Alvaro Gómez Gutiérrez

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• PhD
• Professor (Cátedratico) at University of Extremadura

Image network geometry, including the number and orientation of images, impacts the error, coverage, and processing time of 3‐D terrain mapping performed using Structure‐from‐Motion and MultiView‐Stereo (SfM‐MVS). Few studies have quantified tradeoffs in error and processing time or ways to optimize image acquisition in diverse topographic conditio...

Mass movement hazards in the form of mega-gullies and landslides pose significant risks in urbanizing areas, yet they are poorly documented. To obtain primary data on the size, frequency, and triggers of abrupt mega-gullies and landslides in urban areas, rapid assessment methods based on structure-from-motion (SfM) photogrammetric techniques and wa...

Context Recently, Unoccupied Aerial Systems (UAS) with photographic or Light Detection and Ranging (LIDAR) sensors have incorporated on-board survey-grade Global Navigation Satellite Systems that allow the direct georeferencing of the resulting datasets without Ground Control Points either in Real-Time (RTK) or Post-Processing Kinematic (PPK) modes...

Extensive livestock farming plays a crucial role in the economy of agrosilvopastoral systems of the southwestern Iberian Peninsula (known as dehesas and montados in Spanish and Portuguese, respectively) as well as providing essential ecosystem services. The existence of livestock in these areas heavily relies on the effective management of natural...

Remote sensing techniques have been part of the geomorphologists’ toolkit practically since their initial advances, and used to describe, quantify, and model landscape evolution [...]

Gerra is small beach located at the foot of a cliff on the Western coast of Cantabria (North of Iberian Peninsula). It has a sandy distal part and a proximal part at the foot of the cliff made up of boulders, supported by rockfalls and landslides from the cliff. Claystones, limestones and marls of the Triassic and Cretaceous ages form the cliff. To...

Gully rehabilitation is often applied as part of catchment management strategies aimed at reducing downstream sediment yields. However, the influences of gully control measures on the runoff and sediment transport processes in agroforestry systems have been seldom studied. In this paper, a thorough analysis of these processes was carried out in a v...

El estudio de la dinámica de los cauces efímeros mediterráneos (CEM) resulta de gran interés, al tratarse de sistemas geomorfológicos expuestos a importantes fluctuaciones recientes en los factores extrínsecos e intrínsecos que los gobiernan. Para obtener una aproximación a su modelo dinámico y comprender su adaptación a diferentes perturbaciones,...

Protecting Monumental Stones with Graphene Oxide The coating of carbonated stones from our historical heritage with an aqueous graphene oxide suspension is an efficient and cost-effective method to shield them from climatic erosion, as presented in article number 2101012 by María Fernández-Raga, Jose Miguel González-Domínguez, and co-workers. By si...

The deterioration of monumental stones is a common event occurring to our historical and cultural heritage, threatening the preservation of our social identity and its legacy to future generations. The prolonged effect of inclement weather is very harmful for particular stone materials such as limestone and dolomite, to which a truly effective and...

Watering ponds represent an important part of the hydrological resources in some water-limited environments. Knowledge about their storage capacity and geometrical characteristics is crucial for a better understanding and management of water resources in the context of climate change. In this study, the suitability of different geomatic approaches...

Sediments accumulated in check dams are a valuable measure to estimate soil erosion rates. Here, geographic information systems (GIS) and three machine learning techniques (MARS-multivariate adaptive regression splines, RF-random forest and SVM-support vector machine) were used, for the first time, to predict sediment deposition rate (SR) in check-...

Ephemeral rivers hydromorphological processes are intermittent and many times of fast response. Therefore they remain still quite unknown. The geomorphological mapping of river forms and geomorphological units is a useful tool to recognize the evolution, changes and the response of river adjustments of hydrological events. A diachronic geomorpholo...

Monitoring the dynamics of coastal cliffs is fundamental for the safety of communities, buildings, utilities, and infrastructures located near the coastline. Structure-from-Motion and Multi View Stereo (SfM-MVS) photogrammetry based on Unmanned Aerial Systems (UAS) is a flexible and cost-effective surveying technique for generating a dense 3D point...

Mega-gullies and landslides pose significant hazards to urban development on steep terrain. Water resources infrastructure failures (WRIFs), such as leaks and breaks in water supply pipes, have been postulated as a trigger of mass movement events but data for validation has been challenging to acquire since earthwork proceeds quickly after events t...

