Congreso Internacional sobre Desertificación.

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Open Access
Estimación de volúmenes de suelo perdido por procesos de erosión por piping. Sureste de España.
(2020-03-30) Romero Díaz, María Asunción; Plaza Martínez, J.F; Sánchez Soriano, A.; Belmonte Serrato, F.; Ruiz Sinoga, J.D; Departamento de Geografía, Universidad de Murcia, Campus de La Merced; Departamento de Geografía, Universidad de Málaga, Campus de Teatinos
Piping processes have been widely studied in many countries and regions, but especially in arid environments, on marl soils, reach a great development. We studied eight areas affected by piping, located in the Basin of Mula (Murcia), on terraced farmlands and abandoned about 40 years ago. Have been evaluated sediments mobilized by this process and erosion rates. The erosion rate per plot is 287 t/ha/year, undoubtedly, a very high value of soil losses. For this it is necessary soil conservation practices when these fields are abandoned.
Open Access
El uso de parámetros edáficos como indicadores de riesgo de erosión. Rambla de Las Moreras, Murcia, SE de España
(2020-03-30) Romero Díaz, María Asunción; Quiñonero Rubio, J.M; Ortiz Silla, R.; Sánchez Navarro, Antonio; Fernández-Delgado Juárez, M.; Gil Vazquez, J.M.; Departamento de Geografía, Universidad de Murcia, Campus de La Merced; Centro de Edafología y Biología Aplicada del Segura (CEBAS), CSIC; Departamento de Química Agrícola, Geología y Edafología, Universidad de Murcia
Uno de los factores que más interviene en la erosión del suelo es su erodibilidad, es decir, la vulnerabilidad que el suelo tenga a la erosión. En este trabajo se estudian varios parámetros (textura, estructura, materia orgánica, profundidad, pedregosidad y cobertura vegetal) en la cuenca de la Rambla de Las Moreras (Murcia) con el objetivo de determinar si algunos de ellos pudieran servir de indicadores de riesgo de erosión. Los resultados muestran como la materia orgánica y la estabilidad de agregados pueden ser buenos indicadores de ello.
Open Access
Evaluación y seguimiento multitemporal de la desertificación en Andalucía
(2020-03-30) Rodríguez Surián, M.; Moreira Madueño, J.M; Quijada Muñoz, J.; Corzo Toscano, M.; Gíl Giménez, Y.; Dirección General de Planificación e Información Ambiental. Consejería de Medio Ambiente.; Desarrollo de la Red de Información Ambiental de Andalucía.
Desertification, as a process of degradation caused by the confluence of certain arid or semiarid climatic conditions together with aggressive and barely sustainable human activities in the natural and productive environment, and also bearing in mind the current context of climate change, is an environmental phenomenon whose monitoring would seem to be advisable, both with regard to its evolution in recent years and in relation to the changes that the new climatic scenarios may determine, in order to prepare mitigation or enhancement strategies, and also to raise greater awareness of the approaching problems. The availability of historical information in a Geographic Information System referring to land uses and land cover and to climatic data, together with other environmental information (relief, soils, geology, environment management.....), as well as decade-by-decade climatic information on possible future change scenarios until 2100 in the Andalusian Environmental Information Network (REDIAM), has permitted, within the framework the European projects DesertNet I and DesertNet II, the development of models for diagnosing the areas affected by historical desertification processes and the areas of present and future incidence, while at the same time a common methodology is applied to the European context for the delimitation of degradation-sensitive areas. These models have been applied to the entire territory of Andalusia, providing a view of the temporal and spatial incidence of this phenomenon.
