetation wa...
Conference Paper
sUAS (small-Unmanned Aircraft System) and advanced surface energy balance models allow detailed assessment and monitoring (at plant scale) of different (agricultural, urban, and natural) environments. Significant progress has been made in the understanding and modeling of atmosphere-plant-soil interactions and numerical quantification of the intern...
Poster
Leaf Area Index (LAI) is an important structural property of vegetation canopy and is one of the basic quantities driving the algorithms used in biogeochemical, ecological, and meteorological applications. However, the methods to obtain accurate LAI, even at a field scale, are still challenging. Although direct methods can provide an accurate estim...
Article
Full-text available
Land surface temperature (LST) is a key diagnostic indicator of agricultural water use and crop stress. LST data retrieved from thermal infrared (TIR) band imagery, however, tend to have a coarser spatial resolution (e.g., 100 m for Landsat 8) than surface reflectance (SR) data collected from shortwave bands on the same instrument (e.g., 30 m for L...
Article
Full-text available
Considerable advancement in spatiotemporal resolution of remote sensing and ground-based measurements has enabled refinement of parameters used in land surface models for simulating surface water fluxes. However, land surface modeling capabilities are still inadequate for accurate representation of subsurface properties and processes, which continu...
Article
Full-text available
Nick Dokoozlian, "To what extend does the Eddy Covariance footprint cutoff influence the estimation of surface energy fluxes using two source energy balance model and high-resolution imagery in commercial vineyards?,"
Preprint
Surface temperature is necessary for the estimation of energy fluxes and evapotranspiration from satellites and airborne data sources. For example, the Two-Source Energy Balance (TSEB) model uses thermal information to quantify canopy and soil temperatures as well as their respective energy balance components. While surface (also called kinematic)...
Conference Paper
Full-text available
Validation of surface energy fluxes from remote sensing sources is performed using instantaneous field measurements obtained from eddy covariance (EC) instrumentation. An eddy covariance measurement is characterized by a footprint function / weighted area function that describes the mathematical relationship between the spatial distribution of surf...
Conference Paper
Full-text available
Estimation of surface energy fluxes using thermal remote sensing-based energy balance models (e.g., TSEB2T) involves the use of local micrometeorological input data of air temperature, wind speed, and incoming solar radiation, as well as vegetation cover and accurate land surface temperature (LST). The physically based Two-source Energy Balance wit...
Conference Paper
Surface temperature is necessary for the estimation of energy fluxes and evapotranspiration from satellites and airborne data sources. For example, the Two-Source Energy Balance (TSEB) model uses thermal information to quantify canopy and soil temperatures as well as their respective energy balance components. While surface (also called kinematic)...
Article
Full-text available
Evapotranspiration (ET) is a key variable for hydrology and irrigation water management, with significant importance in drought-stricken regions of the western US. This is particularly true for California, which grows much of the high-value perennial crops in the US. The advent of small Unmanned Aerial System (sUAS) with sensor technology similar t...
Article
Full-text available
Highlights Unmanned aerial systems (UAS) are able to provide data for precision irrigation management. Improvements are needed regarding UAS platforms, sensors, processing software, and regulations. Integration of multi-scale imagery into scientific irrigation scheduling tools are needed for technology adoption. Abstract . Several research institu...
Article
Full-text available
In recent years, the deployment of satellites and unmanned aerial vehicles (UAVs) has led to production of enormous amounts of data and to novel data processing and analysis techniques for monitoring crop conditions. One overlooked data source amid these efforts, however, is incorporation of 3D information derived from multi-spectral imagery and ph...
Article
Full-text available
Flood inundation remains challenging to map, model, and forecast because it requires detailed representations of hydrologic and hydraulic processes. Recently, Continental‐Scale Flood Inundation Mapping (CFIM), an empirical approach with fewer data demands, has been suggested. This approach uses National Water Model forecast discharge with Height Ab...
Conference Paper
Theoretically, the appearance of shadows in aerial imagery is not desirable for researchers because it leads to errors in object classification and bias in the calculation of indices. In contrast, shadows contain useful geometrical information about the objects blocking the light. Several studies have focused on estimation of building heights in ur...
Conference Paper
Soil moisture is a key component of water balance models. Physically, it is a nonlinear function of parameters that are not easily measured spatially, such as soil texture and soil type. Thus, several studies have been conducted on the estimation of soil moisture using remotely sensed data and data mining techniques such as artificial neural networ...
Conference Paper
Tests of the most recent version of the two-source energy balance model have demonstrated that canopy and soil temperatures can be retrieved from high-resolution thermal imagery captured by an unmanned aerial vehicle (UAV). This work has assumed a linear relationship between vegetation indices (VIs) and radiometric temperature in a square grid (i.e...
Conference Paper
Microbolometer thermal cameras in UAVs and manned aircraft allow for the acquisition of highresolution temperature data, which, along with optical reflectance, contributes to monitoring and modeling of agricultural and natural environments. Furthermore, these temperature measurements have facilitated the development of advanced models of crop water...
Conference Paper
Current technologies employed for use of small, unmanned aerial systems (sUAS), or “drones”, for remote sensing (RS) activities that support the information needs of agricultural operations are expensive, provide relatively small geographic coverage, and typically produce data of limited scientific quality. Research is currently underway that will...
Article
Full-text available
The thermal-based Two-Source Energy Balance (TSEB) model partitions the evapotranspiration (ET) and energy fluxes from vegetation and soil components providing the capability for estimating soil evaporation (E) and canopy transpiration (T). However, it is crucial for ET partitioning to retrieve reliable estimates of canopy and soil temperatures and...