Gullies are sources and reservoirs of sediments and perform as efficient transfers of runoff and sediments. In recent years, several techniques and technologies emerged to facilitate monitoring of gully dynamics at unprecedented spatial and temporal resolutions. Here we present a detailed study of a valley-bottom gully in a Mediterranean rangeland...

The drawing of maps of soil quality at a large scale is increasingly being more useful to land planners and stakeholders. Nevertheless, it involves different methodological steps from the description of soil profiles in the field until the regional mapping of integrative soil quality index (IQI) values. The development of proper scoring functions i...

Rangeland (known as Dehesas or Montados) is a characteristic ecosystem of the southwestern part of the Iberian Peninsula that occupies approximately 3.5 million ha, representing the most important agrosilvopastoral system in Europe. Nowadays, this situation is changing, being under circumstances of threat due to different aspects that are causing d...

Gully erosion in valley bottoms is a frequent process with negative consequences in the dehesa environment. Soil loss, decrease of soil and descend in biomass are among the negative aftereffect of gully erosion processes. Studies conducted in agrosilvopastoral systems described the dynamics of gullied channels by means of fixed topographic cross se...

The increasing availability of highly detailed and accurate three-dimensional (3D) geospatial data are currently pushing the 3D change detection analysis towards a new 3D mapping frame. In this paper, medium-term changes (8 years) at a coastal rocky cliff are quantified using and comparing 2.5D and 3D methods to estimate the volume of rockfalls and...

Dimensionless morphological ratios (DMR) generally are used in systemic proposals for stream classification and river restoration projects. Often, such morphometric parameters, including field data from channel cross sections, develop into a template for a given geomorphic reference site. In this study, high-resolution Digital Terrain Models (HRDTM...

Surveying coastal cliffs using two UAV platforms (multi-rotor and fixed-wing) and three different approaches for the estimation of volumetric changes The increasing availability of highly detailed and accurate three dimensional (3D) geospatial data is currently pushing the 3D change detection analysis towards a new 3D mapping frame. In this paper,...

Rainfall is the key factor to understand soil erosion processes, mechanisms, and rates. Most research was conducted to determine rainfall characteristics and their relationship with soil erosion (erosivity) but there is little information about how atmospheric patterns control soil losses, and this is important to enable sustainable environmental p...

Past human activities have influenced present and future landscape dynamics. The agrosilvopastoral systems known as Dehesas, located in Southwest Spain, have been subject to land use and management changes during the last centuries. Nowadays, the soils of Dehesas present a poor state of conservation influenced by accelerated soil erosion, especiall...

A set of dimensionless morphological ratios are commonly used as a basis for studies of stream stability and natural channel restoration. Often, such ratios have been obtained from morphometric measurements made in the field and developed into a template for a given geomorphic reference site. The main objective of the present study is to analyze th...

Changes in land use are common in Mediterranean areas and are reported as having produced changes in the intensity of soil erosion. Dehesas are rangelands with a disperse tree cover, widespread in the south‐western part of the Iberian Peninsula and similar ecosystems are also common in other areas with a Mediterranean climate. The aim of the presen...

A set of dimensionless morphological ratios are commonly used as a basis for studies of stream stability and natural channel restoration. Often, such ratios have been obtained from morphometric measurements made in the field and developed into a template for a given geomorphic reference site. In this study, high resolution aerial photographs from 2...

Lithological and aridity conditions in the central area of the Ebro Basin favour the abundance of intermittent and ephemeral rivers. These rivers suffer important environmental problems but lack specific scientific studies, and in most cases they are not even considered water bodies in their management. A methodological proposal is launched combini...

Soil degradation by water is a serious environmental problem worldwide, with specific climatic factors being the major causes. We investigated the relationships between synoptic atmospheric patterns (i.e. weather types, WTs) and runoff, erosion and sediment yield throughout the Mediterranean basin by analyzing a large database of natural rainfall e...

Soil degradation by water is a serious environmental problem worldwide, with specific climatic factors being the major causes. We investigated the relationships between synoptic atmospheric patterns (i.e. weather types, WTs) and runoff, erosion and sediment yield throughout the Mediterranean basin by analyzing a large database of natural rainfall e...

Soil moisture has a direct influence on biomass production, food security and ecosystem functioning, thus resources management in water‐limited environments could be improved if feedbacks between water and vegetation were fully understood. This study tries to define the sensitivity of annual pastures under the influence of different vegetation cove...