Open Access
An evaluation of the MEDALUS ESA index (environmental sensitivity to land degradation), from regional to plot scale
(2020-04-03) Lavado Contador, J. F; Schnabel, S; Gómez Gutiérrez, A.; Grupo de Investigación GeoAmbiental, Universidad de Extremadura
An assessment of the sensitivity to land degradation have been carried out for the region of Extremadura, SW Spain, by means of the modelling approach developed in the European Commission funded MEDALUS project (Mediterranean Desertification and Land Use) which identifies such areas on the basis of an index (ESA index) that incorporates data on environmental quality (climate, vegetation, soil) as well as on anthropogenic factors (management). Two maps of environmental sensitivity to degradation with different legend resolution (4 and 8 classes of sensitivity) have been made. The results of the model were validated at different spatial scales, i.e.; regional and farm scales. True field data on degradation-related variables at the different spatial scales have been used in order to undertake the validation procedures. Selected farms covering different physiographical and socioeconomic characteristics were used to gather data at farm scale. Data gathered from the National Inventory of Soil Erosion was also used to validate the model at the regional scale.
Open Access
African and local wind-blown dust contributions at three rural sites in SE Spain: the aerosol size distribution
(2020-04-03) Orza, J.A.G.; Cabello, M.; Lidón, V.; Martínez, J.; SCOLAb, Física Aplicada, Universidad Miguel Hernández; Aeolian Erosion Research Group, Universidad Miguel Hernández
The entrainment of particulate material into the atmosphere by wind action on surface soils both disturbed and natural, as well as directly due to human activities like agricultural practices, mineral industry operations, construction works and traffic, is a significant contribution to the aerosol load in Mediterranean semi-arid areas. A further crustal contribution in the region comes from the frequent arrival of African mineral dust plumes. We summarize some of the results obtained after 4-6 -month campaigns at three rural sites in SE Spain where the aerosol number size distribution (31 size bins between 0.25 and 32 μm) was continuously measured. The influence of both local wind speed and the arrival of air masses loaded with African dust on the airborne particulate distribution is assessed. Similarities and differences between the three locations give information that allows a better understanding of the influence of both local wind speed and African dust outbreaks (ADO), while highlight what is mostly related to local features.
Open Access
Aplicación de técnicas hiperespectrales de imagen al estudio de la degradación de suelos en ambientes áridos (Los Monegros, España)
(2020-04-03) Gumuzzio Such, A.; Palacios Orueta, A.; Schmid, T.; Dominguez, J.A.; Gumuzzio, J.; E.T.S.I Montes de Madrid. Departamento de Silvopascicultura, Ciudad Universitaria; CIEMAT, Departamento de Medioambiente, Avda. Complutense; Centro de Estudios Hidrográficos CEDEX; Departamento de Geología y Geoquímica. Universidad Autónoma de Madrid
The aim of this work is to identify characteristics associated to soils affected by degradation within an arid area of Spain using optical hyperspectral airborne data. The methodological approach was developed to determine the spatial distribution of selected soils affected by degradation processes. A satisfactory spatial distribution is obtained where the corresponding soil characteristics are closely related to degradation processes.
Open Access
Analysing the factors affecting gully development and their relationships with land-use changes in the east Alentejo (Portugal)
(2020-04-03) Roxo, M. J.; Calvo-Cases, A.; Departamento de Geografia e Planeamento Regional, Universidade Nova de Lisboa; Departament de Geografia, Universitat de Valencia
The land abandonment and land-use changes as a consequence of the implementation of the European Union Common Agricultural Policy (C.A.P.), in the SE of Portugal, have been generating, differences in the equilibrium of the geomorphic processes. The head waters catchments of some of the Guadiana River tributaries show in the study area several degrees of gully initiation and development both on the hillsides and valley bottom infill. This gully generation process is closely related with the changes in the soil and cover properties occurring when agricultural practises have been replaced by intensive grazing areas or by abandoned land. High resolution panchromatic and Landsat images, dating from the last 40 years have been analysed in combination with field observations and the analysis of the data from soil erosion plots series in the Estação Experimental de Vale Formoso, in order to establish and parameterise the sequence of changes in soil surface properties and vegetation cover and distribution. The results show the connection between the different degrees of gully development and their morphological characteristics with the land cover properties at different times and after different sequences of land-use changes
Open Access
Aportaciones de la teledetección y los SIG para la mejora de los modelos de evaluación de las pérdidas de suelo en Andalucía
(2020-04-03) Moreira Madueño, J.M.; Rodríguez Surián, M.; Ojeda Zújar, J.; Dirección General de Desarrollo Sostenible e Información Ambiental. Consejería de Medio Ambiente.; Departamento de Geografía Física y Análisis Geográfico Regional, Universidad de Sevilla,
The Regional Ministry of the Environment, through the Environmental Information Network (REDIAM), monitors the annual rate of land loss in Andalusia. This phenomenon, which is characterised by a high level of spatial and temporal variance, is particularly influenced by the amount and intensity of rainfall and land uses. The use of high and low resolution satellite images and regional ortophotographs has enabled continuous updating of information on plant cover and land uses, whilst the daily climate information from a network of automated weather and rainfall stations are used to generate monthly rain erosivity maps. This information on land loss is a useful tool for direct analysis or modelling, and provides the basis for identifying and implementing preventive and corrective actions enshrined in the various strategic plans developed by this agency.
