Ana Andreu

Ana Andreu
University of Cordoba (Spain) | UCO · Andalusian Institute for Earth System Research

https://savannahwatch.cc/

About

36
Publications
6,313
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162
Citations
Introduction
I work at the Fluvial Dynamics and Hydrology Group (UCO-DAUCO), focusing on the impact of microclimate conditions on the hydrology of Andalusian mountainous and dehesa areas. Before I was a Marie Curie Fellow at Prof. Baldocchi Biometlab (University of California, Berkeley), with IFAPA Research Center (Cordoba, Spain) as my core institution, modelling savanna water and carbon fluxes integrating multiple source-scale Earth Observation data.
Additional affiliations
November 2011 - December 2014

Publications

Publications (36)
Article
As the availability of satellite and airborne thermal infrared remote sensing (TIR-RS) data increases and their spatial, temporal, and spectral resolutions improve, researchers are finding diverse applications for TIR-RS measurements. TIR-RS is now commonly applied in regional- and continental-scale analyses, such as those focused on fire and surfa...
Article
It is well documented that energy balance and other remote sensing-based evapotranspiration (ET) models face greater uncertainty over water-limited tree-grass ecosystems (TGEs), representing nearly 1/6th of the global land surface. Their dual vegetation strata, the grass dominated understory and tree dominated overstory, make for distinct structura...
Article
In open-canopy ecosystems, thermal imaging affords an unprecedented opportunity to resolve concurrent temperatures of overstory vegetation, understory vegetation, and soil across space and time. This simultaneous view of ecosystem components promises a holistic understanding of ecosystem energy status, defines diverse thermal niches, and can provid...
Article
Full-text available
Mediterranean oak savanna is composed of a mixture of scattered oak trees, crops, pasture, and shrubs. It is the most widespread agroforestry landscape in Europe, and its conservation faces multiple threats including water scarcity, which has been exacerbated by global warming and greater climate variability. Evapotranspiration (ET) can be used as...
Article
Full-text available
Drought is a devastating natural hazard that is difficult to define, detect and quantify. The increased availability of both meteorological and remotely sensed data provides an opportunity to develop new methods to identify drought conditions and characterize how drought changes over space and time. In this paper, we applied the surface energy bala...
Article
The vegetation index (VI)-reference evapotranspiration (ETo) method incorporates the estimation of basal crop coefficients from spectral VIs into the FAO56 guidelines for computing crop evapotranspiration (ET). Previous research pointed to the possibility of the differential spectral response of some Mediterranean crops, specifically olive trees. T...
Preprint
Full-text available
Abstract. Drought is a devastating natural hazard, difficult to define, detect and quantify. Global meteorological data and remote sensing products present new opportunities to characterize drought in an objective way, and to extend this analysis in space and time. In this paper, we applied the surface energy balance model SEBS (Surface Energy Bala...
Article
Full-text available
The use of soil moisture (SM) measurements from satellites has grown in recent years, fostering the development of new products at high resolution. This opens the possibility of using them for certain applications that were normally carried out using in situ data. We investigated this hypothesis through two main analyses using two high-resolution s...
Article
Full-text available
Mediterranean oak savannas (known as dehesas in Spain) are exposed to numerous threats from natural and economic causes. A close monitoring of the use of water resources and the status of the vegetation in these ecosystems can be useful tools for maintaining the production of ecological services. This study explores the estimation of evapotranspira...
Article
Full-text available
Savannas are among the most productive biomes of Africa, where they comprise half of its surface. They support wildlife, livestock, rangelands, crops, and livelihoods, playing an important socioeconomic role in rural areas. These water-limited ecosystems with seasonal water availability are highly sensitive to changes in both climate conditions, an...
Poster
Full-text available
Mediterranean oak savanna, or dehesa, is the most characteristic agroforestry system of the Iberian Peninsula. It is composed by a mosaic of widely-spaced oak trees (primarily Quercus Ilex L. and Quercus Suber L.), crops, pasture and shrubs. In the last decades, this ecosystem has faced numerous threats, such as low profitability, an intensificatio...
Article
Full-text available
Savannas are among the most variable, complex and extensive biomes on Earth, supporting livestock and rural livelihoods. These water-limited ecosystems are highly sensitive to changes in both climatic conditions, and land-use/management practices. The integration of Earth Observation (EO) data into process-based land models enables monitoring ecosy...
Article
Full-text available
Dehesas are highly valuable agro-forestry ecosystems, widely distributed over Mediterranean-type climate areas, which play a key role in rural development, basing their productivity on a sustainable use of multiple resources (crops, livestock, wildlife, etc.). The information derived from remote sensing based models addressing ecosystem water consu...
Article
Full-text available
p>The objective of this work is to provide new insights about the effect of soil water deficit on the vegetation of Mediterranean oak savanna. The evolution of evapotranspiration (ET) and vegetation water stress over this ecosystem, in the Iberian Peninsula, has been monitored for fifteen years through the application of a remote sensing thermal-ba...
Technical Report
Full-text available