Dehesas are agrosilvopastoral systems which have been subject to land use and management changes and water erosion has been reported as an important soil degradation problem. The main objective of the present study is an analysis of the temporal variation of soil erosion, using estimations obtained by applying two complementary methods: the inflect...

p>La erosión por cárcavas supone un proceso de degradación del suelo frecuente en los sistemas agrosilvopastoriles del SO español que ha sido poco estudiado. Se analizan aquí la viabilidad de uso de vehículos aéreos no tripulados (UAV) y la fotogrametría SfM para cartografiar cárcavas de fondo de valle en estos paisajes. Los resultados muestran pre...

Debris talus is a very common landform in the temperate high mountain, so much so that it is the most representative of the periglacial and nival processes. This work studies debris cones in the Picos de Europa, an Atlantic mountain range in the north of the Iberian Peninsula. A detailed geomorphological map was prepared, fieldwork was carried out...

Structure-from-Motion (SfM) photogrammetry is one of the most common approaches used to elaborate high-resolution Digital Elevation Models (DEMs) nowadays. Factors that influence the final error associated to the derived DEM are: camera-to-ground distance, camera-sensor system parameters, image network geometry, matching performance, terrain type,...

Structure-from-Motion (SfM) photogrammetry is one of the most common approaches used to elaborate high-resolution Digital Elevation Models (DEMs) nowadays. Factors that influence the final error associated to the derived DEM are: camera-to-ground distance, camera-sensor system parameters, image network geometry, matching performance, terrain type,...

The exposure of tree or shrub roots represents a clear indicator of soil loss in the surrounding area. Previous studies have used this type of botanical evidence to estimate soil erosion rates, preferring roots at some distance from the tree stem because the inflection point (or root collar) undergoes a vertical displacement caused by basal growth....

This contribution results from international collaborative efforts of different research groups around the Mediterranean basin focusing on soil conservation and water management. We will present the most complete database of runoff and soil erosion information and analyze the records from 68 locations, including more than 22458 detail events betwee...

Hydrological processes were investigated since the year 2000 in a semiarid rangeland with disperse cover of evergreen holm oaks. In this article results are presented on the spatial variation of rainfall in the catchment using a network of 6 raingauges. Results are also presented on soil water dynamics, which were studied under different vegetation...

The ¹³⁷Cs deposited in soil and exposed tree roots have been widely applied to estimate medium-term soil erosion rates. However, comparative studies between these methods are scarce. For this purpose, three hillsides in two Mediterranean dehesas (rangeland with disperse tree cover) were selected. Regarding the ¹³⁷Cs technique, a reference site clos...

Rangelands in SW Spain constitute the most extensive ranching system on the Iberian Peninsula. During the last few decades, a significant increase in livestock numbers, along with a progressive substitution of cattle for sheep, have led to land degradation processes such as the reduction of grass cover and increased soil compaction in heavily graze...

The sustainability of Iberian open wooded rangelands is threatened by recent land use changes and lack of tree recruitment. As trees are key elements of these systems, the characterization of their spatiotemporal trend is essential the for system's management. Our objective is to develop spatial models reflecting the temporal dynamic of trees in te...

Erosion processes and land degradation are recognized as one of the most significant environmental problems worldwide. In the Mediterranean region, intense erosion processes occur as a consequence of complex interactions between environmental conditions (e.g. climate, lithology) and human-related factors (e.g. history of human activity, land use ch...

Erosion processes and land degradation are recognized as one of the most significant environmental problems worldwide. In the Mediterranean region, intense erosion processes occur as a consequence of complex interactions between environmental conditions (e.g. climate, lithology) and human-related factors (e.g. history of human activity, land use ch...

Erosion processes and land degradation are recognized as one of the most significant environmental problems worldwide. In the Mediterranean region, intense erosion processes occur as a consequence of complex interactions between environmental conditions (e.g. climate, lithology) and human-related factors (e.g. history of human activity, land use ch...

Spanish rangelands are considered to be of high nature value and a habitat of interest in the European Union due to their productivity and species diversity. However, they are fragile landscapes where farmers’ decisions, such as changes in livestock pressure, can lead to serious deterioration. Currently, no indicator system is being used in these a...

In this paper, three methods (Terrestrial Laser Scanner (TLS), terrestrial Structure from Motion photogrammetry (SfM) and aerial SfM photogrammetry with an Unmanned Aerial Vehicle (UAV)) were evaluated and compared to produce high resolution point clouds and Digital Elevation Models (DEMs) in a semiarid, complex badland area (Los Aguarales) with to...

Extensive grazing is a key factor for the conservation of High Nature Value (HNV) farming systems such as woody rangelands (dehesas or montados) or grasslands (pastizales) in SW Europe. They have been created from clearing the former Mediterranean forest and have been subject to land use and management changes, particularly during recent decades. E...