Open Access
Agua y agricultura en sistemas áridos: un modelo dinámico del regadío de Mazarrón y Águilas
(2020-04-03) Martínez Fernández, j.; Esteve Selma, Miguel A.; Departamento de Ecología e Hidrología. Universidad de Murcia; Departamento de Ecología e Hidrología. Universidad de Murcia
The intensive use of groundwater resources in the new irrigated lands of Mazarron-Aguilas has led to the over-exploitation of the local aquifers and thus, to seawater intrusion, water salinization and falling off water tables, all of them key processes of desertification. The simulation results show that the unrealistic perceptions about the relationships between irrigated land and water resources constitutes a key factor to explain the highly unsustainable dynamics of irrigated lands in Mazarrón and Aguilas and the whole SE Spain. The increase in water resources does not eliminate the problem because the feedback loops and endogenous factors of the system lead to a further increase in irrigated land and continuation of the water deficit, which shows a highly counter-intuitive behaviour.
Open Access
A procedure to derive intra- and inter-annual changes on vegetation from NDVI time series. A case study in Spain.
(2020-04-03) Gilabert, M.A.; Martínez, B.; Meliá, J.; Departament de Física de la Terra i Termodinàmica, Universitat de València.
The NDVI time series are characterized by patterns like seasonality, trends and localized abrupt changes or discontinuities resulting from disturbance events. Therefore, they allow us to characterize vegetation dynamics on the basis of different temporal scales. In particular, the subtle, long-term changes convey relevant information on land degradation. The objective of this work is to study the spatial patterns of vegetation activity over Spain and its temporal variability throughout the period 1989-2002. A multi-resolution analysis (MRA) based on the wavelet transform has been implemented on NDVI time series from the MEDOKADS database. The MRA decomposes the original signal as a sum of series associated with different temporal scales. Specifically, the intra-annual series is processed to define several key features in relation with the vegetation phenology. In contrast, the interannual component of the signal is used to detect trends by means of a Mann-Kendall test and map the magnitude of the land-cover change. Finally, a comprehensive identification of the areas presenting a negative value of the magnitude of change is carried out to select those linked to land degradation processes. Results show a major presence of these areas the Southeast of Spain.