Article
Full-text available
Significant efforts have been made recently in the application of high-resolution remote sensing imagery (i.e., sub-meter) captured by unmanned aerial vehicles (UAVs) for precision agricultural applications for high-value crops such as wine grapes. However, at such high resolution, shadows will appear in the optical imagery effectively reducing the...
Presentation
Full-text available
There has been considerable advancement in spatiotemporal resolution of remote sensing and ground-based measurements enabling refinements to the parameters used in land surface models for simulating surface fluxes. However, inadequate representation of subsurface processes and soil parameters still create limitations for land surface model simulati...
Article
Full-text available
Accurate spatial and temporal precipitation estimates are important for hydrological studies of irrigation depletion, net irrigation requirement, natural recharge, and hydrological water balances in defined areas. This analysis supports the verification of water savings (reduced depletion) from deficit irrigation of pastures in the Upper Colorado R...
Conference Paper
With the increasing availability of thermal proximity sensors, UAV-borne cameras, and eddy covariance radiometers there may be an assumption that information produced by these sensors is interchangeable or compatible. This assumption is often held for estimation of agricultural parameters such as canopy and soil temperature, energy balance componen...
Conference Paper
Small, unmanned aerial systems (sUAS) for remote sensing represent a relatively new and growing technology to support decisions for agricultural operations. The size and power limitations of these systems present challenges for the weight, size, and capability of the sensors that can be carried, as well as the geographical coverage that is possible...
Conference Paper
Full-text available
Satellites and autonomous unmanned aerial vehicles (UAVs) are two major platforms for acquiring remotely-sensed information of the earth’s surface. Due to the limitations of satellite-based imagery, such as coarse spatial resolution and fixed schedules, applications of UAVs as low-cost remote sensing systems are rapidly expanding in many research a...
Conference Paper
Full-text available
In high-resolution imagery, shadows may cause problems in object segmentation and recognition due to their low reflectance. For instance, the spectral reflectance of shadows and water are similar, particularly in the visible band. In precision agriculture, the vegetation condition in terms of plant water use, plant water stress, and chlorophyll con...
Article
Full-text available
Particularly in light of California’s recent multi-year 1 drought, there is a critical need for accurate and timely evapotranspiration (ET) and crop stress information to ensure long-term sustainability of high-value crops. Providing this information requires the development of tools applicable across the continuum from sub-field scales to improve...
Poster
Full-text available
In high-resolution remote sensing imagery, shadows affect the surface reflectance recorded by imaging sensors. In this research, the performance of four different shadow detection methods are evaluated based on high-resolution imagery collected over a California vineyard during the Grape Remote sensing Atmospheric Profile and Evapotranspiration Exp...
Article
Full-text available
Applications of satellite-borne observations in precision agriculture (PA) are often limited due to the coarse spatial resolution of satellite imagery. This paper uses high-resolution airborne observations to increase the spatial resolution of satellite data for related applications in PA. A new variational downscaling scheme is presented that uses...
Article
Full-text available
In recent years, the availability of lightweight microbolometer thermal cameras compatible with small unmanned aerial systems (sUAS) has allowed their use in diverse scientific and management activities that require sub-meter pixel resolution. Nevertheless, as with sensors already used in temperature remote sensing (e.g., Landsat satellites), a rad...
Article
en Soil moisture is an important parameter in irrigation scheduling and application. Knowledge of root zone volumetric water content can support decisions for more efficient irrigation management by enabling estimation of required water application rates at appropriate temporal and spatial scales. The study presented here proposes a data mining app...
Article
Full-text available
Spatial surface soil moisture can be an important indicator of crop conditions on farmland, but its continuous estimation remains challenging due to coarse spatial and temporal resolution of existing remotely-sensed products. Furthermore, while preceding research on soil moisture using remote sensing (surface energy balance, weather parameters, and...
Conference Paper
Researchers at the Utah Water Research Laboratory at Utah State University have developed a small unmanned aerial system (UAS) called "AggieAir" for use as a precision remote sensing tool. The AggieAir TM UAS platform can be launched and landed almost anywhere. It carries scientific-grade cameras that capture imagery in the visual (red/green/blue),...
Article
Full-text available
Precision agriculture requires high-resolution information to enable greater precision in the management of inputs to production. Actionable information about crop and field status must be acquired at high spatial resolution and at a temporal frequency appropriate for timely responses. In this study, high spatial resolution imagery was obtained thr...
Article
Full-text available
Many crop production management decisions can be informed using data from high-resolution aerial images that provide information about crop health as influenced by soil fertility and moisture. Surface soil moisture is a key component of soil water balance, which addresses water and energy exchanges at the surface/atmosphere interface; however, high...
Conference Paper
Full-text available
There is an increasing trend in crop production management decisions in precision agriculture based on observation of high resolution aerial images from unmanned aerial vehicles (UAV). Nevertheless, there are still limitations in terms of relating the spectral imagery information to the agricultural targets. AggieAir™ is a small, autonomous unmanne...
Article
Evapotranspiration (ET) is an important component of the hydrologic cycle, especially for irrigated agriculture. Direct methods of estimating reference ET are difficult or require many weather variables that are not always available at all weather stations. The Hargreaves equation (HG) requires only measured daily air temperature data and computed...
Conference Paper
Precision agriculture requires high spatial management of the inputs to agricultural production. This requires that actionable information about crop and field status be acquired at the same high spatial resolution and at a temporal frequency appropriate for timely responses. This paper presents some results from an on-going project to explore the...
Article
Modernization of today's irrigation systems attempts to improve system efficiency and management effectiveness of every component of the system (reservoirs, canals, and gates) using automation technologies, along with hydraulic simulation models. The canal flow control scheme resulting from the coupling of the system automation and the simulation m...