A deeper understanding of the spatial variability of soil properties and the relationships betwee... more A deeper understanding of the spatial variability of soil properties and the relationships between them is needed to scale up measured soil properties and to model soil processes. The object of this study was to describe the spatial scaling properties of a set of soil physical properties measured on a common 1024-m transect across arable fields at Silsoe in Bedfordshire, east-central England. Properties studied were volumetric water content (0), total porosity (4>), pH, and N 2 0 flux. We applied entropy as a means of quantifying the scaling behavior of each transect. Finally, we examined the spatial intrascaling behavior of the correlations between 0 and the other soil variables. Relative entropies and increments in relative entropy calculated for 0, 4>, and pH showed maximum structure at the 128-m scale, while N 2 0 flux presented a more complex scale dependency at large and small scales. The intrascale-dependent correlation between 0 and 4> was negative at small scales up to 8 m. The rest of the intrascale-dependent correlation functions between 0 with N 2 0 fluxes and pH were in agreement with previous studies. These techniques allow research on scale effects localized in scale and provide the information that is complementary to the information about scale dependencies found across a range of scales.
This work evaluated the ability of UAVs to detect field heterogeneity and their influences on vin... more This work evaluated the ability of UAVs to detect field heterogeneity and their influences on vineyard development in Yepes (Spain). Under deficit irrigation, vine growth and yield variability are influenced by soil characteristics such as water holding capacity (WHC). Over two irrigation seasons (2021–2022), several vegetation indices (VIs) and parameters of vegetative growth and yield were evaluated in two field zones. Multispectral and thermal information was obtained from bare soils. The water availability showed annual differences; it was reduced by 49% in 2022 compared to 2021, suggesting that no significant differences were found for the parameters studied. The zone with higher WHC also had the higher vegetative growth and yield in 2021. This agreed with the significant differences among the VIs evaluated, especially the ratio vegetation index (RVI). Soil multispectral and thermal bands showed significant differences between zones in both years. This indicated that the soil s...
Andrés F. Almeida-Ñauñay, Ernesto Sanz, Miguel Quemada, Juan C. Losada, Rosa M. Benito, and Ana M... more Andrés F. Almeida-Ñauñay, Ernesto Sanz, Miguel Quemada, Juan C. Losada, Rosa M. Benito, and Ana M. Tarquis Centro de Estudios e Investigación para la Gestión de Riesgos Agrarios y Medioambientales, CEIGRAM, Universidad Politécnica de Madrid, Madrid, Spain (af.almeida@upm.es, ernesto.sanz@upm.es, miguel.quemada@upm.es, anamaria.tarquis@upm.es). Complex Systems Group, Universidad Politécnica de Madrid, Madrid, Spain (juancarlos.losada@upm.es, anamaria.tarquis@upm.es) AgSystem, ETSIAAB, Universidad Politécnica de Madrid, Madrid, Spain
RESUMEN La sequia en Espana es un fenomeno frecuente y de elevada intensidad, para ello se ha dis... more RESUMEN La sequia en Espana es un fenomeno frecuente y de elevada intensidad, para ello se ha disenado el seguro de sequia de pastos, que se basa en la evaluacion de un indice de vegetacion sin la estimacion de la produccion de biomasa del pasto. El objetivo de este trabajo es obtener funciones de produccion de biomasa de los pastos mediante indices de vegetacion que utilicen las bandas espectrales del rojo y del infrarrojo cercano. Para ello desde 2010 a 2013 se realizo un seguimiento del pasto herbaceo en dehesas de El Cubo de Don Sancho (Salamanca), Trujillo (Caceres) y Pozoblanco (Cordoba). Se midio mensualmente la produccion de biomasa del pasto y los indices de vegetacion obtenidos del satelite DEIMOS-1 con una resolucion de 22 m por 22 m. Con los datos de 2010 y 2011 se establecio la funcion de produccion de biomasa del pasto (fresco y seco) a partir del Indice de Vegetacion de la Diferencia Normalizada (NDVI), del Indice de Vegetacion Renormalizado (RDVI), de la Proporcion M...