More than half of the human population currently lives in urban areas and according to the United Nations, cities will be the living space of an additional 2.5 billion people by the year 2050 (UN, 2015b). The proportion and speed of this urban growth increase the pressure on water resources, and this is often seen negatively. However, this challeng...
Book
Full-text available
Savannas are among Africa’s most productive multifunctional landscape – supporting wildlife, livestock, crops, and livelihoods – but experience frequent droughts, aggravated by climate change and other human-induced changes. To maintain ecosystem productivity while ensuring food security, we need to rely on an integrated management and monitoring o...
Presentation
Full-text available
The integration of currently available satellite data into surface energy balance models can provide estimates of evapotranspiration (ET) with spatial and temporal resolutions determined by sensor characteristics. The use of data fusion techniques may increase the temporal resolution of these estimates using multiple satellites, providing a more fr...
Poster
Monitoring savanna water use and water stress from local to regional scales supporting rangeland management (Pilot experience in Kruger National Park, South Africa)
Presentation
Remote Sensing of water management in Kruger Park, South Africa.
Conference Paper
Savanna is among Africa's most productive landscapes, supporting livestock and rural livelihoods. Droughts and erratic rainfall patterns across large parts of Africa results in water-limited environments, sensitive to climatic conditions, environmental changes (i.e. invasive species) and land management practices, jeopardizing this ecosystem’s prod...
Article
The regular monitoring of the evapotranspiration rates and their links with vegetation conditions and soil moisture may support management and hydrological planning leading to reduce the economic and environmental vulnerability of complex water-controlled Mediterranean ecosystems. In this work, the monitoring of water use over a basin with a predom...
Poster
The integration of remotely sensed data into models for estimating evapotranspiration (ET) has increased significantly in recent years, allowing the extension of these models application from point to regional scale. Remote sensors provide distributed information about the status of vegetation and allow for a regular monitoring of water consumption...
Poster
Full-text available
The integration of remotely sensed data into models for estimating evapotranspiration (ET) has increased significantly in recent years, allowing the extension of these models application from point to regional scale. Remote sensors provide distributed information about the status of vegetation and allow for a regular monitoring of water consumption...
Article
Full-text available
An intercomparison between the Energy Water Balance model (FEST-EWB) and the Two-Source Energy Balance model (TSEB) is performed over a heterogeneous agricultural area. TSEB is a residual model which uses Land Surface Temperature (LST) from remote sensing as a main input parameter so that energy fluxes are computed instantaneously at the time of da...
Article
Full-text available
A very simple remote sensing-based model for water use monitoring is presented. The model acronym DATTUTDUT (Deriving Atmosphere Turbulent Transport Useful To Dummies Using Temperature) is a Dutch word which loosely translates as “it’s unbelievable that it works”. DATTUTDUT is fully automated and only requires a surface temperature map, making it s...
Article
Full-text available
A two-source model for deriving surface energy fluxes and their soil and canopy components was evaluated using multi-angle airborne observations. In the original formulation (TSEB1), a single temperature observation, Priestley–Taylor parameterization and the vegetation fraction are used to derive the component fluxes. When temperature observations...
Article
Full-text available
The REFLEX 2012 campaign was initiated as part of a training course on the organization of an airborne campaign to support advancement of the understanding of land-atmosphere interaction processes. This article describes the campaign, its objectives and observations, remote as well as in situ. The observations took place at the experimental Las Tie...
Article
Full-text available
The dehesa, the most widespread agroforest ecosystem in Europe (≍ 3 million ha), is recognized as an example of sustainable land use and for its importance in rural economy. It is characterized by widely-spaced oak trees (mostly Quercus Ilex L.), combined with crops, pasture and shrubs in the sub-canopy region. The estimation of the ecosystem evapo...
Presentation
Full-text available
The Dehesa is the most widespread agroforestry land-use system in Europe, covering more than 3 million hectares in the Iberian Peninsula and Greece (Grove and Rackham, 2001; Papanastasis, 2004). It is an agro-silvo-pastural ecosystem consisting of widely-spaced oak trees (mostly Quercus ilex L.), combined with crops, pasture and Mediterranean shrub...
Article
Full-text available
Evapotranspiration (ET) is a critical variable in hydrological processes and an accurate estimation of the rate of evapotranspiration is required if we wish to apply integrated management procedures to water resources. This study offers new insights into remote sensing-based models that estimate ET at basin scale, evaluating the combination of a su...
Article
Full-text available
A two-source energy balance model that separates surface fluxes of the soil and canopy was applied to a drip-irrigated vineyard in central Spain, using a series of nine Landsat-5 images acquired during the summer of 2007. The model partitions the available energy, using surface radiometric temperatures to constrain the sensible heat flux, and compu...
Article
Full-text available
The integrated water resource management required to face the water scarcity situation in semiarid regions relies on the ability to obtain accurate information about the use of water by crops and natural vegetation. Thermal remote sensing provides key data about the vegetation water status. The integration of this remotely sensed data into water an...