The use of Terrestrial Laser Scanner (TLS) for establishing digital elevation models contributes to a better understanding of spatial and temporal variation of processes that shape the terrestrial surface forms. The aim of the present study is to investigate the relationship between soil erosion rates and the variables that influence erosion proces...

CardilloOak decline and ”seca” of Quercus in the Iberian Peninsula

Gully erosion represents one of the most significant types of land degradation in the Mediterranean areas, giving place to important on- and off-site effects. In this paper, a second-order gully located in SW Spain is analyzed. Along the gully, 28 cross-sections were established and measured with a Leica TCRM1102 laser total station, approximately...

Three-dimensional photo-reconstruction methods based on the use of Structure-from-Motion (SfM) and MultiView-Stereo techniques (MVS) are tested together for measuring, monitoring and quantifying three different geomorphological features: i ) the Corral del Veleta rock glacier (Granada, Spain), ii ) calanchi type badlands (Sicily, Italy) and iii ) f...

The inflection point of trees is an indicator of soil erosion, but its use for estimating erosion rates includes a measurement error due to the basal wood growth of the trees. Therefore, the objective of this work is an analysis of the growth pattern of Holm oaks and whether it can be used for correcting erosion rates that are determined using the...

La mayoría de los estudios que estiman tasas de erosión del suelo a partir del método de raíces expuestas utilizan raíces alejadas del tronco de los árboles y preferentemente aquellas que están totalmente expuestas. De este modo se evita que en los resultados finales influya la deformación de la microtopografía próxima a la base del tronco, produci...

Subsurface water flows play a key role in the distribution of water and solutes and thereby in the water availability for plants. However, the characterization of different flow processes (i.e. matrix and preferential flow), the frequency and factors that cause them, are relatively rare. This characterization enables a better understanding of spati...

The accuracy of different workflows using Structure-from-Motion and Multi-View-Stereo techniques (SfM-MVS) is tested. Twelve point clouds of the Corral del Veleta rock glacier, in Spain, were produced with two different software packages (123D Catch and Agisoft Photoscan), using Low Dynamic Range images and High Dynamic Range compositions (HDR) for...

Estimating historical soil erosion rates in dehesa ecosystems represents a challenge due to its long history of land use. To this end, in previous studies, a methodology based on semi-exposed roots was developed. The morphology of tree stems, semi-exposed roots and micro-topography around a large number of tress was analysed using a 3D model, obtai...

In this work, the hypothesis of improving 3D models obtained with Structure from Motion (SfM) approaches using images pre-processed by High Dynamic Range (HDR) techniques is tested. Photographs of the Veleta Rock Glacier in Spain were captured with different exposure values (EV0, EV+1 and EV-1), two focal lengths (35 and 100 mm) and under different...

Empirical multivariate predictive models represent an important tool to estimate gully erosion susceptibility. Topography, lithology, climate, land use and vegetation cover are commonly used as input for these approaches. In this paper, two multivariate predictive models were generated for two gully erosion processes in San Giorgio basin (Italy) an...

Estimating medium term sheet erosion rates represents a challenge in areas with long land use history. In this work an adaptation of the tree root exposure method for the determination of erosion rates is presented. The methodology is based on analyzing the morphology of tree stems, exposed roots and micro-topography using a dense point cloud with...

In this paper, terrain susceptibility to earth-flow occurrence was evaluated by using geographic information systems (GIS) and two statistical methods: Logistic regression (LR) and multivariate adaptive regression splines (MARS). LR has been already demonstrated to provide reliable predictions of earth-flow occurrence, whereas MARS, as far aswe kno...

Soil sheet erosion rates in rangeland presented high variability in function of vegetation cover and the use of the soil, especially influencing the stock density. It has been observed irregularities of the soil surface under canopy trees, indicating that erosion processes vary in the area of influence of the same, also indicated by LaMarche (1968)...

The paper presents a pilot research on the determination of historical soil erosion rates in rangelands with disperse tree cover using two different methodologies: 137 Cs and exposed tree roots. The study was carried out along a hillslope in a Mediterranean rangeland farm with disperse tree cover of evergreen oaks in SW Spain. Mean soil erosion rat...

Along a representative hillslope of a dehesa spatial variations of soil erosion and some soil properties were investigated, considering (i) three slope sections with different gradients, (ii) open spaces and areas below tree canopies and (iii) different positions below the tree canopies with respect to the stem. The results showed higher soil losse...