Las imagenes satelitales son una importante fuente de informacion para el seguimiento de la veget... more Las imagenes satelitales son una importante fuente de informacion para el seguimiento de la vegetacion y de la cartografia de la tierra en varias escalas. Varios indices de vegetacion se han empleado para evaluar la calidad y cantidad de la vegetacion utilizando datos satelitales. Dado que las caracteristicas de las bandas espectrales del infrarrojo cercano (NIR, radiacion reflejada en la longitud de onda 800 nm) y el rojo (RED, radiacion reflejada en la longitud de onda 670 nm) son muy distintas segun el tipo de sensor, los valores del Indice de Vegetacion de la Diferencia Normalizada (NDVI) variaran segun el tamano del pixel y de la heterogeneidad y la escala de las superficies. Se seleccionaron dos zonas de dehesa (Salamanca y Cordoba) y se tomaron imagenes mensuales del satelite DEIMOS-1 con una resolucion espacial de 22 m × 22 m. El objetivo de este estudio es establecer una comparacion entre diferentes resoluciones, mediante los valores de NDVI obtenidos en diferentes epocas d...
Climatic projections for the Mediterranean basin indicate that the area will suffer a decrease in... more Climatic projections for the Mediterranean basin indicate that the area will suffer a decrease in water resources due to climate change. The key climatic trends identified for the Mediterranean region are continuous temperature increase, further drying with precipitation decrease and the accentuation of climate extremes, such as droughts, heat waves and/or forest fires, which are expected to have a profound effect on agriculture. Indeed, the impact of climate variability on agricultural production is important at local, regional, national, as well as global scales. Agriculture of any kind is strongly influenced by the availability of water. Climate change will modify rainfall, evaporation, runoff, and soil moisture storage patterns. Changes in total seasonal precipitation or in its pattern of variability are both important. Similarly, with higher temperatures, the water-holding capacity of the atmosphere and evaporation into the atmosphere increase, and this favors increased climate...
Rangeland degradation caused by increasing misuses remains a global concern. Rangelands have a re... more Rangeland degradation caused by increasing misuses remains a global concern. Rangelands have a remarkable spatiotemporal heterogeneity, making them suitable to be monitored with remote sensing. Among the remotely sensed vegetation indices, Normalized Difference Vegetation Index (NDVI) is most used in ecology and agriculture. In this paper, we research the relationship of NDVI with temperature, precipitation, and Aridity Index (AI) in four different arid rangeland areas in Spain’s southeast. We focus on the interphase variability, studying time series from 2002 to 2019 with regression analysis and lagged correlation at two different spatial resolutions (500 × 500 and 250 × 250 m2) to understand NDVI response to meteorological variables. Intraseasonal phases were defined based on NDVI patterns. Strong correlation with temperature was reported in phases with high precipitations. The correlation between NDVI and meteorological series showed a time lag effect depending on the area, phase...
A multifractal analysis on a finite-range-scale of the plume concentration images at different ex... more A multifractal analysis on a finite-range-scale of the plume concentration images at different experimental conditions (the height of the source H o ), where the measure is the grey value of the image (from 0 to 255), was applied to study its structure through time. The multifractal spectrum showed the characteristic inverse U-shape and a similar evolution in all H o . The variation of the Hölder exponent ( α) presented different am plitudes at different moments and increased with time. The symmetry of the spectrum ( f ) decreased with time achieving negative values (from left hand asymmetry evolving to right asymmetry). We show the different behaviour of axial velocity ( W ) with α and f . There is a linear relation of entrainment coefficient ( α e ) and the entropy dimension ( α 1 ). Therefore, the multifractal spectrum and the derived parameters can be used as markers of plume evolution as well as to study the effect of experimental conditions.