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Projects

Projects (2)
Project
Savannas are among the most productive biomes of Africa, where they comprise half of its surface. They support wildlife, livestock, rangelands, crops, and livelihoods, playing an important socioeconomic role in rural areas. These water-limited ecosystems with seasonal water availability are highly sensitive to changes in both climate conditions, and in land-use/management practices. In this study we develop a mechanism for monitoring the water used by an African savanna ecosystem, located over the Kruger National Park (South Africa), from fine scale (meters) to watershed scale, integrating the effects of the water stress. Our hypothesis is that the Ecosystem Stress Index (ESI), applied with the new generation ESA sensors of Sentinel 2 (S2) and 3 (S3) satellites, is a valuable tool to downscale timely estimates of actual evapotranspiration at coarse scale. To monitor savanna water fluxes in a semi-continuous way this study integrates two different ET-estimation approaches, with different conceptual/operational capabilities and limitations. KC-FAO56 model (Allen et al., 1998), integrating reflectance-based “crop” coefficients, is used to derive unstressed savanna evapotranspiration (with high spatial resolution), and the two-source surface energy balance model -TSEB (Norman et al., 1995), integrating radiometric surface temperature allows the determination of water stress across savannas (ESI, with low spatial resolution). The choice of the two approaches is based on their proven ability to estimate ET over partially vegetated heterogeneous landscapes.
Project
The aim of SWATCH is to develop a unique information system for quantifying savanna water use and biomass production on a regional scale, with the ultimate objective of supporting decision-making processes. This effort directly addresses the European H2020 priorities of sustainable rural development and food security. Savannas are among the most complex, variable and extensive agrosilvopastoral systems on Earth (~20%). One fifth of the world's population depend upon them, although they are extremely vulnerable to changes in land use and climate. These changes affect not only ecosystem functioning, but also the land-atmosphere linkages and regional carbon cycle, in ways still unknown. Since savannas are greatly influenced by human activities, private/institutional practices play a key role in their conservation. The integration of Earth Observation data into process-based models will enable us to map the evolution of the ecosystem health, improving their management, productivity and resilience. However, to map savanna fluxes, besides the mechanistic understanding of how the climate (dry periods) and the canopy structure (patched multiple canopy layers) interact with land-atmospheric processes, robust techniques to upscale the ecosystem parameters and fluxes over space and time are needed. This project intends to bridge this gap and contribute to: 1) a better mechanistic understanding of savanna water/energy/carbon fluxes, using long-term eddy covariance and ground measurements 2) more accurately modelling these fluxes on a regional scale with different-scale EO data 3) the development of an operational information system to be integrated into decision-making processes, evaluating a pilot experience located over dehesa (Spanish productive Savanna).The outgoing phase with Prof. Baldocchi's group (UC Berkeley, USA) intends to cover first and second objectives, while the third one will be address on the return phase, with Dr. Gonzalez-dugo's group (IFAPA, Spain).