Open Access
Abandonment terraced hillside and answer of the fire system: some results from Mediterranean old fields
(2020-04-03) Llovet López, J.; Ruiz Valera, M.; Josa March, R.; Vallejo Calzada, V.R.; Fundación CEAM, Departament d’Ecologia (CEAM); Departament d’Enginyeria Agroalimentària i Biotecnologia
The abandonment of agricultural lands promotes temporal changes both in soil characteristics (i.e., increasing organic matter and other quality indicators) and in plant community (i.e., changing its composition and structure, and increasing the fuel load). As a consequence, we can expect differences in the resilience to fire as succession progresses. The aim of this work is to analyse the capacity of an ecosystem to return to pre-fire conditions as a function of the stage of abandonment of old agricultural lands. The study was carried out in the north of Alicante province (E Spain). In long-term abandoned lands, post-fire rainfall modulated plant response, which in turn determined soil crusting, runoff and erosion dynamics. In recently-abandoned lands, the plant community seemed less dependent on rain to recover. Results show a large increase in soil surface crusting in the short term after the fire and it remained high at medium term in long-abandoned lands colonised by pine forest. Fire scarcely modified runoff and erosion in recently-abandoned lands whereas in forest lands the post-fire values increased by some orders of magnitude and remained highly dependent on rain characteristics in the short and medium term after the fire. The results obtained show evidences of increased vulnerability to fire in long-abandoned lands colonised by pine forests
Open Access
Aportaciones de la palinología en la reconstrucción del impacto ganadero, en los alrededores de Rascafría (Madrid), durante el Holoceno reciente
(2020-04-03) Gómez González, C.; Ruiz Zapata, M.B.; López-Saez, J.A.; Gil Garcia, M.J.; Departamento de Geología, Universidad de Alcalá,; Laboratorio de Arqueobotánica, Departamento de Historia CSIC
We present the results obtained from the palaeoecological studies about human impact on the vegetal landscape of a peatbog located in Rascafría (Lozoya Valley, Madrid, Central Spain). Palynomorph analysis allows to identify the kind and intensity of human activity and its relation to the trophic changes in the peatbog during the late Holocene (2455±35 BP). Pollen record reveals an anthropic Mediterranean landscape mainly composed by pastures used for grazing. Non Pollen Palynomorphs (NPP) and pH and conductivity sediment have revealed as useful tools for detection of trophic conditions and land use changes.
Open Access
Análisis espacio-temporal de los cambios de usos del suelo en la Cuenca del Río Segura
(2020-04-03) Alonso Sarriá, Francisco; Gomariz Castillo, Francisco; Cánovas García, F.; Moreno Brotóns, J.; Instituto del Agua y Medio Ambiente, Universidad de Murcia, Campus de Espinardo
Land use change is a dynamic process that affects heavily to different environmental processes. In this work, a GIS application is designed to analyse land use changes from landsat imagery since 1976 to 2007, a period with important socioeconomic and land use changes in River Segura Basin. This work describes the methodology used to obtain a yearly series of land cover maps of the Demarcación Hidrográfica del Segura (River Segura basin in South East Spain). In order to analyze this great amount of information for a large (more than 18,000 km2) and heterogeneous area, a unified methodology has been developed. It has been used a supervised classification improved by a previous not supervised classification using both spectral (4 or 6 landsat solar spectrum bands depending on the sensor available, MSS or TM, ETM) and two textural variables. The last ones were obtained estimating the semivariogram frunction from the albedo and NDVI layers. Having used two images from different seasons, the total number of variables included in the classification is 12 or 16 depending on the year. Preliminary results show a reduction of the surfaces with traditional dry crop uses and the important increase of irrigation lands during the first half of the 1980s decade. The increase in bare soil areas also reflects the abandonment of traditional crops. Finally, it has been observed an increase in urban areas attributable to demographic trends.