Nonlinear Processes in Geophysics Discussions, 2016
Several studies have shown that vegetation indexes can be used to estimate root zone soil moistur... more Several studies have shown that vegetation indexes can be used to estimate root zone soil moisture. Earth surface images, obtained by high-resolution satellites, presently give a lot of information on these indexes, based on the data of several wavelengths. Because of the potential capacity for systematic observations at various scales, remote sensing technology extends the possible data archives from the present time to several decades back. Because of this advantage, enormous efforts have been made by researchers and application specialists to delineate vegetation indexes from local scale to global scale by applying remote sensing imagery. In this work, four band images have been considered, which are involved in these vegetation indexes, and were taken by satellites Ikonos-2 and Landsat-7 of the same geographic location, to study the effect of both spatial (pixel size) and radiometric (number of bits coding the image) resolution on these wavelength bands as well as two vegetation indexes: the Normalized Difference Vegetation Index (NDVI) and the Enhanced Vegetation Index (EVI). In order to do so, a multi-fractal analysis of these multispectral images was applied in each of these bands and the two indexes derived. The results showed that spatial resolution has a similar scaling effect in the four bands, but radiometric resolution has a larger influence in blue and green bands than in red and near-infrared bands. The NDVI showed a higher sensitivity to the radiometric resolution than EVI. Both were equally affected by the spatial resolution. From both factors, the spatial resolution has a major impact in the multi-fractal spectrum for all the bands and the vegetation indexes. This information should be taken in to account when vegetation indexes based on different satellite sensors are obtained.
This paper discusses a multifractal analysis of the microscopic structure of peat soil. The aim o... more This paper discusses a multifractal analysis of the microscopic structure of peat soil. The aim of this study was to apply the multifractal technique to analyze the properties of five slices of peat soil (L1-L5). Binary images (220 x 220 pixels, with a conversion value of 9.41 μm/pixel) were made from the thin slices and then analyzed. This analysis was conducted to obtain the relationship between physical parameters and complexity parameters. The results showed that the spectrum of f(α) can describe well the pore size distribution and average size of pores correlated with the value of D(0). A high value of the average pore size is followed by a low D value and vice versa.
Landscape evolution is driven by abiotic, biotic, and anthropic factors. The interactions among t... more Landscape evolution is driven by abiotic, biotic, and anthropic factors. The interactions among these factors and their influence at different scales create a complex dynamic. Landscapes have been shown to exhibit numerous scaling laws, from Horton’s laws to more sophisticated scaling of heights in topography and river network topology. This scaling and multiscaling analysis has the potential to characterise the landscape in terms of the statistical signature of the measure selected. The study zone is a matrix obtained from a digital elevation model (DEM) (map 10 × 10 m, and height 1 m) that corresponds to homogeneous region with respect to soil characteristics and climatology known as “Monte El Pardo” although the water level of a reservoir and the topography play a main role on its organization and evolution. We have investigated whether the multifractal analysis of a DEM shows common features that can be used to reveal the underlying patterns and information associated with the l...
Soil surface roughness (SSR) is a parameter highly suited to the study of soil susceptibility to ... more Soil surface roughness (SSR) is a parameter highly suited to the study of soil susceptibility to wind and water erosion. The development of a methodology for quantifying SSR is therefore instrumental to soil evaluation. We developed such a method, based on the multifractal analysis (MFA) of soil elevation measurements collected at the intersections on a 2‐ by 2‐cm2 grid in a 200‐ by 200‐cm2 plot. Samples were defined using the gliding box algorithm (GB), in which a box of a given size “glides” across the grid map in all possible directions. The advantage of the GB over the box counting algorithm is that it yields a greater number of large sample sizes, which usually leads to better statistical results. Standard deviation, semivariogram fractal dimension, and semivariogram crossover length were estimated for all scenarios to compare the results of SSR multifractal analysis to indices found with traditional techniques. For its high sensitivity to the spatial arrangement implicit in a ...