In this study, statistical models of earth-flow susceptibility were prepared using logistic regression. The analyses were carried out in a small (51 km2) basin of western Sicily, where 1,376 earth-flows were identified. To predict the spatial distribution of the mapped landslides, outcropping lithology and seven topographic attributes were exploite...

In the recent years advanced statistical methods and GIS tools have been frequently used to assess landslide susceptibility. The latter is estimated by establishing statistical relationships between landscape characteristics and spatial distribution of past slope-failures. These are mapped mainly by recognizing changes on slope morphology produced...

In this paper, two methods based on computer vision are presented in order to produce dense point clouds and high resolution DEMs (digital elevation models) of the Corral del Veleta rock glacier in Sierra Nevada (Spain). The first one is a semi-automatic 3D photo-reconstruction method (SA-3D-PR) based on the Scale-Invariant Feature Transform algori...

In this paper, two methods based on computer vision are presented in order to produce dense point clouds and high resolution DEMs (digital elevation models) of the Corral del Veleta rock glacier in Sierra Nevada (Spain). The first one is a semi-automatic 3D photo-reconstruction method (SA-3D-PR) based on the Scale-Invariant Feature Transform algori...

The estimation of medium-term sheet erosion rates represents still a challenge in areas with long land use history. In the present paper, a new methodology for estimating medium-term sheet erosion rates is presented and applied in a wooded rangeland (dehesa). This human-induced semi-natural ecosystem is widespread in SW Iberian Peninsula and is cha...

The estimation of medium-term sheet erosion rates represents still a challenge in areas with long land use history. In the present paper, a new methodology for estimating medium-term sheet erosion rates is presented and applied in a wooded rangeland (dehesa). This human-induced semi-natural ecosystem is widespread in SW Iberian Peninsula and is cha...

Estimating medium term sheet erosion rates represents a challenge in areas with long land use history. In this work an adaptation of the tree root exposure method for the determination of erosion rates is presented. The methodology is based on analyzing the morphology of tree stems, exposed roots and micro-topography using a dense point cloud with...

Recent studies in small experimental catchments under Mediterranean-type climate revealed a complex hydrological catchment response, presenting saturation excess runoff generation and, to a minor degree, infiltration excess flow. Many of these catchments, however, belong to areas with sub-humid or humid Mediterranean climate. Catchment studies were...

In this paper the temporal dynamic of tree cover in 5 woody rangelands (Dehesa farms) of Extremadura (SW Spain) is analyzed. Tree density was also studied in 17 working units selected from the 5 farms plus other additional 3. With this purpose, orthophotos from 1956 and 2009 were classified by object-based classification methods in order to obtain...

Rangelands with a disperse tree cover occupy large areas in the southwestern part of the Iberian Pensinsula and are also found in other parts of the Mediterranean. In these grazed, savannah-like ecosystems water constitutes an important limiting factor for vegetation growth because of the strong summer dry period, being annual potential evapotransp...

In the present paper a new technique for estimating medium-term sheet erosion rates is presented. The methodol-ogy is based on analyzing the morphology of tree stems, exposed roots and surface micro-topography using data obtained with a Laser Terrestrial Scanner. A Leica Scan Station C10 was used to capture a surface of 70 000 square meters in a ra...

Gully erosion plays an important role in degradation processes of Mediterranean environments. In SW Spain, gullies are frequently located on valley bottoms where they erode shallow alluvial deposits. This study was carried out on a small discontinuous gully in a wooded rangeland catchment (99.5 ha). The objectives of this work were: (i) to quantify...

Rangelands with a disperse tree cover occupy large areas in the southwestern part of the Iberian Pensinsula and are also found in other parts of the Mediterranean. In these grazed, savannah-like ecosystems water constitutes an important limiting factor for vegetation growth because of the strong summer dry period, being annual potential evapotransp...

RESUMEN En este trabajo se presenta una completa revisión bibliográfica sobre algunos aspectos de la erosión por cárcavas dirigida a investigadores, docentes y alumnos predoctorales que pre-tenden profundizar en el tema. Se analizan los procesos de formación y desarrollo así como los factores que influyen y determinan la intensidad del acarcavamien...

In this paper, five topsoil properties (clay, silt, sand, organic matter and bulk density) have been modeled using accessible environmental information in order to improve pedological cartography in the Extremadura region (Spain). Independent variables related to topography, climate, lithology and vegetation cover were used to generate the models....

A complete revision of some aspects of gully erosion is presented in this paper. The article is directed to researchers, teachers and PhD students who want to go into greater depth in this topic. The processes of initiation and development of gullies are analyzed as well as the factors influencing process intensity. In addition, the on-site and off...