Open Access
Relaciones agua-suelo-vegetación.-Efficiency assessment of runoff harvesting techniques using a 3D coupled surface-subsurface hydrological model
Verbist, K.; Cornelis, W.M.; McLaren, R.; Gabriels, D.; Soto, G.; Universidad de Murcia
ABSTRACT In arid and semi-arid zones runoff harvesting techniques are often applied to increase the water retention and infiltration on steep slopes. Additionally, they act as an erosion control measure to reduce land degradation hazards. Both in literature and in the field, a large variety of runoff collecting systems are found, as well as large variations in design and dimensions. Therefore, detailed measurements were performed on a semi-arid slope in central Chile to allow identification of the effect of a simple water harvesting technique on soil water availability. For this purpose, twenty two TDR-probes were installed and were monitored continuously during and after a simulated rainfall event. These data were used to calibrate the 3D distributed flow model HydroGeoSphere, to assess the runoff components and soil water retention as influenced by the water harvesting technique, both under simulated and natural rainfall conditions. Preliminary results show important design flaws that do not take into account local soil and climatic conditions adequately, resulting in a low water harvesting efficiency. The proposed methodology can be used to improve the design of water harvesting techniques, to optimally apply scarce financial sources in order to obtain maximal efficiency from runoff harvesting techniques in semi-arid regions.lengua.es
Open Access
Morfología Fluvial.-Morpholgical change in a stream channel as consequence of the fluvial dynamics (Vallcebre)
Soler, M.; Nord, G.; Latron, J.; Gallart, F.; Universidad de Murcia
ABSTRACT This study shows the morpholgical changes observed in a stream channel as consequence of the fluvial dynamics in an experimental research basin (Vallcebre,Eastern Pyrenees). Three cross sections were surveyed along a 100 metres distance near the basin outlet. The cross sections were measured 21 times from 2003 to 2008. Along the study period, higher deposition rates were observed in summer whereas higher erosion rates were observed in April. Considering the whole period, an average resulting deposition of 7 cm has been measured. At the flood scale, correlation analysis, revealed weak correlations between the magnitude of the changes in the stream bed and the main hydrometeorological variables
Open Access
Erosión y desertificación.-Environmental risks associated to wind erosion in a metal mining area from SE Spain
Garcia Fernández, G.; Romero Díaz, A.; Universidad de Murcia
ABSTRACT Soils and mining wastes from the Mediterranean mining area placed in the Sierra Minera Mountains are highly enriched in heavy metals such as lead and zinc, but also other metals such as cadmium and arsenic. Wind erosion in this area could be considered extremely high and hazards associated to this eroded sediments seems to be high because the huge amount of metals present in this wastes. Therefore, combination of high erosion rates and high metal concentration in this mining waste, make those environmental risks can be considered high for the surrounding ecosystems, but also for public health of the nearby villages and towns. In order, to study these wind erosion processes over these mining materials, some experiments for the evaluation of the transportation of soil particles were carried out. Erosion rates in this realm is particularly important during spring months, when increased activity of the eastern winds brings intense soil dragging, with strong effects on the metals dispersion, including the massive removal of sediments.
Open Access
Relaciones agua-suelo-vegetación.-Evaluation of two methods for measuring saturated hydraulic conductivity of soils under two vegetation covers
Rubio, C.M.; Josa, R.; Poyatos, R.; Llorens, P.; Gallart, F.; Latron, J.; Ferrer, F.
ABSTRACT The main goal of this work is to determine and to evaluate the saturated hydraulic conductivity for a silt loam soil in field and laboratory conditions. The experimental area was located in the Vallcebre research catchments, in headwaters of the Llobregat River (NE Spain). Hydraulic conductivity was measured in the field using the Guelph permeameter and field saturated hydraulic conductivity (Kfs) based on Elrick equation was calculated. The Guelph permeameter measures were made in two conditions (dry and wet) and in profiles below two vegetation covers (meadows and forest). To determine the saturated hydraulic conductivity at the laboratory (Ks) the constant head permeameter was used. The average Kfs values for the wet period was about 2 cm·h-1. During the dry period, both soil profiles presented higher values, about 7.5 cm·h-1. Under laboratory conditions, mean observed Ks values were between 12 and 25 cm·h-1. The relationship Kfs/Ks was of 0.1 cm·h-1 in wet conditions and about 0.4 cm·h-1 in dry conditions. The results indicated significant differences between both methods and between both seasons. Differences can be explained by the anisotropy of soils as a consequence of vegetation root system that promotes preferential flows paths.