Scaling processes are increasingly understood to be the result of nonlinear dynamic mechanisms re... more Scaling processes are increasingly understood to be the result of nonlinear dynamic mechanisms repeating scale after scale from large to small scales leading to nonclassical resolution dependencies. This means that the statistical properties systematically vary in strong, power‐law ways with the resolution. When present in geophysical and remotely sensed fields, it implies that when classical (single‐scale) remote sensing algorithms are used to determine surrogates of various geophysical fields, they can at most be correct at the unique (and subjective) calibration resolution. Scaling analysis and modeling techniques were applied to MODIS TERRA Bands 1 through 7 and to the standard derived vegetation and soil moisture indices in order to quantitatively characterize the wide range of scaling of these fields. The scaling exponents we found are not so large; however, they act across wide scale ranges and imply large effects. For example, for the statistics near the mean, the MODIS (500...
DN on multiscale landscape analysis defined soils as "four dimensional natural bodies . . . with ... more DN on multiscale landscape analysis defined soils as "four dimensional natural bodies . . . with the key characteristic of varying with place and time" . Such variation affects how tions are interpreted regarding the evolution, diversity, and dynamics of the soil ecosystem . Soil variability has often been considered to be composed of "functional" (explained) variations plus random fluctuations or noise. However, the distinction between these two components is scale dependent because increasing the scale of observation almost always reveals structure in the noise . Soils can be seen as the result of spatial variation operating over several scales, indicating that factors influencing spatial variability differ with scale. This observation points to variability as a key soil attribute that should be studied . Geostatistical methods and, more recently, fractal-multifractal and wavelet techniques have been used to characterize scaling of soil properties . The book edited by Sposito (1998) includes several chapters that discuss various hydrological applications of scaling. Western et al. (2002) reviewed different techniques for scaling soil moisture, including statistical approaches and processbased indices. Hopmans et al. (2002) presented the historical use of scaling in hydrology and discussed the need to extend measurements beyond the laboratory scale to the field or watershed scale. The book by Pachepsky et al. (2003) covers many aspects of scaling and how to reconstruct landscape and watershed processes from small-scale measurements. McBratney et al. (2003) reviewed soil mapping at different scales and approaches for relating soil properties to processes. The group of papers introduced by Pachepsky et al. (2006) dealt with applications of fractal geometry to scaling in soil and related hierarchical systems. Lin et al. (2006) detailed several hypotheses related to the concept of hydropedology to help bridge across disciplines that focus on different ranges of scale. Vereecken et al. (2007) reviewed techniques to upscale soil hydraulic properties, including several "forward" techniques as well as inverse modeling approaches. An integration of various sources of information and synthesis of diverse approaches is required to study multiscale features that are the product of coexistence, hierarchy, complexity, chaos, and in some cases, self-organization. Understanding the interrelationships between physical, chemical, and biological factors at different scales is essential for research in agriculture, engineering, hydrology, and the environment. The emergence of a more holistic approach to soil science may facilitate a better understanding of both temporal and spatial variability. Concurrent with this recognition, there is a growing interest in the application of multiscale approaches (e.g., for studying the critical zone. Such methodologies may help to identify typologies of system behavior that many scientists have anticipated to be highly complex, with chaotic characteristics at a fine scale of examination to more regulated or ordered and stable characteristics at larger scales . The 18th World Congress of Soil Science took place in July 2006 in Philadelphia, PA, with the theme "Frontiers of Soil Science: Technology and the Information Age." The scientific program included topics on remote sensing, geographic information systems, landscape analysis, computer modeling, precision agriculture, and other applications of information science and technology as related to soils. A symposium held at the congress titled "Multiscale Mapping of Soil Properties for Environmental Studies, Agriculture, and Decision-Making" focused on techniques used in multiscale mapping of soil properties and processes. Papers covered theoretical and applied aspects of interpolation and extrapolation schemes, self-similar, hierarchal, and fractal organizations, spatial associations between variables,
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Papers by Ana Tarquis