Open Access
Erosión y desertificación.-Mecanismos de erosión en arcillas miocenas de la Formación Tudela (Bardenas Reales, Navarra, España)
Marín, C.; Desir, G.; Universidad de Murcia
ABSTRACT In Bardenas Reales area (located in the central-western part of the Ebro Depression) several erosion rates have been measured along the last years. The mean annual erosion rates are of 32 Tm/Ha/yr. Due to semiarid conditions, precipitation is irregularly distributed along the year with maximums on spring and autumn when the great erosion is produced. There are intensity and quantity thresholds below which erosion does not take place. In Bardenas Reales some erosion processes act (mudslides and armoured mud balls among others). Mudslides are mobilised on spring when the sediment have reached its plastic limit and could slide due to heavy rains. Armored mud balls are produced by the enhancement of popcorn cracks that individualize clays cores which are rounded by water. The same kind of strong precipitation that mobilised mudslides is the responsible of armoured mud ball’s destruction because the conditions to its maintenance are very limited.
Open Access
Erosión y desertificación.-Characteristics and distribution of soil piping erosion in loess-derived soils of Belgium
Verachtert, Els; Van Den Eeckhaut, Miet; Poesen, Jean; Deckers, Seppe; Universidad de Murcia
ABSTRACT Subsurface erosion (piping, tunnel erosion) in non-karstic landscapes has been considered of little importance compared to sheet and gully erosion for a long time. Although the basic factors responsible for piping in certain environments are well understood, there is still uncertainty about the topographic and soil properties inducing subsurface pipe development in loess-derived soils under temperate climate. Therefore, this research aims at understanding the factors controlling the occurrence of piping erosion in the loess-derived soils of the Flemish Ardennes (Belgium). Analysis of orthophotos as well as field surveys were conducted to detect the sites with piping in the study area. Enquiries among farmers and technical services were carried out. In total, 114 sites (parcels) with 301 collapsed soil pipes were found in a 179 km² study area. For each site with piping, data was collected on possible controlling factors: topographic parameters, land use, lithology and soil type. Land use plays an important role as 94% of the sites with piping are found under pasture. Furthermore, the probability of piping increases rapidly on slopes with gradients exceeding 8%. The areas with the Aalbeke Member, a relatively thin layer of homogenous blue massive clays, under the shallow loess cover are most prone to piping. Over 28% of the sites with piping are located on this lithologic layer, while this layer covers only 8% of the study area. The rest of the sites with piping are located on two lithologic layers containing clay as well as silt and sand.
Open Access
Relaciones agua-suelo-vegetación.-Incidencia del stress hídrico en las relaciones suelo-agua-planta a lo largo de un gradiente pluviométrico en el sur de España
Ruiz-Sinoga, J.D.; Ferre Bueno, E.; Martínez-Murillo, J.F.; Martínez-Murillo, M.A.; Universidad de Murcia
ABSTRACT The Andalusian Mediterranean Watershed, in the South of the Iberian Peninsula, shows a climatic gradient from the Straits of Gibraltar (1,600 mm year-1) to the Cabo de Gata (150 mm year-1). Climate conditions differences are translating into variations in the elements of the eco-geomorphological system at hillslope scale. In this study has been analysed the immediate consequences of a period of two years drought (2004-06) on several elements of the Mediterranean eco-geomorphological system at three hillslopes (sub-humid, dry Mediterranean and semi-arid). The soil water content, the pattern of vegetation and some soil properties (organic matter content, aggregate stability and permeability) were analysed before (Nov-2003) and during (Nov-2005) the drought period. Final results have shown: i) reduction in soil water content which reached in the wet seasons values below wilting point, affecting negatively to the water available for vegetation and especially in the wettest sites; ii) reduction in vegetation cover and in the number of plants, especially at semi-arid field site; iii) changes in the organic matter content which aggravates the loss of stability of soil aggregates, a process seen more clearly under more arid conditions; and iv) reduction of soil permeability in all situations in the climate gradient studied, which supposes a priori an increase in erosive processes due to surface runoff. These results indicate increased vulnerability of the eco-geomorphological system because of the rainfall drought situation.

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